polyglot_sql/

parser.rs

//! SQL Parser -- recursive-descent parser that converts a token stream into an AST.
//!
//! The central type is [`Parser`], which consumes tokens produced by the
//! [`Tokenizer`](crate::tokens::Tokenizer) and builds a tree of [`Expression`]
//! nodes covering the full SQL grammar: queries, DML, DDL, set operations,
//! window functions, CTEs, and dialect-specific extensions for 30+ databases.
//!
//! The simplest entry point is [`Parser::parse_sql`], which tokenizes and
//! parses a SQL string in one call.
//!
//! # Static configuration maps
//!
//! This module also exports several `LazyLock<HashSet<TokenType>>` constants
//! (ported from Python sqlglot's `parser.py`) that classify token types:
//!
//! - [`TYPE_TOKENS`] -- all tokens that represent SQL data types
//! - [`NESTED_TYPE_TOKENS`] -- parametric types like `ARRAY`, `MAP`, `STRUCT`
//! - [`RESERVED_TOKENS`] -- tokens that cannot be used as unquoted identifiers
//! - [`NO_PAREN_FUNCTIONS`] / [`NO_PAREN_FUNCTION_NAMES`] -- zero-argument
//!   functions that may be written without parentheses (e.g. `CURRENT_DATE`)
//! - [`DB_CREATABLES`] -- object kinds valid after `CREATE` (TABLE, VIEW, etc.)
//! - [`SUBQUERY_PREDICATES`] -- tokens introducing subquery predicates (ANY, ALL, EXISTS)

use crate::error::{Error, Result};
use crate::expressions::*;
use crate::tokens::{Span, Token, TokenType, Tokenizer, TokenizerConfig};
use std::collections::HashSet;
use std::sync::LazyLock;

// =============================================================================
// Parser Configuration Maps (ported from Python SQLGlot parser.py)
// =============================================================================

/// NO_PAREN_FUNCTIONS: Functions that can be called without parentheses
/// Maps TokenType to the function name for generation
/// Python: NO_PAREN_FUNCTIONS = {TokenType.CURRENT_DATE: exp.CurrentDate, ...}
pub static NO_PAREN_FUNCTIONS: LazyLock<HashSet<TokenType>> = LazyLock::new(|| {
    let mut set = HashSet::new();
    set.insert(TokenType::CurrentDate);
    set.insert(TokenType::CurrentDateTime);
    set.insert(TokenType::CurrentTime);
    set.insert(TokenType::CurrentTimestamp);
    set.insert(TokenType::CurrentUser);
    set.insert(TokenType::CurrentRole);
    set.insert(TokenType::CurrentSchema);
    set.insert(TokenType::CurrentCatalog);
    // Additional no-paren functions (from tokens.rs)
    set.insert(TokenType::LocalTime);
    set.insert(TokenType::LocalTimestamp);
    set.insert(TokenType::SysTimestamp);
    set.insert(TokenType::UtcDate);
    set.insert(TokenType::UtcTime);
    set.insert(TokenType::UtcTimestamp);
    set.insert(TokenType::SessionUser);
    set
});

/// NO_PAREN_FUNCTION_NAMES: String names that can be no-paren functions
/// These are often tokenized as Var/Identifier instead of specific TokenTypes
pub static NO_PAREN_FUNCTION_NAMES: LazyLock<HashSet<&'static str>> = LazyLock::new(|| {
    crate::function_registry::NO_PAREN_FUNCTION_NAME_LIST
        .iter()
        .copied()
        .collect()
});

/// STRUCT_TYPE_TOKENS: Tokens that represent struct-like types
/// Python: STRUCT_TYPE_TOKENS = {TokenType.FILE, TokenType.NESTED, TokenType.OBJECT, ...}
pub static STRUCT_TYPE_TOKENS: LazyLock<HashSet<TokenType>> = LazyLock::new(|| {
    let mut set = HashSet::new();
    set.insert(TokenType::File);
    set.insert(TokenType::Nested);
    set.insert(TokenType::Object);
    set.insert(TokenType::Struct);
    // Note: UNION is part of STRUCT_TYPE_TOKENS in Python but we handle it as a set operation
    set
});

/// NESTED_TYPE_TOKENS: Tokens that can have nested type parameters
/// Python: NESTED_TYPE_TOKENS = {TokenType.ARRAY, TokenType.LIST, ...}
pub static NESTED_TYPE_TOKENS: LazyLock<HashSet<TokenType>> = LazyLock::new(|| {
    let mut set = HashSet::new();
    set.insert(TokenType::Array);
    set.insert(TokenType::List);
    set.insert(TokenType::LowCardinality);
    set.insert(TokenType::Map);
    set.insert(TokenType::Nullable);
    set.insert(TokenType::Range);
    // Include STRUCT_TYPE_TOKENS
    set.insert(TokenType::File);
    set.insert(TokenType::Nested);
    set.insert(TokenType::Object);
    set.insert(TokenType::Struct);
    set
});

/// Check if an uppercased type name is a known SQL custom type that should stay uppercased.
/// Used to distinguish between known types like DATETIME2, SYSNAME etc. and user-defined types
/// like UserDefinedTableType that should preserve their original case.
fn convert_name_is_known_custom(name: &str) -> bool {
    // Known SQL types that appear in the _ (default) branch of parse_data_type
    // These should remain uppercased.
    matches!(
        name,
        "DATETIME2"
            | "DATETIMEOFFSET"
            | "SMALLDATETIME"
            | "DATETIME"
            | "NVARCHAR2"
            | "VARCHAR2"
            | "NCHAR"
            | "MONEY"
            | "SMALLMONEY"
            | "TINYINT"
            | "MEDIUMINT"
            | "BYTEINT"
            | "SUPER"
            | "HLLSKETCH"
            | "TIMETZ"
            | "TIMESTAMPTZ"
            | "SYSNAME"
            | "XML"
            | "SQL_VARIANT"
            | "HIERARCHYID"
            | "ROWVERSION"
            | "IMAGE"
            | "CURSOR"
            | "TABLE"
            | "UNIQUEIDENTIFIER"
            | "VARIANT"
            | "OBJECT"
            | "NUMBER"
            | "BINARY_FLOAT"
            | "BINARY_DOUBLE"
            | "CLOB"
            | "NCLOB"
            | "RAW"
            | "LONG"
            | "MEDIUMTEXT"
            | "LONGTEXT"
            | "MEDIUMBLOB"
            | "LONGBLOB"
            | "TINYTEXT"
            | "TINYBLOB"
            | "INT2"
            | "INT4"
            | "INT8"
            | "FLOAT4"
            | "FLOAT8"
            | "SERIAL"
            | "BIGSERIAL"
            | "SMALLSERIAL"
            | "YEAR"
            | "FIXED"
            | "SIGNED"
            | "UNSIGNED"
            | "ROW"
            | "BIT"
            | "BOOLEAN"
            | "BOOL"
            | "TEXT"
            | "STRING"
            | "NTEXT"
            | "INT128"
            | "INT256"
            | "UINT8"
            | "UINT16"
            | "UINT32"
            | "UINT64"
            | "UINT128"
            | "UINT256"
            | "FLOAT32"
            | "FLOAT64"
            | "LOWCARDINALITY"
            | "NULLABLE"
            | "IPADDRESS"
            | "IPV4"
            | "IPV6"
            | "AGGREGATEFUNCTION"
            | "SIMPLEAGGREGATEFUNCTION"
            | "FIXEDSTRING"
            | "RING"
            | "NESTED"
    )
}

/// ENUM_TYPE_TOKENS: Tokens that represent enum types
/// Python: ENUM_TYPE_TOKENS = {TokenType.DYNAMIC, TokenType.ENUM, ...}
pub static ENUM_TYPE_TOKENS: LazyLock<HashSet<TokenType>> = LazyLock::new(|| {
    let mut set = HashSet::new();
    set.insert(TokenType::Dynamic);
    set.insert(TokenType::Enum);
    set.insert(TokenType::Enum8);
    set.insert(TokenType::Enum16);
    set
});

/// AGGREGATE_TYPE_TOKENS: Tokens for aggregate function types (ClickHouse)
/// Python: AGGREGATE_TYPE_TOKENS = {TokenType.AGGREGATEFUNCTION, ...}
pub static AGGREGATE_TYPE_TOKENS: LazyLock<HashSet<TokenType>> = LazyLock::new(|| {
    let mut set = HashSet::new();
    set.insert(TokenType::AggregateFunction);
    set.insert(TokenType::SimpleAggregateFunction);
    set
});

/// TYPE_TOKENS: All tokens that represent data types
/// Python: TYPE_TOKENS = {TokenType.BIT, TokenType.BOOLEAN, ...}
pub static TYPE_TOKENS: LazyLock<HashSet<TokenType>> = LazyLock::new(|| {
    let mut set = HashSet::new();
    // Basic types
    set.insert(TokenType::Bit);
    set.insert(TokenType::Boolean);
    // Integer types
    set.insert(TokenType::TinyInt);
    set.insert(TokenType::UTinyInt);
    set.insert(TokenType::SmallInt);
    set.insert(TokenType::USmallInt);
    set.insert(TokenType::MediumInt);
    set.insert(TokenType::UMediumInt);
    set.insert(TokenType::Int);
    set.insert(TokenType::UInt);
    set.insert(TokenType::BigInt);
    set.insert(TokenType::UBigInt);
    set.insert(TokenType::BigNum);
    set.insert(TokenType::Int128);
    set.insert(TokenType::UInt128);
    set.insert(TokenType::Int256);
    set.insert(TokenType::UInt256);
    // Floating point types
    set.insert(TokenType::Float);
    set.insert(TokenType::Double);
    set.insert(TokenType::UDouble);
    // Decimal types
    set.insert(TokenType::Decimal);
    set.insert(TokenType::Decimal32);
    set.insert(TokenType::Decimal64);
    set.insert(TokenType::Decimal128);
    set.insert(TokenType::Decimal256);
    set.insert(TokenType::DecFloat);
    set.insert(TokenType::UDecimal);
    set.insert(TokenType::BigDecimal);
    // String types
    set.insert(TokenType::Char);
    set.insert(TokenType::NChar);
    set.insert(TokenType::VarChar);
    set.insert(TokenType::NVarChar);
    set.insert(TokenType::BpChar);
    set.insert(TokenType::Text);
    set.insert(TokenType::MediumText);
    set.insert(TokenType::LongText);
    set.insert(TokenType::TinyText);
    set.insert(TokenType::Name);
    set.insert(TokenType::FixedString);
    // Binary types
    set.insert(TokenType::Binary);
    set.insert(TokenType::VarBinary);
    set.insert(TokenType::Blob);
    set.insert(TokenType::MediumBlob);
    set.insert(TokenType::LongBlob);
    set.insert(TokenType::TinyBlob);
    // Date/time types
    set.insert(TokenType::Date);
    set.insert(TokenType::Date32);
    set.insert(TokenType::Time);
    set.insert(TokenType::TimeTz);
    set.insert(TokenType::TimeNs);
    set.insert(TokenType::Timestamp);
    set.insert(TokenType::TimestampTz);
    set.insert(TokenType::TimestampLtz);
    set.insert(TokenType::TimestampNtz);
    set.insert(TokenType::TimestampS);
    set.insert(TokenType::TimestampMs);
    set.insert(TokenType::TimestampNs);
    set.insert(TokenType::DateTime);
    set.insert(TokenType::DateTime2);
    set.insert(TokenType::DateTime64);
    set.insert(TokenType::SmallDateTime);
    set.insert(TokenType::Year);
    set.insert(TokenType::Interval);
    // JSON types
    set.insert(TokenType::Json);
    set.insert(TokenType::JsonB);
    // UUID
    set.insert(TokenType::Uuid);
    // Spatial types
    set.insert(TokenType::Geography);
    set.insert(TokenType::GeographyPoint);
    set.insert(TokenType::Geometry);
    set.insert(TokenType::Point);
    set.insert(TokenType::Ring);
    set.insert(TokenType::LineString);
    set.insert(TokenType::MultiLineString);
    set.insert(TokenType::Polygon);
    set.insert(TokenType::MultiPolygon);
    // Range types (PostgreSQL)
    set.insert(TokenType::Int4Range);
    set.insert(TokenType::Int4MultiRange);
    set.insert(TokenType::Int8Range);
    set.insert(TokenType::Int8MultiRange);
    set.insert(TokenType::NumRange);
    set.insert(TokenType::NumMultiRange);
    set.insert(TokenType::TsRange);
    set.insert(TokenType::TsMultiRange);
    set.insert(TokenType::TsTzRange);
    set.insert(TokenType::TsTzMultiRange);
    set.insert(TokenType::DateRange);
    set.insert(TokenType::DateMultiRange);
    // PostgreSQL special types
    set.insert(TokenType::HllSketch);
    set.insert(TokenType::HStore);
    set.insert(TokenType::Serial);
    set.insert(TokenType::SmallSerial);
    set.insert(TokenType::BigSerial);
    // XML
    set.insert(TokenType::Xml);
    // Other special types
    set.insert(TokenType::Super);
    set.insert(TokenType::PseudoType);
    set.insert(TokenType::UserDefined);
    set.insert(TokenType::Money);
    set.insert(TokenType::SmallMoney);
    set.insert(TokenType::RowVersion);
    set.insert(TokenType::Image);
    set.insert(TokenType::Variant);
    set.insert(TokenType::Object);
    set.insert(TokenType::ObjectIdentifier);
    set.insert(TokenType::Inet);
    set.insert(TokenType::IpAddress);
    set.insert(TokenType::IpPrefix);
    set.insert(TokenType::Ipv4);
    set.insert(TokenType::Ipv6);
    set.insert(TokenType::Unknown);
    set.insert(TokenType::Null);
    set.insert(TokenType::TDigest);
    set.insert(TokenType::Vector);
    set.insert(TokenType::Void);
    // Include ENUM_TYPE_TOKENS
    set.insert(TokenType::Dynamic);
    set.insert(TokenType::Enum);
    set.insert(TokenType::Enum8);
    set.insert(TokenType::Enum16);
    // Include NESTED_TYPE_TOKENS
    set.insert(TokenType::Array);
    set.insert(TokenType::List);
    set.insert(TokenType::LowCardinality);
    set.insert(TokenType::Map);
    set.insert(TokenType::Nullable);
    set.insert(TokenType::Range);
    set.insert(TokenType::File);
    set.insert(TokenType::Nested);
    set.insert(TokenType::Struct);
    // Include AGGREGATE_TYPE_TOKENS
    set.insert(TokenType::AggregateFunction);
    set.insert(TokenType::SimpleAggregateFunction);
    set
});

/// SIGNED_TO_UNSIGNED_TYPE_TOKEN: Maps signed types to unsigned types
/// Python: SIGNED_TO_UNSIGNED_TYPE_TOKEN = {TokenType.BIGINT: TokenType.UBIGINT, ...}
pub static SIGNED_TO_UNSIGNED_TYPE_TOKEN: LazyLock<
    std::collections::HashMap<TokenType, TokenType>,
> = LazyLock::new(|| {
    let mut map = std::collections::HashMap::new();
    map.insert(TokenType::BigInt, TokenType::UBigInt);
    map.insert(TokenType::Int, TokenType::UInt);
    map.insert(TokenType::MediumInt, TokenType::UMediumInt);
    map.insert(TokenType::SmallInt, TokenType::USmallInt);
    map.insert(TokenType::TinyInt, TokenType::UTinyInt);
    map.insert(TokenType::Decimal, TokenType::UDecimal);
    map.insert(TokenType::Double, TokenType::UDouble);
    map
});

/// SUBQUERY_PREDICATES: Tokens that introduce subquery predicates
/// Python: SUBQUERY_PREDICATES = {TokenType.ANY: exp.Any, ...}
pub static SUBQUERY_PREDICATES: LazyLock<HashSet<TokenType>> = LazyLock::new(|| {
    let mut set = HashSet::new();
    set.insert(TokenType::Any);
    set.insert(TokenType::All);
    set.insert(TokenType::Exists);
    set.insert(TokenType::Some);
    set
});

/// DB_CREATABLES: Object types that can be created with CREATE
/// Python: DB_CREATABLES = {TokenType.DATABASE, TokenType.SCHEMA, ...}
pub static DB_CREATABLES: LazyLock<HashSet<TokenType>> = LazyLock::new(|| {
    let mut set = HashSet::new();
    set.insert(TokenType::Database);
    set.insert(TokenType::Dictionary);
    set.insert(TokenType::FileFormat);
    set.insert(TokenType::Model);
    set.insert(TokenType::Namespace);
    set.insert(TokenType::Schema);
    set.insert(TokenType::SemanticView);
    set.insert(TokenType::Sequence);
    set.insert(TokenType::Sink);
    set.insert(TokenType::Source);
    set.insert(TokenType::Stage);
    set.insert(TokenType::StorageIntegration);
    set.insert(TokenType::Streamlit);
    set.insert(TokenType::Table);
    set.insert(TokenType::Tag);
    set.insert(TokenType::View);
    set.insert(TokenType::Warehouse);
    set
});

/// RESERVED_TOKENS: Tokens that cannot be used as identifiers without quoting
/// These are typically structural keywords that affect query parsing
pub static RESERVED_TOKENS: LazyLock<HashSet<TokenType>> = LazyLock::new(|| {
    let mut set = HashSet::new();
    // Query structure keywords
    set.insert(TokenType::Select);
    set.insert(TokenType::From);
    set.insert(TokenType::Where);
    set.insert(TokenType::GroupBy);
    set.insert(TokenType::OrderBy);
    set.insert(TokenType::Having);
    set.insert(TokenType::Limit);
    set.insert(TokenType::Offset);
    set.insert(TokenType::Union);
    set.insert(TokenType::Intersect);
    set.insert(TokenType::Except);
    set.insert(TokenType::Join);
    set.insert(TokenType::On);
    set.insert(TokenType::With);
    set.insert(TokenType::Into);
    set.insert(TokenType::Values);
    set.insert(TokenType::Set);
    // DDL keywords
    set.insert(TokenType::Create);
    set.insert(TokenType::Drop);
    set.insert(TokenType::Alter);
    set.insert(TokenType::Truncate);
    // DML keywords
    set.insert(TokenType::Insert);
    set.insert(TokenType::Update);
    set.insert(TokenType::Delete);
    set.insert(TokenType::Merge);
    // Control flow
    set.insert(TokenType::Case);
    set.insert(TokenType::When);
    set.insert(TokenType::Then);
    set.insert(TokenType::Else);
    set.insert(TokenType::End);
    // Boolean operators
    set.insert(TokenType::And);
    set.insert(TokenType::Or);
    set.insert(TokenType::Not);
    // Comparison
    set.insert(TokenType::In);
    set.insert(TokenType::Is);
    set.insert(TokenType::Between);
    set.insert(TokenType::Like);
    set.insert(TokenType::ILike);
    set.insert(TokenType::Exists);
    // Literals
    set.insert(TokenType::Null);
    set.insert(TokenType::True);
    set.insert(TokenType::False);
    // Punctuation tokens (these are always reserved)
    set.insert(TokenType::LParen);
    set.insert(TokenType::RParen);
    set.insert(TokenType::LBracket);
    set.insert(TokenType::RBracket);
    set.insert(TokenType::LBrace);
    set.insert(TokenType::RBrace);
    set.insert(TokenType::Comma);
    set.insert(TokenType::Semicolon);
    set.insert(TokenType::Star);
    set.insert(TokenType::Eq);
    set.insert(TokenType::Neq);
    set.insert(TokenType::Lt);
    set.insert(TokenType::Lte);
    set.insert(TokenType::Gt);
    set.insert(TokenType::Gte);
    set
});

// Note: Function name normalization is handled directly in parse_typed_function
// by matching all aliases to the same typed expression, following Python SQLGlot's pattern.
// The generator then outputs dialect-specific names via TRANSFORMS.

/// Recursive-descent SQL parser that converts a token stream into an AST.
///
/// The parser consumes a `Vec<Token>` produced by the [`Tokenizer`](crate::tokens::Tokenizer)
/// and builds a tree of [`Expression`] nodes. It supports the full SQL grammar
/// including SELECT, DML (INSERT/UPDATE/DELETE/MERGE), DDL (CREATE/ALTER/DROP),
/// window functions, CTEs, set operations, and 30+ dialect-specific extensions.
///
/// # Quick start
///
/// For most use cases the static helper [`Parser::parse_sql`] is the simplest entry point:
///
/// ```rust,ignore
/// use polyglot_sql::parser::Parser;
///
/// let statements = Parser::parse_sql("SELECT 1; SELECT 2")?;
/// assert_eq!(statements.len(), 2);
/// ```
///
/// For dialect-aware parsing, use [`Parser::with_config`] or
/// [`Parser::parse_sql_with_config`].
pub struct Parser {
    tokens: Vec<Token>,
    current: usize,
    config: ParserConfig,
    /// Original source SQL (used for preserving exact text in Command expressions)
    source: Option<String>,
    /// Comments captured by parse_comparison when no comparison operator follows.
    /// These are leading comments from the first token of an expression that need
    /// to be placed by the caller (e.g., after an alias, or after an AND operand).
    pending_leading_comments: Vec<String>,
}

/// Configuration for the SQL [`Parser`].
///
/// Controls dialect-specific parsing behavior. Most users can rely on the
/// `Default` implementation; set `dialect` when you need to handle syntax
/// that is unique to a particular database engine (e.g. BigQuery backtick
/// quoting, TSQL square-bracket identifiers, Snowflake QUALIFY clause).
#[derive(Debug, Clone, Default)]
pub struct ParserConfig {
    /// Allow trailing commas in SELECT lists (e.g. BigQuery permits `SELECT a, b, FROM t`).
    pub allow_trailing_commas: bool,
    /// Dialect type for dialect-specific parsing behavior.
    pub dialect: Option<crate::dialects::DialectType>,
}

impl Parser {
    /// Create a new parser from a pre-tokenized token stream with default configuration.
    ///
    /// Prefer [`Parser::parse_sql`] if you are starting from a raw SQL string.
    pub fn new(tokens: Vec<Token>) -> Self {
        Self {
            tokens,
            current: 0,
            config: ParserConfig::default(),
            source: None,
            pending_leading_comments: Vec::new(),
        }
    }

    /// Create a parser from a pre-tokenized token stream with a custom [`ParserConfig`].
    pub fn with_config(tokens: Vec<Token>, config: ParserConfig) -> Self {
        Self {
            tokens,
            current: 0,
            config,
            source: None,
            pending_leading_comments: Vec::new(),
        }
    }

    /// Create a parser with source SQL attached.
    ///
    /// The original SQL text is stored so that `Command` expressions (unparsed
    /// dialect-specific statements) can preserve the exact source verbatim.
    pub fn with_source(tokens: Vec<Token>, config: ParserConfig, source: String) -> Self {
        Self {
            tokens,
            current: 0,
            config,
            source: Some(source),
            pending_leading_comments: Vec::new(),
        }
    }

    /// Parse one or more SQL statements from a raw string.
    ///
    /// This is the main entry point for most callers. It tokenizes the input with
    /// the default [`TokenizerConfig`], then parses all semicolon-separated
    /// statements and returns them as a `Vec<Expression>`.
    ///
    /// # Errors
    ///
    /// Returns an error if the input contains invalid tokens or syntax that the
    /// parser cannot recognize.
    ///
    /// # Example
    ///
    /// ```rust,ignore
    /// let stmts = Parser::parse_sql("SELECT a FROM t WHERE x = 1")?;
    /// ```
    pub fn parse_sql(sql: &str) -> Result<Vec<Expression>> {
        let tokenizer = Tokenizer::default();
        let tokens = tokenizer.tokenize(sql)?;
        let mut parser = Parser::with_source(tokens, ParserConfig::default(), sql.to_string());
        parser.parse()
    }

    /// Parse SQL from a string using a custom [`TokenizerConfig`].
    ///
    /// Use this variant when the source dialect requires non-default tokenizer
    /// settings (e.g. different string quoting or comment syntax).
    pub fn parse_sql_with_config(
        sql: &str,
        tokenizer_config: TokenizerConfig,
    ) -> Result<Vec<Expression>> {
        let tokenizer = Tokenizer::new(tokenizer_config);
        let tokens = tokenizer.tokenize(sql)?;
        let mut parser = Parser::with_source(tokens, ParserConfig::default(), sql.to_string());
        parser.parse()
    }

    /// Parse all remaining statements from the token stream.
    ///
    /// Consumes tokens until the end of input, splitting on semicolons.
    /// Returns one `Expression` per statement.
    pub fn parse(&mut self) -> Result<Vec<Expression>> {
        let mut statements = Vec::new();

        while !self.is_at_end() {
            let mut stmt = self.parse_statement()?;

            // Before consuming the semicolon, capture its leading comments
            // and attach them to the statement (e.g., SELECT foo\n/* comment */\n;)
            if self.check(TokenType::Semicolon) {
                let semi_comments = self.current_leading_comments();
                if !semi_comments.is_empty() {
                    stmt = Expression::Annotated(Box::new(Annotated {
                        this: stmt,
                        trailing_comments: semi_comments,
                    }));
                }
            }

            // ClickHouse: consume trailing SETTINGS key=val, ... after any statement
            if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && self.check(TokenType::Settings)
            {
                self.advance(); // consume SETTINGS
                let _ = self.parse_settings_property()?;
            }

            // ClickHouse: consume trailing FORMAT <name> after any statement
            if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && self.check(TokenType::Format)
            {
                self.advance(); // consume FORMAT
                                // Accept any identifier/keyword/Null as format name
                if self.check(TokenType::Null) {
                    self.advance();
                } else if self.is_identifier_token() || self.check_keyword() {
                    self.advance();
                }
            }

            // ClickHouse: PARALLEL WITH between statements (multi-statement execution)
            if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && self.check_identifier("PARALLEL")
                && self.check_next(TokenType::With)
            {
                self.advance(); // consume PARALLEL
                self.advance(); // consume WITH
                statements.push(stmt);
                continue;
            }

            // After parsing a statement, the next token must be a semicolon or EOF.
            // If not, there are unconsumed tokens which indicates a parse error.
            // This matches Python sqlglot's behavior (parser.py line 1826-1827).
            if !self.is_at_end() && !self.check(TokenType::Semicolon) {
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) {
                    // ClickHouse fallback: consume unconsumed tokens until semicolon/EOF.
                    // This matches Python sqlglot's _parse_as_command behavior for
                    // ClickHouse-specific syntax that we don't fully parse yet.
                    while !self.is_at_end() && !self.check(TokenType::Semicolon) {
                        self.advance();
                    }
                } else {
                    return Err(self.parse_error("Invalid expression / Unexpected token"));
                }
            }

            // Consume optional semicolons (ClickHouse allows multiple like `;;`)
            while self.match_token(TokenType::Semicolon) {}

            statements.push(stmt);
        }

        Ok(statements)
    }

    /// Parse a single SQL statement from the current position in the token stream.
    ///
    /// Dispatches to the appropriate sub-parser based on the leading keyword
    /// (SELECT, INSERT, CREATE, etc.). Unknown or dialect-specific statements
    /// fall through to a `Command` expression that preserves the raw SQL text.
    pub fn parse_statement(&mut self) -> Result<Expression> {
        // Skip any leading semicolons
        while self.match_token(TokenType::Semicolon) {}

        if self.is_at_end() {
            return Err(self.parse_error("Unexpected end of input"));
        }

        match self.peek().token_type {
            // Handle hint comment /*+ ... */ before a statement - convert to regular comment
            TokenType::Hint => {
                let hint_token = self.advance();
                let hint_text = hint_token.text.clone();
                // Convert hint to regular comment (preserve the + as part of the content)
                let comment = format!("/* + {} */", hint_text.trim());

                // Parse the following statement
                let mut stmt = self.parse_statement()?;

                // Attach the comment to the statement's leading_comments
                match &mut stmt {
                    Expression::Select(select) => {
                        select.leading_comments.insert(0, comment);
                    }
                    Expression::Insert(insert) => {
                        insert.leading_comments.insert(0, comment);
                    }
                    Expression::Update(update) => {
                        update.leading_comments.insert(0, comment);
                    }
                    Expression::Delete(delete) => {
                        delete.leading_comments.insert(0, comment);
                    }
                    Expression::CreateTable(ct) => {
                        ct.leading_comments.insert(0, comment);
                    }
                    _ => {
                        // For other statement types, we can't attach comments
                        // but at least the statement parses successfully
                    }
                }
                Ok(stmt)
            }
            TokenType::Select => self.parse_select(),
            TokenType::With => self.parse_with(),
            TokenType::Insert => self.parse_insert(),
            TokenType::Replace => self.parse_replace(),
            TokenType::Update => self.parse_update(),
            TokenType::Delete => self.parse_delete(),
            TokenType::Create => self.parse_create(),
            TokenType::Drop => self.parse_drop(),
            TokenType::Alter => self.parse_alter(),
            TokenType::Truncate => {
                // TRUNCATE could be TRUNCATE TABLE (statement) or TRUNCATE(a, b) (function)
                // Check if followed by ( to determine which
                if self.check_next(TokenType::LParen) {
                    // TRUNCATE(a, b) - function call
                    self.parse_expression()
                } else {
                    self.parse_truncate()
                }
            }
            TokenType::Values => {
                // VALUES could be VALUES(...) statement or VALUES 1, 2, 3 (bare values)
                if self.check_next(TokenType::LParen)
                    || self.check_next(TokenType::Number)
                    || self.check_next(TokenType::String)
                {
                    self.parse_values()
                } else {
                    // "values" by itself is an identifier/expression
                    self.parse_expression()
                }
            }
            TokenType::Use => self.parse_use(),
            TokenType::Cache => self.parse_cache(),
            TokenType::Uncache => self.parse_uncache(),
            TokenType::Refresh => {
                self.advance(); // consume REFRESH
                self.parse_refresh()?
                    .ok_or_else(|| self.parse_error("Failed to parse REFRESH statement"))
            }
            TokenType::Load => self.parse_load_data(),
            TokenType::Grant => self.parse_grant(),
            TokenType::Revoke => self.parse_revoke(),
            TokenType::Comment => self.parse_comment(),
            TokenType::Merge => {
                self.advance(); // consume MERGE
                self.parse_merge()?
                    .ok_or_else(|| self.parse_error("Failed to parse MERGE statement"))
            }
            TokenType::Set => self.parse_set(),
            TokenType::Database
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::Teradata)
                ) =>
            {
                // Teradata: DATABASE tduser -> USE tduser
                self.advance(); // consume DATABASE
                let name = self.expect_identifier_or_keyword()?;
                Ok(Expression::Use(Box::new(Use {
                    kind: None,
                    this: Identifier::new(name),
                })))
            }
            TokenType::Lock
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::Teradata)
                ) =>
            {
                self.parse_locking_statement()
            }
            TokenType::Command => {
                self.advance(); // consume command keyword
                self.parse_command()?
                    .ok_or_else(|| self.parse_error("Failed to parse COMMAND statement"))
            }
            TokenType::Rename
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::Teradata)
                        | Some(crate::dialects::DialectType::ClickHouse)
                ) =>
            {
                self.advance(); // consume RENAME
                self.parse_command()?
                    .ok_or_else(|| self.parse_error("Failed to parse RENAME statement"))
            }
            TokenType::Pragma => self.parse_pragma(),
            TokenType::Rollback => self.parse_rollback(),
            TokenType::Commit => self.parse_commit(),
            TokenType::Begin => self.parse_transaction(),
            TokenType::End => {
                // In PostgreSQL, END is an alias for COMMIT (END [WORK|TRANSACTION])
                // In TSQL and other dialects, END is a block delimiter (BEGIN...END)
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::PostgreSQL)
                ) {
                    self.parse_end_transaction()
                } else {
                    self.advance(); // consume END
                    Ok(Expression::Command(Box::new(Command {
                        this: "END".to_string(),
                    })))
                }
            }
            TokenType::Start => self.parse_start_transaction(),
            TokenType::Describe | TokenType::Desc => self.parse_describe(),
            TokenType::Show => self.parse_show(),
            TokenType::Copy => self.parse_copy(),
            TokenType::Put => self.parse_put(),
            TokenType::Kill
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) =>
            {
                self.advance(); // consume KILL
                self.parse_command()?
                    .ok_or_else(|| self.parse_error("Failed to parse KILL statement"))
            }
            TokenType::Kill => self.parse_kill(),
            TokenType::Execute => {
                // ClickHouse: EXECUTE AS username statement → parse as command
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) {
                    self.advance(); // consume EXECUTE
                    self.parse_command()?
                        .ok_or_else(|| self.parse_error("Failed to parse EXECUTE statement"))
                } else {
                    self.parse_execute()
                }
            }
            TokenType::Declare => {
                self.advance(); // consume DECLARE
                self.parse_declare()?
                    .ok_or_else(|| self.parse_error("Failed to parse DECLARE statement"))
            }
            // GET is a command only when followed by @ (stage reference), otherwise it's a function
            // If followed by ( it should be parsed as GET() function, so fall through to expression parsing
            TokenType::Get
                if self.check_next(TokenType::DAt) || !self.check_next(TokenType::LParen) =>
            {
                self.parse_get_command()
            }
            TokenType::Var
                if self.peek().text.eq_ignore_ascii_case("RM")
                    || self.peek().text.eq_ignore_ascii_case("REMOVE") =>
            {
                self.parse_rm_command()
            }
            TokenType::Var if self.peek().text.eq_ignore_ascii_case("CALL") => self.parse_call(),
            TokenType::Var
                if self.peek().text.eq_ignore_ascii_case("EXCHANGE")
                    && matches!(
                        self.config.dialect,
                        Some(crate::dialects::DialectType::ClickHouse)
                    ) =>
            {
                self.advance(); // consume EXCHANGE
                self.parse_command()?
                    .ok_or_else(|| self.parse_error("Failed to parse EXCHANGE statement"))
            }
            // EXPLAIN is treated as DESCRIBE (MySQL maps EXPLAIN -> DESCRIBE)
            TokenType::Var if self.peek().text.eq_ignore_ascii_case("EXPLAIN") => {
                self.parse_describe()
            }
            // LOCK TABLES / UNLOCK TABLES (MySQL)
            TokenType::Var
                if self.peek().text.eq_ignore_ascii_case("LOCK")
                    || self.peek().text.eq_ignore_ascii_case("UNLOCK") =>
            {
                self.advance(); // consume LOCK/UNLOCK
                self.parse_command()?
                    .ok_or_else(|| self.parse_error("Failed to parse LOCK/UNLOCK statement"))
            }
            TokenType::Var if self.peek().text.eq_ignore_ascii_case("ANALYZE") => {
                self.advance(); // consume ANALYZE
                self.parse_analyze()?
                    .ok_or_else(|| self.parse_error("Failed to parse ANALYZE statement"))
            }
            // TSQL: PRINT expression
            TokenType::Var if self.peek().text.eq_ignore_ascii_case("PRINT") => {
                self.advance(); // consume PRINT
                self.parse_command()?
                    .ok_or_else(|| self.parse_error("Failed to parse PRINT statement"))
            }
            // ClickHouse: CHECK TABLE t [PARTITION p] [SETTINGS ...]
            TokenType::Check
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) =>
            {
                self.advance(); // consume CHECK
                self.parse_command()?
                    .ok_or_else(|| self.parse_error("Failed to parse CHECK statement"))
            }
            // ClickHouse: SETTINGS key=value, ... (standalone statement or after another statement)
            TokenType::Settings
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) =>
            {
                self.advance(); // consume SETTINGS
                self.parse_command()?
                    .ok_or_else(|| self.parse_error("Failed to parse SETTINGS statement"))
            }
            // ClickHouse: SYSTEM STOP/START MERGES, etc.
            TokenType::System
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) =>
            {
                self.advance(); // consume SYSTEM
                self.parse_command()?
                    .ok_or_else(|| self.parse_error("Failed to parse SYSTEM statement"))
            }
            // ClickHouse: RENAME TABLE db.t1 TO db.t2 [, db.t3 TO db.t4 ...]
            TokenType::Var
                if self.peek().text.eq_ignore_ascii_case("RENAME")
                    && matches!(
                        self.config.dialect,
                        Some(crate::dialects::DialectType::ClickHouse)
                    ) =>
            {
                self.advance(); // consume RENAME
                self.parse_command()?
                    .ok_or_else(|| self.parse_error("Failed to parse RENAME statement"))
            }
            // ClickHouse: OPTIMIZE TABLE t [FINAL] [DEDUPLICATE [BY ...]]
            TokenType::Var
                if self.peek().text.eq_ignore_ascii_case("OPTIMIZE")
                    && matches!(
                        self.config.dialect,
                        Some(crate::dialects::DialectType::ClickHouse)
                    ) =>
            {
                self.advance(); // consume OPTIMIZE
                self.parse_command()?
                    .ok_or_else(|| self.parse_error("Failed to parse OPTIMIZE statement"))
            }
            // ClickHouse: EXISTS [TEMPORARY] TABLE/DATABASE/DICTIONARY ...
            TokenType::Exists
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) && !self.check_next(TokenType::LParen) =>
            {
                self.advance(); // consume EXISTS
                self.parse_command()?
                    .ok_or_else(|| self.parse_error("Failed to parse EXISTS statement"))
            }
            // ClickHouse: SHOW ... (various SHOW commands beyond what's already handled)
            TokenType::Var
                if self.peek().text.eq_ignore_ascii_case("EXISTS")
                    && matches!(
                        self.config.dialect,
                        Some(crate::dialects::DialectType::ClickHouse)
                    ) =>
            {
                self.advance(); // consume EXISTS
                self.parse_command()?
                    .ok_or_else(|| self.parse_error("Failed to parse EXISTS statement"))
            }
            // DuckDB: ATTACH [DATABASE] [IF NOT EXISTS] 'path' [AS alias] [(options)]
            TokenType::Var if self.peek().text.eq_ignore_ascii_case("ATTACH") => {
                self.advance(); // consume ATTACH
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) {
                    self.parse_command()?
                        .ok_or_else(|| self.parse_error("Failed to parse ATTACH statement"))
                } else {
                    self.parse_attach_detach(true)
                }
            }
            // ClickHouse: UNDROP TABLE [IF EXISTS] ... [UUID '...'] [ON CLUSTER ...]
            TokenType::Var
                if self.peek().text.eq_ignore_ascii_case("UNDROP")
                    && matches!(
                        self.config.dialect,
                        Some(crate::dialects::DialectType::ClickHouse)
                    ) =>
            {
                self.advance(); // consume UNDROP
                self.parse_command()?
                    .ok_or_else(|| self.parse_error("Failed to parse UNDROP statement"))
            }
            // ClickHouse: DETACH TABLE [IF EXISTS] ... [ON CLUSTER ...]
            TokenType::Var
                if self.peek().text.eq_ignore_ascii_case("DETACH")
                    && matches!(
                        self.config.dialect,
                        Some(crate::dialects::DialectType::ClickHouse)
                    ) =>
            {
                self.advance(); // consume DETACH
                self.parse_command()?
                    .ok_or_else(|| self.parse_error("Failed to parse DETACH statement"))
            }
            // DuckDB: DETACH [DATABASE] [IF EXISTS] name
            TokenType::Var if self.peek().text.eq_ignore_ascii_case("DETACH") => {
                self.advance(); // consume DETACH
                self.parse_attach_detach(false)
            }
            // DuckDB: INSTALL extension [FROM source]
            TokenType::Var if self.peek().text.eq_ignore_ascii_case("INSTALL") => {
                self.advance(); // consume INSTALL
                self.parse_install(false)
            }
            // DuckDB: FORCE INSTALL extension | FORCE CHECKPOINT db
            TokenType::Var if self.peek().text.eq_ignore_ascii_case("FORCE") => {
                self.advance(); // consume FORCE
                self.parse_force_statement()
            }
            // DuckDB: SUMMARIZE [TABLE] expression
            TokenType::Var if self.peek().text.eq_ignore_ascii_case("SUMMARIZE") => {
                self.advance(); // consume SUMMARIZE
                self.parse_summarize_statement()
            }
            // DuckDB: RESET [SESSION|GLOBAL|LOCAL] variable
            TokenType::Var if self.peek().text.eq_ignore_ascii_case("RESET") => {
                self.advance(); // consume RESET
                self.parse_as_command()?
                    .ok_or_else(|| self.parse_error("Failed to parse RESET statement"))
            }
            // DuckDB statement-level PIVOT/UNPIVOT/PIVOT_WIDER syntax
            TokenType::Pivot => {
                self.advance(); // consume PIVOT
                self.parse_simplified_pivot(false)?
                    .ok_or_else(|| self.parse_error("Failed to parse PIVOT statement"))
            }
            TokenType::Unpivot => {
                self.advance(); // consume UNPIVOT
                self.parse_simplified_pivot(true)?
                    .ok_or_else(|| self.parse_error("Failed to parse UNPIVOT statement"))
            }
            // DuckDB: PIVOT_WIDER is an alias for PIVOT
            TokenType::Var if self.peek().text.eq_ignore_ascii_case("PIVOT_WIDER") => {
                self.advance(); // consume PIVOT_WIDER
                self.parse_simplified_pivot(false)?
                    .ok_or_else(|| self.parse_error("Failed to parse PIVOT_WIDER statement"))
            }
            // BigQuery procedural FOR...IN...DO loop
            TokenType::For => {
                self.advance(); // consume FOR
                self.parse_for_in()
            }
            // BigQuery/procedural LOOP, REPEAT, WHILE control flow statements
            TokenType::Var if self.peek().text.eq_ignore_ascii_case("LOOP") => {
                self.advance(); // consume LOOP
                self.parse_command()?
                    .ok_or_else(|| self.parse_error("Failed to parse LOOP statement"))
            }
            TokenType::Var if self.peek().text.eq_ignore_ascii_case("REPEAT") => {
                self.advance(); // consume REPEAT
                self.parse_command()?
                    .ok_or_else(|| self.parse_error("Failed to parse REPEAT statement"))
            }
            TokenType::Var if self.peek().text.eq_ignore_ascii_case("WHILE") => {
                self.advance(); // consume WHILE
                self.parse_command()?
                    .ok_or_else(|| self.parse_error("Failed to parse WHILE statement"))
            }
            // Athena/Presto: UNLOAD (SELECT ...) TO 'location' WITH (options)
            TokenType::Var if self.peek().text.eq_ignore_ascii_case("UNLOAD") => {
                self.parse_unload()
            }
            // Athena: USING EXTERNAL FUNCTION ... SELECT ...
            TokenType::Using => self.parse_using_external_function(),
            // BigQuery: EXPORT DATA [WITH CONNECTION conn] OPTIONS (...) AS SELECT ...
            TokenType::Var if self.peek().text.eq_ignore_ascii_case("EXPORT") => {
                self.parse_export_data()
            }
            // Presto/Trino: DEALLOCATE PREPARE <name>
            TokenType::Var if self.peek().text.eq_ignore_ascii_case("DEALLOCATE") => {
                self.parse_deallocate_prepare()
            }
            // DuckDB FROM-first syntax: FROM tbl = SELECT * FROM tbl
            TokenType::From => self.parse_from_first_query(),
            TokenType::LParen => {
                // Check if this is a parenthesized query (SELECT, WITH, PIVOT, UNPIVOT, FROM, or EXPLAIN inside)
                // by looking ahead after the opening paren
                let next_is_explain = self.current + 1 < self.tokens.len()
                    && self.tokens[self.current + 1].token_type == TokenType::Var
                    && self.tokens[self.current + 1]
                        .text
                        .eq_ignore_ascii_case("EXPLAIN");
                if self.check_next(TokenType::Select)
                    || self.check_next(TokenType::With)
                    || self.check_next(TokenType::Pivot)
                    || self.check_next(TokenType::Unpivot)
                    || self.check_next(TokenType::From)
                    || next_is_explain
                {
                    // Parse parenthesized query: (SELECT ...) ORDER BY x LIMIT y OFFSET z
                    self.advance(); // consume (
                    let inner = self.parse_statement()?;
                    self.expect(TokenType::RParen)?;
                    // Wrap in Subquery to preserve parentheses when used in set operations
                    let subquery = Expression::Subquery(Box::new(Subquery {
                        this: inner,
                        alias: None,
                        column_aliases: Vec::new(),
                        order_by: None,
                        limit: None,
                        offset: None,
                        distribute_by: None,
                        sort_by: None,
                        cluster_by: None,
                        lateral: false,
                        modifiers_inside: false,
                        trailing_comments: Vec::new(),
                        inferred_type: None,
                    }));
                    // Check for set operations after the parenthesized query
                    let result = self.parse_set_operation(subquery)?;
                    // Check for ORDER BY, LIMIT, OFFSET after parenthesized subquery
                    self.parse_query_modifiers(result)
                } else if self.check_next(TokenType::LParen) {
                    // Nested parentheses - could be ((SELECT...)) or ((a, b))
                    // For deeply nested queries like (((SELECT 1) UNION SELECT 1) UNION SELECT 1),
                    // recurse into parse_statement to handle the inner parenthesized query with set ops
                    self.advance(); // consume (
                    let inner = self.parse_statement()?;
                    // Check for set operations inside the outer parens
                    let result = self.parse_set_operation(inner)?;
                    self.expect(TokenType::RParen)?;
                    let subquery = Expression::Subquery(Box::new(Subquery {
                        this: result,
                        alias: None,
                        column_aliases: Vec::new(),
                        order_by: None,
                        limit: None,
                        offset: None,
                        distribute_by: None,
                        sort_by: None,
                        cluster_by: None,
                        lateral: false,
                        modifiers_inside: false,
                        trailing_comments: Vec::new(),
                        inferred_type: None,
                    }));
                    // Check for set operations after the outer parenthesized query
                    let result = self.parse_set_operation(subquery)?;
                    let pre_alias_comments = self.previous_trailing_comments();
                    if self.match_token(TokenType::As) {
                        let alias = self.expect_identifier_or_keyword_with_quoted()?;
                        let trailing_comments = self.previous_trailing_comments();
                        Ok(Expression::Alias(Box::new(Alias {
                            this: result,
                            alias,
                            column_aliases: Vec::new(),
                            pre_alias_comments,
                            trailing_comments,
                            inferred_type: None,
                        })))
                    } else {
                        // Check for LIMIT/OFFSET after parenthesized expression
                        // e.g., ((SELECT 1)) LIMIT 1
                        self.parse_query_modifiers(result)
                    }
                } else {
                    // Regular parenthesized expression like (a, b) or (x)
                    // Let parse_expression handle it
                    let expr = self.parse_expression()?;
                    let pre_alias_comments = self.previous_trailing_comments();
                    if self.match_token(TokenType::As) {
                        // Check for tuple alias: AS ("a", "b", ...)
                        if self.match_token(TokenType::LParen) {
                            let mut column_aliases = Vec::new();
                            loop {
                                let col_alias = self.expect_identifier_or_keyword_with_quoted()?;
                                column_aliases.push(col_alias);
                                if !self.match_token(TokenType::Comma) {
                                    break;
                                }
                            }
                            self.expect(TokenType::RParen)?;
                            let trailing_comments = self.previous_trailing_comments();
                            Ok(Expression::Alias(Box::new(Alias {
                                this: expr,
                                alias: Identifier::empty(),
                                column_aliases,
                                pre_alias_comments,
                                trailing_comments,
                                inferred_type: None,
                            })))
                        } else {
                            let alias = self.expect_identifier_or_keyword_with_quoted()?;
                            let trailing_comments = self.previous_trailing_comments();
                            Ok(Expression::Alias(Box::new(Alias {
                                this: expr,
                                alias,
                                column_aliases: Vec::new(),
                                pre_alias_comments,
                                trailing_comments,
                                inferred_type: None,
                            })))
                        }
                    } else {
                        Ok(expr)
                    }
                }
            }
            _ => {
                // Capture leading comments from the first token before parsing
                let leading_comments = self.current_leading_comments();
                // Parse expression and check for optional alias
                let expr = self.parse_expression()?;
                // Capture any comments between expression and AS keyword
                let pre_alias_comments = self.previous_trailing_comments();
                if self.match_token(TokenType::As) {
                    // Capture comments from AS token (e.g., AS /* foo */ (a, b, c))
                    // These go into trailing_comments (after the alias), not pre_alias_comments
                    let as_comments = self.previous_trailing_comments();
                    // Check for tuple alias: AS ("a", "b", ...)
                    if self.match_token(TokenType::LParen) {
                        let mut column_aliases = Vec::new();
                        loop {
                            let col_alias = self.expect_identifier_or_keyword_with_quoted()?;
                            column_aliases.push(col_alias);
                            if !self.match_token(TokenType::Comma) {
                                break;
                            }
                        }
                        self.expect(TokenType::RParen)?;
                        let mut trailing_comments = as_comments;
                        trailing_comments.extend(self.previous_trailing_comments());
                        Ok(Expression::Alias(Box::new(Alias {
                            this: expr,
                            alias: Identifier::empty(),
                            column_aliases,
                            pre_alias_comments,
                            trailing_comments,
                            inferred_type: None,
                        })))
                    } else {
                        let alias = self.expect_identifier_or_keyword_with_quoted()?;
                        let mut trailing_comments = self.previous_trailing_comments();
                        // If there were leading comments on the expression (from a separate line),
                        // add them as trailing comments after the alias
                        trailing_comments.extend(leading_comments.iter().cloned());
                        Ok(Expression::Alias(Box::new(Alias {
                            this: expr,
                            alias,
                            column_aliases: Vec::new(),
                            pre_alias_comments,
                            trailing_comments,
                            inferred_type: None,
                        })))
                    }
                } else if (self.check(TokenType::Var) && !self.check_keyword())
                    || self.is_command_keyword_as_alias()
                {
                    // Implicit alias (without AS) - e.g., "1. x" or "1.x" -> "1. AS x"
                    // This handles cases like PostgreSQL's "1.x" which parses as float 1. with alias x
                    let alias_text = self.advance().text.clone();
                    let trailing_comments = self.previous_trailing_comments();
                    Ok(Expression::Alias(Box::new(Alias {
                        this: expr,
                        alias: Identifier::new(alias_text),
                        column_aliases: Vec::new(),
                        pre_alias_comments,
                        trailing_comments,
                        inferred_type: None,
                    })))
                } else if !pre_alias_comments.is_empty() {
                    // Wrap in Annotated to preserve trailing comments for expressions without aliases
                    match &expr {
                        Expression::Literal(_) | Expression::Boolean(_) | Expression::Null(_) => {
                            Ok(Expression::Annotated(Box::new(
                                crate::expressions::Annotated {
                                    this: expr,
                                    trailing_comments: pre_alias_comments,
                                },
                            )))
                        }
                        // For expressions that already have trailing_comments fields, don't double-wrap
                        _ => Ok(expr),
                    }
                } else if !leading_comments.is_empty() {
                    // Wrap in Annotated to preserve leading comments as trailing comments
                    // This matches Python sqlglot which converts leading line comments to trailing block comments
                    Ok(Expression::Annotated(Box::new(
                        crate::expressions::Annotated {
                            this: expr,
                            trailing_comments: leading_comments,
                        },
                    )))
                } else {
                    Ok(expr)
                }
            }
        }
    }

    /// Parse a SELECT statement
    fn parse_select(&mut self) -> Result<Expression> {
        // Capture the SELECT token to get its comments
        let select_token = self.expect(TokenType::Select)?;
        let leading_comments = select_token.comments;
        let post_select_comments = select_token.trailing_comments;

        // Parse query hint /*+ ... */ if present (comes immediately after SELECT)
        let hint = if self.check(TokenType::Hint) {
            Some(self.parse_hint()?)
        } else {
            None
        };

        // Parse TOP clause (SQL Server style - comes before DISTINCT)
        // But not if TOP is followed by DOT (e.g., SELECT top.x - top is a table alias)
        let top = if self.check(TokenType::Top)
            && !self.check_next(TokenType::Dot)
            && self.match_token(TokenType::Top)
        {
            // TOP can have parentheses: TOP (10) or without: TOP 10
            let (amount, parenthesized) = if self.match_token(TokenType::LParen) {
                let expr = self.parse_expression()?;
                self.expect(TokenType::RParen)?;
                (expr, true)
            } else {
                (self.parse_primary()?, false)
            };
            let percent = self.match_token(TokenType::Percent);
            let with_ties = self.match_keywords(&[TokenType::With, TokenType::Ties]);
            Some(Top {
                this: amount,
                percent,
                with_ties,
                parenthesized,
            })
        } else {
            None
        };

        // Parse DISTINCT / DISTINCT ON / DISTINCTROW / ALL
        // Oracle: UNIQUE is equivalent to DISTINCT (SELECT UNIQUE ... is old-style Oracle syntax)
        let is_distinct_token = self.match_token(TokenType::Distinct)
            || (matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::Oracle)
            ) && self.match_token(TokenType::Unique));
        let (distinct, distinct_on) = if is_distinct_token {
            if self.match_token(TokenType::On) {
                // DISTINCT ON (expr, ...)
                self.expect(TokenType::LParen)?;
                let exprs = self.parse_expression_list()?;
                self.expect(TokenType::RParen)?;
                (true, Some(exprs))
            } else {
                (true, None)
            }
        } else if self.check_identifier("DISTINCTROW") {
            // MySQL DISTINCTROW - equivalent to DISTINCT
            self.advance();
            (true, None)
        } else {
            // Only consume ALL if it's the SELECT ALL modifier, not if it's a column reference like "all.count"
            if self.check(TokenType::All) && !self.check_next(TokenType::Dot) {
                self.advance();
            }
            (false, None)
        };

        // TSQL: SELECT DISTINCT TOP n - TOP can come after DISTINCT
        // If no TOP was parsed before DISTINCT, check for TOP after DISTINCT
        let top = if top.is_none()
            && self.check(TokenType::Top)
            && !self.check_next(TokenType::Dot)
            && self.match_token(TokenType::Top)
        {
            let (amount, parenthesized) = if self.match_token(TokenType::LParen) {
                let expr = self.parse_expression()?;
                self.expect(TokenType::RParen)?;
                (expr, true)
            } else {
                (self.parse_primary()?, false)
            };
            let percent = self.match_token(TokenType::Percent);
            let with_ties = self.match_keywords(&[TokenType::With, TokenType::Ties]);
            Some(Top {
                this: amount,
                percent,
                with_ties,
                parenthesized,
            })
        } else {
            top
        };

        // Parse MySQL operation modifiers (HIGH_PRIORITY, STRAIGHT_JOIN, SQL_CALC_FOUND_ROWS, etc.)
        // These appear after DISTINCT/ALL and before the projections
        // Only apply for MySQL-family dialects - other dialects treat these as identifiers
        let mut operation_modifiers = Vec::new();
        let is_mysql_dialect = matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::MySQL)
                | Some(crate::dialects::DialectType::SingleStore)
                | Some(crate::dialects::DialectType::StarRocks)
                | Some(crate::dialects::DialectType::TiDB)
                | Some(crate::dialects::DialectType::Doris)
        );
        if is_mysql_dialect {
            const MYSQL_MODIFIERS: &[&str] = &[
                "HIGH_PRIORITY",
                "STRAIGHT_JOIN",
                "SQL_SMALL_RESULT",
                "SQL_BIG_RESULT",
                "SQL_BUFFER_RESULT",
                "SQL_NO_CACHE",
                "SQL_CALC_FOUND_ROWS",
            ];
            loop {
                if self.check(TokenType::StraightJoin) {
                    self.advance();
                    operation_modifiers.push("STRAIGHT_JOIN".to_string());
                } else if self.check(TokenType::Var) {
                    let upper = self.peek().text.to_uppercase();
                    if MYSQL_MODIFIERS.contains(&upper.as_str()) {
                        self.advance();
                        operation_modifiers.push(upper);
                    } else {
                        break;
                    }
                } else {
                    break;
                }
            }
        }

        // Parse BigQuery SELECT AS STRUCT / SELECT AS VALUE
        let kind = if self.match_token(TokenType::As) {
            if self.match_identifier("STRUCT") {
                Some("STRUCT".to_string())
            } else if self.match_identifier("VALUE") {
                Some("VALUE".to_string())
            } else {
                // Not AS STRUCT/VALUE, backtrack the AS token
                self.current -= 1;
                None
            }
        } else {
            None
        };

        // Parse select expressions
        let mut expressions = self.parse_select_expressions()?;

        // Redshift: EXCLUDE clause at the end of the projection list
        // e.g., SELECT *, 4 AS col4 EXCLUDE (col2, col3) FROM ...
        // e.g., SELECT col1, *, col2 EXCLUDE(col3) FROM ...
        // e.g., SELECT *, 4 AS col4 EXCLUDE col2, col3 FROM ...
        // In Python sqlglot, this is handled by overriding _parse_projections in the Redshift parser.
        // The EXCLUDE clause is separate from * EXCLUDE — it applies to the entire projection list.
        let exclude = if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::Redshift)
        ) {
            // Check if previous token was EXCLUDE (parsed as implicit alias).
            // e.g., SELECT *, 4 AS col4 EXCLUDE col2, col3 FROM ...
            //   → "col4 EXCLUDE" was parsed as (col4 aliased-as EXCLUDE), then "col2" as next projection
            //   → We need to strip the EXCLUDE alias from the last projection and retreat
            // Also handle: EXCLUDE was consumed as a bare column name if no AS was present
            let mut retreat_for_exclude = false;
            if let Some(last_expr) = expressions.last() {
                // Case: "4 AS col4 EXCLUDE" without parens — parsed as separate column "EXCLUDE"
                // Actually with the comma break, this won't happen. But "col2 EXCLUDE(col3)" might.
                match last_expr {
                    Expression::Alias(alias) if alias.alias.name.eq_ignore_ascii_case("EXCLUDE") => {
                        // The last expression is "something AS EXCLUDE" or implicit alias EXCLUDE
                        // Strip the alias and check if EXCLUDE is followed by paren or identifier
                        if self.check(TokenType::LParen) || self.is_identifier_token() || self.is_safe_keyword_as_identifier() {
                            // Strip the EXCLUDE alias from the last expression
                            let stripped = alias.this.clone();
                            if let Some(last) = expressions.last_mut() {
                                *last = stripped;
                            }
                            retreat_for_exclude = true;
                        }
                    }
                    _ => {}
                }
            }

            if retreat_for_exclude || self.check(TokenType::Exclude) {
                if !retreat_for_exclude {
                    self.advance(); // consume EXCLUDE
                }
                // Parse EXCLUDE columns - with or without parens
                let mut exclude_cols = Vec::new();
                if self.match_token(TokenType::LParen) {
                    // Parenthesized list: EXCLUDE (col1, col2, ...)
                    loop {
                        let col_expr = self.parse_expression()?;
                        exclude_cols.push(col_expr);
                        if !self.match_token(TokenType::Comma) {
                            break;
                        }
                    }
                    self.match_token(TokenType::RParen);
                } else {
                    // Non-parenthesized: EXCLUDE col1, col2, ...
                    // Parse comma-separated identifiers until FROM or other clause boundary
                    loop {
                        if self.is_at_end() || self.check(TokenType::From) || self.check(TokenType::Where)
                            || self.check(TokenType::Semicolon) || self.check(TokenType::RParen)
                        {
                            break;
                        }
                        let col_expr = self.parse_expression()?;
                        exclude_cols.push(col_expr);
                        if !self.match_token(TokenType::Comma) {
                            break;
                        }
                    }
                }
                if exclude_cols.is_empty() { None } else { Some(exclude_cols) }
            } else {
                None
            }
        } else {
            None
        };

        // Parse INTO clause (SELECT ... INTO [TEMPORARY|UNLOGGED] table_name)
        // Also handles Oracle PL/SQL: BULK COLLECT INTO v1, v2, ...
        let into = if self.match_text_seq(&["BULK", "COLLECT", "INTO"]) {
            // Oracle PL/SQL: BULK COLLECT INTO var1, var2, ...
            // Parse target variables as a comma-separated list
            let mut target_expressions = vec![self.parse_expression()?];
            while self.match_token(TokenType::Comma) {
                target_expressions.push(self.parse_expression()?);
            }
            if target_expressions.len() == 1 {
                Some(SelectInto {
                    this: target_expressions.remove(0),
                    temporary: false,
                    unlogged: false,
                    bulk_collect: true,
                    expressions: Vec::new(),
                })
            } else {
                // Multiple targets - use first as `this` and rest as `expressions`
                // Actually, to match Python sqlglot behavior, store all in expressions
                Some(SelectInto {
                    this: Expression::Null(Null),
                    temporary: false,
                    unlogged: false,
                    bulk_collect: true,
                    expressions: target_expressions,
                })
            }
        } else if self.match_token(TokenType::Into) {
            // Check for TEMPORARY/TEMP/UNLOGGED keyword (PostgreSQL)
            let temporary = self.match_token(TokenType::Temporary) || self.match_identifier("TEMP");
            let unlogged = !temporary && self.match_identifier("UNLOGGED");
            // Parse first target (table name or PL/SQL variable)
            let table_name = self.parse_table_ref()?;
            // Oracle PL/SQL: SELECT ... INTO var1, var2, ... FROM ...
            // If followed by comma, parse additional target variables
            if self.match_token(TokenType::Comma) {
                let mut target_expressions = vec![Expression::Table(table_name)];
                target_expressions.push(self.parse_expression()?);
                while self.match_token(TokenType::Comma) {
                    target_expressions.push(self.parse_expression()?);
                }
                Some(SelectInto {
                    this: Expression::Null(Null),
                    temporary,
                    unlogged,
                    bulk_collect: false,
                    expressions: target_expressions,
                })
            } else {
                Some(SelectInto {
                    this: Expression::Table(table_name),
                    temporary,
                    unlogged,
                    bulk_collect: false,
                    expressions: Vec::new(),
                })
            }
        } else {
            None
        };

        // Parse FROM clause
        let from = if self.match_token(TokenType::From) {
            Some(self.parse_from()?)
        } else {
            None
        };

        // Parse JOINs
        let mut joins = self.parse_joins()?;

        // Handle PIVOT/UNPIVOT that comes after JOINs (e.g., SELECT * FROM a JOIN b ON ... PIVOT(...))
        // Store PIVOT/UNPIVOT in the last join's pivots field (this matches SQLGlot's semantics)
        while self.check(TokenType::Pivot) || self.check(TokenType::Unpivot) {
            if !joins.is_empty() {
                let last_idx = joins.len() - 1;
                // Parse the pivot/unpivot and store in the join's pivots vector
                // We pass a Null expression as the `this` since the pivot applies to the entire join result
                if self.match_token(TokenType::Pivot) {
                    let pivot = self.parse_pivot(Expression::Null(crate::expressions::Null))?;
                    joins[last_idx].pivots.push(pivot);
                } else if self.match_token(TokenType::Unpivot) {
                    let unpivot = self.parse_unpivot(Expression::Null(crate::expressions::Null))?;
                    joins[last_idx].pivots.push(unpivot);
                }
            } else {
                // No joins - break to avoid infinite loop
                break;
            }
        }

        // Parse LATERAL VIEW clauses (Hive/Spark)
        let lateral_views = self.parse_lateral_views()?;

        // Parse PREWHERE clause (ClickHouse specific)
        let prewhere = if self.match_token(TokenType::Prewhere) {
            Some(self.parse_expression()?)
        } else {
            None
        };

        // Parse WHERE clause
        let mut where_clause = if self.match_token(TokenType::Where) {
            Some(Where {
                this: self.parse_expression()?,
            })
        } else {
            None
        };

        // Parse CONNECT BY clause (Oracle hierarchical queries)
        let connect = self.parse_connect()?;

        // Parse GROUP BY
        let group_by = if self.check(TokenType::Group) {
            let group_comments = self.current_leading_comments();
            if self.match_keywords(&[TokenType::Group, TokenType::By]) {
                let mut gb = self.parse_group_by()?;
                gb.comments = group_comments;
                Some(gb)
            } else {
                None
            }
        } else if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) && self.check(TokenType::With)
            && (self.check_next_identifier("TOTALS")
                || self.check_next(TokenType::Rollup)
                || self.check_next(TokenType::Cube))
        {
            // ClickHouse: WITH TOTALS/ROLLUP/CUBE without GROUP BY
            self.advance(); // consume WITH
            let totals = self.match_identifier("TOTALS");
            let mut expressions = Vec::new();
            if self.match_token(TokenType::Rollup) {
                expressions.push(Expression::Rollup(Box::new(Rollup {
                    expressions: Vec::new(),
                })));
            } else if self.match_token(TokenType::Cube) {
                expressions.push(Expression::Cube(Box::new(Cube {
                    expressions: Vec::new(),
                })));
            }
            // Check for chained WITH TOTALS after WITH ROLLUP/CUBE
            if !totals && self.check(TokenType::With) && self.check_next_identifier("TOTALS") {
                self.advance();
                self.advance();
            }
            Some(GroupBy {
                expressions,
                all: None,
                totals,
                comments: Vec::new(),
            })
        } else {
            None
        };

        // Parse HAVING
        let having = if self.check(TokenType::Having) {
            let having_comments = self.current_leading_comments();
            self.advance(); // consume HAVING
            Some(Having {
                this: self.parse_expression()?,
                comments: having_comments,
            })
        } else {
            None
        };

        // Parse QUALIFY clause (Snowflake, BigQuery, DuckDB)
        // QUALIFY can appear before or after WINDOW clause
        let mut qualify = if self.match_token(TokenType::Qualify) {
            Some(Qualify {
                this: self.parse_expression()?,
            })
        } else {
            None
        };

        // Parse WINDOW clause (named windows)
        // Only match WINDOW if followed by identifier AS ( (a real window definition)
        // Otherwise "window" may be a table alias (e.g., SELECT * FROM foo window)
        let windows = if self.check(TokenType::Window) && {
            let next_pos = self.current + 1;
            next_pos < self.tokens.len()
                && (self.tokens[next_pos].token_type == TokenType::Var
                    || self.tokens[next_pos].token_type == TokenType::Identifier)
        } {
            self.advance(); // consume WINDOW
            Some(self.parse_named_windows()?)
        } else {
            None
        };

        // QUALIFY can also appear after WINDOW clause (DuckDB)
        let qualify_after_window = if qualify.is_none() && self.match_token(TokenType::Qualify) {
            qualify = Some(Qualify {
                this: self.parse_expression()?,
            });
            true
        } else {
            false
        };

        // Parse DISTRIBUTE BY (Hive/Spark) - comes before SORT BY
        let distribute_by = if self.match_keywords(&[TokenType::Distribute, TokenType::By]) {
            Some(self.parse_distribute_by()?)
        } else {
            None
        };

        // Parse CLUSTER BY (Hive/Spark)
        let cluster_by = if self.match_keywords(&[TokenType::Cluster, TokenType::By]) {
            Some(self.parse_cluster_by()?)
        } else {
            None
        };

        // Parse SORT BY (Hive/Spark) - can come before ORDER BY
        let sort_by = if self.match_keywords(&[TokenType::Sort, TokenType::By]) {
            Some(self.parse_sort_by()?)
        } else {
            None
        };

        // Parse ORDER BY or ORDER SIBLINGS BY (Oracle) - comes after SORT BY
        let order_by = if self.check(TokenType::Order) {
            let order_comments = self.current_leading_comments();
            if self.match_keywords(&[TokenType::Order, TokenType::Siblings, TokenType::By]) {
                // ORDER SIBLINGS BY (Oracle hierarchical queries)
                let mut ob = self.parse_order_by_with_siblings(true)?;
                ob.comments = order_comments;
                Some(ob)
            } else if self.match_keywords(&[TokenType::Order, TokenType::By]) {
                let mut ob = self.parse_order_by()?;
                ob.comments = order_comments;
                Some(ob)
            } else {
                None
            }
        } else {
            None
        };

        // Parse LIMIT (supports MySQL syntax: LIMIT offset, count)
        // DuckDB supports: LIMIT 10 PERCENT or LIMIT 10%
        // Capture trailing comments from the token before LIMIT (e.g., WHERE condition's last token)
        // These comments should be emitted after the LIMIT value, not before LIMIT.
        let pre_limit_comments = if self.check(TokenType::Limit) {
            let mut comments = self.previous_trailing_comments();
            // Also capture leading comments on the LIMIT token (comments on a separate line before LIMIT)
            comments.extend(self.current_leading_comments());
            comments
        } else {
            Vec::new()
        };
        let (limit, offset) = if self.match_token(TokenType::Limit) {
            // Clear the pre-LIMIT comments from the WHERE condition expression to avoid duplication
            if !pre_limit_comments.is_empty() {
                if let Some(ref mut w) = where_clause {
                    Self::clear_rightmost_trailing_comments(&mut w.this);
                }
            }
            // First try parse_unary to check for PERCENT/% modifier.
            // This avoids parse_expression consuming % as the modulo operator.
            // Both "PERCENT" and "%" tokens have TokenType::Percent, but we need to
            // distinguish PERCENT-as-modifier from %-as-modulo. "%" is PERCENT when
            // followed by a clause boundary (OFFSET, end, semicolon, etc.).
            let saved_pos = self.current;
            let (first_expr, has_percent) = {
                let unary_result = self.parse_unary();
                match unary_result {
                    Ok(expr) => {
                        if self.check(TokenType::Percent) && self.is_percent_modifier() {
                            // Found PERCENT keyword or % symbol used as PERCENT modifier
                            self.advance();
                            (expr, true)
                        } else {
                            // No PERCENT - backtrack and use full parse_expression
                            self.current = saved_pos;
                            let full_expr = self.parse_expression()?;
                            // Check again for PERCENT keyword (e.g., after complex expression)
                            let has_pct =
                                if self.check(TokenType::Percent) && self.is_percent_modifier() {
                                    self.advance();
                                    true
                                } else {
                                    false
                                };
                            (full_expr, has_pct)
                        }
                    }
                    Err(_) => {
                        // Unary parsing failed - backtrack and use parse_expression
                        self.current = saved_pos;
                        let full_expr = self.parse_expression()?;
                        let has_pct =
                            if self.check(TokenType::Percent) && self.is_percent_modifier() {
                                self.advance();
                                true
                            } else {
                                false
                            };
                        (full_expr, has_pct)
                    }
                }
            };
            // MySQL syntax: LIMIT offset, count
            if self.match_token(TokenType::Comma) {
                let second_expr = self.parse_expression()?;
                // First expression is offset, second is count
                (
                    Some(Limit {
                        this: second_expr,
                        percent: false,
                        comments: pre_limit_comments.clone(),
                    }),
                    Some(Offset {
                        this: first_expr,
                        rows: None,
                    }),
                )
            } else {
                // Standard: LIMIT count [PERCENT]
                (
                    Some(Limit {
                        this: first_expr,
                        percent: has_percent,
                        comments: pre_limit_comments,
                    }),
                    None,
                )
            }
        } else {
            (None, None)
        };

        // WITH TIES after LIMIT (ClickHouse, DuckDB)
        if limit.is_some() {
            let _ = self.match_keywords(&[TokenType::With, TokenType::Ties]);
        }

        // Parse OFFSET (if not already parsed from MySQL LIMIT syntax)
        // Standard SQL syntax: OFFSET n [ROW|ROWS]
        // Some dialects (Presto/Trino) support: OFFSET n LIMIT m
        let (limit, offset) = if offset.is_none() && self.match_token(TokenType::Offset) {
            let expr = self.parse_expression()?;
            // Consume optional ROW or ROWS keyword and track it
            let rows = if self.match_token(TokenType::Row) || self.match_token(TokenType::Rows) {
                Some(true)
            } else {
                None
            };
            let offset = Some(Offset { this: expr, rows });

            // Check for LIMIT after OFFSET (Presto/Trino syntax: OFFSET n LIMIT m)
            let limit = if limit.is_none() && self.match_token(TokenType::Limit) {
                let limit_expr = self.parse_expression()?;
                Some(Limit {
                    this: limit_expr,
                    percent: false,
                    comments: Vec::new(),
                })
            } else {
                limit
            };

            (limit, offset)
        } else {
            (limit, offset)
        };

        // ClickHouse: LIMIT ... BY expressions
        let limit_by = if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) && limit.is_some()
            && self.match_token(TokenType::By)
        {
            let expressions = self.parse_expression_list()?;
            if expressions.is_empty() {
                return Err(self.parse_error("Expected expression after LIMIT BY"));
            }
            Some(expressions)
        } else {
            None
        };

        // ClickHouse: second LIMIT after LIMIT BY (LIMIT n BY expr LIMIT m)
        // Also supports LIMIT offset, count syntax
        let (limit, offset) = if limit_by.is_some() && self.match_token(TokenType::Limit) {
            let first_expr = self.parse_expression()?;
            if self.match_token(TokenType::Comma) {
                // LIMIT offset, count
                let count_expr = self.parse_expression()?;
                (
                    Some(Limit {
                        this: count_expr,
                        percent: false,
                        comments: Vec::new(),
                    }),
                    Some(Offset {
                        this: first_expr,
                        rows: None,
                    }),
                )
            } else {
                (
                    Some(Limit {
                        this: first_expr,
                        percent: false,
                        comments: Vec::new(),
                    }),
                    offset,
                )
            }
        } else {
            (limit, offset)
        };

        // Parse FETCH FIRST/NEXT clause
        let fetch = if self.match_token(TokenType::Fetch) {
            Some(self.parse_fetch()?)
        } else {
            None
        };

        // Parse SAMPLE / TABLESAMPLE clause
        let sample = self.parse_sample_clause()?;

        // Parse FOR UPDATE/SHARE locks or FOR XML (T-SQL)
        let (locks, for_xml) = self.parse_locks_and_for_xml()?;

        // TSQL: OPTION clause (e.g., OPTION(LABEL = 'foo', HASH JOIN))
        let option = if self.check_identifier("OPTION") && self.check_next(TokenType::LParen) {
            self.advance(); // consume OPTION
            self.advance(); // consume (
            let mut content = String::from("OPTION(");
            let mut depth = 1;
            while !self.is_at_end() && depth > 0 {
                let tok = self.advance();
                if tok.token_type == TokenType::LParen {
                    depth += 1;
                } else if tok.token_type == TokenType::RParen {
                    depth -= 1;
                }
                if depth > 0 {
                    if tok.token_type == TokenType::String {
                        if content.len() > 7 && !content.ends_with('(') && !content.ends_with(' ') {
                            content.push(' ');
                        }
                        content.push('\'');
                        content.push_str(&tok.text.replace('\'', "''"));
                        content.push('\'');
                    } else if tok.token_type == TokenType::Eq {
                        content.push_str(" = ");
                    } else if tok.token_type == TokenType::Comma {
                        content.push_str(", ");
                    } else {
                        if content.len() > 7 && !content.ends_with('(') && !content.ends_with(' ') {
                            content.push(' ');
                        }
                        content.push_str(&tok.text);
                    }
                }
            }
            content.push(')');
            Some(content)
        } else {
            None
        };

        // ClickHouse: SETTINGS and FORMAT clauses after LIMIT/OFFSET/FETCH
        let (settings, format) = if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) {
            let mut settings: Option<Vec<Expression>> = None;
            let mut format: Option<Expression> = None;

            loop {
                if settings.is_none() && self.match_token(TokenType::Settings) {
                    let mut settings_exprs = Vec::new();
                    loop {
                        settings_exprs.push(self.parse_expression()?);
                        if !self.match_token(TokenType::Comma) {
                            break;
                        }
                    }
                    settings = Some(settings_exprs);
                    continue;
                }

                if format.is_none() && self.match_token(TokenType::Format) {
                    // ClickHouse: FORMAT Null is valid (Null is a keyword token, not an identifier)
                    let ident = if self.check(TokenType::Null) {
                        let text = self.advance().text;
                        Identifier::new(text)
                    } else {
                        self.expect_identifier_or_keyword_with_quoted()?
                    };
                    format = Some(Expression::Identifier(ident));
                    // ClickHouse: FORMAT <name> may be followed by inline data
                    // (CSV rows, JSON objects, etc.) — consume to semicolon
                    if matches!(
                        self.config.dialect,
                        Some(crate::dialects::DialectType::ClickHouse)
                    ) && !self.is_at_end()
                        && !self.check(TokenType::Semicolon)
                        && !self.check(TokenType::Settings)
                    {
                        while !self.is_at_end() && !self.check(TokenType::Semicolon) {
                            self.advance();
                        }
                    }
                    continue;
                }

                break;
            }

            (settings, format)
        } else {
            (None, None)
        };

        let select = Select {
            expressions,
            from,
            joins,
            lateral_views,
            prewhere,
            where_clause,
            group_by,
            having,
            qualify,
            order_by,
            distribute_by,
            cluster_by,
            sort_by,
            limit,
            offset,
            limit_by,
            fetch,
            distinct,
            distinct_on,
            top,
            with: None,
            sample,
            settings,
            format,
            windows,
            hint,
            connect,
            into,
            locks,
            for_xml,
            leading_comments,
            post_select_comments,
            kind,
            operation_modifiers,
            qualify_after_window,
            option,
            exclude,
        };

        // Check for set operations (UNION, INTERSECT, EXCEPT)
        let result = Expression::Select(Box::new(select));
        self.parse_set_operation(result)
    }

    /// Parse a WITH clause (CTEs)
    fn parse_with(&mut self) -> Result<Expression> {
        use crate::dialects::DialectType;

        let with_token = self.expect(TokenType::With)?;
        let leading_comments = with_token.comments;

        let recursive = self.match_token(TokenType::Recursive);
        let mut ctes = Vec::new();

        loop {
            // ClickHouse supports expression-first WITH items:
            // WITH <expr> AS <alias> SELECT ...
            if matches!(self.config.dialect, Some(DialectType::ClickHouse)) {
                let saved_pos = self.current;
                if let Ok(expr) = self.parse_expression() {
                    // Check if parse_expression already consumed the AS alias
                    // (e.g., `(1, 2) AS a` gets parsed as Alias(Tuple, "a") by the tuple alias handler)
                    let (inner_expr, alias_opt) = if let Expression::Alias(ref alias_box) = expr {
                        (alias_box.this.clone(), Some(alias_box.alias.clone()))
                    } else {
                        (expr, None)
                    };

                    if let Some(alias) = alias_opt {
                        // Expression already had AS alias consumed
                        ctes.push(Cte {
                            alias,
                            this: inner_expr,
                            columns: Vec::new(),
                            materialized: None,
                            key_expressions: Vec::new(),
                            alias_first: false,
                            comments: Vec::new(),
                        });

                        if self.match_token(TokenType::Comma) {
                            continue;
                        }
                        break;
                    } else if self.match_token(TokenType::As)
                        && self.is_identifier_or_keyword_token()
                    {
                        // Require AS <alias> to disambiguate from standard CTE syntax
                        let alias = self.expect_identifier_or_keyword_with_quoted()?;
                        ctes.push(Cte {
                            alias,
                            this: inner_expr,
                            columns: Vec::new(),
                            materialized: None,
                            key_expressions: Vec::new(),
                            alias_first: false,
                            comments: Vec::new(),
                        });

                        if self.match_token(TokenType::Comma) {
                            continue;
                        }
                        break;
                    } else if self.check(TokenType::Select) || self.check(TokenType::Comma) {
                        // ClickHouse: WITH expr SELECT ... (unaliased expression in CTE)
                        ctes.push(Cte {
                            alias: Identifier::new(format!("{}", inner_expr)),
                            this: inner_expr,
                            columns: Vec::new(),
                            materialized: None,
                            key_expressions: Vec::new(),
                            alias_first: false,
                            comments: Vec::new(),
                        });

                        if self.match_token(TokenType::Comma) {
                            continue;
                        }
                        break;
                    }
                }
                // Fall back to standard CTE parsing
                self.current = saved_pos;
            }

            // CTE names can be keywords like 'view', 'use', 'all', etc.
            let name = self.expect_identifier_or_alias_keyword_with_quoted()?;

            // Optional column list
            // But first check for Snowflake-style CTE: WITH t (SELECT ...) - no AS keyword
            // In that case, LParen is followed by SELECT, not column names
            let columns = if self.check(TokenType::LParen) && !self.check_next(TokenType::Select) {
                self.advance(); // consume LParen
                let cols = self.parse_identifier_list()?;
                self.expect(TokenType::RParen)?;
                cols
            } else {
                Vec::new()
            };

            // Optional USING KEY (columns) for DuckDB recursive CTEs
            let key_expressions = if self.match_keywords(&[TokenType::Using, TokenType::Key]) {
                self.expect(TokenType::LParen)?;
                let keys = self.parse_identifier_list()?;
                self.expect(TokenType::RParen)?;
                keys
            } else {
                Vec::new()
            };

            // ClickHouse: keyword -> body AS alias (single-param lambda where param is a keyword)
            // e.g., WITH time -> sin(time * 2 * pi()) AS sine_wave
            if matches!(self.config.dialect, Some(DialectType::ClickHouse))
                && self.check(TokenType::Arrow)
            {
                self.advance(); // consume ->
                let body = self.parse_expression()?;
                let lambda = Expression::Lambda(Box::new(LambdaExpr {
                    parameters: vec![name.clone()],
                    body,
                    colon: false,
                    parameter_types: Vec::new(),
                }));
                // Expect AS alias
                if self.match_token(TokenType::As) && self.is_identifier_or_keyword_token() {
                    let alias = self.expect_identifier_or_keyword_with_quoted()?;
                    ctes.push(Cte {
                        alias,
                        this: lambda,
                        columns: Vec::new(),
                        materialized: None,
                        key_expressions: Vec::new(),
                        alias_first: false,
                        comments: Vec::new(),
                    });
                } else {
                    // Unaliased lambda CTE
                    ctes.push(Cte {
                        alias: name,
                        this: lambda,
                        columns: Vec::new(),
                        materialized: None,
                        key_expressions: Vec::new(),
                        alias_first: false,
                        comments: Vec::new(),
                    });
                }
                if self.match_token(TokenType::Comma) {
                    continue;
                }
                break;
            }

            // AS is optional (Snowflake allows WITH t (SELECT ...) without AS)
            let cte_comments = if self.match_token(TokenType::As) {
                // Capture trailing comments from the AS token
                // e.g., "WITH a AS /* comment */ (...)" -> comment goes after alias
                self.previous_trailing_comments()
            } else {
                Vec::new()
            };

            // Check for MATERIALIZED or NOT MATERIALIZED
            let materialized = if self.match_token(TokenType::Materialized) {
                Some(true)
            } else if self.match_token(TokenType::Not) {
                self.expect(TokenType::Materialized)?;
                Some(false)
            } else {
                None
            };

            self.expect(TokenType::LParen)?;
            let query = self.parse_statement()?;
            self.expect(TokenType::RParen)?;

            ctes.push(Cte {
                alias: name,
                this: query,
                columns,
                materialized,
                key_expressions,
                alias_first: true,
                comments: cte_comments,
            });

            if !self.match_token(TokenType::Comma) {
                // Check for WITH merging: WITH a AS (...) WITH b AS (...) -> merged
                // If the next token is WITH (not followed by nothing), continue parsing CTEs
                if self.check(TokenType::With) {
                    self.advance(); // consume the redundant WITH keyword
                                    // Check if this WITH is also RECURSIVE
                    if self.match_token(TokenType::Recursive) && !recursive {
                        // If second WITH is RECURSIVE but first wasn't, ignore (keep non-recursive)
                    }
                    continue; // continue the loop to parse more CTEs
                }
                break;
            }
            // WI-14f: Skip redundant WITH keyword after comma in CTE list
            // e.g., WITH a AS (SELECT 1), WITH b AS (SELECT 2) SELECT *
            self.match_token(TokenType::With);
        }

        // Parse optional SEARCH/CYCLE clause for recursive CTEs (PostgreSQL)
        // Syntax: SEARCH BREADTH|DEPTH FIRST BY column SET column [USING column]
        //     or: CYCLE column SET column USING column
        let search = self.parse_recursive_with_search()?;

        // Parse the main query
        let mut main_query = self.parse_statement()?;

        // Unwrap parenthesized wrappers to find the inner SELECT
        // (matching Python sqlglot: while isinstance(this, Subquery) and this.is_wrapper)
        loop {
            match main_query {
                Expression::Paren(paren) => {
                    main_query = paren.this;
                }
                Expression::Subquery(ref sub)
                    if sub.alias.is_none()
                        && sub.order_by.is_none()
                        && sub.limit.is_none()
                        && sub.offset.is_none() =>
                {
                    // Unwrap Subquery wrapper (parenthesized query without modifiers)
                    if let Expression::Subquery(sub) = main_query {
                        main_query = sub.this;
                    } else {
                        break;
                    }
                }
                _ => break,
            }
        }

        // Attach WITH to the main query
        let with_clause = With {
            ctes,
            recursive,
            leading_comments,
            search,
        };
        match &mut main_query {
            Expression::Select(ref mut select) => {
                select.with = Some(with_clause);
            }
            Expression::Union(ref mut union) => {
                union.with = Some(with_clause);
            }
            Expression::Intersect(ref mut intersect) => {
                intersect.with = Some(with_clause);
            }
            Expression::Except(ref mut except) => {
                except.with = Some(with_clause);
            }
            Expression::Update(ref mut update) => {
                update.with = Some(with_clause);
            }
            Expression::Insert(ref mut insert) => {
                insert.with = Some(with_clause);
            }
            Expression::Delete(ref mut delete) => {
                delete.with = Some(with_clause);
            }
            Expression::CreateTable(ref mut ct) => {
                ct.with_cte = Some(with_clause);
            }
            Expression::Pivot(ref mut pivot) => {
                pivot.with = Some(with_clause);
            }
            _ => {}
        }

        Ok(main_query)
    }

    /// Parse SELECT expressions
    fn parse_select_expressions(&mut self) -> Result<Vec<Expression>> {
        let mut expressions = Vec::new();

        loop {
            // Check if we're at end of select list (empty list case for TSQL TOP)
            // This allows queries like "SELECT TOP 10 PERCENT" with no columns
            // Also check for Oracle BULK COLLECT INTO sequence
            // ClickHouse: minus() is tokenized as Except but should be treated as function
            let is_ch_keyword_func = matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && (self.check(TokenType::Except)
                || self.check(TokenType::Intersect))
                && self.check_next(TokenType::LParen);
            // ClickHouse: `from`/`except` can be column names when followed by an operator
            // (e.g., `from + from`, `from in [0]`, `from, ...`)
            // Also: `from FROM t` — two consecutive FROM tokens means first is column name
            let is_ch_keyword_as_column = matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && (self.check(TokenType::From)
                || self.check(TokenType::Except))
                && {
                    let next_tt = self
                        .peek_nth(1)
                        .map(|t| t.token_type)
                        .unwrap_or(TokenType::Semicolon);
                    matches!(
                        next_tt,
                        TokenType::Plus | TokenType::Dash | TokenType::Star | TokenType::Slash
                        | TokenType::Percent | TokenType::Eq | TokenType::Neq | TokenType::Lt
                        | TokenType::Gt | TokenType::Lte | TokenType::Gte
                        | TokenType::And | TokenType::Or | TokenType::Comma | TokenType::Dot
                        | TokenType::In | TokenType::Is | TokenType::Not | TokenType::Like
                        | TokenType::Between | TokenType::Semicolon | TokenType::RParen
                        | TokenType::As | TokenType::DPipe | TokenType::Amp | TokenType::Pipe
                        | TokenType::LBracket
                        // Two consecutive FROM tokens: first is column name (e.g., SELECT from FROM t)
                        | TokenType::From
                    )
                };
            if !is_ch_keyword_func
                && !is_ch_keyword_as_column
                && (self.is_at_end()
                    || self.check(TokenType::From)
                    || self.check(TokenType::Where)
                    || self.check(TokenType::Into)
                    || self.check(TokenType::Union)
                    || self.check(TokenType::Intersect)
                    || self.check(TokenType::Except)
                    || self.check(TokenType::Order)
                    || self.check(TokenType::Limit)
                    || self.check(TokenType::Semicolon)
                    || self.check_text_seq(&["BULK", "COLLECT", "INTO"]))
            {
                break;
            }

            // Handle star
            if self.check(TokenType::Star) {
                self.advance();
                let star_trailing_comments = self.previous_trailing_comments();
                let star = self.parse_star_modifiers_with_comments(None, star_trailing_comments)?;
                let mut star_expr = Expression::Star(star);
                // ClickHouse: * APPLY(func) or * APPLY func or * APPLY(x -> expr) column transformer
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) {
                    while self.check(TokenType::Apply) {
                        self.advance(); // consume APPLY
                        let apply_expr = if self.match_token(TokenType::LParen) {
                            // Could be APPLY(func_name) or APPLY(x -> expr)
                            let expr = self.parse_expression()?;
                            self.expect(TokenType::RParen)?;
                            expr
                        } else {
                            // APPLY func or APPLY x -> expr (no parens)
                            // Parse as expression to handle lambdas
                            self.parse_expression()?
                        };
                        star_expr = Expression::Apply(Box::new(crate::expressions::Apply {
                            this: Box::new(star_expr),
                            expression: Box::new(apply_expr),
                        }));
                    }
                }
                // ClickHouse: Also handle EXCEPT/REPLACE between APPLYs:
                // * APPLY(toDate) EXCEPT(i, j) APPLY(any)
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) && (self.check(TokenType::Except)
                    || self.check(TokenType::Exclude)
                    || self.check(TokenType::Replace))
                {
                    // Consume EXCEPT/REPLACE modifiers after APPLY
                    self.parse_star_modifiers(None)?;
                    // Continue with more APPLYs
                    while self.check(TokenType::Apply) {
                        self.advance();
                        let apply_expr = if self.match_token(TokenType::LParen) {
                            let expr = self.parse_expression()?;
                            self.expect(TokenType::RParen)?;
                            expr
                        } else {
                            self.parse_expression()?
                        };
                        star_expr = Expression::Apply(Box::new(crate::expressions::Apply {
                            this: Box::new(star_expr),
                            expression: Box::new(apply_expr),
                        }));
                    }
                }
                // ClickHouse: * followed by operators (e.g., * IS NOT NULL, * AND expr)
                // Treat * as a regular expression and continue parsing operators
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) && matches!(
                    self.peek().token_type,
                    TokenType::Is
                        | TokenType::And
                        | TokenType::Or
                        | TokenType::Eq
                        | TokenType::Neq
                        | TokenType::Lt
                        | TokenType::Gt
                        | TokenType::Lte
                        | TokenType::Gte
                        | TokenType::Not
                        | TokenType::Plus
                        | TokenType::Dash
                        | TokenType::Slash
                        | TokenType::Percent
                        | TokenType::Like
                        | TokenType::Between
                        | TokenType::In
                ) {
                    // Re-parse from the operator with star_expr as the left side
                    let left = star_expr;
                    // Use parse_comparison / parse_is chain
                    if self.check(TokenType::Is) {
                        self.advance(); // consume IS
                        let not = self.match_token(TokenType::Not);
                        if self.match_token(TokenType::Null) {
                            star_expr = if not {
                                Expression::Not(Box::new(UnaryOp {
                                    this: Expression::Is(Box::new(BinaryOp::new(
                                        left,
                                        Expression::Null(Null),
                                    ))),
                                    inferred_type: None,
                                }))
                            } else {
                                Expression::Is(Box::new(BinaryOp::new(
                                    left,
                                    Expression::Null(Null),
                                )))
                            };
                        } else {
                            let right = self.parse_or()?;
                            star_expr = if not {
                                Expression::Not(Box::new(UnaryOp {
                                    this: Expression::Is(Box::new(BinaryOp::new(left, right))),
                                    inferred_type: None,
                                }))
                            } else {
                                Expression::Is(Box::new(BinaryOp::new(left, right)))
                            };
                        }
                    } else if self.match_token(TokenType::And) {
                        let right = self.parse_or()?;
                        star_expr = Expression::And(Box::new(BinaryOp::new(left, right)));
                    } else if self.match_token(TokenType::Or) {
                        let right = self.parse_or()?;
                        star_expr = Expression::Or(Box::new(BinaryOp::new(left, right)));
                    } else {
                        let op_token = self.advance();
                        let right = self.parse_or()?;
                        star_expr = match op_token.token_type {
                            TokenType::Eq => Expression::Eq(Box::new(BinaryOp::new(left, right))),
                            TokenType::Neq => Expression::Neq(Box::new(BinaryOp::new(left, right))),
                            TokenType::Lt => Expression::Lt(Box::new(BinaryOp::new(left, right))),
                            TokenType::Gt => Expression::Gt(Box::new(BinaryOp::new(left, right))),
                            TokenType::Lte => Expression::Lte(Box::new(BinaryOp::new(left, right))),
                            TokenType::Gte => Expression::Gte(Box::new(BinaryOp::new(left, right))),
                            TokenType::Plus => {
                                Expression::Add(Box::new(BinaryOp::new(left, right)))
                            }
                            TokenType::Dash => {
                                Expression::Sub(Box::new(BinaryOp::new(left, right)))
                            }
                            _ => left, // fallback
                        };
                    }
                }
                expressions.push(star_expr);
            } else {
                // Capture leading comments from the first token before parsing
                // These are comments on a separate line before the expression
                let leading_comments = self.current_leading_comments();
                let expr = self.parse_expression()?;

                // ClickHouse: COLUMNS(id, value) EXCEPT (id) REPLACE (5 AS id) APPLY func
                // Also: a.* APPLY(toDate) EXCEPT(i, j) APPLY(any) - qualified star with APPLY
                let expr = if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) {
                    let is_columns_func = match &expr {
                        Expression::Function(f) => f.name.eq_ignore_ascii_case("COLUMNS"),
                        Expression::MethodCall(m) => m.method.name.eq_ignore_ascii_case("COLUMNS"),
                        Expression::Columns(_) => true,
                        _ => false,
                    };
                    let is_qualified_star = matches!(&expr, Expression::Star(_));
                    if (is_columns_func || is_qualified_star)
                        && (self.check(TokenType::Except)
                            || self.check(TokenType::Exclude)
                            || self.check(TokenType::Replace)
                            || self.check(TokenType::Apply))
                    {
                        let mut result = expr;
                        // Parse any mix of EXCEPT/REPLACE/APPLY in any order
                        // e.g., * APPLY(toDate) EXCEPT(i, j) APPLY(any)
                        loop {
                            if self.check(TokenType::Except) || self.check(TokenType::Exclude) {
                                // Parse EXCEPT/EXCLUDE modifier
                                self.advance();
                                self.match_identifier("STRICT");
                                if self.match_token(TokenType::LParen) {
                                    loop {
                                        if self.check(TokenType::RParen) {
                                            break;
                                        }
                                        let _ = self.parse_expression()?;
                                        if !self.match_token(TokenType::Comma) {
                                            break;
                                        }
                                    }
                                    self.expect(TokenType::RParen)?;
                                } else if self.is_identifier_token()
                                    || self.is_safe_keyword_as_identifier()
                                {
                                    let _ = self.parse_expression()?;
                                }
                            } else if self.check(TokenType::Replace) {
                                // Parse REPLACE modifier: REPLACE (expr AS alias, ...)
                                self.advance();
                                self.match_identifier("STRICT");
                                if self.match_token(TokenType::LParen) {
                                    loop {
                                        if self.check(TokenType::RParen) {
                                            break;
                                        }
                                        let _ = self.parse_expression()?;
                                        if self.match_token(TokenType::As) {
                                            if self.is_identifier_token()
                                                || self.is_safe_keyword_as_identifier()
                                            {
                                                self.advance();
                                            }
                                        }
                                        if !self.match_token(TokenType::Comma) {
                                            break;
                                        }
                                    }
                                    self.expect(TokenType::RParen)?;
                                } else {
                                    let _ = self.parse_expression()?;
                                    if self.match_token(TokenType::As) {
                                        if self.is_identifier_token()
                                            || self.is_safe_keyword_as_identifier()
                                        {
                                            self.advance();
                                        }
                                    }
                                }
                            } else if self.check(TokenType::Apply) {
                                // Parse APPLY transformer
                                self.advance();
                                let apply_expr = if self.match_token(TokenType::LParen) {
                                    let e = self.parse_expression()?;
                                    self.expect(TokenType::RParen)?;
                                    e
                                } else {
                                    self.parse_expression()?
                                };
                                result = Expression::Apply(Box::new(crate::expressions::Apply {
                                    this: Box::new(result),
                                    expression: Box::new(apply_expr),
                                }));
                            } else {
                                break;
                            }
                        }
                        result
                    } else {
                        expr
                    }
                } else {
                    expr
                };

                // Capture comments between expression and potential AS
                let pre_alias_comments = self.previous_trailing_comments();

                // DuckDB prefix alias syntax: identifier: expression (e.g., "foo: 1" means "1 AS foo")
                // Check if the expression is a simple identifier followed by a colon
                let expr = if self.check(TokenType::Colon) && !self.check_next(TokenType::Colon) {
                    // Extract the alias name from the identifier expression
                    let alias_ident = match &expr {
                        Expression::Identifier(id) => Some(id.clone()),
                        Expression::Column(col) if col.table.is_none() => Some(col.name.clone()),
                        _ => None,
                    };
                    if let Some(alias) = alias_ident {
                        // Consume the colon
                        self.advance();
                        let colon_comments = self.previous_trailing_comments();
                        // Parse the actual value expression
                        let value = self.parse_expression()?;
                        let value_trailing = self.previous_trailing_comments();
                        // For colon-alias (foo: expr), comments between alias and colon should
                        // become trailing comments (placed after the alias in output).
                        // Comments after the value expression are also trailing.
                        let mut all_trailing = pre_alias_comments.clone();
                        all_trailing.extend(colon_comments);
                        all_trailing.extend(value_trailing);
                        Expression::Alias(Box::new(Alias {
                            this: value,
                            alias,
                            column_aliases: Vec::new(),
                            pre_alias_comments: Vec::new(),
                            trailing_comments: all_trailing,
                            inferred_type: None,
                        }))
                    } else {
                        // Not a simple identifier, fall through to normal alias handling
                        // (this handles cases where the expression is complex before the colon)
                        expr
                    }
                } else if self.match_token(TokenType::As) {
                    // Capture comments from AS token (e.g., AS /* foo */ (a, b, c))
                    // These go into trailing_comments (after the alias), not pre_alias_comments
                    let as_comments = self.previous_trailing_comments();
                    // Check for column aliases: AS (col1, col2) - used by POSEXPLODE etc.
                    if self.match_token(TokenType::LParen) {
                        let mut column_aliases = Vec::new();
                        loop {
                            if let Some(col_expr) = self.parse_id_var()? {
                                if let Expression::Identifier(id) = col_expr {
                                    column_aliases.push(id);
                                }
                            } else {
                                break;
                            }
                            if !self.match_token(TokenType::Comma) {
                                break;
                            }
                        }
                        self.match_token(TokenType::RParen);
                        let mut trailing_comments = as_comments;
                        trailing_comments.extend(self.previous_trailing_comments());
                        Expression::Alias(Box::new(Alias {
                            this: expr,
                            alias: Identifier::new(String::new()),
                            column_aliases,
                            pre_alias_comments,
                            trailing_comments,
                            inferred_type: None,
                        }))
                    } else {
                        // Allow keywords as aliases (e.g., SELECT 1 AS filter)
                        // Use _with_quoted to preserve quoted alias
                        let alias = self.expect_identifier_or_keyword_with_quoted()?;
                        let mut trailing_comments = self.previous_trailing_comments();
                        // If parse_comparison stored pending leading comments (no comparison
                        // followed), use those. Otherwise use the leading_comments we captured
                        // before parse_expression(). Both come from the same token, so we
                        // only add one set to avoid duplication.
                        if !self.pending_leading_comments.is_empty() {
                            trailing_comments.extend(self.pending_leading_comments.drain(..));
                        } else {
                            trailing_comments.extend(leading_comments.iter().cloned());
                        }
                        Expression::Alias(Box::new(Alias {
                            this: expr,
                            alias,
                            column_aliases: Vec::new(),
                            pre_alias_comments,
                            trailing_comments,
                            inferred_type: None,
                        }))
                    }
                } else if ((self.check(TokenType::Var) && !self.check_keyword()) || self.check(TokenType::QuotedIdentifier) || self.can_be_alias_keyword() || self.is_command_keyword_as_alias() || self.check(TokenType::Overlaps)
                    // ClickHouse: APPLY without ( is an implicit alias (e.g., SELECT col apply)
                    || (self.check(TokenType::Apply) && !self.check_next(TokenType::LParen)
                        && matches!(self.config.dialect, Some(crate::dialects::DialectType::ClickHouse))))
                    && !self.check_text_seq(&["BULK", "COLLECT", "INTO"])
                    // ClickHouse clauses must not be consumed as implicit aliases.
                    && !(matches!(self.config.dialect, Some(crate::dialects::DialectType::ClickHouse))
                        && (self.check(TokenType::Format) || self.check(TokenType::Settings)))
                    // LIMIT/OFFSET/FETCH are clause starters in most dialects and must not
                    // be consumed as implicit aliases in SELECT lists.
                    && !(
                        self.check(TokenType::Fetch)
                        || ((self.check(TokenType::Limit) || self.check(TokenType::Offset))
                            && !matches!(
                                self.config.dialect,
                                Some(crate::dialects::DialectType::Spark)
                                    | Some(crate::dialects::DialectType::Hive)
                            ))
                    )
                    // GROUP BY / ORDER BY are clause boundaries, not aliases.
                    && !self.check_text_seq(&["GROUP", "BY"])
                    && !self.check_text_seq(&["ORDER", "BY"])
                    // WINDOW is a clause boundary (named window definitions), not an alias.
                    && !self.check(TokenType::Window)
                    // ClickHouse: PARALLEL WITH is a statement separator, not an alias.
                    && !(self.check_identifier("PARALLEL") && self.check_next(TokenType::With)
                        && matches!(self.config.dialect, Some(crate::dialects::DialectType::ClickHouse)))
                {
                    // Implicit alias (without AS) - allow Var tokens, QuotedIdentifiers, command keywords (like GET, PUT, etc.), and OVERLAPS
                    // But NOT when it's the Oracle BULK COLLECT INTO sequence
                    let alias_token = self.advance();
                    let alias_text = alias_token.text.clone();
                    let is_quoted = alias_token.token_type == TokenType::QuotedIdentifier;
                    let trailing_comments = self.previous_trailing_comments();
                    Expression::Alias(Box::new(Alias {
                        this: expr,
                        alias: Identifier {
                            name: alias_text,
                            quoted: is_quoted,
                            trailing_comments: Vec::new(),
                            span: None,
                        },
                        column_aliases: Vec::new(),
                        pre_alias_comments,
                        trailing_comments,
                        inferred_type: None,
                    }))
                } else if !pre_alias_comments.is_empty() {
                    // Only wrap in Annotated if the expression doesn't already handle trailing comments.
                    // BinaryOp, Column, Cast, Function, etc. have their own trailing_comments field that the generator uses.
                    let already_has_trailing = matches!(
                        &expr,
                        Expression::Add(_)
                            | Expression::Sub(_)
                            | Expression::Mul(_)
                            | Expression::Div(_)
                            | Expression::Mod(_)
                            | Expression::Concat(_)
                            | Expression::BitwiseAnd(_)
                            | Expression::BitwiseOr(_)
                            | Expression::BitwiseXor(_)
                            | Expression::Column(_)
                            | Expression::Paren(_)
                            | Expression::Annotated(_)
                            | Expression::Cast(_)
                            | Expression::Function(_)
                            | Expression::Subquery(_)
                    );
                    if already_has_trailing {
                        expr
                    } else {
                        // Wrap in Annotated to preserve trailing comments
                        Expression::Annotated(Box::new(Annotated {
                            this: expr,
                            trailing_comments: pre_alias_comments,
                        }))
                    }
                } else if !leading_comments.is_empty() {
                    // Wrap in Annotated to preserve leading comments as trailing comments
                    Expression::Annotated(Box::new(Annotated {
                        this: expr,
                        trailing_comments: leading_comments,
                    }))
                } else {
                    expr
                };

                expressions.push(expr);
            }

            if !self.match_token(TokenType::Comma) {
                break;
            }

            // Handle trailing comma (ClickHouse supports trailing commas in SELECT)
            // ClickHouse: `from` after comma is a column name if followed by an operator
            // (e.g., `from + from` or `from in [0]`), comma, or line-end
            let from_is_column = matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && self.check(TokenType::From)
                && {
                    let next_tt = self
                        .peek_nth(1)
                        .map(|t| t.token_type)
                        .unwrap_or(TokenType::Semicolon);
                    matches!(
                        next_tt,
                        TokenType::Plus
                            | TokenType::Dash
                            | TokenType::Star
                            | TokenType::Slash
                            | TokenType::Percent
                            | TokenType::Eq
                            | TokenType::Neq
                            | TokenType::Lt
                            | TokenType::Gt
                            | TokenType::Lte
                            | TokenType::Gte
                            | TokenType::And
                            | TokenType::Or
                            | TokenType::Comma
                            | TokenType::Dot
                            | TokenType::In
                            | TokenType::Is
                            | TokenType::Not
                            | TokenType::Like
                            | TokenType::Between
                            | TokenType::Semicolon
                            | TokenType::RParen
                            | TokenType::As
                            | TokenType::DPipe
                            | TokenType::Amp
                            | TokenType::Pipe
                            | TokenType::LBracket
                    )
                };
            if (self.config.allow_trailing_commas
                || matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ))
                && (!from_is_column && self.check_from_keyword()
                    || self.check(TokenType::Where)
                    || self.check(TokenType::GroupBy)
                    || self.check(TokenType::Having)
                    || self.check(TokenType::Order)
                    || self.check(TokenType::Limit)
                    || self.check(TokenType::Union)
                    || self.check(TokenType::Intersect)
                    || (self.check(TokenType::Except) && !self.check_next(TokenType::LParen) && !self.check_next(TokenType::Comma))
                    || self.check(TokenType::Semicolon)
                    || self.check(TokenType::RParen)
                    // SETTINGS/FORMAT only as boundaries when NOT followed by ( or [ (function/column ref)
                    || (self.check(TokenType::Settings) && !self.check_next(TokenType::LParen) && !self.check_next(TokenType::LBracket))
                    || (self.check(TokenType::Format) && !self.check_next(TokenType::LParen))
                    || self.is_at_end())
            {
                break;
            }
        }

        Ok(expressions)
    }

    /// Parse DuckDB FROM-first query syntax
    /// FROM tbl = SELECT * FROM tbl
    /// FROM tbl SELECT col1, col2 = SELECT col1, col2 FROM tbl
    fn parse_from_first_query(&mut self) -> Result<Expression> {
        self.expect(TokenType::From)?;

        // Parse the FROM clause (table references)
        let from = self.parse_from()?;

        // Check if there's an explicit SELECT clause after FROM
        let expressions = if self.check(TokenType::Select) {
            self.advance(); // consume SELECT
            self.parse_select_expressions()?
        } else {
            // No explicit SELECT means SELECT *
            vec![Expression::Star(crate::expressions::Star {
                table: None,
                except: None,
                replace: None,
                rename: None,
                trailing_comments: Vec::new(),
                span: None,
            })]
        };

        // Parse PREWHERE clause (ClickHouse specific)
        let prewhere = if self.match_token(TokenType::Prewhere) {
            Some(self.parse_expression()?)
        } else {
            None
        };

        // Parse WHERE clause
        let where_clause = if self.match_token(TokenType::Where) {
            Some(Where {
                this: self.parse_expression()?,
            })
        } else {
            None
        };

        // Parse GROUP BY
        let group_by = if self.match_token(TokenType::Group) {
            self.expect(TokenType::By)?;
            let mut groups = Vec::new();
            loop {
                groups.push(self.parse_expression()?);
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            Some(GroupBy {
                expressions: groups,
                all: None,
                totals: false,
                comments: Vec::new(),
            })
        } else {
            None
        };

        // Parse HAVING
        let having = if self.match_token(TokenType::Having) {
            Some(Having {
                this: self.parse_expression()?,
                comments: Vec::new(),
            })
        } else {
            None
        };

        // Parse ORDER BY
        let order_by = if self.match_token(TokenType::Order) {
            self.expect(TokenType::By)?;
            Some(self.parse_order_by()?)
        } else {
            None
        };

        // Parse LIMIT
        let limit = if self.match_token(TokenType::Limit) {
            let first_expr = self.parse_expression()?;
            Some(Limit {
                this: first_expr,
                percent: false,
                comments: Vec::new(),
            })
        } else {
            None
        };

        // Parse OFFSET
        let offset = if self.match_token(TokenType::Offset) {
            let expr = self.parse_expression()?;
            let rows = if self.match_token(TokenType::Row) || self.match_token(TokenType::Rows) {
                Some(true)
            } else {
                None
            };
            Some(Offset { this: expr, rows })
        } else {
            None
        };

        // Build SELECT expression
        let select = Select {
            expressions,
            from: Some(from),
            joins: Vec::new(),
            lateral_views: Vec::new(),
            prewhere,
            where_clause,
            group_by,
            having,
            qualify: None,
            order_by,
            distribute_by: None,
            cluster_by: None,
            sort_by: None,
            limit,
            offset,
            limit_by: None,
            fetch: None,
            distinct: false,
            distinct_on: None,
            top: None,
            with: None,
            sample: None,
            settings: None,
            format: None,
            windows: None,
            hint: None,
            connect: None,
            into: None,
            locks: Vec::new(),
            for_xml: Vec::new(),
            leading_comments: Vec::new(),
            post_select_comments: Vec::new(),
            kind: None,
            operation_modifiers: Vec::new(),
            qualify_after_window: false,
            option: None,
            exclude: None,
        };

        // Check for set operations (UNION, INTERSECT, EXCEPT)
        let result = Expression::Select(Box::new(select));
        self.parse_set_operation(result)
    }

    /// Parse FROM clause
    fn parse_from(&mut self) -> Result<From> {
        let mut expressions = Vec::new();

        loop {
            let table = self.parse_table_expression()?;
            expressions.push(table);

            if !self.match_token(TokenType::Comma) {
                break;
            }

            // Handle trailing comma in FROM clause (Snowflake allows this)
            // If next token is a clause boundary keyword or end of input, break
            // Note: For Redshift, UNPIVOT after comma is a table expression (SUPER object traversal),
            // so we don't treat it as a boundary in that case
            let is_redshift = matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::Redshift)
            );
            let is_unpivot_boundary = !is_redshift && self.check(TokenType::Unpivot);
            if self.is_at_end()
                || is_unpivot_boundary
                || matches!(
                    self.peek().token_type,
                    TokenType::Where
                        | TokenType::GroupBy
                        | TokenType::Having
                        | TokenType::Order
                        | TokenType::Limit
                        | TokenType::Offset
                        | TokenType::Union
                        | TokenType::Intersect
                        | TokenType::Except
                        | TokenType::Semicolon
                        | TokenType::RParen
                        | TokenType::Window
                        | TokenType::Qualify
                        | TokenType::Distribute
                        | TokenType::Cluster
                        | TokenType::Pivot
                )
            {
                break;
            }
        }

        Ok(From { expressions })
    }

    /// Parse a table expression (table name, subquery, etc.)
    fn parse_table_expression(&mut self) -> Result<Expression> {
        // Handle PostgreSQL ONLY modifier: FROM ONLY t1
        // ONLY prevents scanning child tables in inheritance hierarchy
        let has_only = self.match_token(TokenType::Only);

        // Handle PostgreSQL ROWS FROM syntax:
        // ROWS FROM (func1(args) AS alias1(col1 type1), func2(args) AS alias2(col2 type2)) [WITH ORDINALITY] [AS alias(cols)]
        if self.match_text_seq(&["ROWS", "FROM"]) {
            return self.parse_rows_from();
        }

        // Redshift UNPIVOT in FROM clause for SUPER object traversal:
        // UNPIVOT expr [AS val_alias AT attr_alias]
        // Examples:
        //   UNPIVOT c.c_orders[0]
        //   UNPIVOT c.c_orders AS val AT attr
        if self.match_token(TokenType::Unpivot) {
            return self.parse_redshift_unpivot_table();
        }

        let mut expr = if self.check(TokenType::Values) && self.check_next(TokenType::LParen) {
            // VALUES as table expression: FROM (VALUES ...)
            // In ClickHouse, bare `values` without ( is a table name
            self.parse_values()?
        } else if self.check(TokenType::Values)
            && matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            )
        {
            // ClickHouse: `values` as a table name (not followed by LParen)
            let token = self.advance();
            let ident = Identifier::new(token.text);
            let trailing_comments = self.previous_trailing_comments();
            Expression::Table(TableRef {
                name: ident,
                schema: None,
                catalog: None,
                alias: None,
                alias_explicit_as: false,
                column_aliases: Vec::new(),
                trailing_comments,
                when: None,
                only: false,
                final_: false,
                table_sample: None,
                hints: Vec::new(),
                system_time: None,
                partitions: Vec::new(),
                identifier_func: None,
                changes: None,
                version: None,
                span: None,
            })
        } else if self.check(TokenType::DAt) {
            // Snowflake stage reference: @stage_name or @"stage_name" or @namespace.stage/path
            self.parse_stage_reference()?
        } else if self.check(TokenType::Var) && self.peek().text.starts_with('@') {
            // Snowflake stage reference tokenized as Var: @mystage/path
            // When @ is followed by alphanumeric, tokenizer creates a Var token instead of DAt
            self.parse_stage_reference_from_var()?
        } else if self.check(TokenType::String) && self.peek().text.starts_with('@') {
            // Snowflake stage reference in string: '@mystage' or '@external/location'
            self.parse_stage_reference_from_string()?
        } else if self.match_token(TokenType::Lateral) {
            if self.check(TokenType::LParen) {
                // LATERAL (SELECT ...) or LATERAL (table_expression) or LATERAL (FROM ...) for DuckDB
                self.expect(TokenType::LParen)?;
                if self.check(TokenType::Select)
                    || self.check(TokenType::With)
                    || self.check(TokenType::From)
                {
                    let query = self.parse_statement()?;
                    self.expect(TokenType::RParen)?;
                    Expression::Subquery(Box::new(Subquery {
                        this: query,
                        alias: None,
                        column_aliases: Vec::new(),
                        order_by: None,
                        limit: None,
                        offset: None,
                        lateral: true,
                        modifiers_inside: false,
                        trailing_comments: Vec::new(),
                        distribute_by: None,
                        sort_by: None,
                        cluster_by: None,
                        inferred_type: None,
                    }))
                } else {
                    // LATERAL (table_function()) - parenthesized non-subquery
                    let table_expr = self.parse_table_expression()?;
                    self.expect(TokenType::RParen)?;
                    Expression::Subquery(Box::new(Subquery {
                        this: table_expr,
                        alias: None,
                        column_aliases: Vec::new(),
                        order_by: None,
                        limit: None,
                        offset: None,
                        lateral: true,
                        modifiers_inside: false,
                        trailing_comments: Vec::new(),
                        distribute_by: None,
                        sort_by: None,
                        cluster_by: None,
                        inferred_type: None,
                    }))
                }
            } else {
                // LATERAL function_name(args) [WITH ORDINALITY] [AS alias(columns)]
                // Parse function name
                let first_ident = self.expect_identifier_or_keyword_with_quoted()?;
                let first_name = first_ident.name.clone();

                // Parse function arguments
                self.expect(TokenType::LParen)?;
                let args = if self.check(TokenType::RParen) {
                    Vec::new()
                } else {
                    self.parse_function_arguments()?
                };
                self.expect(TokenType::RParen)?;

                // Handle UNNEST specially to create UnnestFunc expression
                let mut func_expr = if first_name.to_uppercase() == "UNNEST" {
                    let mut args_iter = args.into_iter();
                    let this = args_iter
                        .next()
                        .ok_or_else(|| self.parse_error("Expected expression in UNNEST"))?;
                    let expressions: Vec<Expression> = args_iter.collect();
                    Expression::Unnest(Box::new(crate::expressions::UnnestFunc {
                        this,
                        expressions,
                        with_ordinality: false,
                        alias: None,
                        offset_alias: None,
                    }))
                } else {
                    Expression::Function(Box::new(Function {
                        name: first_name,
                        args,
                        distinct: false,
                        trailing_comments: Vec::new(),
                        use_bracket_syntax: false,
                        no_parens: false,
                        quoted: false,
                        span: None,
                        inferred_type: None,
                    }))
                };

                // Check for WITH ORDINALITY (Presto) or WITH OFFSET (BigQuery)
                let mut with_offset_alias: Option<crate::expressions::Identifier> = None;
                let ordinality = if self.match_token(TokenType::With) {
                    if self.match_token(TokenType::Ordinality) {
                        Some(Box::new(Expression::Boolean(BooleanLiteral {
                            value: true,
                        })))
                    } else if self.check(TokenType::Offset) || self.check_identifier("OFFSET") {
                        // BigQuery: WITH OFFSET [AS alias]
                        self.advance(); // consume OFFSET
                                        // Check for optional offset alias: WITH OFFSET AS y or WITH OFFSET y
                        if matches!(
                            self.config.dialect,
                            Some(crate::dialects::DialectType::BigQuery)
                        ) {
                            let has_as = self.match_token(TokenType::As);
                            if has_as
                                || self.check(TokenType::Identifier)
                                || self.check(TokenType::Var)
                            {
                                let alias_name = self.advance().text;
                                with_offset_alias = Some(crate::expressions::Identifier {
                                    name: alias_name,
                                    quoted: false,
                                    trailing_comments: Vec::new(),
                                    span: None,
                                });
                            }
                        }
                        Some(Box::new(Expression::Boolean(BooleanLiteral {
                            value: true,
                        })))
                    } else {
                        // Not ORDINALITY or OFFSET, put back WITH
                        self.current -= 1;
                        None
                    }
                } else {
                    None
                };

                // Update the inner UnnestFunc with WITH ORDINALITY/OFFSET info
                if ordinality.is_some() {
                    if let Expression::Unnest(ref mut u) = func_expr {
                        u.with_ordinality = true;
                        u.offset_alias = with_offset_alias;
                    }
                }

                // Parse optional alias: AS alias or just alias
                let alias_ident = if self.match_token(TokenType::As) {
                    Some(self.expect_identifier_or_keyword_with_quoted()?)
                } else if !self.is_at_end()
                    && !self.check(TokenType::Comma)
                    && !self.check(TokenType::RParen)
                    && !self.check(TokenType::On)
                    && !self.check(TokenType::Cross)
                    && !self.check(TokenType::Inner)
                    && !self.check(TokenType::Left)
                    && !self.check(TokenType::Right)
                    && !self.check(TokenType::Full)
                    && !self.check(TokenType::Join)
                    && !self.check(TokenType::Where)
                    && !self.check(TokenType::Order)
                    && !self.check(TokenType::Limit)
                    && !self.check(TokenType::Semicolon)
                    && (self.check(TokenType::Identifier) || self.check(TokenType::Var))
                {
                    Some(self.expect_identifier_or_keyword_with_quoted()?)
                } else {
                    None
                };
                let alias_quoted = alias_ident.as_ref().map_or(false, |id| id.quoted);
                let alias = alias_ident.map(|id| id.name);

                // Parse column aliases: (col1, col2, ...)
                let column_aliases = if alias.is_some() && self.match_token(TokenType::LParen) {
                    let mut cols = Vec::new();
                    loop {
                        cols.push(self.expect_identifier_or_keyword()?);
                        if !self.match_token(TokenType::Comma) {
                            break;
                        }
                    }
                    self.expect(TokenType::RParen)?;
                    cols
                } else {
                    Vec::new()
                };

                Expression::Lateral(Box::new(Lateral {
                    this: Box::new(func_expr),
                    view: None,
                    outer: None,
                    alias,
                    alias_quoted,
                    cross_apply: None,
                    ordinality,
                    column_aliases,
                }))
            }
        } else if self.match_token(TokenType::LParen) {
            // Subquery or parenthesized set operation or (VALUES ...)
            if self.check(TokenType::Values) {
                // (VALUES (...), (...)) AS t(c1, c2) or (VALUES (0) foo(bar))
                let mut values = self.parse_values()?;
                self.expect(TokenType::RParen)?;
                // Extract alias from Values if present and move to Subquery
                let (alias, column_aliases) = if let Expression::Values(ref mut v) = values {
                    (v.alias.take(), std::mem::take(&mut v.column_aliases))
                } else {
                    (None, Vec::new())
                };
                Expression::Subquery(Box::new(Subquery {
                    this: values,
                    alias,
                    column_aliases,
                    order_by: None,
                    limit: None,
                    offset: None,
                    distribute_by: None,
                    sort_by: None,
                    cluster_by: None,
                    lateral: false,
                    modifiers_inside: false,
                    trailing_comments: self.previous_trailing_comments(),
                    inferred_type: None,
                }))
            } else if self.check(TokenType::Select)
                || self.check(TokenType::With)
                || self.check(TokenType::Pivot)
                || self.check(TokenType::Unpivot)
                || self.check(TokenType::From)
                || self.check(TokenType::Merge)
                || self.check(TokenType::Describe)
                || (self.check(TokenType::Var) && self.peek().text.eq_ignore_ascii_case("EXPLAIN"))
                || (self.check(TokenType::Var) && self.peek().text.eq_ignore_ascii_case("SUMMARIZE"))
            {
                let query = self.parse_statement()?;
                self.expect(TokenType::RParen)?;
                let trailing = self.previous_trailing_comments();
                // Check for set operations after parenthesized query
                // If there's a set operation, wrap query in Subquery first to preserve parens
                // e.g., (SELECT 1) UNION (SELECT 2) - the left operand needs Subquery wrapper
                let result = if self.check(TokenType::Union)
                    || self.check(TokenType::Intersect)
                    || self.check(TokenType::Except)
                {
                    let left = Expression::Subquery(Box::new(Subquery {
                        this: query,
                        alias: None,
                        column_aliases: Vec::new(),
                        order_by: None,
                        limit: None,
                        offset: None,
                        lateral: false,
                        modifiers_inside: false,
                        trailing_comments: Vec::new(),
                        distribute_by: None,
                        sort_by: None,
                        cluster_by: None,
                        inferred_type: None,
                    }));
                    self.parse_set_operation(left)?
                } else {
                    query
                };
                Expression::Subquery(Box::new(Subquery {
                    this: result,
                    alias: None,
                    column_aliases: Vec::new(),
                    order_by: None,
                    limit: None,
                    offset: None,
                    distribute_by: None,
                    sort_by: None,
                    cluster_by: None,
                    lateral: false,
                    modifiers_inside: false,
                    trailing_comments: trailing,
                    inferred_type: None,
                }))
            } else if self.check(TokenType::LParen) {
                // Nested parens like ((SELECT ...)) or ((x))
                // Also handles ((SELECT 1) UNION (SELECT 2)) - set operations inside parens
                let inner = self.parse_table_expression()?;

                // Handle alias on subquery before set operation: ((SELECT 1) AS a UNION ALL (SELECT 2) AS b)
                let inner = if self.match_token(TokenType::As) {
                    let alias = self.expect_identifier()?;
                    if let Expression::Subquery(mut subq) = inner {
                        subq.alias = Some(Identifier::new(alias));
                        Expression::Subquery(subq)
                    } else {
                        Expression::Alias(Box::new(Alias::new(inner, Identifier::new(alias))))
                    }
                } else if self.is_identifier_token()
                    && !self.check(TokenType::Union)
                    && !self.check(TokenType::Intersect)
                    && !self.check(TokenType::Except)
                    && !self.check(TokenType::Cross)
                    && !self.check(TokenType::Inner)
                    && !self.check(TokenType::Left)
                    && !self.check(TokenType::Right)
                    && !self.check(TokenType::Full)
                    && !self.check(TokenType::Join)
                    && !self.check(TokenType::Order)
                    && !self.check(TokenType::Limit)
                    && !self.check(TokenType::Offset)
                    && !self.check(TokenType::Xor)
                {
                    // Implicit alias (no AS keyword)
                    let alias = self.expect_identifier()?;
                    if let Expression::Subquery(mut subq) = inner {
                        subq.alias = Some(Identifier::new(alias));
                        Expression::Subquery(subq)
                    } else {
                        Expression::Alias(Box::new(Alias::new(inner, Identifier::new(alias))))
                    }
                } else {
                    inner
                };

                // ClickHouse: ((SELECT 1) AS x, (SELECT 2) AS y) — tuple of aliased subqueries
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) && self.check(TokenType::Comma)
                {
                    let mut exprs = vec![inner];
                    while self.match_token(TokenType::Comma) {
                        if self.check(TokenType::RParen) {
                            break;
                        }
                        let e = self.parse_expression()?;
                        exprs.push(e);
                    }
                    self.expect(TokenType::RParen)?;
                    return Ok(Expression::Tuple(Box::new(Tuple { expressions: exprs })));
                }

                // Check for set operations after the first table expression
                let had_set_operation = self.check(TokenType::Union)
                    || self.check(TokenType::Intersect)
                    || self.check(TokenType::Except);
                let result = if had_set_operation {
                    // This is a set operation like ((SELECT 1) UNION (SELECT 2))
                    // Wrap inner in a subquery-like expression and parse set operation
                    let set_result = self.parse_set_operation(inner)?;
                    set_result
                } else if self.check(TokenType::Cross)
                    || self.check(TokenType::Inner)
                    || self.check(TokenType::Left)
                    || self.check(TokenType::Right)
                    || self.check(TokenType::Full)
                    || self.check(TokenType::Join)
                {
                    // This is a join: ((SELECT 1) CROSS JOIN (SELECT 2))
                    let joins = self.parse_joins()?;
                    let lateral_views = self.parse_lateral_views()?;
                    Expression::JoinedTable(Box::new(JoinedTable {
                        left: inner,
                        joins,
                        lateral_views,
                        alias: None,
                    }))
                } else {
                    inner
                };

                // Handle ORDER BY, LIMIT, OFFSET after set operations inside parens
                let result = if self.check(TokenType::Order) {
                    // Wrap in a subquery with order/limit
                    self.expect(TokenType::Order)?;
                    self.expect(TokenType::By)?;
                    let order_by = self.parse_order_by()?;
                    let limit = if self.match_token(TokenType::Limit) {
                        Some(Limit {
                            this: self.parse_expression()?,
                            percent: false,
                            comments: Vec::new(),
                        })
                    } else {
                        None
                    };
                    let offset = if self.match_token(TokenType::Offset) {
                        Some(Offset {
                            this: self.parse_expression()?,
                            rows: None,
                        })
                    } else {
                        None
                    };
                    Expression::Subquery(Box::new(Subquery {
                        this: result,
                        alias: None,
                        column_aliases: Vec::new(),
                        order_by: Some(order_by),
                        limit,
                        offset,
                        distribute_by: None,
                        sort_by: None,
                        cluster_by: None,
                        lateral: false,
                        modifiers_inside: true, // ORDER BY was inside the parens
                        trailing_comments: Vec::new(),
                        inferred_type: None,
                    }))
                } else if self.check(TokenType::Limit) || self.check(TokenType::Offset) {
                    // LIMIT/OFFSET without ORDER BY
                    let limit = if self.match_token(TokenType::Limit) {
                        Some(Limit {
                            this: self.parse_expression()?,
                            percent: false,
                            comments: Vec::new(),
                        })
                    } else {
                        None
                    };
                    let offset = if self.match_token(TokenType::Offset) {
                        Some(Offset {
                            this: self.parse_expression()?,
                            rows: None,
                        })
                    } else {
                        None
                    };
                    Expression::Subquery(Box::new(Subquery {
                        this: result,
                        alias: None,
                        column_aliases: Vec::new(),
                        order_by: None,
                        limit,
                        offset,
                        distribute_by: None,
                        sort_by: None,
                        cluster_by: None,
                        lateral: false,
                        modifiers_inside: true, // LIMIT/OFFSET was inside the parens
                        trailing_comments: Vec::new(),
                        inferred_type: None,
                    }))
                } else {
                    result
                };

                self.expect(TokenType::RParen)?;
                // Wrap result in Paren to preserve the outer parentheses when needed
                // Cases:
                // - ((SELECT 1)) -> Paren(Subquery(Select)) - inner was subquery of SELECT, wrap in Paren
                // - ((SELECT 1) UNION (SELECT 2)) -> Subquery(Union) - recursive call handled set op, don't add Paren
                // - ((SELECT 1) AS a UNION ALL ...) -> Union - we handled set op, need to add Paren
                // - (((SELECT 1) UNION SELECT 2) ORDER BY x) -> Subquery with modifiers_inside=true
                let had_modifiers = matches!(&result, Expression::Subquery(s) if s.order_by.is_some() || s.limit.is_some() || s.offset.is_some());
                let result_is_subquery_of_set_op = matches!(&result, Expression::Subquery(s) if matches!(&s.this, Expression::Union(_) | Expression::Intersect(_) | Expression::Except(_)));
                if had_modifiers || result_is_subquery_of_set_op {
                    // Subquery with modifiers or Subquery(Union) - already has proper structure
                    result
                } else {
                    // All other cases need Paren wrapper to preserve outer parentheses
                    Expression::Paren(Box::new(Paren {
                        this: result,
                        trailing_comments: Vec::new(),
                    }))
                }
            } else if self.is_identifier_token()
                || self.is_safe_keyword_as_identifier()
                || self.can_be_alias_keyword()
            {
                // Parenthesized join expression: (tbl1 CROSS JOIN tbl2) or just (x)
                // Also allow safe keywords and alias keywords (all, left, etc.) as table names
                let (left, joins) = self.parse_table_expression_with_joins()?;
                // Parse LATERAL VIEW after joins: (x CROSS JOIN foo LATERAL VIEW EXPLODE(y))
                let lateral_views = self.parse_lateral_views()?;
                self.expect(TokenType::RParen)?;
                if joins.is_empty() && lateral_views.is_empty() {
                    // Just a parenthesized table expression, wrap in Paren to preserve parens
                    Expression::Paren(Box::new(Paren {
                        this: left,
                        trailing_comments: Vec::new(),
                    }))
                } else {
                    // Create a JoinedTable
                    Expression::JoinedTable(Box::new(JoinedTable {
                        left,
                        joins,
                        lateral_views,
                        alias: None, // Alias is parsed separately after this
                    }))
                }
            } else {
                let query = self.parse_statement()?;
                self.expect(TokenType::RParen)?;
                Expression::Subquery(Box::new(Subquery {
                    this: query,
                    alias: None,
                    column_aliases: Vec::new(),
                    order_by: None,
                    limit: None,
                    offset: None,
                    distribute_by: None,
                    sort_by: None,
                    cluster_by: None,
                    lateral: false,
                    modifiers_inside: false,
                    trailing_comments: self.previous_trailing_comments(),
                    inferred_type: None,
                }))
            }
        } else if self.is_identifier_token() || self.is_safe_keyword_as_identifier() || self.can_be_alias_keyword()
            || (matches!(self.config.dialect, Some(crate::dialects::DialectType::BigQuery)) && self.check(TokenType::Number))
            || self.is_mysql_numeric_identifier()
            // PIVOT/UNPIVOT can be table names when not followed by (
            || (self.check(TokenType::Pivot) && !self.check_next(TokenType::LParen))
            || (self.check(TokenType::Unpivot) && !self.check_next(TokenType::LParen))
            // ClickHouse: braced query parameters as table names {db:Identifier}.table
            || (matches!(self.config.dialect, Some(crate::dialects::DialectType::ClickHouse)) && self.check(TokenType::LBrace))
            // ClickHouse: allow union/except/intersect as table names when not followed by ALL/DISTINCT/SELECT/(
            || (matches!(self.config.dialect, Some(crate::dialects::DialectType::ClickHouse))
                && (self.check(TokenType::Union) || self.check(TokenType::Except) || self.check(TokenType::Intersect))
                && !self.check_next(TokenType::All) && !self.check_next(TokenType::Distinct)
                && !self.check_next(TokenType::Select) && !self.check_next(TokenType::LParen))
        {
            // Table name - could be simple, qualified, or table function
            // Also allow safe keywords (like 'table', 'view', 'case', 'all', etc.) as table names
            // BigQuery: also allows numeric table parts and hyphenated identifiers
            // MySQL: allows numeric-starting identifiers (e.g., 00f, 1d)

            // DuckDB prefix alias syntax: alias: table (e.g., "foo: bar" means "bar AS foo")
            // Check if next token is COLON (but not :: which is DCOLON for casts)
            if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::DuckDB)
            ) && self.check_next(TokenType::Colon)
                && !(self.current + 2 < self.tokens.len()
                    && self.tokens[self.current + 2].token_type == TokenType::Colon)
            {
                // Parse the alias identifier
                let alias_ident = self.parse_bigquery_table_part()?;
                let pre_alias_comments = self.previous_trailing_comments();
                // Consume the colon
                self.expect(TokenType::Colon)?;
                let colon_comments = self.previous_trailing_comments();
                // Parse the actual table expression recursively
                let mut table_expr = self.parse_table_expression()?;
                // Merge comments
                let mut all_comments = pre_alias_comments;
                all_comments.extend(colon_comments);
                // Apply the alias to the table expression
                match &mut table_expr {
                    Expression::Table(ref mut t) => {
                        t.alias = Some(alias_ident);
                        t.alias_explicit_as = true; // Output AS keyword (required by expected format)
                                                    // Store prefix alias comments - they should come BEFORE the table's trailing comments
                                                    // For "foo /* bla */: bar /* baz */", output is "bar AS foo /* bla */ /* baz */"
                                                    // So alias comments (/* bla */) come first, then table comments (/* baz */)
                        if !all_comments.is_empty() {
                            let existing_comments = std::mem::take(&mut t.trailing_comments);
                            t.trailing_comments = all_comments;
                            t.trailing_comments.extend(existing_comments);
                        }
                    }
                    Expression::Subquery(ref mut s) => {
                        s.alias = Some(alias_ident);
                    }
                    Expression::Function(ref mut _f) => {
                        // Wrap function in alias
                        return Ok(Expression::Alias(Box::new(Alias {
                            this: table_expr,
                            alias: alias_ident,
                            column_aliases: Vec::new(),
                            pre_alias_comments: all_comments,
                            trailing_comments: Vec::new(),
                            inferred_type: None,
                        })));
                    }
                    _ => {
                        // For other expressions, wrap in Alias
                        return Ok(Expression::Alias(Box::new(Alias {
                            this: table_expr,
                            alias: alias_ident,
                            column_aliases: Vec::new(),
                            pre_alias_comments: all_comments,
                            trailing_comments: Vec::new(),
                            inferred_type: None,
                        })));
                    }
                }
                return Ok(table_expr);
            }

            let first_ident = self.parse_bigquery_table_part()?;
            let first_name = first_ident.name.clone();

            // Check for qualified name (schema.table) or table function
            if self.match_token(TokenType::Dot) {
                // Handle TSQL a..b syntax (database..table with empty schema)
                if self.check(TokenType::Dot) {
                    // Two consecutive dots: a..b means catalog..table (empty schema)
                    self.advance(); // consume second dot
                    let table_ident = self.parse_bigquery_table_part()?;
                    let trailing_comments = self.previous_trailing_comments();
                    return Ok(Expression::Table(TableRef {
                        catalog: Some(first_ident),
                        schema: Some(Identifier::new("")), // Empty schema represents ..
                        name: table_ident,
                        alias: None,
                        alias_explicit_as: false,
                        column_aliases: Vec::new(),
                        trailing_comments,
                        when: None,
                        only: false,
                        final_: false,
                        table_sample: None,
                        hints: Vec::new(),
                        system_time: None,
                        partitions: Vec::new(),
                        identifier_func: None,
                        changes: None,
                        version: None,
                        span: None,
                    }));
                }

                // BigQuery: handle x.* wildcard table reference (e.g., SELECT * FROM x.*)
                // After the first dot, if we see a Star token, it's a wildcard table name
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::BigQuery)
                ) && self.check(TokenType::Star)
                {
                    self.advance(); // consume *
                    let trailing_comments = self.previous_trailing_comments();
                    return Ok(Expression::Table(TableRef {
                        catalog: None,
                        schema: Some(first_ident),
                        name: Identifier::new("*"),
                        alias: None,
                        alias_explicit_as: false,
                        column_aliases: Vec::new(),
                        trailing_comments,
                        when: None,
                        only: false,
                        final_: false,
                        table_sample: None,
                        hints: Vec::new(),
                        system_time: None,
                        partitions: Vec::new(),
                        identifier_func: None,
                        changes: None,
                        version: None,
                        span: None,
                    }));
                }

                // schema.table or schema.function()
                // Allow keywords as table/schema names (e.g., schema.table, catalog.view)
                let second_ident = self.parse_bigquery_table_part()?;
                let second_name = second_ident.name.clone();

                if self.match_token(TokenType::Dot) {
                    // BigQuery: handle a.b.* wildcard table reference
                    if matches!(
                        self.config.dialect,
                        Some(crate::dialects::DialectType::BigQuery)
                    ) && self.check(TokenType::Star)
                    {
                        self.advance(); // consume *
                        let trailing_comments = self.previous_trailing_comments();
                        return Ok(Expression::Table(TableRef {
                            catalog: Some(first_ident),
                            schema: Some(second_ident),
                            name: Identifier::new("*"),
                            alias: None,
                            alias_explicit_as: false,
                            column_aliases: Vec::new(),
                            trailing_comments,
                            when: None,
                            only: false,
                            final_: false,
                            table_sample: None,
                            hints: Vec::new(),
                            system_time: None,
                            partitions: Vec::new(),
                            identifier_func: None,
                            changes: None,
                            version: None,
                            span: None,
                        }));
                    }
                    // catalog.schema.table or catalog.schema.function()
                    let third_ident = self.parse_bigquery_table_part()?;
                    let third_name = third_ident.name.clone();

                    // Check for 4-part name (e.g., project.dataset.INFORMATION_SCHEMA.TABLES)
                    if self.match_token(TokenType::Dot) {
                        let fourth_ident = self.parse_bigquery_table_part()?;
                        // BigQuery wildcard table suffix: a.b.c.d* matches all tables starting with d
                        let mut table_name = fourth_ident;
                        if matches!(
                            self.config.dialect,
                            Some(crate::dialects::DialectType::BigQuery)
                        ) && self.check(TokenType::Star)
                            && self.is_connected()
                        {
                            self.advance(); // consume *
                            table_name.name.push('*');
                        }
                        let trailing_comments = self.previous_trailing_comments();
                        // For 4-part names, combine first two parts as catalog, third as schema
                        Expression::Table(TableRef {
                            catalog: Some(Identifier::new(format!(
                                "{}.{}",
                                first_name, second_name
                            ))),
                            schema: Some(third_ident),
                            name: table_name,
                            alias: None,
                            alias_explicit_as: false,
                            column_aliases: Vec::new(),
                            trailing_comments,
                            when: None,
                            only: false,
                            final_: false,
                            table_sample: None,
                            hints: Vec::new(),
                            system_time: None,
                            partitions: Vec::new(),
                            identifier_func: None,
                            changes: None,
                            version: None,
                            span: None,
                        })
                    } else if self.match_token(TokenType::LParen) {
                        // catalog.schema.function() - table-valued function
                        let args = if self.check(TokenType::RParen) {
                            Vec::new()
                        } else {
                            self.parse_function_arguments()?
                        };
                        self.expect(TokenType::RParen)?;
                        let trailing_comments = self.previous_trailing_comments();
                        Expression::Function(Box::new(Function {
                            name: format!("{}.{}.{}", first_name, second_name, third_name),
                            args,
                            distinct: false,
                            trailing_comments,
                            use_bracket_syntax: false,
                            no_parens: false,
                            quoted: false,
                            span: None,
                            inferred_type: None,
                        }))
                    } else {
                        // catalog.schema.table
                        // BigQuery wildcard table suffix: x.y.z* matches all tables starting with z
                        let mut table_name = third_ident;
                        if matches!(
                            self.config.dialect,
                            Some(crate::dialects::DialectType::BigQuery)
                        ) && self.check(TokenType::Star)
                            && self.is_connected()
                        {
                            self.advance(); // consume *
                            table_name.name.push('*');
                        }
                        let trailing_comments = self.previous_trailing_comments();
                        Expression::Table(TableRef {
                            catalog: Some(first_ident),
                            schema: Some(second_ident),
                            name: table_name,
                            alias: None,
                            alias_explicit_as: false,
                            column_aliases: Vec::new(),
                            trailing_comments,
                            when: None,
                            only: false,
                            final_: false,
                            table_sample: None,
                            hints: Vec::new(),
                            system_time: None,
                            partitions: Vec::new(),
                            identifier_func: None,
                            changes: None,
                            version: None,
                            span: None,
                        })
                    }
                } else if self.match_token(TokenType::LParen) {
                    // schema.function() - table-valued function
                    let args = if self.check(TokenType::RParen) {
                        Vec::new()
                    } else {
                        self.parse_function_arguments()?
                    };
                    self.expect(TokenType::RParen)?;
                    let trailing_comments = self.previous_trailing_comments();
                    Expression::Function(Box::new(Function {
                        name: format!("{}.{}", first_name, second_name),
                        args,
                        distinct: false,
                        trailing_comments,
                        use_bracket_syntax: false,
                        no_parens: false,
                        quoted: false,
                        span: None,
                        inferred_type: None,
                    }))
                } else {
                    // schema.table
                    // BigQuery wildcard table suffix: x.y* matches all tables starting with y
                    let mut table_name = second_ident;
                    if matches!(
                        self.config.dialect,
                        Some(crate::dialects::DialectType::BigQuery)
                    ) && self.check(TokenType::Star)
                        && self.is_connected()
                    {
                        self.advance(); // consume *
                        table_name.name.push('*');
                    }
                    let trailing_comments = self.previous_trailing_comments();
                    Expression::Table(TableRef {
                        catalog: None,
                        schema: Some(first_ident),
                        name: table_name,
                        alias: None,
                        alias_explicit_as: false,
                        column_aliases: Vec::new(),
                        trailing_comments,
                        when: None,
                        only: false,
                        final_: false,
                        table_sample: None,
                        hints: Vec::new(),
                        system_time: None,
                        partitions: Vec::new(),
                        identifier_func: None,
                        changes: None,
                        version: None,
                        span: None,
                    })
                }
            } else if self.match_token(TokenType::LParen) {
                // Handle JSON_TABLE specially - it has COLUMNS clause syntax
                if first_name.to_uppercase() == "JSON_TABLE" {
                    // Parse the JSON expression (use parse_bitwise to avoid consuming FORMAT)
                    let this = self
                        .parse_bitwise()?
                        .unwrap_or(Expression::Null(crate::expressions::Null));

                    // Check for FORMAT JSON after the expression
                    let this_with_format = if self.match_text_seq(&["FORMAT", "JSON"]) {
                        Expression::JSONFormat(Box::new(crate::expressions::JSONFormat {
                            this: Some(Box::new(this)),
                            options: Vec::new(),
                            is_json: None,
                            to_json: None,
                        }))
                    } else {
                        this
                    };

                    // Parse path (after comma)
                    let path = if self.match_token(TokenType::Comma) {
                        if let Some(s) = self.parse_string()? {
                            Some(Box::new(s))
                        } else {
                            None
                        }
                    } else {
                        None
                    };

                    // Oracle uses "ERROR ON ERROR" (value then behavior) instead of "ON ERROR ERROR"
                    // Parse error handling: ERROR ON ERROR or NULL ON ERROR
                    let error_handling = if self.match_identifier("ERROR")
                        && self.match_text_seq(&["ON", "ERROR"])
                    {
                        Some(Box::new(Expression::Var(Box::new(Var {
                            this: "ERROR ON ERROR".to_string(),
                        }))))
                    } else if self.match_text_seq(&["NULL", "ON", "ERROR"]) {
                        Some(Box::new(Expression::Var(Box::new(Var {
                            this: "NULL ON ERROR".to_string(),
                        }))))
                    } else {
                        None
                    };

                    // Parse empty handling: ERROR ON EMPTY or NULL ON EMPTY
                    let empty_handling = if self.match_identifier("ERROR")
                        && self.match_text_seq(&["ON", "EMPTY"])
                    {
                        Some(Box::new(Expression::Var(Box::new(Var {
                            this: "ERROR ON EMPTY".to_string(),
                        }))))
                    } else if self.match_text_seq(&["NULL", "ON", "EMPTY"]) {
                        Some(Box::new(Expression::Var(Box::new(Var {
                            this: "NULL ON EMPTY".to_string(),
                        }))))
                    } else {
                        None
                    };

                    // Parse COLUMNS clause
                    let schema = self.parse_json_table_columns()?;

                    self.expect(TokenType::RParen)?;

                    Expression::JSONTable(Box::new(JSONTable {
                        this: Box::new(this_with_format),
                        schema: schema.map(Box::new),
                        path,
                        error_handling,
                        empty_handling,
                    }))
                } else if first_name.to_uppercase() == "XMLTABLE" {
                    // Handle XMLTABLE specially - it has COLUMNS clause syntax
                    // XMLTABLE([XMLNAMESPACES(...),] '/xpath' PASSING xml_doc COLUMNS ...)
                    if let Some(xml_table) = self.parse_xml_table()? {
                        self.expect(TokenType::RParen)?;
                        xml_table
                    } else {
                        return Err(self.parse_error("Failed to parse XMLTABLE"));
                    }
                } else if first_name.to_uppercase() == "OPENJSON" {
                    // Handle OPENJSON specially - it has WITH clause for column definitions
                    // OPENJSON(json[, path]) [WITH (col1 type1 'path' [AS JSON], ...)]
                    if let Some(openjson_expr) = self.parse_open_json()? {
                        openjson_expr
                    } else {
                        return Err(self.parse_error("Failed to parse OPENJSON"));
                    }
                } else if first_name.to_uppercase() == "SEMANTIC_VIEW" {
                    // Handle SEMANTIC_VIEW specially - it has METRICS/DIMENSIONS/FACTS/WHERE syntax
                    // SEMANTIC_VIEW(table METRICS a.b, a.c DIMENSIONS a.b, a.c WHERE expr)
                    let semantic_view = self.parse_semantic_view()?;
                    self.expect(TokenType::RParen)?;
                    semantic_view
                } else if (first_name.eq_ignore_ascii_case("view")
                    || first_name.eq_ignore_ascii_case("merge"))
                    && (self.check(TokenType::Select) || self.check(TokenType::With))
                {
                    // ClickHouse: view(SELECT ...) and merge(SELECT ...) table functions
                    // contain a subquery as the argument
                    let query = self.parse_statement()?;
                    self.expect(TokenType::RParen)?;
                    let trailing_comments = self.previous_trailing_comments();
                    Expression::Function(Box::new(Function {
                        name: first_name.to_string(),
                        args: vec![query],
                        distinct: false,
                        trailing_comments,
                        use_bracket_syntax: false,
                        no_parens: false,
                        quoted: false,
                        span: None,
                        inferred_type: None,
                    }))
                } else {
                    // Simple table function like UNNEST(), GAP_FILL(), etc.
                    let args = if self.check(TokenType::RParen) {
                        Vec::new()
                    } else {
                        self.parse_function_arguments()?
                    };
                    self.expect(TokenType::RParen)?;
                    let trailing_comments = self.previous_trailing_comments();

                    // Handle UNNEST specially to create UnnestFunc expression
                    if first_name.to_uppercase() == "UNNEST" {
                        // Check for WITH ORDINALITY (Presto) or WITH OFFSET (BigQuery)
                        // Both are semantically the same - provide an ordinal/offset column
                        let with_ordinality = self
                            .match_keywords(&[TokenType::With, TokenType::Ordinality])
                            || self.match_text_seq(&["WITH", "OFFSET"]);
                        // If WITH OFFSET matched, check for optional offset alias: WITH OFFSET AS y or WITH OFFSET y
                        let offset_alias = if with_ordinality
                            && matches!(
                                self.config.dialect,
                                Some(crate::dialects::DialectType::BigQuery)
                            ) {
                            let has_as = self.match_token(TokenType::As);
                            if has_as
                                || (self.check(TokenType::Identifier) || self.check(TokenType::Var))
                            {
                                let alias_name = self.advance().text;
                                Some(crate::expressions::Identifier {
                                    name: alias_name,
                                    quoted: false,
                                    trailing_comments: Vec::new(),
                                    span: None,
                                })
                            } else {
                                None
                            }
                        } else {
                            None
                        };
                        let mut args_iter = args.into_iter();
                        let this = args_iter
                            .next()
                            .ok_or_else(|| self.parse_error("Expected expression in UNNEST"))?;
                        let expressions: Vec<Expression> = args_iter.collect();
                        Expression::Unnest(Box::new(crate::expressions::UnnestFunc {
                            this,
                            expressions,
                            with_ordinality,
                            alias: None,
                            offset_alias,
                        }))
                    } else {
                        // Check for WITH ORDINALITY after any table-valued function
                        let with_ordinality =
                            self.match_keywords(&[TokenType::With, TokenType::Ordinality]);
                        let func_name = if with_ordinality {
                            format!("{} WITH ORDINALITY", first_name)
                        } else {
                            first_name.clone()
                        };
                        let func = Function {
                            name: func_name,
                            args,
                            distinct: false,
                            trailing_comments,
                            use_bracket_syntax: false,
                            no_parens: false,
                            quoted: false,
                            span: None,
                            inferred_type: None,
                        };
                        Expression::Function(Box::new(func))
                    }
                }
            } else {
                // Simple table name
                // BigQuery wildcard table suffix: x* matches all tables starting with x
                let mut table_name = first_ident;
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::BigQuery)
                ) && self.check(TokenType::Star)
                    && self.is_connected()
                {
                    self.advance(); // consume *
                    table_name.name.push('*');
                }
                let trailing_comments = self.previous_trailing_comments();
                Expression::Table(TableRef {
                    catalog: None,
                    schema: None,
                    name: table_name,
                    alias: None,
                    alias_explicit_as: false,
                    column_aliases: Vec::new(),
                    trailing_comments,
                    when: None,
                    only: false,
                    final_: false,
                    table_sample: None,
                    hints: Vec::new(),
                    system_time: None,
                    partitions: Vec::new(),
                    identifier_func: None,
                    changes: None,
                    version: None,
                    span: None,
                })
            }
        } else if self.check(TokenType::LBrace) {
            // ClickHouse query parameter: {name: Type}
            if let Some(param) = self.parse_clickhouse_braced_parameter()? {
                param
            } else {
                // Spark/Databricks widget template variable: {name}
                self.advance(); // consume {
                if self.is_identifier_token() || self.is_safe_keyword_as_identifier() {
                    let name_token = self.advance();
                    self.expect(TokenType::RBrace)?;
                    Expression::Parameter(Box::new(Parameter {
                        name: Some(name_token.text.clone()),
                        index: None,
                        style: ParameterStyle::Brace,
                        quoted: false,
                        string_quoted: false,
                        expression: None,
                    }))
                } else {
                    return Err(self.parse_error("Expected identifier after {"));
                }
            }
        } else if self.check(TokenType::Dollar) && self.check_next(TokenType::LBrace) {
            // Template variable as table reference: ${variable_name} or ${kind:name}
            // This is used in Databricks/Hive for parameterized queries
            self.advance(); // consume $
            self.advance(); // consume {
            if self.is_identifier_token() || self.is_safe_keyword_as_identifier() {
                let name_token = self.advance();
                // Check for ${kind:name} syntax (e.g., ${hiveconf:some_var})
                let expression = if self.match_token(TokenType::Colon) {
                    if self.is_identifier_token() || self.is_safe_keyword_as_identifier() {
                        let expr_token = self.advance();
                        Some(expr_token.text.clone())
                    } else {
                        return Err(self.parse_error("Expected identifier after : in ${...}"));
                    }
                } else {
                    None
                };
                self.expect(TokenType::RBrace)?;
                Expression::Parameter(Box::new(Parameter {
                    name: Some(name_token.text.clone()),
                    index: None,
                    style: ParameterStyle::DollarBrace,
                    quoted: false,
                    string_quoted: false,
                    expression,
                }))
            } else {
                return Err(self.parse_error("Expected identifier after ${"));
            }
        } else if self.check(TokenType::String) {
            // DuckDB allows string literals as table names: SELECT * FROM 'x.y'
            // Convert to a quoted identifier
            let string_token = self.advance();
            let table_name = Identifier {
                name: string_token.text.clone(),
                quoted: true,
                trailing_comments: Vec::new(),
                span: None,
            };
            let trailing_comments = self.previous_trailing_comments();
            Expression::Table(TableRef {
                catalog: None,
                schema: None,
                name: table_name,
                alias: None,
                alias_explicit_as: false,
                column_aliases: Vec::new(),
                trailing_comments,
                when: None,
                only: false,
                final_: false,
                table_sample: None,
                hints: Vec::new(),
                system_time: None,
                partitions: Vec::new(),
                identifier_func: None,
                changes: None,
                version: None,
                span: None,
            })
        } else {
            return Err(self.parse_error(format!(
                "Expected table name or subquery, got {:?}",
                self.peek().token_type
            )));
        };

        // Postgres supports a wildcard (table) suffix operator, which is a no-op in this context.
        // e.g., FROM t1* means "include inherited tables". Matches Python sqlglot behavior.
        self.match_token(TokenType::Star);

        // Check for Snowflake CHANGES clause: CHANGES (INFORMATION => ...) AT|BEFORE (...) END (...)
        // Must be checked before time travel since CHANGES includes its own AT/BEFORE clauses
        if self.check_keyword_text("CHANGES") {
            if let Some(changes_expr) = self.parse_changes()? {
                if let Expression::Table(ref mut table) = expr {
                    if let Expression::Changes(changes_box) = changes_expr {
                        table.changes = Some(changes_box);
                    }
                }
            }
        }

        // Check for Snowflake time travel: BEFORE (STATEMENT => ...) or AT (TIMESTAMP => ...)
        if self.check(TokenType::Before) || self.check_keyword_text("AT") {
            if let Some(historical_expr) = self.parse_historical_data()? {
                // Attach historical data to the table expression
                if let Expression::Table(ref mut table) = expr {
                    if let Expression::HistoricalData(hd) = historical_expr {
                        table.when = Some(hd);
                    }
                }
            }
        }

        // Check for TSQL FOR SYSTEM_TIME temporal clause (not BigQuery - handled post-alias)
        // Syntax: FOR SYSTEM_TIME AS OF expr
        //         FOR SYSTEM_TIME FROM expr TO expr
        //         FOR SYSTEM_TIME BETWEEN expr AND expr
        //         FOR SYSTEM_TIME CONTAINED IN (expr, expr)
        //         FOR SYSTEM_TIME ALL
        if !matches!(self.config.dialect, Some(crate::dialects::DialectType::BigQuery))
            && self.check(TokenType::For)
            && self.current + 1 < self.tokens.len()
            && self.tokens[self.current + 1]
                .text
                .eq_ignore_ascii_case("SYSTEM_TIME")
        {
            self.advance(); // consume FOR
            self.advance(); // consume SYSTEM_TIME
            let system_time_str = if self.match_token(TokenType::As) {
                // AS OF expr
                if self.check_keyword_text("OF") {
                    self.advance(); // consume OF
                    let start = self.current;
                    // Collect expression tokens until we hit a clause boundary
                    while !self.is_at_end()
                        && !self.check(TokenType::Semicolon)
                        && !self.check(TokenType::Where)
                        && !self.check(TokenType::Join)
                        && !self.check(TokenType::Left)
                        && !self.check(TokenType::Right)
                        && !self.check(TokenType::Inner)
                        && !self.check(TokenType::Outer)
                        && !self.check(TokenType::Full)
                        && !self.check(TokenType::Cross)
                        && !self.check(TokenType::Order)
                        && !self.check(TokenType::Group)
                        && !self.check(TokenType::Having)
                        && !self.check(TokenType::Limit)
                        && !self.check(TokenType::Union)
                        && !self.check(TokenType::Except)
                        && !self.check(TokenType::Intersect)
                        && !self.check(TokenType::As)
                        && !self.check(TokenType::Comma)
                        && !self.check(TokenType::RParen)
                        && !self.check(TokenType::With)
                        && !self.check(TokenType::Pivot)
                        && !self.check(TokenType::Unpivot)
                    {
                        self.advance();
                    }
                    let expr_text = self.tokens_to_sql_uppercased(start, self.current);
                    format!("FOR SYSTEM_TIME AS OF {}", expr_text)
                } else {
                    "FOR SYSTEM_TIME AS".to_string()
                }
            } else if self.match_token(TokenType::Between) {
                // BETWEEN expr AND expr
                let start = self.current;
                while !self.is_at_end() && !self.check(TokenType::And) {
                    self.advance();
                }
                let expr1_text = self.tokens_to_sql_uppercased(start, self.current);
                self.advance(); // consume AND
                let start2 = self.current;
                while !self.is_at_end()
                    && !self.check(TokenType::Semicolon)
                    && !self.check(TokenType::Where)
                    && !self.check(TokenType::Join)
                    && !self.check(TokenType::Left)
                    && !self.check(TokenType::Right)
                    && !self.check(TokenType::Inner)
                    && !self.check(TokenType::Outer)
                    && !self.check(TokenType::Full)
                    && !self.check(TokenType::Cross)
                    && !self.check(TokenType::Order)
                    && !self.check(TokenType::Group)
                    && !self.check(TokenType::Having)
                    && !self.check(TokenType::Limit)
                    && !self.check(TokenType::Union)
                    && !self.check(TokenType::Except)
                    && !self.check(TokenType::Intersect)
                    && !self.check(TokenType::As)
                    && !self.check(TokenType::Comma)
                    && !self.check(TokenType::RParen)
                    && !self.check(TokenType::With)
                    && !self.check(TokenType::Pivot)
                    && !self.check(TokenType::Unpivot)
                {
                    self.advance();
                }
                let expr2_text = self.tokens_to_sql_uppercased(start2, self.current);
                format!("FOR SYSTEM_TIME BETWEEN {} AND {}", expr1_text, expr2_text)
            } else if self.match_token(TokenType::From) {
                // FROM expr TO expr
                let start = self.current;
                while !self.is_at_end() && !self.check(TokenType::To) {
                    self.advance();
                }
                let expr1_text = self.tokens_to_sql_uppercased(start, self.current);
                self.advance(); // consume TO
                let start2 = self.current;
                while !self.is_at_end()
                    && !self.check(TokenType::Semicolon)
                    && !self.check(TokenType::Where)
                    && !self.check(TokenType::As)
                    && !self.check(TokenType::Comma)
                    && !self.check(TokenType::RParen)
                {
                    self.advance();
                }
                let expr2_text = self.tokens_to_sql_uppercased(start2, self.current);
                format!("FOR SYSTEM_TIME FROM {} TO {}", expr1_text, expr2_text)
            } else if self.check_identifier("CONTAINED") {
                self.advance(); // consume CONTAINED
                self.expect(TokenType::In)?;
                self.expect(TokenType::LParen)?;
                let start = self.current;
                let mut depth = 1;
                while !self.is_at_end() && depth > 0 {
                    if self.check(TokenType::LParen) {
                        depth += 1;
                    }
                    if self.check(TokenType::RParen) {
                        depth -= 1;
                        if depth == 0 {
                            break;
                        }
                    }
                    self.advance();
                }
                let inner_text = self.tokens_to_sql_uppercased(start, self.current);
                self.expect(TokenType::RParen)?;
                format!("FOR SYSTEM_TIME CONTAINED IN ({})", inner_text)
            } else if self.match_token(TokenType::All) {
                "FOR SYSTEM_TIME ALL".to_string()
            } else {
                "FOR SYSTEM_TIME".to_string()
            };
            if let Expression::Table(ref mut table) = expr {
                table.system_time = Some(system_time_str);
            }
        }

        // Check for Presto/Trino time travel: FOR VERSION AS OF / FOR TIMESTAMP AS OF
        // Syntax: FOR VERSION AS OF <snapshot_id>
        //         FOR TIMESTAMP AS OF <timestamp_expr>
        if self.check(TokenType::For) && self.current + 1 < self.tokens.len() {
            let next_text = self.tokens[self.current + 1].text.to_uppercase();
            if next_text == "VERSION" || next_text == "TIMESTAMP" {
                self.advance(); // consume FOR
                let version_kind = self.advance().text.to_uppercase(); // consume VERSION or TIMESTAMP

                // Expect AS OF
                if self.match_token(TokenType::As) && self.check_keyword_text("OF") {
                    self.advance(); // consume OF

                    // Parse the expression value
                    if let Some(value_expr) = self.parse_bitwise()? {
                        let version = crate::expressions::Version {
                            this: Box::new(Expression::Identifier(Identifier::new(&version_kind))),
                            kind: "AS OF".to_string(),
                            expression: Some(Box::new(value_expr)),
                        };
                        if let Expression::Table(ref mut table) = expr {
                            table.version = Some(Box::new(version));
                        }
                    }
                }
            }
        }

        // Check for Hive-style time travel: TIMESTAMP AS OF / VERSION AS OF (without FOR)
        // Syntax: TIMESTAMP AS OF <timestamp_expr>
        //         VERSION AS OF <snapshot_id>
        if self.current < self.tokens.len() {
            let current_text = self.tokens[self.current].text.to_uppercase();
            if (current_text == "TIMESTAMP" || current_text == "VERSION")
                && self.current + 2 < self.tokens.len()
                && self.tokens[self.current + 1].token_type == TokenType::As
                && self.tokens[self.current + 2]
                    .text
                    .eq_ignore_ascii_case("OF")
            {
                let version_kind = self.advance().text.to_uppercase(); // consume TIMESTAMP or VERSION
                self.advance(); // consume AS
                self.advance(); // consume OF

                // Parse the expression value
                if let Some(value_expr) = self.parse_bitwise()? {
                    let version = crate::expressions::Version {
                        this: Box::new(Expression::Identifier(Identifier::new(&version_kind))),
                        kind: "AS OF".to_string(),
                        expression: Some(Box::new(value_expr)),
                    };
                    if let Expression::Table(ref mut table) = expr {
                        table.version = Some(Box::new(version));
                    }
                }
            }
        }

        // Check for MySQL PARTITION(p0, p1, ...) clause
        // Only supported by MySQL-compatible dialects (not generic dialect)
        let supports_partition_selection = matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::MySQL)
                | Some(crate::dialects::DialectType::SingleStore)
                | Some(crate::dialects::DialectType::Doris)
                | Some(crate::dialects::DialectType::StarRocks)
        );
        if supports_partition_selection && self.match_token(TokenType::Partition) {
            if self.match_token(TokenType::LParen) {
                let mut partitions = Vec::new();
                loop {
                    let partition_name = self.expect_identifier_or_keyword_with_quoted()?;
                    partitions.push(partition_name);
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
                self.expect(TokenType::RParen)?;
                if let Expression::Table(ref mut table) = expr {
                    table.partitions = partitions;
                }
            }
        }

        // Check for table-level TABLESAMPLE/SAMPLE: tbl TABLESAMPLE METHOD(size) or tbl SAMPLE ROW(0)
        // Snowflake supports both TABLESAMPLE and SAMPLE
        if self.check(TokenType::TableSample) || self.check(TokenType::Sample) {
            if let Some(sample) = self.parse_table_level_sample()? {
                if let Expression::Table(ref mut table) = expr {
                    table.table_sample = Some(Box::new(sample));
                } else {
                    // For non-Table expressions (subqueries, functions, etc.),
                    // wrap in TableSample expression node
                    expr = Expression::TableSample(Box::new(crate::expressions::TableSample {
                        this: Some(Box::new(expr)),
                        sample: Some(Box::new(sample)),
                        expressions: Vec::new(),
                        method: None,
                        bucket_numerator: None,
                        bucket_denominator: None,
                        bucket_field: None,
                        percent: None,
                        rows: None,
                        size: None,
                        seed: None,
                    }));
                }
            }
        }

        // Check for TSQL table hints: WITH (TABLOCK, INDEX(myindex), ...)
        if self.check(TokenType::With) && self.check_next(TokenType::LParen) {
            if let Expression::Table(ref mut table) = expr {
                if let Some(hint_expr) = self.parse_table_hints()? {
                    // parse_table_hints returns a Tuple wrapping individual hint expressions.
                    // Extract the inner hints so we store them directly.
                    match hint_expr {
                        Expression::Tuple(tuple) => {
                            table.hints = tuple.expressions;
                        }
                        other => {
                            table.hints = vec![other];
                        }
                    }
                }
            }
        }

        // Check for MySQL index hints: USE INDEX, IGNORE INDEX, FORCE INDEX
        if self.check_keyword_text("USE")
            || self.check(TokenType::Ignore)
            || self.check_keyword_text("FORCE")
        {
            // Peek ahead to see if next token after USE/IGNORE/FORCE is INDEX or KEY
            let next_idx = self.current + 1;
            let is_index_hint = next_idx < self.tokens.len() && {
                let next_text = self.tokens[next_idx].text.to_uppercase();
                next_text == "INDEX" || next_text == "KEY"
            };
            if is_index_hint {
                if let Expression::Table(ref mut table) = expr {
                    if let Some(hint_expr) = self.parse_table_hints()? {
                        match hint_expr {
                            Expression::Tuple(tuple) => {
                                table.hints = tuple.expressions;
                            }
                            other => {
                                table.hints = vec![other];
                            }
                        }
                    }
                }
            }
        }

        // Check for SQLite INDEXED BY or NOT INDEXED table hints
        if self.check_identifier("INDEXED") {
            self.advance(); // consume INDEXED
            self.expect(TokenType::By)?;
            // Parse index name (can be qualified: schema.index)
            let first_part = self.expect_identifier_or_keyword()?;
            let index_name = if self.match_token(TokenType::Dot) {
                let second_part = self.expect_identifier_or_keyword()?;
                format!("{}.{}", first_part, second_part)
            } else {
                first_part
            };
            if let Expression::Table(ref mut table) = expr {
                table.hints.push(Expression::Identifier(Identifier {
                    name: format!("INDEXED BY {}", index_name),
                    quoted: false,
                    trailing_comments: Vec::new(),
                    span: None,
                }));
            }
        } else if self.check(TokenType::Not) && self.check_next_identifier("INDEXED") {
            self.advance(); // consume NOT
            self.advance(); // consume INDEXED
            if let Expression::Table(ref mut table) = expr {
                table.hints.push(Expression::Identifier(Identifier {
                    name: "NOT INDEXED".to_string(),
                    quoted: false,
                    trailing_comments: Vec::new(),
                    span: None,
                }));
            }
        }

        // Check for PIVOT (can be followed by UNPIVOT)
        // Only treat as PIVOT clause when followed by ( — otherwise it's a table alias
        if self.check(TokenType::Pivot) && self.check_next(TokenType::LParen) {
            self.advance(); // consume PIVOT
            expr = self.parse_pivot(expr)?;
        }
        // Check for UNPIVOT (can follow PIVOT or be standalone)
        // Only treat as UNPIVOT clause when followed by (, INCLUDE, or EXCLUDE — otherwise it's a table alias
        if self.check(TokenType::Unpivot) && self.is_unpivot_clause_start() {
            self.advance(); // consume UNPIVOT
            expr = self.parse_unpivot(expr)?;
        }
        // Check for MATCH_RECOGNIZE
        else if self.check(TokenType::MatchRecognize)
            && !matches!(&expr, Expression::Pivot(_) | Expression::Unpivot(_))
        {
            self.advance();
            expr = self.parse_match_recognize(Some(expr))?;
        }

        // Check for alias
        if self.match_token(TokenType::As) {
            // Handle AS (col1, col2) without alias name - used by POSEXPLODE etc.
            if self.check(TokenType::LParen) {
                self.advance(); // consume LParen
                let mut column_aliases = Vec::new();
                loop {
                    if self.check(TokenType::RParen) {
                        break;
                    }
                    column_aliases.push(Identifier::new(self.expect_identifier_or_keyword()?));
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
                self.expect(TokenType::RParen)?;
                expr = Expression::Alias(Box::new(Alias {
                    this: expr,
                    alias: Identifier::new(String::new()),
                    column_aliases,
                    pre_alias_comments: Vec::new(),
                    trailing_comments: Vec::new(),
                    inferred_type: None,
                }));
            } else {
                let alias_ident_parsed = self.expect_identifier_or_alias_keyword_with_quoted()?;
                let alias = alias_ident_parsed.name;
                let alias_is_quoted = alias_ident_parsed.quoted;
                let make_alias_ident = |name: String| -> Identifier {
                    if alias_is_quoted {
                        Identifier::quoted(name)
                    } else {
                        Identifier::new(name)
                    }
                };
                // Check for column aliases: AS t(c1, c2) or AS t(c1 type1, c2 type2) for table functions
                if self.match_token(TokenType::LParen) {
                    // Check if this is typed column definitions (for table functions like JSON_TO_RECORDSET)
                    // by looking ahead: if we see identifier followed by another identifier/type (not comma/rparen),
                    // it's typed columns
                    let has_typed_columns = self.check_typed_column_list();

                    if has_typed_columns {
                        // Parse typed column definitions like: (col1 type1, col2 type2)
                        let mut typed_cols = Vec::new();
                        loop {
                            if self.check(TokenType::RParen) {
                                break;
                            }
                            // Parse column name (can be quoted)
                            let col_name = self.expect_identifier_or_keyword_with_quoted()?;
                            // Parse column type
                            let col_type = self.parse_data_type()?;
                            // Create ColumnDef expression, preserving the quoted status
                            let mut col_def = ColumnDef::new(col_name.name.clone(), col_type);
                            col_def.name = col_name;
                            typed_cols.push(Expression::ColumnDef(Box::new(col_def)));

                            if !self.match_token(TokenType::Comma) {
                                break;
                            }
                        }
                        self.expect(TokenType::RParen)?;

                        // Create TableAlias with typed columns
                        let table_alias = Expression::TableAlias(Box::new(TableAlias {
                            this: Some(Box::new(Expression::Identifier(make_alias_ident(alias)))),
                            columns: typed_cols,
                        }));

                        // Wrap function with TableAlias using Tuple pattern (like ROWS FROM)
                        expr = Expression::Tuple(Box::new(Tuple {
                            expressions: vec![expr, table_alias],
                        }));
                    } else {
                        // Parse simple column aliases: (c1, c2, ...)
                        // Use expect_identifier_or_keyword to allow keywords like KEY, INDEX, VALUE as column aliases
                        let mut aliases = Vec::new();
                        loop {
                            if self.check(TokenType::RParen) {
                                break;
                            }
                            aliases.push(Identifier::new(self.expect_identifier_or_keyword()?));
                            if !self.match_token(TokenType::Comma) {
                                break;
                            }
                        }
                        self.expect(TokenType::RParen)?;

                        expr = match expr {
                            Expression::Table(mut t) => {
                                t.alias = Some(make_alias_ident(alias));
                                t.alias_explicit_as = true;
                                t.column_aliases = aliases;
                                Expression::Table(t)
                            }
                            Expression::Subquery(mut s) => {
                                s.alias = Some(make_alias_ident(alias));
                                s.column_aliases = aliases;
                                Expression::Subquery(s)
                            }
                            Expression::Pivot(mut p) => {
                                p.alias = Some(make_alias_ident(alias));
                                Expression::Pivot(p)
                            }
                            Expression::Unpivot(mut u) => {
                                u.alias = Some(make_alias_ident(alias));
                                Expression::Unpivot(u)
                            }
                            Expression::MatchRecognize(mut mr) => {
                                mr.alias = Some(make_alias_ident(alias));
                                mr.alias_explicit_as = true;
                                Expression::MatchRecognize(mr)
                            }
                            Expression::JoinedTable(mut jt) => {
                                jt.alias = Some(make_alias_ident(alias));
                                Expression::JoinedTable(jt)
                            }
                            _ => Expression::Alias(Box::new(Alias {
                                this: expr,
                                alias: make_alias_ident(alias),
                                column_aliases: aliases,
                                pre_alias_comments: Vec::new(),
                                trailing_comments: Vec::new(),
                                inferred_type: None,
                            })),
                        };
                    }
                } else {
                    // No column aliases, just simple alias
                    let default_column_aliases = if matches!(
                        self.config.dialect,
                        Some(crate::dialects::DialectType::ClickHouse)
                    ) && matches!(&expr, Expression::Function(func) if func.name.eq_ignore_ascii_case("generate_series"))
                    {
                        vec![Identifier::new("generate_series")]
                    } else {
                        Vec::new()
                    };
                    expr = match expr {
                        Expression::Table(mut t) => {
                            t.alias = Some(make_alias_ident(alias));
                            t.alias_explicit_as = true;
                            t.column_aliases = Vec::new();
                            Expression::Table(t)
                        }
                        Expression::Subquery(mut s) => {
                            s.alias = Some(make_alias_ident(alias));
                            s.column_aliases = Vec::new();
                            Expression::Subquery(s)
                        }
                        Expression::Pivot(mut p) => {
                            p.alias = Some(make_alias_ident(alias));
                            Expression::Pivot(p)
                        }
                        Expression::Unpivot(mut u) => {
                            u.alias = Some(make_alias_ident(alias));
                            Expression::Unpivot(u)
                        }
                        Expression::MatchRecognize(mut mr) => {
                            mr.alias = Some(make_alias_ident(alias));
                            mr.alias_explicit_as = true;
                            Expression::MatchRecognize(mr)
                        }
                        Expression::JoinedTable(mut jt) => {
                            jt.alias = Some(make_alias_ident(alias));
                            Expression::JoinedTable(jt)
                        }
                        _ => Expression::Alias(Box::new(Alias {
                            this: expr,
                            alias: make_alias_ident(alias),
                            column_aliases: default_column_aliases,
                            pre_alias_comments: Vec::new(),
                            trailing_comments: Vec::new(),
                            inferred_type: None,
                        })),
                    };
                }
            } // close the else for AS (col1, col2) handling
        } else if (self.check(TokenType::QuotedIdentifier)
            || (self.check(TokenType::Var) && !self.check_keyword() && !self.check_identifier("MATCH_CONDITION")
                && !(self.check_identifier("ARRAY") && self.check_next(TokenType::Join)
                     && matches!(self.config.dialect, Some(crate::dialects::DialectType::ClickHouse)))
                // TSQL: OPTION(LABEL = 'foo') is a query hint, not an alias
                && !(self.check_identifier("OPTION") && self.check_next(TokenType::LParen))
                // MySQL: LOCK IN SHARE MODE is a locking clause, not an alias
                && !(self.check_identifier("LOCK") && self.check_next(TokenType::In))
                // ClickHouse: PARALLEL WITH is a statement separator, not a table alias
                && !(self.check_identifier("PARALLEL") && self.check_next(TokenType::With)
                     && matches!(self.config.dialect, Some(crate::dialects::DialectType::ClickHouse)))
                // DuckDB: POSITIONAL JOIN is a join method, not a table alias
                && !(self.check_identifier("POSITIONAL") && self.check_next(TokenType::Join))))
            || self.is_command_keyword_as_alias()
            // ClickHouse: allow FIRST/LAST as implicit table aliases
            // (they're keywords used in NULLS FIRST/LAST but also valid as identifiers)
            || (matches!(self.config.dialect, Some(crate::dialects::DialectType::ClickHouse))
                && (self.check(TokenType::First) || self.check(TokenType::Last)))
            // PIVOT/UNPIVOT can be table aliases when not followed by clause-starting tokens
            || (self.check(TokenType::Pivot) && !self.check_next(TokenType::LParen))
            || (self.check(TokenType::Unpivot) && !self.is_unpivot_clause_start())
            // PARTITION can be a table alias when the dialect doesn't support partition selection
            || (self.check(TokenType::Partition) && !matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::MySQL)
                | Some(crate::dialects::DialectType::SingleStore)
                | Some(crate::dialects::DialectType::Doris)
                | Some(crate::dialects::DialectType::StarRocks)
            ))
            || (self.check(TokenType::Window) && {
                // WINDOW can be a table alias if NOT followed by an identifier (window definition)
                let next_pos = self.current + 1;
                next_pos >= self.tokens.len()
                    || (self.tokens[next_pos].token_type != TokenType::Var
                        && self.tokens[next_pos].token_type != TokenType::Identifier)
            })
        {
            // Implicit alias (but not MATCH_CONDITION which is a join condition keyword)
            // Also allow command keywords (GET, PUT, etc.) and WINDOW (when not a clause) as implicit table aliases
            let is_keyword_alias = self.peek().token_type.is_keyword();
            let is_quoted_alias = self.peek().token_type == TokenType::QuotedIdentifier;
            let alias = self.advance().text.clone();
            // Check for column aliases: t(c1, c2)
            // Use expect_identifier_or_keyword to allow keywords like KEY, INDEX, VALUE as column aliases
            let mut column_aliases = if self.match_token(TokenType::LParen) {
                let mut aliases = Vec::new();
                loop {
                    aliases.push(Identifier::new(self.expect_identifier_or_keyword()?));
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
                self.expect(TokenType::RParen)?;
                aliases
            } else {
                Vec::new()
            };
            if column_aliases.is_empty()
                && matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                )
                && matches!(&expr, Expression::Function(func) if func.name.eq_ignore_ascii_case("generate_series"))
            {
                column_aliases = vec![Identifier::new("generate_series")];
            }
            let make_alias_ident = |name: String| -> Identifier {
                if is_quoted_alias {
                    Identifier::quoted(name)
                } else {
                    Identifier::new(name)
                }
            };
            expr = match expr {
                Expression::Table(mut t) => {
                    t.alias = Some(make_alias_ident(alias));
                    t.alias_explicit_as = is_keyword_alias;
                    t.column_aliases = column_aliases;
                    Expression::Table(t)
                }
                Expression::Subquery(mut s) => {
                    s.alias = Some(make_alias_ident(alias));
                    s.column_aliases = column_aliases;
                    Expression::Subquery(s)
                }
                Expression::Pivot(mut p) => {
                    p.alias = Some(make_alias_ident(alias));
                    Expression::Pivot(p)
                }
                Expression::Unpivot(mut u) => {
                    u.alias = Some(make_alias_ident(alias));
                    Expression::Unpivot(u)
                }
                Expression::MatchRecognize(mut mr) => {
                    mr.alias = Some(make_alias_ident(alias));
                    Expression::MatchRecognize(mr)
                }
                Expression::JoinedTable(mut jt) => {
                    jt.alias = Some(make_alias_ident(alias));
                    Expression::JoinedTable(jt)
                }
                _ => Expression::Alias(Box::new(Alias {
                    this: expr,
                    alias: make_alias_ident(alias),
                    column_aliases,
                    pre_alias_comments: Vec::new(),
                    trailing_comments: Vec::new(),
                    inferred_type: None,
                })),
            };
        }

        // ClickHouse: subquery column alias list without alias name: FROM (...) (c0, c1)
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) && self.check(TokenType::LParen)
            && matches!(&expr, Expression::Subquery(s) if s.alias.is_none())
        {
            // Lookahead: check if this is (identifier, identifier, ...) — column alias list
            let mut look = self.current + 1;
            let mut is_col_list = true;
            let mut col_count = 0;
            loop {
                if look >= self.tokens.len() {
                    is_col_list = false;
                    break;
                }
                let tt = self.tokens[look].token_type;
                if tt == TokenType::Identifier
                    || tt == TokenType::Var
                    || tt == TokenType::QuotedIdentifier
                    || tt.is_keyword()
                {
                    col_count += 1;
                    look += 1;
                } else {
                    is_col_list = false;
                    break;
                }
                if look >= self.tokens.len() {
                    is_col_list = false;
                    break;
                }
                if self.tokens[look].token_type == TokenType::Comma {
                    look += 1;
                } else if self.tokens[look].token_type == TokenType::RParen {
                    break;
                } else {
                    is_col_list = false;
                    break;
                }
            }
            if is_col_list && col_count >= 1 {
                self.advance(); // consume LParen
                let mut aliases = Vec::new();
                loop {
                    aliases.push(Identifier::new(self.advance().text.clone()));
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
                self.expect(TokenType::RParen)?;
                if let Expression::Subquery(ref mut s) = expr {
                    s.column_aliases = aliases;
                }
            }
        }

        // ClickHouse FINAL modifier: table [AS alias] FINAL
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) && self.match_token(TokenType::Final)
        {
            if let Expression::Table(ref mut table) = expr {
                table.final_ = true;
            }
        }

        // Check for SQLite INDEXED BY after alias: t AS t INDEXED BY idx
        if self.check_identifier("INDEXED") {
            self.advance(); // consume INDEXED
            self.expect(TokenType::By)?;
            let first_part = self.expect_identifier_or_keyword()?;
            let index_name = if self.match_token(TokenType::Dot) {
                let second_part = self.expect_identifier_or_keyword()?;
                format!("{}.{}", first_part, second_part)
            } else {
                first_part
            };
            if let Expression::Table(ref mut table) = expr {
                table.hints.push(Expression::Identifier(Identifier {
                    name: format!("INDEXED BY {}", index_name),
                    quoted: false,
                    trailing_comments: Vec::new(),
                    span: None,
                }));
            }
        }

        // Check for PIVOT/UNPIVOT after alias (some dialects allow this order)
        // Only treat as PIVOT/UNPIVOT clause when followed by ( — otherwise it's a table alias
        if self.check(TokenType::Pivot) && self.check_next(TokenType::LParen) {
            self.advance(); // consume PIVOT
            expr = self.parse_pivot(expr)?;
        } else if self.check(TokenType::Unpivot) && self.is_unpivot_clause_start() {
            self.advance(); // consume UNPIVOT
            expr = self.parse_unpivot(expr)?;
        }

        // Check for Redshift AT index clause for array unnesting
        // Syntax: table_alias.array_column AS element_alias AT index_alias
        // e.g., c.c_orders AS orders AT index
        // https://docs.aws.amazon.com/redshift/latest/dg/query-super.html
        if self.match_identifier("AT") {
            let index_alias = self.expect_identifier_or_keyword()?;
            // Convert the table expression to a column for AtIndex
            let column_expr = match expr {
                Expression::Table(t) => {
                    // Convert Table to Column reference
                    // For c.c_orders, table=c, name=c_orders -> column name should be c.c_orders
                    let mut parts = Vec::new();
                    if let Some(cat) = t.catalog {
                        parts.push(cat.name);
                    }
                    if let Some(schema) = t.schema {
                        parts.push(schema.name);
                    }
                    parts.push(t.name.name);
                    let col_name = parts.join(".");
                    let alias_expr = if let Some(alias) = t.alias {
                        Expression::Alias(Box::new(Alias {
                            this: Expression::Column(Column {
                                name: Identifier::new(&col_name),
                                table: None,
                                join_mark: false,
                                trailing_comments: Vec::new(),
                                span: None,
                                inferred_type: None,
                            }),
                            alias,
                            column_aliases: t.column_aliases,
                            pre_alias_comments: Vec::new(),
                            trailing_comments: t.trailing_comments,
                            inferred_type: None,
                        }))
                    } else {
                        Expression::Column(Column {
                            name: Identifier::new(&col_name),
                            table: None,
                            join_mark: false,
                            trailing_comments: t.trailing_comments,
                            span: None,
                            inferred_type: None,
                        })
                    };
                    alias_expr
                }
                other => other, // Keep as is for non-table expressions
            };
            expr = Expression::AtIndex(Box::new(AtIndex {
                this: Box::new(column_expr),
                expression: Box::new(Expression::Identifier(Identifier::new(index_alias))),
            }));
        }

        // Check for TABLESAMPLE/SAMPLE after alias (Snowflake ALIAS_POST_TABLESAMPLE)
        // e.g., table2 AS t2 TABLESAMPLE BERNOULLI (50), table2 AS t2 SAMPLE ROW (0)
        if self.check(TokenType::TableSample) || self.check(TokenType::Sample) {
            if let Some(sample) = self.parse_table_level_sample()? {
                // Capture trailing comments after the SAMPLE clause (e.g., -- 25% of rows in table1)
                let post_sample_comments = self.previous_trailing_comments();
                if let Expression::Table(ref mut table) = expr {
                    table.table_sample = Some(Box::new(sample));
                    if !post_sample_comments.is_empty() {
                        table.trailing_comments.extend(post_sample_comments);
                    }
                } else {
                    // For non-Table expressions, wrap in TableSample expression node
                    expr = Expression::TableSample(Box::new(crate::expressions::TableSample {
                        this: Some(Box::new(expr)),
                        sample: Some(Box::new(sample)),
                        expressions: Vec::new(),
                        method: None,
                        bucket_numerator: None,
                        bucket_denominator: None,
                        bucket_field: None,
                        percent: None,
                        rows: None,
                        size: None,
                        seed: None,
                    }));
                }
            }
        }

        // Apply PostgreSQL ONLY modifier if present
        if has_only {
            if let Expression::Table(ref mut table) = expr {
                table.only = true;
            }
        }

        // BigQuery: FOR SYSTEM_TIME AS OF after alias
        // e.g., FROM foo AS t0 FOR SYSTEM_TIME AS OF '2026-01-01'
        if self.check(TokenType::For)
            && self.current + 1 < self.tokens.len()
            && self.tokens[self.current + 1]
                .text
                .eq_ignore_ascii_case("SYSTEM_TIME")
        {
            self.advance(); // consume FOR
            self.advance(); // consume SYSTEM_TIME
            if self.match_token(TokenType::As) && self.check_keyword_text("OF") {
                self.advance(); // consume OF
                let start = self.current;
                // Collect expression tokens until clause boundary
                while !self.is_at_end()
                    && !self.check(TokenType::Semicolon)
                    && !self.check(TokenType::Where)
                    && !self.check(TokenType::Join)
                    && !self.check(TokenType::Left)
                    && !self.check(TokenType::Right)
                    && !self.check(TokenType::Inner)
                    && !self.check(TokenType::Outer)
                    && !self.check(TokenType::Full)
                    && !self.check(TokenType::Cross)
                    && !self.check(TokenType::Order)
                    && !self.check(TokenType::Group)
                    && !self.check(TokenType::Having)
                    && !self.check(TokenType::Limit)
                    && !self.check(TokenType::Union)
                    && !self.check(TokenType::Except)
                    && !self.check(TokenType::Intersect)
                    && !self.check(TokenType::Comma)
                    && !self.check(TokenType::RParen)
                {
                    self.advance();
                }
                let expr_text = self.tokens_to_sql(start, self.current);
                let system_time_str = format!("FOR SYSTEM_TIME AS OF {}", expr_text);
                if let Expression::Table(ref mut table) = expr {
                    table.system_time = Some(system_time_str);
                }
            }
        }

        // BigQuery INFORMATION_SCHEMA handling
        // When INFORMATION_SCHEMA is part of a table reference, merge it with the table name
        // into a single quoted identifier and auto-add an alias if not present
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::BigQuery)
        ) {
            if let Expression::Table(ref mut table) = expr {
                // Case 1: Single quoted identifier containing INFORMATION_SCHEMA (e.g., `proj.dataset.INFORMATION_SCHEMA.SOME_VIEW`)
                // Add an alias that is the same as the table name (only if no alias)
                if table.schema.is_none() && table.catalog.is_none() && table.alias.is_none() {
                    let name_upper = table.name.name.to_uppercase();
                    if name_upper.contains("INFORMATION_SCHEMA.") {
                        // Set alias to be the full quoted table name
                        table.alias = Some(table.name.clone());
                        table.alias_explicit_as = true;
                    }
                }
                // Case 2: Multi-part name where schema part is INFORMATION_SCHEMA
                // e.g., region_or_dataset.INFORMATION_SCHEMA.TABLES -> region_or_dataset.`INFORMATION_SCHEMA.TABLES` AS TABLES
                // e.g., proj.region_or_dataset.INFORMATION_SCHEMA.TABLES -> proj.region_or_dataset.`INFORMATION_SCHEMA.TABLES` AS TABLES
                // This applies even if an alias is already set (we still need to merge the parts)
                else if let Some(ref schema) = table.schema {
                    if schema.name.eq_ignore_ascii_case("INFORMATION_SCHEMA") {
                        // Merge schema (INFORMATION_SCHEMA) with table name into a single quoted identifier
                        let merged_name = format!("{}.{}", schema.name, table.name.name);
                        let original_table_name = table.name.name.clone();

                        // Set alias to original table name (TABLES, VIEWS, etc.) only if no alias exists
                        if table.alias.is_none() {
                            table.alias = Some(Identifier::new(original_table_name));
                            table.alias_explicit_as = true;
                        }

                        // Create new quoted identifier
                        table.name = Identifier {
                            name: merged_name,
                            quoted: true,
                            trailing_comments: Vec::new(),
                            span: None,
                        };

                        // Shift: schema becomes catalog, catalog becomes None or stays
                        table.schema = table.catalog.take();
                        // catalog is now None
                    }
                }
            }
        }

        Ok(expr)
    }

    /// Parse standard PIVOT clause (in FROM clause)
    /// PIVOT(agg_func [AS alias], ... FOR column IN (value [AS alias], ...) [GROUP BY ...])
    fn parse_pivot(&mut self, source: Expression) -> Result<Expression> {
        self.expect(TokenType::LParen)?;

        // Parse aggregation functions (comma-separated, may have aliases)
        // Stop when we see FOR keyword
        // Use parse_primary() to handle keyword function names like FIRST, LAST
        let mut expressions = Vec::new();
        loop {
            if self.check(TokenType::For) || self.check(TokenType::RParen) {
                break;
            }
            // Parse the aggregation expression using parse_primary (handles keyword functions)
            let func = self.parse_primary()?;
            // Check for alias (AS alias or just identifier after function)
            let expr = if self.match_token(TokenType::As) {
                // AS alias
                let alias_name = self.expect_identifier_or_keyword()?;
                Expression::Alias(Box::new(Alias::new(func, Identifier::new(alias_name))))
            } else if !self.check(TokenType::Comma)
                && !self.check(TokenType::For)
                && !self.check(TokenType::RParen)
            {
                // Implicit alias (no AS keyword): SUM(b) d
                if let Some(id) = self.parse_id_var()? {
                    let alias_name = match &id {
                        Expression::Identifier(ident) => ident.name.clone(),
                        Expression::Column(col) => col.name.name.clone(),
                        _ => String::new(),
                    };
                    if !alias_name.is_empty() {
                        Expression::Alias(Box::new(Alias::new(func, Identifier::new(alias_name))))
                    } else {
                        func
                    }
                } else {
                    func
                }
            } else {
                func
            };
            expressions.push(expr);
            if !self.match_token(TokenType::Comma) {
                break;
            }
            // After consuming comma, if next is FOR, break (comma before FOR is optional/dropped)
            if self.check(TokenType::For) {
                break;
            }
        }

        // FOR column IN (values)
        self.expect(TokenType::For)?;

        let mut fields = Vec::new();
        loop {
            let field = self.parse_standard_pivot_in()?;
            fields.push(field);

            // Check for additional FOR clauses (rare but possible)
            if !self.match_token(TokenType::For) {
                break;
            }
        }

        // Handle Snowflake's DEFAULT ON NULL (default_value) clause
        let default_on_null = if self.match_text_seq(&["DEFAULT", "ON", "NULL"]) {
            if self.match_token(TokenType::LParen) {
                let val = self.parse_expression()?;
                self.expect(TokenType::RParen)?;
                Some(Box::new(val))
            } else {
                None
            }
        } else {
            None
        };

        // Parse optional GROUP BY inside PIVOT parens
        let group = self.parse_group()?;

        self.expect(TokenType::RParen)?;

        Ok(Expression::Pivot(Box::new(Pivot {
            this: source,
            expressions,
            fields,
            using: Vec::new(),
            group: group.map(Box::new),
            unpivot: false,
            into: None,
            alias: None,
            include_nulls: None,
            default_on_null,
            with: None,
        })))
    }

    /// Parse FOR column IN (...) part of standard PIVOT
    fn parse_standard_pivot_in(&mut self) -> Result<Expression> {
        // Parse the column being pivoted
        let column = self.parse_primary()?;

        // IN keyword
        self.expect(TokenType::In)?;

        // IN values - can be parenthesized or bare identifier
        if self.match_token(TokenType::LParen) {
            // Check for ANY keyword
            let in_exprs = if self.match_text_seq(&["ANY"]) {
                let order = self.parse_order()?;
                vec![Expression::PivotAny(Box::new(PivotAny {
                    this: order.map(Box::new),
                }))]
            } else {
                // Parse comma-separated values with optional aliases
                let mut vals = Vec::new();
                loop {
                    if self.check(TokenType::RParen) {
                        break;
                    }
                    if let Some(val) = self.parse_select_or_expression()? {
                        // Check for alias - alias can be an identifier or an expression
                        // (e.g., 'PREFIX ' || CHR(38) || ' SUFFIX' in Oracle)
                        let val = if self.match_token(TokenType::As) {
                            // Parse the alias as an expression (not just an identifier)
                            // This allows for string concatenation aliases
                            let alias_expr = self.parse_bitwise()?.ok_or_else(|| {
                                self.parse_error(
                                    "Expected expression after AS in PIVOT/UNPIVOT IN clause",
                                )
                            })?;
                            Expression::PivotAlias(Box::new(PivotAlias {
                                this: val,
                                alias: alias_expr,
                            }))
                        } else {
                            val
                        };
                        vals.push(val);
                    }
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
                vals
            };
            self.expect(TokenType::RParen)?;
            Ok(Expression::In(Box::new(In {
                this: column,
                expressions: in_exprs,
                query: None,
                not: false,
                global: false,
                unnest: None,
                is_field: false,
            })))
        } else {
            // Bare identifier: FOR foo IN y_enum (no parentheses)
            // Store in query field to distinguish from parenthesized IN
            let field_id = self.parse_id_var()?.unwrap_or(Expression::Null(Null));
            Ok(Expression::In(Box::new(In {
                this: column,
                expressions: Vec::new(),
                query: Some(field_id),
                not: false,
                global: false,
                unnest: None,
                is_field: true,
            })))
        }
    }

    /// Parse UNPIVOT clause
    /// UNPIVOT (value_column FOR name_column IN (col1, col2, ...))
    /// UNPIVOT ((col1, col2) FOR name_column IN (col1, col2, ...))
    /// UNPIVOT INCLUDE NULLS (value_column FOR name_column IN (...))
    /// UNPIVOT EXCLUDE NULLS (value_column FOR name_column IN (...))
    fn parse_unpivot(&mut self, source: Expression) -> Result<Expression> {
        // Check for optional INCLUDE NULLS or EXCLUDE NULLS
        let include_nulls = if self.match_text_seq(&["INCLUDE", "NULLS"]) {
            Some(true)
        } else if self.match_text_seq(&["EXCLUDE", "NULLS"]) {
            Some(false)
        } else {
            None
        };

        self.expect(TokenType::LParen)?;

        // Value column(s) - can be identifier or (col1, col2, ...)
        // Allow keywords as identifiers (e.g., "values" is a common column name in UNPIVOT)
        let (value_column, value_column_parenthesized, extra_value_columns) =
            if self.match_token(TokenType::LParen) {
                // Parenthesized value column(s)
                let col = self.expect_identifier_or_keyword()?;
                let mut extra_cols = Vec::new();
                while self.match_token(TokenType::Comma) {
                    extra_cols.push(Identifier::new(self.expect_identifier_or_keyword()?));
                }
                self.expect(TokenType::RParen)?;
                (Identifier::new(col), true, extra_cols)
            } else {
                (
                    Identifier::new(self.expect_identifier_or_keyword()?),
                    false,
                    Vec::new(),
                )
            };

        // FOR name_column
        self.expect(TokenType::For)?;
        let name_column = Identifier::new(self.expect_identifier_or_keyword()?);

        // IN (columns with optional aliases)
        // Format: col1 [AS alias1], col2 [AS alias2], ...
        // Or tuple format: (col1, col2) [AS alias1], (col3, col4) [AS alias2], ...
        // Aliases can be expressions like 'PREFIX ' || CHR(38) || ' SUFFIX'
        self.expect(TokenType::In)?;
        self.expect(TokenType::LParen)?;
        let columns = {
            let mut cols = Vec::new();
            loop {
                if self.check(TokenType::RParen) {
                    break;
                }
                // Check if this is a tuple of columns: (col1, col2)
                let col_expr = if self.check(TokenType::LParen) {
                    // Could be a tuple of columns for multi-value unpivot
                    let saved = self.current;
                    self.advance(); // consume (
                                    // Try parsing as identifier list (tuple of columns)
                    let mut tuple_cols = Vec::new();
                    let first = self.expect_identifier_or_keyword();
                    if let Ok(first_id) = first {
                        tuple_cols.push(Expression::column(first_id));
                        while self.match_token(TokenType::Comma) {
                            if let Ok(id) = self.expect_identifier_or_keyword() {
                                tuple_cols.push(Expression::column(id));
                            } else {
                                break;
                            }
                        }
                        if self.match_token(TokenType::RParen) && tuple_cols.len() > 1 {
                            // Successful tuple parse
                            Some(Expression::Tuple(Box::new(Tuple {
                                expressions: tuple_cols,
                            })))
                        } else {
                            // Not a tuple, backtrack
                            self.current = saved;
                            self.parse_select_or_expression()?
                        }
                    } else {
                        // Not an identifier, backtrack
                        self.current = saved;
                        self.parse_select_or_expression()?
                    }
                } else {
                    self.parse_select_or_expression()?
                };

                if let Some(col) = col_expr {
                    // Check for alias
                    let col = if self.match_token(TokenType::As) {
                        // Parse the alias as an expression (allows string concatenation)
                        let alias_expr = self.parse_bitwise()?.ok_or_else(|| {
                            self.parse_error("Expected expression after AS in UNPIVOT IN clause")
                        })?;
                        Expression::PivotAlias(Box::new(PivotAlias {
                            this: col,
                            alias: alias_expr,
                        }))
                    } else {
                        col
                    };
                    cols.push(col);
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            cols
        };
        self.expect(TokenType::RParen)?;

        self.expect(TokenType::RParen)?;

        Ok(Expression::Unpivot(Box::new(Unpivot {
            this: source,
            value_column,
            name_column,
            columns,
            alias: None,
            value_column_parenthesized,
            include_nulls,
            extra_value_columns,
        })))
    }

    /// Parse Redshift UNPIVOT in FROM clause for SUPER object traversal
    /// Syntax: UNPIVOT expr [AS val_alias AT attr_alias]
    /// Examples:
    ///   FROM t, UNPIVOT t.arr[0]
    ///   FROM t, UNPIVOT t.arr AS val AT attr
    fn parse_redshift_unpivot_table(&mut self) -> Result<Expression> {
        // Parse the expression (column reference with possible array subscript)
        // We need to parse a primary expression that can include:
        // - Simple column: c.c_orders
        // - Array subscript: c.c_orders[0]
        // - Multiple subscripts: c.c_orders[0].items[1]
        // Using parse_primary which handles column refs with subscripts
        let this = self.parse_primary()?;

        // Check for optional AS val_alias AT attr_alias
        let alias = if self.match_token(TokenType::As) {
            let val_alias = self.expect_identifier_or_keyword()?;
            // Check for AT attr_alias
            if self.match_text_seq(&["AT"]) {
                let attr_alias = self.expect_identifier_or_keyword()?;
                // Create alias expression that captures both aliases
                // We'll use the val_alias as the main alias and store attr_alias in a way
                // the generator can reconstruct "AS val AT attr"
                Some(Identifier::new(format!("{} AT {}", val_alias, attr_alias)))
            } else {
                Some(Identifier::new(val_alias))
            }
        } else {
            None
        };

        // Return a Pivot expression with unpivot=true
        // Use the simplified form pattern where:
        // - this: the expression being unpivoted
        // - expressions: empty (no ON expressions)
        // - unpivot: true
        // - alias: captured above
        Ok(Expression::Pivot(Box::new(Pivot {
            this,
            expressions: Vec::new(),
            fields: Vec::new(),
            using: Vec::new(),
            group: None,
            unpivot: true,
            into: None,
            alias,
            include_nulls: None,
            default_on_null: None,
            with: None,
        })))
    }

    /// BigQuery: Parse a table part that may contain hyphens (e.g., project-id)
    /// Also handles numeric table parts (e.g., foo.bar.25 -> foo.bar.`25`)
    /// Returns the identifier, possibly with merged hyphenated parts and quoted flag set.
    fn parse_bigquery_table_part(&mut self) -> Result<Identifier> {
        use crate::dialects::DialectType;

        // Try to parse a number for BigQuery numeric table parts (e.g., foo.bar.25)
        if matches!(self.config.dialect, Some(DialectType::BigQuery))
            && self.check(TokenType::Number)
        {
            let num_token = self.advance().clone();
            let mut name = num_token.text.clone();

            // Check if followed by more connected tokens (e.g., 25x, 25_, 25ab)
            // Numbers followed immediately by identifiers without whitespace are merged
            while !self.is_at_end() && self.is_connected() {
                let tok = self.advance().clone();
                name.push_str(&tok.text);
            }

            return Ok(Identifier {
                name,
                quoted: true,
                trailing_comments: Vec::new(),
                span: None,
            });
        }

        // MySQL numeric-starting identifiers (e.g., 00f, 1d)
        if matches!(self.config.dialect, Some(DialectType::MySQL)) && self.check(TokenType::Number)
        {
            let num_token = self.advance().clone();
            let mut name = num_token.text.clone();

            // Merge with connected identifier/var tokens only (not punctuation)
            while !self.is_at_end()
                && self.is_connected()
                && (self.check(TokenType::Var) || self.check(TokenType::Identifier))
            {
                let tok = self.advance().clone();
                name.push_str(&tok.text);
            }

            return Ok(Identifier {
                name,
                quoted: true,
                trailing_comments: Vec::new(),
                span: None,
            });
        }

        let mut ident = self.expect_identifier_or_keyword_with_quoted()?;

        // BigQuery: merge hyphenated parts (e.g., pro-ject_id -> `pro-ject_id`)
        if matches!(self.config.dialect, Some(DialectType::BigQuery)) && !ident.quoted {
            // Check if next token is a dash and it looks connected (no space)
            if self.check(TokenType::Dash) && self.is_connected_dash() {
                let mut name = ident.name.clone();

                while self.check(TokenType::Dash) && self.is_connected_dash() {
                    self.advance(); // consume dash
                    name.push('-');
                    // Consume the next part
                    let part = self.advance().clone();
                    name.push_str(&part.text);
                    // Continue consuming connected tokens (for things like a-b-c)
                    while !self.is_at_end()
                        && self.is_connected()
                        && !self.check(TokenType::Dot)
                        && !self.check(TokenType::Dash)
                        && !self.check(TokenType::LParen)
                        && !self.check(TokenType::RParen)
                    {
                        let tok = self.advance().clone();
                        name.push_str(&tok.text);
                    }
                }

                ident = Identifier {
                    name,
                    quoted: false,
                    trailing_comments: Vec::new(),
                    span: None,
                };
            }
        }

        Ok(ident)
    }

    /// Check if the current dash token is "connected" to the next token
    /// (i.e., the dash and next token are part of a hyphenated identifier)
    fn is_connected_dash(&self) -> bool {
        if !self.check(TokenType::Dash) {
            return false;
        }
        if self.current + 1 >= self.tokens.len() {
            return false;
        }
        let dash_token = &self.tokens[self.current];
        let next_token = &self.tokens[self.current + 1];

        // The next token after dash must be an identifier, number, or keyword
        // and it must be adjacent (no whitespace between dash and next token)
        let next_is_valid = matches!(
            next_token.token_type,
            TokenType::Identifier
                | TokenType::Var
                | TokenType::Number
                | TokenType::All
                | TokenType::Select
                | TokenType::From
                | TokenType::Where
        ) || next_token.token_type.is_keyword();

        // Check adjacency: dash ends at dash.end, next starts at next.start
        let adjacent = dash_token.span.end + 1 == next_token.span.start
            || dash_token.span.end == next_token.span.start;

        next_is_valid && adjacent
    }

    /// Check if the current token is "connected" to the previous token (no whitespace)
    fn is_connected(&self) -> bool {
        if self.current == 0 || self.current >= self.tokens.len() {
            return false;
        }
        let prev_token = &self.tokens[self.current - 1];
        let curr_token = &self.tokens[self.current];
        // Tokens are connected if they are immediately adjacent (no characters between them)
        // span.end is exclusive, so if prev.end == curr.start, they are adjacent
        prev_token.span.end == curr_token.span.start
    }

    /// Parse a table reference (schema.table format)
    fn parse_table_ref(&mut self) -> Result<TableRef> {
        // Check for Snowflake IDENTIFIER() function: IDENTIFIER('string') or IDENTIFIER($var)
        if self.check_identifier("IDENTIFIER") && self.check_next(TokenType::LParen) {
            self.advance(); // consume IDENTIFIER
            self.advance(); // consume (
                            // Parse the argument: either a string literal, a variable ($foo), or identifier
            let arg = if self.check(TokenType::String) {
                let s = self.advance().text.clone();
                Expression::Literal(Literal::String(s))
            } else if self.check(TokenType::Parameter) {
                // ?-style parameter
                let var = self.advance().text.clone();
                Expression::Var(Box::new(crate::expressions::Var { this: var }))
            } else if self.check(TokenType::Dollar) {
                // $foo style variable - Dollar followed by identifier
                self.advance(); // consume $
                let var_name = self.expect_identifier()?;
                Expression::Var(Box::new(crate::expressions::Var {
                    this: format!("${}", var_name),
                }))
            } else {
                // Could be an identifier too
                let ident = self.expect_identifier()?;
                Expression::Identifier(Identifier::new(ident))
            };
            self.expect(TokenType::RParen)?;
            let trailing_comments = self.previous_trailing_comments();
            // Create a Function expression to represent IDENTIFIER(arg)
            let identifier_func = Expression::Function(Box::new(crate::expressions::Function {
                name: "IDENTIFIER".to_string(),
                args: vec![arg],
                distinct: false,
                trailing_comments: Vec::new(),
                use_bracket_syntax: false,
                no_parens: false,
                quoted: false,
                span: None,
                inferred_type: None,
            }));
            return Ok(TableRef {
                catalog: None,
                schema: None,
                name: Identifier::empty(),
                alias: None,
                alias_explicit_as: false,
                column_aliases: Vec::new(),
                trailing_comments,
                when: None,
                only: false,
                final_: false,
                table_sample: None,
                hints: Vec::new(),
                system_time: None,
                partitions: Vec::new(),
                identifier_func: Some(Box::new(identifier_func)),
                changes: None,
                version: None,
                span: None,
            });
        }

        let first = self.parse_bigquery_table_part()?;

        // Check for schema.table format
        if self.match_token(TokenType::Dot) {
            // Handle TSQL a..b syntax (database..table with empty schema)
            if self.check(TokenType::Dot) {
                // Two consecutive dots: a..b means catalog..table (empty schema)
                self.advance(); // consume second dot
                let table = self.parse_bigquery_table_part()?;
                let trailing_comments = self.previous_trailing_comments();
                Ok(TableRef {
                    catalog: Some(first),
                    schema: Some(Identifier::new("")), // Empty schema represents ..
                    name: table,
                    alias: None,
                    alias_explicit_as: false,
                    column_aliases: Vec::new(),
                    trailing_comments,
                    when: None,
                    only: false,
                    final_: false,
                    table_sample: None,
                    hints: Vec::new(),
                    system_time: None,
                    partitions: Vec::new(),
                    identifier_func: None,
                    changes: None,
                    version: None,
                    span: None,
                })
            } else {
                // BigQuery: handle x.* wildcard table reference (e.g., SELECT * FROM x.*)
                // After the first dot, if we see a Star token, it's a wildcard table name
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::BigQuery)
                ) && self.check(TokenType::Star)
                {
                    self.advance(); // consume *
                    let trailing_comments = self.previous_trailing_comments();
                    return Ok(TableRef {
                        catalog: None,
                        schema: Some(first),
                        name: Identifier::new("*"),
                        alias: None,
                        alias_explicit_as: false,
                        column_aliases: Vec::new(),
                        trailing_comments,
                        when: None,
                        only: false,
                        final_: false,
                        table_sample: None,
                        hints: Vec::new(),
                        system_time: None,
                        partitions: Vec::new(),
                        identifier_func: None,
                        changes: None,
                        version: None,
                        span: None,
                    });
                }
                let table = self.parse_bigquery_table_part()?;
                // Check for catalog.schema.table format
                if self.match_token(TokenType::Dot) {
                    // BigQuery: handle a.b.* wildcard table reference
                    if matches!(
                        self.config.dialect,
                        Some(crate::dialects::DialectType::BigQuery)
                    ) && self.check(TokenType::Star)
                    {
                        self.advance(); // consume *
                        let trailing_comments = self.previous_trailing_comments();
                        return Ok(TableRef {
                            catalog: Some(first),
                            schema: Some(table),
                            name: Identifier::new("*"),
                            alias: None,
                            alias_explicit_as: false,
                            column_aliases: Vec::new(),
                            trailing_comments,
                            when: None,
                            only: false,
                            final_: false,
                            table_sample: None,
                            hints: Vec::new(),
                            system_time: None,
                            partitions: Vec::new(),
                            identifier_func: None,
                            changes: None,
                            version: None,
                            span: None,
                        });
                    }
                    let actual_table = self.parse_bigquery_table_part()?;
                    let trailing_comments = self.previous_trailing_comments();
                    Ok(TableRef {
                        catalog: Some(first),
                        schema: Some(table),
                        name: actual_table,
                        alias: None,
                        alias_explicit_as: false,
                        column_aliases: Vec::new(),
                        trailing_comments,
                        when: None,
                        only: false,
                        final_: false,
                        table_sample: None,
                        hints: Vec::new(),
                        system_time: None,
                        partitions: Vec::new(),
                        identifier_func: None,
                        changes: None,
                        version: None,
                        span: None,
                    })
                } else {
                    let trailing_comments = self.previous_trailing_comments();
                    Ok(TableRef {
                        catalog: None,
                        schema: Some(first),
                        name: table,
                        alias: None,
                        alias_explicit_as: false,
                        column_aliases: Vec::new(),
                        trailing_comments,
                        when: None,
                        only: false,
                        final_: false,
                        table_sample: None,
                        hints: Vec::new(),
                        system_time: None,
                        partitions: Vec::new(),
                        identifier_func: None,
                        changes: None,
                        version: None,
                        span: None,
                    })
                }
            }
        } else {
            let trailing_comments = self.previous_trailing_comments();
            Ok(TableRef {
                catalog: None,
                schema: None,
                name: first,
                alias: None,
                alias_explicit_as: false,
                column_aliases: Vec::new(),
                trailing_comments,
                when: None,
                only: false,
                final_: false,
                table_sample: None,
                hints: Vec::new(),
                system_time: None,
                partitions: Vec::new(),
                identifier_func: None,
                changes: None,
                version: None,
                span: None,
            })
        }
    }

    /// Parse a datetime field for EXTRACT function (YEAR, MONTH, DAY, etc.)
    fn parse_datetime_field(&mut self) -> Result<DateTimeField> {
        let token = self.advance();
        let original_name = token.text.clone();
        let name = original_name.to_uppercase();
        match name.as_str() {
            "YEAR" => Ok(DateTimeField::Year),
            "MONTH" => Ok(DateTimeField::Month),
            "DAY" => Ok(DateTimeField::Day),
            "HOUR" => Ok(DateTimeField::Hour),
            "MINUTE" => Ok(DateTimeField::Minute),
            "SECOND" => Ok(DateTimeField::Second),
            "MILLISECOND" => Ok(DateTimeField::Millisecond),
            "MICROSECOND" => Ok(DateTimeField::Microsecond),
            "DOW" | "DAYOFWEEK" => Ok(DateTimeField::DayOfWeek),
            "DOY" | "DAYOFYEAR" => Ok(DateTimeField::DayOfYear),
            "WEEK" => {
                // Check for modifier like WEEK(monday)
                if self.match_token(TokenType::LParen) {
                    let modifier = self.expect_identifier_or_keyword()?;
                    self.expect(TokenType::RParen)?;
                    Ok(DateTimeField::WeekWithModifier(modifier))
                } else {
                    Ok(DateTimeField::Week)
                }
            }
            "QUARTER" => Ok(DateTimeField::Quarter),
            "EPOCH" => Ok(DateTimeField::Epoch),
            "TIMEZONE" => Ok(DateTimeField::Timezone),
            "TIMEZONE_HOUR" => Ok(DateTimeField::TimezoneHour),
            "TIMEZONE_MINUTE" => Ok(DateTimeField::TimezoneMinute),
            "DATE" => Ok(DateTimeField::Date),
            "TIME" => Ok(DateTimeField::Time),
            // Allow arbitrary field names for dialect-specific functionality
            _ => Ok(DateTimeField::Custom(original_name)),
        }
    }

    /// Parse a table expression followed by any joins
    /// Used for parenthesized join expressions like (tbl1 CROSS JOIN tbl2)
    fn parse_table_expression_with_joins(&mut self) -> Result<(Expression, Vec<Join>)> {
        // First parse the left table expression
        let left = self.parse_table_expression()?;

        // Then parse any joins
        let joins = self.parse_joins()?;

        Ok((left, joins))
    }

    /// Parse JOIN clauses
    ///
    /// Supports right-associative chained JOINs where ON/USING clauses are assigned right-to-left:
    /// - `a JOIN b JOIN c ON cond1 ON cond2` means `a JOIN (b JOIN c ON cond1) ON cond2`
    /// - The rightmost ON applies to the rightmost unconditioned JOIN
    fn parse_joins(&mut self) -> Result<Vec<Join>> {
        let mut joins = Vec::new();
        let mut nesting_group: usize = 0;

        // Loop: Phase 1 (parse JOINs) + Phase 2 (assign deferred conditions)
        // After phase 2, if there are more JOIN keywords, continue with another round
        loop {
            let joins_before = joins.len();

            // Phase 1: Parse all JOINs with optional inline ON/USING conditions
            loop {
                let pos_before_join_kind = self.current;
                let join_kind_result = self.try_parse_join_kind();
                let (kind, needs_join_keyword, use_inner_keyword, use_outer_keyword, join_hint) =
                    match join_kind_result {
                        Some(r) => r,
                        None => break,
                    };
                // Collect comments from all tokens consumed by try_parse_join_kind:
                // - Leading comments on the first token (comments on a separate line before the join)
                // - Trailing comments between join keywords (e.g., INNER /* comment */ JOIN)
                let mut join_comments = Vec::new();
                // Capture leading comments from the first token of the join kind
                if pos_before_join_kind < self.tokens.len() {
                    join_comments
                        .extend(self.tokens[pos_before_join_kind].comments.iter().cloned());
                }
                for i in pos_before_join_kind..self.current {
                    if i < self.tokens.len() {
                        join_comments.extend(self.tokens[i].trailing_comments.iter().cloned());
                    }
                }
                // Snowflake: DIRECTED keyword before JOIN (e.g., CROSS DIRECTED JOIN)
                let directed = if needs_join_keyword && self.check_identifier("DIRECTED") {
                    self.advance();
                    true
                } else {
                    false
                };
                if needs_join_keyword {
                    self.expect(TokenType::Join)?;
                }

                // ClickHouse: ARRAY JOIN uses expressions, not table references
                let table = if matches!(kind, JoinKind::Array | JoinKind::LeftArray) {
                    let mut items = Vec::new();
                    // Handle ARRAY JOIN with no arguments (intentional error test)
                    if !self.is_at_end()
                        && !self.check(TokenType::Semicolon)
                        && !self.check(TokenType::RParen)
                    {
                        loop {
                            let expr = self.parse_expression()?;
                            let item = if self.match_token(TokenType::As) {
                                let alias_name = self.expect_identifier_or_safe_keyword()?;
                                Expression::Alias(Box::new(Alias {
                                    this: expr,
                                    alias: Identifier::new(alias_name),
                                    column_aliases: Vec::new(),
                                    pre_alias_comments: Vec::new(),
                                    trailing_comments: Vec::new(),
                                    inferred_type: None,
                                }))
                            } else {
                                expr
                            };
                            items.push(item);
                            if !self.match_token(TokenType::Comma) {
                                break;
                            }
                        }
                    } // end if !is_at_end check
                    if items.len() == 1 {
                        items.pop().unwrap()
                    } else if items.is_empty() {
                        Expression::Null(Null)
                    } else {
                        Expression::Tuple(Box::new(Tuple { expressions: items }))
                    }
                } else {
                    self.parse_table_expression()?
                };

                // Snowflake ASOF JOIN: OFFSET/LIMIT before MATCH_CONDITION are table aliases
                let table = if matches!(
                    kind,
                    JoinKind::AsOf | JoinKind::AsOfLeft | JoinKind::AsOfRight
                ) && (self.check(TokenType::Offset) || self.check(TokenType::Limit))
                    && self
                        .peek_nth(1)
                        .map(|t| t.text.eq_ignore_ascii_case("MATCH_CONDITION"))
                        == Some(true)
                {
                    let alias_name = self.advance().text.clone();
                    Expression::Alias(Box::new(Alias {
                        this: table,
                        alias: Identifier::new(alias_name),
                        column_aliases: Vec::new(),
                        pre_alias_comments: Vec::new(),
                        trailing_comments: Vec::new(),
                        inferred_type: None,
                    }))
                } else {
                    table
                };

                // Try to parse inline MATCH_CONDITION/ON/USING (only if not followed by another JOIN)
                // We need to peek ahead to see if there's another JOIN keyword coming
                let has_match_condition = self.check_identifier("MATCH_CONDITION");
                let has_inline_condition = self.check(TokenType::On)
                    || self.check(TokenType::Using)
                    || has_match_condition;
                let next_is_join = self.check_join_keyword();

                // Parse MATCH_CONDITION first (Snowflake ASOF JOIN can have MATCH_CONDITION before ON)
                let match_condition = if has_match_condition && !next_is_join {
                    if self.match_identifier("MATCH_CONDITION") {
                        self.expect(TokenType::LParen)?;
                        let condition = self.parse_expression()?;
                        self.expect(TokenType::RParen)?;
                        Some(condition)
                    } else {
                        None
                    }
                } else {
                    None
                };

                let (on, using) = if (has_inline_condition || match_condition.is_some())
                    && !self.check_join_keyword()
                {
                    // Parse inline condition only if there's no more JOINs following
                    if self.match_token(TokenType::On) {
                        (Some(self.parse_expression()?), Vec::new())
                    } else if self.match_token(TokenType::Using) {
                        // ClickHouse allows USING without parentheses
                        let has_parens = self.match_token(TokenType::LParen);
                        // Use parse_using_column_list to handle qualified names like t1.col
                        let cols = self.parse_using_column_list()?;
                        if has_parens {
                            self.expect(TokenType::RParen)?;
                        }
                        (None, cols)
                    } else {
                        (None, Vec::new())
                    }
                } else {
                    (None, Vec::new())
                };

                joins.push(Join {
                    this: table,
                    on,
                    using,
                    kind,
                    use_inner_keyword,
                    use_outer_keyword,
                    deferred_condition: false,
                    join_hint,
                    match_condition,
                    pivots: Vec::new(),
                    comments: join_comments,
                    nesting_group,
                    directed,
                });
            }

            // Phase 2: Assign deferred ON/USING conditions to unconditioned joins (right-to-left)
            // Only consider joins from the current batch (joins_before..)
            let unconditioned: Vec<usize> = joins[joins_before..]
                .iter()
                .enumerate()
                .filter(|(_, j)| j.on.is_none() && j.using.is_empty())
                .map(|(i, _)| joins_before + i)
                .collect();

            let mut idx = unconditioned.len();
            while idx > 0 {
                if self.match_token(TokenType::On) {
                    idx -= 1;
                    let join_idx = unconditioned[idx];
                    joins[join_idx].on = Some(self.parse_expression()?);
                    joins[join_idx].deferred_condition = true;
                } else if self.match_token(TokenType::Using) {
                    idx -= 1;
                    let join_idx = unconditioned[idx];
                    let has_parens = self.match_token(TokenType::LParen);
                    // Handle empty USING ()
                    let cols = if has_parens && self.check(TokenType::RParen) {
                        Vec::new()
                    } else {
                        // Use parse_using_column_list to handle qualified names like t1.col
                        self.parse_using_column_list()?
                    };
                    joins[join_idx].using = cols;
                    if has_parens {
                        self.expect(TokenType::RParen)?;
                    }
                    joins[join_idx].deferred_condition = true;
                } else {
                    break;
                }
            }

            // If no new joins were parsed in this round, we're done
            if joins.len() == joins_before {
                break;
            }

            // If there are more JOIN keywords after deferred conditions, continue with another round
            if !self.check_join_keyword() {
                break;
            }
            nesting_group += 1;
        }

        Ok(joins)
    }

    /// Check if the current token starts a JOIN clause
    fn check_join_keyword(&self) -> bool {
        self.check(TokenType::Join) ||
        self.check(TokenType::Inner) ||
        self.check(TokenType::Left) ||
        self.check(TokenType::Right) ||
        self.check(TokenType::Full) ||
        self.check(TokenType::Cross) ||
        self.check(TokenType::Natural) ||
        self.check(TokenType::Outer) ||
        // ClickHouse: ARRAY JOIN, GLOBAL JOIN, ALL JOIN, ANY JOIN, PASTE JOIN
        (matches!(self.config.dialect, Some(crate::dialects::DialectType::ClickHouse)) &&
            (self.check_identifier("ARRAY") || self.check_identifier("GLOBAL") || self.check(TokenType::All) || self.check(TokenType::Any) || self.check_identifier("PASTE")))
    }

    /// Try to parse a JOIN kind
    /// Returns (JoinKind, needs_join_keyword, use_inner_keyword, use_outer_keyword, join_hint)
    fn try_parse_join_kind(&mut self) -> Option<(JoinKind, bool, bool, bool, Option<String>)> {
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) {
            let start = self.current;
            let mut global = false;
            let mut strictness: Option<String> = None;
            let mut kind: Option<JoinKind> = None;
            let mut use_outer = false;
            let mut use_inner = false;

            if self.match_identifier("GLOBAL") {
                global = true;
            }

            loop {
                if strictness.is_none() && self.match_token(TokenType::All) {
                    strictness = Some("ALL".to_string());
                    continue;
                }
                if strictness.is_none() && self.match_token(TokenType::Any) {
                    strictness = Some("ANY".to_string());
                    continue;
                }
                if strictness.is_none() && self.match_token(TokenType::AsOf) {
                    strictness = Some("ASOF".to_string());
                    continue;
                }
                if strictness.is_none() && self.match_token(TokenType::Semi) {
                    strictness = Some("SEMI".to_string());
                    continue;
                }
                if strictness.is_none() && self.match_token(TokenType::Anti) {
                    strictness = Some("ANTI".to_string());
                    continue;
                }
                if kind.is_none() && self.match_token(TokenType::Left) {
                    use_outer = self.match_token(TokenType::Outer);
                    use_inner = self.match_token(TokenType::Inner);
                    kind = Some(JoinKind::Left);
                    continue;
                }
                if kind.is_none() && self.match_token(TokenType::Right) {
                    use_outer = self.match_token(TokenType::Outer);
                    use_inner = self.match_token(TokenType::Inner);
                    kind = Some(JoinKind::Right);
                    continue;
                }
                if kind.is_none() && self.match_token(TokenType::Full) {
                    use_outer = self.match_token(TokenType::Outer);
                    kind = Some(JoinKind::Full);
                    continue;
                }
                if kind.is_none() && self.match_token(TokenType::Inner) {
                    use_inner = true;
                    kind = Some(JoinKind::Inner);
                    continue;
                }
                break;
            }

            // ClickHouse: ARRAY JOIN or LEFT ARRAY JOIN
            if self.check_identifier("ARRAY") && self.check_next(TokenType::Join) {
                let array_kind = if matches!(kind, Some(JoinKind::Left)) {
                    JoinKind::LeftArray
                } else {
                    JoinKind::Array
                };
                self.advance(); // consume ARRAY
                                // JOIN will be consumed by caller
                return Some((array_kind, true, false, false, None));
            }

            // ClickHouse: PASTE JOIN (positional join, no ON/USING)
            if self.check_identifier("PASTE") && self.check_next(TokenType::Join) {
                self.advance(); // consume PASTE
                                // JOIN will be consumed by caller
                return Some((JoinKind::Paste, true, false, false, None));
            }

            if global || strictness.is_some() || kind.is_some() {
                if self.check(TokenType::Join) {
                    let join_kind = kind.unwrap_or(JoinKind::Inner);
                    let mut hints = Vec::new();
                    if global {
                        hints.push("GLOBAL".to_string());
                    }
                    if let Some(strict) = strictness {
                        hints.push(strict);
                    }
                    let join_hint = if hints.is_empty() {
                        None
                    } else {
                        Some(hints.join(" "))
                    };
                    return Some((join_kind, true, use_inner, use_outer, join_hint));
                } else {
                    self.current = start;
                }
            }
        }

        // Check for ASOF first (DuckDB/Snowflake) - can be followed by LEFT/RIGHT/etc.
        if self.match_token(TokenType::AsOf) {
            // ASOF can be followed by LEFT, RIGHT, INNER, or standalone
            if self.match_token(TokenType::Left) {
                let use_outer = self.match_token(TokenType::Outer);
                Some((JoinKind::AsOfLeft, true, false, use_outer, None))
            } else if self.match_token(TokenType::Right) {
                let use_outer = self.match_token(TokenType::Outer);
                Some((JoinKind::AsOfRight, true, false, use_outer, None))
            } else if self.match_token(TokenType::Inner) {
                Some((JoinKind::AsOf, true, true, false, None))
            } else {
                // Standalone ASOF JOIN
                Some((JoinKind::AsOf, true, false, false, None))
            }
        } else if self.check(TokenType::Inner) {
            // Check if INNER is followed by a set operation (BigQuery INNER UNION/INTERSECT/EXCEPT)
            // In that case, don't treat it as a JOIN keyword
            let saved = self.current;
            self.advance(); // consume INNER
            if self.check(TokenType::Union)
                || self.check(TokenType::Intersect)
                || self.check(TokenType::Except)
            {
                self.current = saved; // backtrack
                return None;
            }
            // Check for TSQL join hints: INNER LOOP JOIN, INNER HASH JOIN, INNER MERGE JOIN
            let join_hint = self.parse_tsql_join_hint();
            Some((JoinKind::Inner, true, true, false, join_hint)) // INNER keyword was explicit
        } else if self.check(TokenType::Left) {
            // Check if LEFT is followed by a set operation (BigQuery LEFT UNION/INTERSECT/EXCEPT)
            let saved = self.current;
            self.advance(); // consume LEFT
                            // LEFT can be followed by OUTER/INNER then set op, or directly by set op
            let at_set_op = self.check(TokenType::Union)
                || self.check(TokenType::Intersect)
                || self.check(TokenType::Except);
            let at_inner_set_op = self.check(TokenType::Inner) && {
                let saved2 = self.current;
                self.advance();
                let is_setop = self.check(TokenType::Union)
                    || self.check(TokenType::Intersect)
                    || self.check(TokenType::Except);
                self.current = saved2;
                is_setop
            };
            if at_set_op || at_inner_set_op {
                self.current = saved; // backtrack
                return None;
            }
            // Continue with normal LEFT JOIN parsing
            self.current = saved;
            self.match_token(TokenType::Left); // re-consume LEFT
            let use_outer = self.match_token(TokenType::Outer);
            let use_inner = self.match_token(TokenType::Inner);
            let join_hint = self.parse_tsql_join_hint();
            // Check for SEMI, ANTI, or LATERAL
            if self.match_token(TokenType::Semi) {
                Some((JoinKind::LeftSemi, true, use_inner, use_outer, join_hint))
            } else if self.match_token(TokenType::Anti) {
                Some((JoinKind::LeftAnti, true, use_inner, use_outer, join_hint))
            } else if self.match_token(TokenType::Lateral) {
                Some((JoinKind::LeftLateral, true, use_inner, use_outer, join_hint))
            } else {
                Some((JoinKind::Left, true, use_inner, use_outer, join_hint))
            }
        } else if self.check(TokenType::Right) {
            // Check if RIGHT is followed by a set operation (BigQuery RIGHT UNION/INTERSECT/EXCEPT)
            let saved = self.current;
            self.advance(); // consume RIGHT
            let at_set_op = self.check(TokenType::Union)
                || self.check(TokenType::Intersect)
                || self.check(TokenType::Except);
            let at_inner_set_op = self.check(TokenType::Inner) && {
                let saved2 = self.current;
                self.advance();
                let is_setop = self.check(TokenType::Union)
                    || self.check(TokenType::Intersect)
                    || self.check(TokenType::Except);
                self.current = saved2;
                is_setop
            };
            if at_set_op || at_inner_set_op {
                self.current = saved; // backtrack
                return None;
            }
            // Continue with normal RIGHT JOIN parsing
            self.current = saved;
            self.match_token(TokenType::Right); // re-consume RIGHT
            let use_outer = self.match_token(TokenType::Outer);
            let use_inner = self.match_token(TokenType::Inner);
            let join_hint = self.parse_tsql_join_hint();
            // Check for SEMI or ANTI
            if self.match_token(TokenType::Semi) {
                Some((JoinKind::RightSemi, true, use_inner, use_outer, join_hint))
            } else if self.match_token(TokenType::Anti) {
                Some((JoinKind::RightAnti, true, use_inner, use_outer, join_hint))
            } else {
                Some((JoinKind::Right, true, use_inner, use_outer, join_hint))
            }
        } else if self.check(TokenType::Full) {
            // Check if FULL is followed by a set operation (BigQuery FULL UNION/INTERSECT/EXCEPT)
            let saved = self.current;
            self.advance(); // consume FULL
            let at_set_op = self.check(TokenType::Union)
                || self.check(TokenType::Intersect)
                || self.check(TokenType::Except);
            let at_inner_set_op = self.check(TokenType::Inner) && {
                let saved2 = self.current;
                self.advance();
                let is_setop = self.check(TokenType::Union)
                    || self.check(TokenType::Intersect)
                    || self.check(TokenType::Except);
                self.current = saved2;
                is_setop
            };
            if at_set_op || at_inner_set_op {
                self.current = saved; // backtrack
                return None;
            }
            // Continue with normal FULL JOIN parsing
            self.current = saved;
            self.match_token(TokenType::Full); // re-consume FULL
            let use_outer = self.match_token(TokenType::Outer);
            let join_hint = self.parse_tsql_join_hint();
            Some((JoinKind::Full, true, false, use_outer, join_hint))
        } else if self.match_token(TokenType::Cross) {
            // CROSS JOIN or CROSS APPLY
            if self.match_token(TokenType::Apply) {
                Some((JoinKind::CrossApply, false, false, false, None))
            } else {
                Some((JoinKind::Cross, true, false, false, None))
            }
        } else if self.match_token(TokenType::Natural) {
            // NATURAL can be followed by LEFT, RIGHT, INNER, FULL, or just JOIN
            if self.match_token(TokenType::Left) {
                let use_outer = self.match_token(TokenType::Outer);
                Some((JoinKind::NaturalLeft, true, false, use_outer, None))
            } else if self.match_token(TokenType::Right) {
                let use_outer = self.match_token(TokenType::Outer);
                Some((JoinKind::NaturalRight, true, false, use_outer, None))
            } else if self.match_token(TokenType::Full) {
                let use_outer = self.match_token(TokenType::Outer);
                Some((JoinKind::NaturalFull, true, false, use_outer, None))
            } else if self.match_token(TokenType::Inner) {
                Some((JoinKind::Natural, true, true, false, None))
            } else {
                Some((JoinKind::Natural, true, false, false, None))
            }
        } else if self.match_token(TokenType::Outer) {
            // OUTER APPLY or standalone OUTER JOIN
            if self.match_token(TokenType::Apply) {
                Some((JoinKind::OuterApply, false, false, true, None))
            } else {
                // Standalone OUTER JOIN (without LEFT/RIGHT/FULL)
                Some((JoinKind::Outer, true, false, true, None))
            }
        } else if self.check(TokenType::Lateral) {
            // Check if this is LATERAL VIEW (Hive/Spark syntax) vs LATERAL JOIN
            if self.current + 1 < self.tokens.len()
                && self.tokens[self.current + 1].token_type == TokenType::View
            {
                // LATERAL VIEW is not a JOIN type, return None
                None
            } else {
                self.advance(); // Consume LATERAL
                Some((JoinKind::Lateral, true, false, false, None))
            }
        } else if self.match_token(TokenType::Semi) {
            Some((JoinKind::Semi, true, false, false, None))
        } else if self.match_token(TokenType::Anti) {
            Some((JoinKind::Anti, true, false, false, None))
        } else if self.check_identifier("POSITIONAL") && self.check_next(TokenType::Join) {
            // DuckDB POSITIONAL JOIN
            self.advance(); // consume POSITIONAL
            Some((JoinKind::Positional, true, false, false, None))
        } else if self.match_token(TokenType::StraightJoin) {
            // STRAIGHT_JOIN in MySQL - doesn't need JOIN keyword after it
            Some((JoinKind::Straight, false, false, false, None))
        } else if self.check(TokenType::Join) {
            Some((JoinKind::Inner, true, false, false, None)) // Default JOIN is INNER (without explicit INNER keyword)
        } else if self.match_token(TokenType::Comma) {
            // Comma-separated tables: FROM a, b (old-style ANSI join syntax)
            Some((JoinKind::Implicit, false, false, false, None)) // No JOIN keyword needed
        } else {
            None
        }
    }

    /// Parse TSQL join hints: LOOP, HASH, MERGE, REMOTE
    fn parse_tsql_join_hint(&mut self) -> Option<String> {
        if self.check_identifier("LOOP") {
            self.advance();
            Some("LOOP".to_string())
        } else if self.check_identifier("HASH") {
            self.advance();
            Some("HASH".to_string())
        } else if self.check_identifier("REMOTE") {
            self.advance();
            Some("REMOTE".to_string())
        } else if self.check(TokenType::Merge) && {
            // Be careful: MERGE is also a keyword for MERGE statement
            // Only treat as hint if followed by JOIN
            let next_pos = self.current + 1;
            next_pos < self.tokens.len() && self.tokens[next_pos].token_type == TokenType::Join
        } {
            self.advance();
            Some("MERGE".to_string())
        } else {
            None
        }
    }

    /// Parse GROUP BY clause
    fn parse_group_by(&mut self) -> Result<GroupBy> {
        // Check for optional ALL/DISTINCT modifier
        // Some(true) = ALL, Some(false) = DISTINCT, None = no modifier
        let all = if self.match_token(TokenType::All) {
            Some(true)
        } else if self.match_token(TokenType::Distinct) {
            Some(false)
        } else {
            None
        };

        let mut expressions = Vec::new();

        // GROUP BY ALL / GROUP BY DISTINCT without following CUBE/ROLLUP/expressions
        // should return early (e.g., Snowflake's "GROUP BY ALL" without column list).
        // But in Presto/Trino, ALL/DISTINCT can be followed by CUBE/ROLLUP expressions.
        if all.is_some() && self.is_at_query_modifier_or_end() {
            return Ok(GroupBy {
                expressions,
                all,
                totals: false,
                comments: Vec::new(),
            });
        }

        // GROUP BY ALL WITH ROLLUP/CUBE/TOTALS — skip expression parsing, go straight to modifiers
        if all.is_some()
            && self.check(TokenType::With)
            && (self.check_next(TokenType::Cube)
                || self.check_next(TokenType::Rollup)
                || self.check_next_identifier("TOTALS"))
        {
            let mut totals = false;
            // Process WITH ROLLUP/CUBE
            if self.check_next(TokenType::Cube) || self.check_next(TokenType::Rollup) {
                self.advance(); // consume WITH
                if self.match_token(TokenType::Cube) {
                    expressions.push(Expression::Cube(Box::new(Cube {
                        expressions: Vec::new(),
                    })));
                } else if self.match_token(TokenType::Rollup) {
                    expressions.push(Expression::Rollup(Box::new(Rollup {
                        expressions: Vec::new(),
                    })));
                }
            }
            // Check for WITH TOTALS (possibly chained after ROLLUP/CUBE)
            if self.check(TokenType::With) && self.check_next_identifier("TOTALS") {
                self.advance(); // WITH
                self.advance(); // TOTALS
                totals = true;
            }
            return Ok(GroupBy {
                expressions,
                all,
                totals,
                comments: Vec::new(),
            });
        }

        loop {
            // Check for GROUPING SETS, CUBE, ROLLUP
            let expr = if self.check_identifier("GROUPING")
                && self
                    .peek_nth(1)
                    .map_or(false, |t| t.text.eq_ignore_ascii_case("SETS"))
                && {
                    self.advance();
                    self.advance();
                    true
                } {
                // GROUPING SETS (...)
                self.expect(TokenType::LParen)?;
                let args = self.parse_grouping_sets_args()?;
                self.expect(TokenType::RParen)?;
                Expression::Function(Box::new(Function {
                    name: "GROUPING SETS".to_string(),
                    args,
                    distinct: false,
                    trailing_comments: Vec::new(),
                    use_bracket_syntax: false,
                    no_parens: false,
                    quoted: false,
                    span: None,
                    inferred_type: None,
                }))
            } else if self.match_token(TokenType::Cube) {
                // CUBE (...)
                self.expect(TokenType::LParen)?;
                let args = self.parse_expression_list()?;
                self.expect(TokenType::RParen)?;
                Expression::Function(Box::new(Function {
                    name: "CUBE".to_string(),
                    args,
                    distinct: false,
                    trailing_comments: Vec::new(),
                    use_bracket_syntax: false,
                    no_parens: false,
                    quoted: false,
                    span: None,
                    inferred_type: None,
                }))
            } else if self.match_token(TokenType::Rollup) {
                // ROLLUP (...)
                self.expect(TokenType::LParen)?;
                let args = self.parse_expression_list()?;
                self.expect(TokenType::RParen)?;
                Expression::Function(Box::new(Function {
                    name: "ROLLUP".to_string(),
                    args,
                    distinct: false,
                    trailing_comments: Vec::new(),
                    use_bracket_syntax: false,
                    no_parens: false,
                    quoted: false,
                    span: None,
                    inferred_type: None,
                }))
            } else {
                self.parse_expression()?
            };

            // ClickHouse: GROUP BY expr AS alias
            let expr = if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && self.check(TokenType::As)
                && !self.check_next(TokenType::LParen)
            {
                self.advance(); // consume AS
                let alias = self.expect_identifier_or_keyword_with_quoted()?;
                Expression::Alias(Box::new(Alias::new(expr, alias)))
            } else {
                expr
            };

            expressions.push(expr);

            if !self.match_token(TokenType::Comma) {
                // Allow adjacent CUBE/ROLLUP/GROUPING SETS without comma separator
                // e.g., GROUP BY CUBE(a) ROLLUP(b), GROUPING SETS((c, d))
                if self.check(TokenType::Cube)
                    || self.check(TokenType::Rollup)
                    || (self.check_identifier("GROUPING")
                        && self
                            .peek_nth(1)
                            .map_or(false, |t| t.text.eq_ignore_ascii_case("SETS")))
                {
                    continue;
                }
                break;
            }
        }

        // Check for trailing WITH CUBE or WITH ROLLUP (Hive/MySQL syntax)
        // This is different from CUBE(...) or ROLLUP(...) which are parsed inline above
        // Use lookahead to avoid consuming WITH if it's not followed by CUBE or ROLLUP
        // (e.g., Redshift's WITH NO SCHEMA BINDING should not be consumed here)
        if self.check(TokenType::With)
            && (self.check_next(TokenType::Cube) || self.check_next(TokenType::Rollup))
        {
            self.advance(); // consume WITH
            if self.match_token(TokenType::Cube) {
                // WITH CUBE - add Cube with empty expressions
                expressions.push(Expression::Cube(Box::new(Cube {
                    expressions: Vec::new(),
                })));
            } else if self.match_token(TokenType::Rollup) {
                // WITH ROLLUP - add Rollup with empty expressions
                expressions.push(Expression::Rollup(Box::new(Rollup {
                    expressions: Vec::new(),
                })));
            }
        }

        // ClickHouse: WITH TOTALS
        let totals = if self.check(TokenType::With) && self.check_next_identifier("TOTALS") {
            self.advance(); // consume WITH
            self.advance(); // consume TOTALS
            true
        } else {
            false
        };

        Ok(GroupBy {
            expressions,
            all,
            totals,
            comments: Vec::new(),
        })
    }

    /// Parse GROUPING SETS arguments which can include tuples like (x, y), nested GROUPING SETS, CUBE, ROLLUP
    fn parse_grouping_sets_args(&mut self) -> Result<Vec<Expression>> {
        let mut args = Vec::new();

        loop {
            // Check for nested GROUPING SETS, CUBE, ROLLUP
            let expr = if self.check_identifier("GROUPING")
                && self
                    .peek_nth(1)
                    .map_or(false, |t| t.text.eq_ignore_ascii_case("SETS"))
                && {
                    self.advance();
                    self.advance();
                    true
                } {
                // Nested GROUPING SETS (...)
                self.expect(TokenType::LParen)?;
                let inner_args = self.parse_grouping_sets_args()?;
                self.expect(TokenType::RParen)?;
                Expression::Function(Box::new(Function {
                    name: "GROUPING SETS".to_string(),
                    args: inner_args,
                    distinct: false,
                    trailing_comments: Vec::new(),
                    use_bracket_syntax: false,
                    no_parens: false,
                    quoted: false,
                    span: None,
                    inferred_type: None,
                }))
            } else if self.match_token(TokenType::Cube) {
                // CUBE (...)
                self.expect(TokenType::LParen)?;
                let inner_args = self.parse_expression_list()?;
                self.expect(TokenType::RParen)?;
                Expression::Function(Box::new(Function {
                    name: "CUBE".to_string(),
                    args: inner_args,
                    distinct: false,
                    trailing_comments: Vec::new(),
                    use_bracket_syntax: false,
                    no_parens: false,
                    quoted: false,
                    span: None,
                    inferred_type: None,
                }))
            } else if self.match_token(TokenType::Rollup) {
                // ROLLUP (...)
                self.expect(TokenType::LParen)?;
                let inner_args = self.parse_expression_list()?;
                self.expect(TokenType::RParen)?;
                Expression::Function(Box::new(Function {
                    name: "ROLLUP".to_string(),
                    args: inner_args,
                    distinct: false,
                    trailing_comments: Vec::new(),
                    use_bracket_syntax: false,
                    no_parens: false,
                    quoted: false,
                    span: None,
                    inferred_type: None,
                }))
            } else if self.check(TokenType::LParen) {
                // This could be a tuple like (x, y) or empty ()
                self.advance(); // consume (
                if self.check(TokenType::RParen) {
                    // Empty tuple ()
                    self.advance();
                    Expression::Tuple(Box::new(Tuple {
                        expressions: Vec::new(),
                    }))
                } else {
                    let inner = self.parse_expression_list()?;
                    self.expect(TokenType::RParen)?;
                    Expression::Tuple(Box::new(Tuple { expressions: inner }))
                }
            } else {
                self.parse_expression()?
            };

            args.push(expr);

            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        Ok(args)
    }

    /// Parse ORDER BY clause
    fn parse_order_by(&mut self) -> Result<OrderBy> {
        self.parse_order_by_with_siblings(false)
    }

    /// Parse ORDER BY clause with optional siblings flag (Oracle ORDER SIBLINGS BY)
    fn parse_order_by_with_siblings(&mut self, siblings: bool) -> Result<OrderBy> {
        let mut expressions = Vec::new();

        loop {
            let expr = self.parse_expression()?;

            // ClickHouse: ORDER BY expr AS alias — allow AS alias before DESC/ASC
            // But NOT AS SELECT/WITH which would be CREATE TABLE ... AS SELECT
            let expr = if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && self.check(TokenType::As)
                && !self.check_next(TokenType::LParen)
                && !self.check_next(TokenType::Select)
                && !self.check_next(TokenType::With)
            {
                self.advance(); // consume AS
                let alias = self.expect_identifier_or_keyword_with_quoted()?;
                Expression::Alias(Box::new(Alias::new(expr, alias)))
            } else {
                expr
            };

            let (desc, explicit_asc) = if self.match_token(TokenType::Desc) {
                (true, false)
            } else if self.match_token(TokenType::Asc) {
                (false, true)
            } else {
                (false, false)
            };

            let nulls_first = if self.match_token(TokenType::Nulls) {
                if self.match_token(TokenType::First) {
                    Some(true)
                } else if self.match_token(TokenType::Last) {
                    Some(false)
                } else {
                    return Err(self.parse_error("Expected FIRST or LAST after NULLS"));
                }
            } else {
                None
            };

            // Parse optional WITH FILL clause (ClickHouse)
            let with_fill = if self.match_text_seq(&["WITH", "FILL"]) {
                let from_ = if self.match_token(TokenType::From) {
                    Some(Box::new(self.parse_or()?))
                } else {
                    None
                };
                let to = if self.match_text_seq(&["TO"]) {
                    Some(Box::new(self.parse_or()?))
                } else {
                    None
                };
                let step = if self.match_text_seq(&["STEP"]) {
                    Some(Box::new(self.parse_or()?))
                } else {
                    None
                };
                // ClickHouse: STALENESS [INTERVAL] expr
                let staleness = if self.match_text_seq(&["STALENESS"]) {
                    Some(Box::new(self.parse_or()?))
                } else {
                    None
                };
                let interpolate = if self.match_text_seq(&["INTERPOLATE"]) {
                    if self.match_token(TokenType::LParen) {
                        // Parse INTERPOLATE items: identifier [AS expression], ...
                        let mut items = Vec::new();
                        loop {
                            if self.check(TokenType::RParen) {
                                break;
                            }
                            let quoted = self.check(TokenType::QuotedIdentifier);
                            let name_text = self.expect_identifier_or_safe_keyword()?;
                            let name_id = Identifier {
                                name: name_text,
                                quoted,
                                trailing_comments: Vec::new(),
                                span: None,
                            };
                            let item = if self.match_token(TokenType::As) {
                                let expr = self.parse_expression()?;
                                // Store as Alias: this=expression, alias=name
                                Expression::Alias(Box::new(Alias {
                                    this: expr,
                                    alias: name_id,
                                    column_aliases: Vec::new(),
                                    pre_alias_comments: Vec::new(),
                                    trailing_comments: Vec::new(),
                                    inferred_type: None,
                                }))
                            } else {
                                Expression::Identifier(name_id)
                            };
                            items.push(item);
                            if !self.match_token(TokenType::Comma) {
                                break;
                            }
                        }
                        self.expect(TokenType::RParen)?;
                        if items.len() == 1 {
                            Some(Box::new(items.into_iter().next().unwrap()))
                        } else {
                            Some(Box::new(Expression::Tuple(Box::new(
                                crate::expressions::Tuple { expressions: items },
                            ))))
                        }
                    } else {
                        None
                    }
                } else {
                    None
                };
                Some(Box::new(WithFill {
                    from_,
                    to,
                    step,
                    staleness,
                    interpolate,
                }))
            } else {
                None
            };

            expressions.push(Ordered {
                this: expr,
                desc,
                nulls_first,
                explicit_asc,
                with_fill,
            });

            if !self.match_token(TokenType::Comma) {
                break;
            }

            // Handle trailing comma: if at end of input or semicolon, break
            if self.is_at_end() || self.check(TokenType::Semicolon) {
                break;
            }
        }

        Ok(OrderBy {
            expressions,
            siblings,
            comments: Vec::new(),
        })
    }

    /// Parse query modifiers (ORDER BY, LIMIT, OFFSET, DISTRIBUTE BY, SORT BY, CLUSTER BY) for parenthesized queries
    /// e.g., (SELECT 1) ORDER BY x LIMIT 1 OFFSET 1
    /// e.g., (SELECT 1 UNION SELECT 2) DISTRIBUTE BY z SORT BY x
    fn parse_query_modifiers(&mut self, inner: Expression) -> Result<Expression> {
        // Parse DISTRIBUTE BY (Hive/Spark)
        let distribute_by = if self.match_keywords(&[TokenType::Distribute, TokenType::By]) {
            let exprs = self.parse_expression_list()?;
            Some(DistributeBy { expressions: exprs })
        } else {
            None
        };

        // Parse SORT BY (Hive/Spark) or CLUSTER BY (Hive/Spark)
        let (sort_by, cluster_by) = if self.match_keywords(&[TokenType::Sort, TokenType::By]) {
            // SORT BY
            let mut orders = Vec::new();
            loop {
                if let Some(ordered) = self.parse_ordered_item()? {
                    orders.push(ordered);
                } else {
                    break;
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            (
                Some(SortBy {
                    expressions: orders,
                }),
                None,
            )
        } else if self.match_keywords(&[TokenType::Cluster, TokenType::By]) {
            // CLUSTER BY
            let mut orders = Vec::new();
            loop {
                if let Some(ordered) = self.parse_ordered_item()? {
                    orders.push(ordered);
                } else {
                    break;
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            (
                None,
                Some(ClusterBy {
                    expressions: orders,
                }),
            )
        } else {
            (None, None)
        };

        // Parse ORDER BY
        let order_by = if self.match_keywords(&[TokenType::Order, TokenType::By]) {
            Some(self.parse_order_by()?)
        } else {
            None
        };

        // Parse LIMIT
        let limit = if self.match_token(TokenType::Limit) {
            Some(Limit {
                this: self.parse_expression()?,
                percent: false,
                comments: Vec::new(),
            })
        } else {
            None
        };

        // Parse OFFSET
        let offset = if self.match_token(TokenType::Offset) {
            Some(Offset {
                this: self.parse_expression()?,
                rows: None,
            })
        } else {
            None
        };

        // If we have any modifiers, wrap in a Subquery with the modifiers
        if order_by.is_some()
            || limit.is_some()
            || offset.is_some()
            || distribute_by.is_some()
            || sort_by.is_some()
            || cluster_by.is_some()
        {
            // If inner is already a Subquery, add modifiers to it instead of double-wrapping
            if let Expression::Subquery(mut subq) = inner {
                subq.order_by = order_by;
                subq.limit = limit;
                subq.offset = offset;
                subq.distribute_by = distribute_by;
                subq.sort_by = sort_by;
                subq.cluster_by = cluster_by;
                Ok(Expression::Subquery(subq))
            } else if let Expression::Paren(paren) = inner {
                // If inner is a Paren containing a Subquery or other query, unwrap it
                // and add modifiers to a new Subquery wrapping the Paren
                // This handles cases like ((SELECT 1)) LIMIT 1
                Ok(Expression::Subquery(Box::new(Subquery {
                    this: Expression::Paren(paren),
                    alias: None,
                    column_aliases: Vec::new(),
                    order_by,
                    limit,
                    offset,
                    distribute_by,
                    sort_by,
                    cluster_by,
                    lateral: false,
                    modifiers_inside: false,
                    trailing_comments: Vec::new(),
                    inferred_type: None,
                })))
            } else {
                Ok(Expression::Subquery(Box::new(Subquery {
                    this: inner,
                    alias: None,
                    column_aliases: Vec::new(),
                    order_by,
                    limit,
                    offset,
                    distribute_by,
                    sort_by,
                    cluster_by,
                    lateral: false,
                    modifiers_inside: false,
                    trailing_comments: Vec::new(),
                    inferred_type: None,
                })))
            }
        } else {
            // No modifiers - return inner as-is (don't double-wrap if already a Subquery)
            Ok(inner)
        }
    }

    /// Parse ORDER BY expressions for use inside aggregate functions
    /// Returns Vec<Ordered> instead of OrderBy struct
    fn parse_order_by_list(&mut self) -> Result<Vec<Ordered>> {
        let mut expressions = Vec::new();

        loop {
            let expr = self.parse_expression()?;

            let (desc, explicit_asc) = if self.match_token(TokenType::Desc) {
                (true, false)
            } else if self.match_token(TokenType::Asc) {
                (false, true)
            } else {
                (false, false)
            };

            let nulls_first = if self.match_token(TokenType::Nulls) {
                if self.match_token(TokenType::First) {
                    Some(true)
                } else if self.match_token(TokenType::Last) {
                    Some(false)
                } else {
                    return Err(self.parse_error("Expected FIRST or LAST after NULLS"));
                }
            } else {
                None
            };

            expressions.push(Ordered {
                this: expr,
                desc,
                nulls_first,
                explicit_asc,
                with_fill: None,
            });

            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        Ok(expressions)
    }

    /// Parse DISTRIBUTE BY clause (Hive/Spark)
    fn parse_distribute_by(&mut self) -> Result<DistributeBy> {
        let mut expressions = Vec::new();

        loop {
            expressions.push(self.parse_expression()?);
            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        Ok(DistributeBy { expressions })
    }

    /// Parse CLUSTER BY clause (Hive/Spark)
    fn parse_cluster_by(&mut self) -> Result<ClusterBy> {
        let mut expressions = Vec::new();

        loop {
            let expr = self.parse_expression()?;

            let (desc, explicit_asc) = if self.match_token(TokenType::Desc) {
                (true, false)
            } else if self.match_token(TokenType::Asc) {
                (false, true)
            } else {
                (false, false)
            };

            expressions.push(Ordered {
                this: expr,
                desc,
                nulls_first: None,
                explicit_asc,
                with_fill: None,
            });

            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        Ok(ClusterBy { expressions })
    }

    /// Parse SORT BY clause (Hive/Spark)
    fn parse_sort_by(&mut self) -> Result<SortBy> {
        let mut expressions = Vec::new();

        loop {
            let expr = self.parse_expression()?;

            let (desc, explicit_asc) = if self.match_token(TokenType::Desc) {
                (true, false)
            } else if self.match_token(TokenType::Asc) {
                (false, true)
            } else {
                (false, false)
            };

            let nulls_first = if self.match_token(TokenType::Nulls) {
                if self.match_token(TokenType::First) {
                    Some(true)
                } else if self.match_token(TokenType::Last) {
                    Some(false)
                } else {
                    return Err(self.parse_error("Expected FIRST or LAST after NULLS"));
                }
            } else {
                None
            };

            expressions.push(Ordered {
                this: expr,
                desc,
                nulls_first,
                explicit_asc,
                with_fill: None,
            });

            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        Ok(SortBy { expressions })
    }

    /// Parse FOR UPDATE/SHARE locking clauses or FOR XML (T-SQL)
    /// Syntax: FOR UPDATE|SHARE|NO KEY UPDATE|KEY SHARE [OF tables] [NOWAIT|WAIT n|SKIP LOCKED]
    /// Also handles: LOCK IN SHARE MODE (MySQL)
    /// Also handles: FOR XML PATH|RAW|AUTO|EXPLICIT [, options...] (T-SQL)
    fn parse_locks_and_for_xml(&mut self) -> Result<(Vec<Lock>, Vec<Expression>)> {
        let mut locks = Vec::new();
        let mut for_xml = Vec::new();

        loop {
            let (update, key) = if self.match_keywords(&[TokenType::For, TokenType::Update]) {
                // FOR UPDATE
                (
                    Some(Box::new(Expression::Boolean(BooleanLiteral {
                        value: true,
                    }))),
                    None,
                )
            } else if self.check(TokenType::For) && self.check_next_identifier("XML") {
                // FOR XML (T-SQL) - parse XML options
                self.advance(); // consume FOR
                self.advance(); // consume XML
                for_xml = self.parse_for_xml_options()?;
                break; // FOR XML is always the last clause
            } else if self.check(TokenType::For) && self.check_next_identifier("SHARE") {
                // FOR SHARE
                self.advance(); // consume FOR
                self.advance(); // consume SHARE
                (None, None)
            } else if self.check_identifier("LOCK") && self.check_next(TokenType::In) {
                // LOCK IN SHARE MODE (MySQL) -> converted to FOR SHARE
                self.advance(); // consume LOCK
                self.advance(); // consume IN
                if self.match_identifier("SHARE") {
                    let _ = self.match_identifier("MODE");
                }
                (None, None)
            } else if self.check(TokenType::For) && self.check_next(TokenType::Key) {
                // FOR KEY SHARE (PostgreSQL)
                self.advance(); // consume FOR
                self.advance(); // consume KEY
                if !self.match_identifier("SHARE") {
                    break; // Not a valid lock clause
                }
                (
                    None,
                    Some(Box::new(Expression::Boolean(BooleanLiteral {
                        value: true,
                    }))),
                )
            } else if self.check(TokenType::For) && self.check_next(TokenType::No) {
                // FOR NO KEY UPDATE (PostgreSQL)
                self.advance(); // consume FOR
                self.advance(); // consume NO
                if !self.match_identifier("KEY") || !self.match_token(TokenType::Update) {
                    break; // Not a valid lock clause
                }
                (
                    Some(Box::new(Expression::Boolean(BooleanLiteral {
                        value: true,
                    }))),
                    Some(Box::new(Expression::Boolean(BooleanLiteral {
                        value: true,
                    }))),
                )
            } else {
                // No more lock clauses
                break;
            };

            // Parse optional OF clause: OF table1, table2
            let expressions = if self.match_token(TokenType::Of) {
                let mut tables = Vec::new();
                loop {
                    // Parse table reference (can be schema.table or just table)
                    let table = self.parse_table_ref()?;
                    tables.push(Expression::Table(table));
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
                tables
            } else {
                Vec::new()
            };

            // Parse wait option: NOWAIT, WAIT n, or SKIP LOCKED
            // Following Python sqlglot convention:
            // - NOWAIT -> Boolean(true)
            // - SKIP LOCKED -> Boolean(false)
            // - WAIT n -> Literal (the number)
            let wait = if self.match_identifier("NOWAIT") {
                // NOWAIT -> represented as Boolean(true)
                Some(Box::new(Expression::Boolean(BooleanLiteral {
                    value: true,
                })))
            } else if self.match_identifier("WAIT") {
                // WAIT n -> wait = expression (the number/literal)
                Some(Box::new(self.parse_primary()?))
            } else if self.match_identifier("SKIP") && self.match_identifier("LOCKED") {
                // SKIP LOCKED -> represented as Boolean(false)
                Some(Box::new(Expression::Boolean(BooleanLiteral {
                    value: false,
                })))
            } else {
                None
            };

            locks.push(Lock {
                update,
                expressions,
                wait,
                key,
            });
        }

        Ok((locks, for_xml))
    }

    /// Parse FOR XML options (T-SQL)
    /// Syntax: FOR XML PATH|RAW|AUTO|EXPLICIT [('element')] [, BINARY BASE64] [, ELEMENTS [XSINIL|ABSENT]] [, TYPE] [, ROOT('name')]
    fn parse_for_xml_options(&mut self) -> Result<Vec<Expression>> {
        let mut options = Vec::new();

        loop {
            // Parse XML option: could be a known option (PATH, RAW, AUTO, EXPLICIT, BINARY, ELEMENTS, TYPE, ROOT)
            // or an XMLKeyValueOption like PATH('element')
            if let Some(opt) = self.parse_for_xml_single_option()? {
                options.push(opt);
            } else {
                break;
            }

            // Check for comma to continue parsing more options
            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        Ok(options)
    }

    /// Parse a single FOR XML option
    fn parse_for_xml_single_option(&mut self) -> Result<Option<Expression>> {
        // Known XML modes: PATH, RAW, AUTO, EXPLICIT
        // Known options: BINARY BASE64, ELEMENTS [XSINIL|ABSENT], TYPE, ROOT('name')

        // Try to match known patterns
        if self.match_identifier("PATH") {
            let expression = if self.match_token(TokenType::LParen) {
                let expr = self.parse_string()?;
                self.expect(TokenType::RParen)?;
                expr
            } else {
                None
            };
            return Ok(Some(Expression::QueryOption(Box::new(QueryOption {
                this: Box::new(Expression::Var(Box::new(Var {
                    this: "PATH".to_string(),
                }))),
                expression: expression.map(|e| Box::new(e)),
            }))));
        }

        if self.match_identifier("RAW") {
            let expression = if self.match_token(TokenType::LParen) {
                let expr = self.parse_string()?;
                self.expect(TokenType::RParen)?;
                expr
            } else {
                None
            };
            return Ok(Some(Expression::QueryOption(Box::new(QueryOption {
                this: Box::new(Expression::Var(Box::new(Var {
                    this: "RAW".to_string(),
                }))),
                expression: expression.map(|e| Box::new(e)),
            }))));
        }

        if self.match_identifier("AUTO") {
            return Ok(Some(Expression::QueryOption(Box::new(QueryOption {
                this: Box::new(Expression::Var(Box::new(Var {
                    this: "AUTO".to_string(),
                }))),
                expression: None,
            }))));
        }

        if self.match_identifier("EXPLICIT") {
            return Ok(Some(Expression::QueryOption(Box::new(QueryOption {
                this: Box::new(Expression::Var(Box::new(Var {
                    this: "EXPLICIT".to_string(),
                }))),
                expression: None,
            }))));
        }

        if self.match_identifier("TYPE") {
            return Ok(Some(Expression::QueryOption(Box::new(QueryOption {
                this: Box::new(Expression::Var(Box::new(Var {
                    this: "TYPE".to_string(),
                }))),
                expression: None,
            }))));
        }

        if self.match_identifier("BINARY") {
            // BINARY BASE64
            if self.match_identifier("BASE64") {
                return Ok(Some(Expression::QueryOption(Box::new(QueryOption {
                    this: Box::new(Expression::Var(Box::new(Var {
                        this: "BINARY BASE64".to_string(),
                    }))),
                    expression: None,
                }))));
            } else {
                return Ok(Some(Expression::QueryOption(Box::new(QueryOption {
                    this: Box::new(Expression::Var(Box::new(Var {
                        this: "BINARY".to_string(),
                    }))),
                    expression: None,
                }))));
            }
        }

        if self.match_identifier("ELEMENTS") {
            // ELEMENTS [XSINIL|ABSENT]
            let suboption = if self.match_identifier("XSINIL") {
                Some("XSINIL".to_string())
            } else if self.match_identifier("ABSENT") {
                Some("ABSENT".to_string())
            } else {
                None
            };
            let option_name = match &suboption {
                Some(sub) => format!("ELEMENTS {}", sub),
                None => "ELEMENTS".to_string(),
            };
            return Ok(Some(Expression::QueryOption(Box::new(QueryOption {
                this: Box::new(Expression::Var(Box::new(Var { this: option_name }))),
                expression: None,
            }))));
        }

        if self.match_identifier("ROOT") {
            let expression = if self.match_token(TokenType::LParen) {
                let expr = self.parse_string()?;
                self.expect(TokenType::RParen)?;
                expr
            } else {
                None
            };
            return Ok(Some(Expression::QueryOption(Box::new(QueryOption {
                this: Box::new(Expression::Var(Box::new(Var {
                    this: "ROOT".to_string(),
                }))),
                expression: expression.map(|e| Box::new(e)),
            }))));
        }

        // No more options recognized
        Ok(None)
    }

    /// Parse CONNECT BY clause (Oracle hierarchical queries)
    /// Syntax: [START WITH condition] CONNECT BY [NOCYCLE] condition [START WITH condition]
    /// START WITH can appear before or after CONNECT BY
    fn parse_connect(&mut self) -> Result<Option<Connect>> {
        // Check for START WITH first (can appear before CONNECT BY)
        let start_before = if self.match_keywords(&[TokenType::Start, TokenType::With]) {
            Some(self.parse_expression()?)
        } else {
            None
        };

        // Check for CONNECT BY
        if !self.match_keywords(&[TokenType::Connect, TokenType::By]) {
            if start_before.is_some() {
                return Err(self.parse_error("START WITH without CONNECT BY"));
            }
            return Ok(None);
        }

        // Check for NOCYCLE
        let nocycle = self.match_token(TokenType::NoCycle);

        // Parse the CONNECT BY condition with PRIOR support
        let connect = self.parse_connect_expression()?;

        // START WITH can also appear after CONNECT BY
        let start = if start_before.is_some() {
            start_before
        } else if self.match_keywords(&[TokenType::Start, TokenType::With]) {
            Some(self.parse_expression()?)
        } else {
            None
        };

        Ok(Some(Connect {
            start,
            connect,
            nocycle,
        }))
    }

    /// Parse expression in CONNECT BY context, treating PRIOR as prefix operator
    fn parse_connect_expression(&mut self) -> Result<Expression> {
        self.parse_connect_or()
    }

    /// Parse OR expression in CONNECT BY context
    fn parse_connect_or(&mut self) -> Result<Expression> {
        let mut left = self.parse_connect_and()?;

        while self.match_token(TokenType::Or) {
            let right = self.parse_connect_and()?;
            left = Expression::Or(Box::new(BinaryOp::new(left, right)));
        }

        Ok(Self::maybe_rebalance_boolean_chain(left, false))
    }

    /// Parse AND expression in CONNECT BY context
    fn parse_connect_and(&mut self) -> Result<Expression> {
        let mut left = self.parse_connect_comparison()?;

        while self.match_token(TokenType::And) {
            let right = self.parse_connect_comparison()?;
            left = Expression::And(Box::new(BinaryOp::new(left, right)));
        }

        Ok(Self::maybe_rebalance_boolean_chain(left, true))
    }

    /// Parse comparison in CONNECT BY context
    fn parse_connect_comparison(&mut self) -> Result<Expression> {
        let left = self.parse_connect_primary()?;

        if self.match_token(TokenType::Eq) {
            let right = self.parse_connect_primary()?;
            return Ok(Expression::Eq(Box::new(BinaryOp::new(left, right))));
        }
        if self.match_token(TokenType::Neq) {
            let right = self.parse_connect_primary()?;
            return Ok(Expression::Neq(Box::new(BinaryOp::new(left, right))));
        }
        if self.match_token(TokenType::Lt) {
            let right = self.parse_connect_primary()?;
            return Ok(Expression::Lt(Box::new(BinaryOp::new(left, right))));
        }
        if self.match_token(TokenType::Lte) {
            let right = self.parse_connect_primary()?;
            return Ok(Expression::Lte(Box::new(BinaryOp::new(left, right))));
        }
        if self.match_token(TokenType::Gt) {
            let right = self.parse_connect_primary()?;
            return Ok(Expression::Gt(Box::new(BinaryOp::new(left, right))));
        }
        if self.match_token(TokenType::Gte) {
            let right = self.parse_connect_primary()?;
            return Ok(Expression::Gte(Box::new(BinaryOp::new(left, right))));
        }

        Ok(left)
    }

    /// Parse primary in CONNECT BY context with PRIOR support
    fn parse_connect_primary(&mut self) -> Result<Expression> {
        // Handle PRIOR as prefix operator
        if self.match_token(TokenType::Prior) {
            let expr = self.parse_primary()?;
            return Ok(Expression::Prior(Box::new(Prior { this: expr })));
        }

        if let Some(connect_by_root) = self.try_parse_connect_by_root_expression()? {
            return Ok(connect_by_root);
        }

        self.parse_primary()
    }

    /// Parse Oracle CONNECT_BY_ROOT in either supported form:
    /// CONNECT_BY_ROOT col
    /// CONNECT_BY_ROOT(col)
    fn try_parse_connect_by_root_expression(&mut self) -> Result<Option<Expression>> {
        if !(self.check(TokenType::Var) && self.peek().text.eq_ignore_ascii_case("CONNECT_BY_ROOT"))
        {
            return Ok(None);
        }

        self.advance();

        let this = if self.match_token(TokenType::LParen) {
            let expr = self.parse_expression()?;
            self.expect(TokenType::RParen)?;
            expr
        } else {
            self.parse_column()?.ok_or_else(|| {
                self.parse_error("Expected expression or column after CONNECT_BY_ROOT")
            })?
        };

        Ok(Some(Expression::ConnectByRoot(Box::new(ConnectByRoot {
            this,
        }))))
    }

    /// Parse MATCH_RECOGNIZE clause (Oracle/Snowflake/Presto/Trino pattern matching)
    /// MATCH_RECOGNIZE ( [PARTITION BY ...] [ORDER BY ...] [MEASURES ...] [rows] [after] PATTERN (...) DEFINE ... )
    fn parse_match_recognize(&mut self, source: Option<Expression>) -> Result<Expression> {
        self.expect(TokenType::LParen)?;

        // PARTITION BY (optional)
        let partition_by = if self.match_keywords(&[TokenType::Partition, TokenType::By]) {
            Some(self.parse_expression_list()?)
        } else {
            None
        };

        // ORDER BY (optional)
        let order_by = if self.match_keywords(&[TokenType::Order, TokenType::By]) {
            Some(self.parse_order_by()?.expressions)
        } else {
            None
        };

        // MEASURES (optional)
        let measures = if self.match_token(TokenType::Measures) {
            Some(self.parse_match_recognize_measures()?)
        } else {
            None
        };

        // Row semantics: ONE ROW PER MATCH / ALL ROWS PER MATCH
        let rows = self.parse_match_recognize_rows()?;

        // AFTER MATCH SKIP
        let after = self.parse_match_recognize_after()?;

        // PATTERN
        let pattern = if self.match_token(TokenType::Pattern) {
            Some(self.parse_match_recognize_pattern()?)
        } else {
            None
        };

        // DEFINE
        let define = if self.match_token(TokenType::Define) {
            Some(self.parse_match_recognize_define()?)
        } else {
            None
        };

        self.expect(TokenType::RParen)?;

        // Alias is handled by the caller

        Ok(Expression::MatchRecognize(Box::new(MatchRecognize {
            this: source.map(Box::new),
            partition_by,
            order_by,
            measures,
            rows,
            after,
            pattern,
            define,
            alias: None,
            alias_explicit_as: false,
        })))
    }

    /// Parse MEASURES clause in MATCH_RECOGNIZE
    fn parse_match_recognize_measures(&mut self) -> Result<Vec<MatchRecognizeMeasure>> {
        let mut measures = Vec::new();

        loop {
            // Check for RUNNING or FINAL
            let window_frame = if self.match_token(TokenType::Running) {
                Some(MatchRecognizeSemantics::Running)
            } else if self.match_token(TokenType::Final) {
                Some(MatchRecognizeSemantics::Final)
            } else {
                None
            };

            let mut expr = self.parse_expression()?;

            // Handle AS alias for measures
            if self.match_token(TokenType::As) {
                let alias = Identifier::new(self.expect_identifier()?);
                expr = Expression::Alias(Box::new(Alias::new(expr, alias)));
            }

            measures.push(MatchRecognizeMeasure {
                this: expr,
                window_frame,
            });

            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        Ok(measures)
    }

    /// Parse row semantics in MATCH_RECOGNIZE
    fn parse_match_recognize_rows(&mut self) -> Result<Option<MatchRecognizeRows>> {
        // ONE ROW PER MATCH
        if self.check(TokenType::Var) && self.peek().text.to_uppercase() == "ONE" {
            self.advance(); // consume ONE
            if !self.match_token(TokenType::Row) {
                return Err(self.parse_error("Expected ROW after ONE"));
            }
            if !(self.check(TokenType::Var) && self.peek().text.to_uppercase() == "PER") {
                return Err(self.parse_error("Expected PER after ONE ROW"));
            }
            self.advance(); // consume PER
            if !self.match_token(TokenType::Match) {
                return Err(self.parse_error("Expected MATCH after ONE ROW PER"));
            }
            return Ok(Some(MatchRecognizeRows::OneRowPerMatch));
        }

        // ALL ROWS PER MATCH [variants]
        if self.match_token(TokenType::All) {
            if !self.match_token(TokenType::Rows) {
                return Err(self.parse_error("Expected ROWS after ALL"));
            }
            if !(self.check(TokenType::Var) && self.peek().text.to_uppercase() == "PER") {
                return Err(self.parse_error("Expected PER after ALL ROWS"));
            }
            self.advance(); // consume PER
            if !self.match_token(TokenType::Match) {
                return Err(self.parse_error("Expected MATCH after ALL ROWS PER"));
            }

            // Check for optional modifiers
            if self.check(TokenType::Var) && self.peek().text.to_uppercase() == "SHOW" {
                self.advance();
                if self.check(TokenType::Var) && self.peek().text.to_uppercase() == "EMPTY" {
                    self.advance();
                    if self.check(TokenType::Var) && self.peek().text.to_uppercase() == "MATCHES" {
                        self.advance();
                        return Ok(Some(MatchRecognizeRows::AllRowsPerMatchShowEmptyMatches));
                    }
                }
                return Err(self.parse_error("Expected EMPTY MATCHES after SHOW"));
            }

            if self.check(TokenType::Var) && self.peek().text.to_uppercase() == "OMIT" {
                self.advance();
                if self.check(TokenType::Var) && self.peek().text.to_uppercase() == "EMPTY" {
                    self.advance();
                    if self.check(TokenType::Var) && self.peek().text.to_uppercase() == "MATCHES" {
                        self.advance();
                        return Ok(Some(MatchRecognizeRows::AllRowsPerMatchOmitEmptyMatches));
                    }
                }
                return Err(self.parse_error("Expected EMPTY MATCHES after OMIT"));
            }

            if self.match_token(TokenType::With) {
                if self.check(TokenType::Var) && self.peek().text.to_uppercase() == "UNMATCHED" {
                    self.advance();
                    if self.match_token(TokenType::Rows) {
                        return Ok(Some(MatchRecognizeRows::AllRowsPerMatchWithUnmatchedRows));
                    }
                }
                return Err(self.parse_error("Expected UNMATCHED ROWS after WITH"));
            }

            return Ok(Some(MatchRecognizeRows::AllRowsPerMatch));
        }

        Ok(None)
    }

    /// Parse AFTER MATCH SKIP clause in MATCH_RECOGNIZE
    fn parse_match_recognize_after(&mut self) -> Result<Option<MatchRecognizeAfter>> {
        if !self.match_token(TokenType::After) {
            return Ok(None);
        }

        if !self.match_token(TokenType::Match) {
            return Err(self.parse_error("Expected MATCH after AFTER"));
        }

        // Check for SKIP (it might be an identifier)
        if !(self.check(TokenType::Var) && self.peek().text.to_uppercase() == "SKIP") {
            return Err(self.parse_error("Expected SKIP after AFTER MATCH"));
        }
        self.advance(); // consume SKIP

        // PAST LAST ROW
        if self.check(TokenType::Var) && self.peek().text.to_uppercase() == "PAST" {
            self.advance();
            if self.match_token(TokenType::Last) {
                if self.match_token(TokenType::Row) {
                    return Ok(Some(MatchRecognizeAfter::PastLastRow));
                }
            }
            return Err(self.parse_error("Expected LAST ROW after PAST"));
        }

        // TO NEXT ROW / TO FIRST x / TO LAST x
        if self.match_token(TokenType::To) {
            if self.check(TokenType::Var) && self.peek().text.to_uppercase() == "NEXT" {
                self.advance();
                if self.match_token(TokenType::Row) {
                    return Ok(Some(MatchRecognizeAfter::ToNextRow));
                }
                return Err(self.parse_error("Expected ROW after NEXT"));
            }

            if self.match_token(TokenType::First) {
                let name = self.expect_identifier()?;
                return Ok(Some(MatchRecognizeAfter::ToFirst(Identifier::new(name))));
            }

            if self.match_token(TokenType::Last) {
                let name = self.expect_identifier()?;
                return Ok(Some(MatchRecognizeAfter::ToLast(Identifier::new(name))));
            }

            return Err(self.parse_error("Expected NEXT ROW, FIRST x, or LAST x after TO"));
        }

        Err(self.parse_error("Expected PAST LAST ROW or TO ... after AFTER MATCH SKIP"))
    }

    /// Parse PATTERN clause in MATCH_RECOGNIZE using bracket counting
    fn parse_match_recognize_pattern(&mut self) -> Result<String> {
        self.expect(TokenType::LParen)?;

        let mut depth = 1;
        let mut pattern = String::new();

        while depth > 0 && !self.is_at_end() {
            let token = self.advance();
            match token.token_type {
                TokenType::LParen => {
                    depth += 1;
                    pattern.push('(');
                }
                TokenType::RParen => {
                    depth -= 1;
                    if depth > 0 {
                        pattern.push(')');
                    }
                }
                _ => {
                    // Pattern quantifiers (+, *, ?, {n,m}) should not have a space before them
                    let is_quantifier = matches!(token.text.as_str(), "+" | "*" | "?")
                        || token.text.starts_with('{');

                    if !pattern.is_empty()
                        && !pattern.ends_with('(')
                        && !pattern.ends_with(' ')
                        && !is_quantifier
                    {
                        pattern.push(' ');
                    }
                    pattern.push_str(&token.text);
                }
            }
        }

        if depth > 0 {
            return Err(self.parse_error("Unclosed parenthesis in PATTERN clause"));
        }

        Ok(pattern.trim().to_string())
    }

    /// Parse DEFINE clause in MATCH_RECOGNIZE
    fn parse_match_recognize_define(&mut self) -> Result<Vec<(Identifier, Expression)>> {
        let mut definitions = Vec::new();

        loop {
            let name = Identifier::new(self.expect_identifier()?);
            self.expect(TokenType::As)?;
            let expr = self.parse_expression()?;

            definitions.push((name, expr));

            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        Ok(definitions)
    }

    /// Parse LATERAL VIEW clauses (Hive/Spark)
    /// Syntax: LATERAL VIEW [OUTER] generator_function(args) table_alias AS col1 [, col2, ...]
    fn parse_lateral_views(&mut self) -> Result<Vec<LateralView>> {
        let mut views = Vec::new();

        while self.match_keywords(&[TokenType::Lateral, TokenType::View]) {
            // Check for OUTER keyword
            let outer = self.match_token(TokenType::Outer);

            // Parse the generator function (EXPLODE, POSEXPLODE, INLINE, etc.)
            // This is a function call expression
            let this = self.parse_primary()?;

            // Parse table alias (comes before AS)
            let table_alias = if self.check(TokenType::Var) && !self.check_keyword() {
                Some(Identifier::new(self.expect_identifier()?))
            } else {
                None
            };

            // Parse column aliases after AS keyword
            // Supports both: AS a, b and AS (a, b)
            let column_aliases = if self.match_token(TokenType::As) {
                let mut aliases = Vec::new();
                // Check for parenthesized alias list: AS ("a", "b")
                if self.match_token(TokenType::LParen) {
                    loop {
                        aliases.push(Identifier::new(self.expect_identifier_or_keyword()?));
                        if !self.match_token(TokenType::Comma) {
                            break;
                        }
                    }
                    self.expect(TokenType::RParen)?;
                } else {
                    // Non-parenthesized aliases: AS a, b, c
                    // Use expect_identifier_or_keyword because aliases like "key", "value", "pos" may be keywords
                    loop {
                        aliases.push(Identifier::new(self.expect_identifier_or_keyword()?));
                        if !self.match_token(TokenType::Comma) {
                            break;
                        }
                        // Check if next token is still an identifier or keyword (column alias)
                        // vs starting a new LATERAL VIEW or other clause
                        if !self.is_identifier_or_keyword_token() {
                            break;
                        }
                        // Check for keywords that would end the column list
                        if self.peek().token_type == TokenType::Lateral
                            || self.peek().token_type == TokenType::Where
                            || self.peek().token_type == TokenType::Group
                            || self.peek().token_type == TokenType::Having
                            || self.peek().token_type == TokenType::Order
                            || self.peek().token_type == TokenType::Limit
                        {
                            break;
                        }
                    }
                }
                aliases
            } else {
                Vec::new()
            };

            views.push(LateralView {
                this,
                table_alias,
                column_aliases,
                outer,
            });
        }

        Ok(views)
    }

    /// Parse named windows (WINDOW w AS (...), ...)
    fn parse_named_windows(&mut self) -> Result<Vec<NamedWindow>> {
        let mut windows = Vec::new();

        loop {
            let name = self.expect_identifier()?;
            self.expect(TokenType::As)?;
            self.expect(TokenType::LParen)?;

            // Parse optional base window name reference (e.g., w1 AS (w0 ORDER BY ...))
            let window_name = if (self.check(TokenType::Identifier)
                || self.check(TokenType::Var)
                || self.check(TokenType::QuotedIdentifier))
                && !self.check(TokenType::Partition)
                && !self.check(TokenType::Order)
                && self.peek_nth(1).map_or(true, |t| {
                    matches!(
                        t.token_type,
                        TokenType::Partition
                            | TokenType::Order
                            | TokenType::Rows
                            | TokenType::Range
                            | TokenType::Groups
                            | TokenType::RParen
                            | TokenType::Comma
                    )
                }) {
                Some(self.expect_identifier()?)
            } else {
                None
            };

            // Parse window specification
            let partition_by = if self.match_keywords(&[TokenType::Partition, TokenType::By]) {
                Some(self.parse_expression_list()?)
            } else {
                None
            };

            let order_by = if self.match_keywords(&[TokenType::Order, TokenType::By]) {
                Some(self.parse_order_by()?)
            } else {
                None
            };

            let frame = self.parse_window_frame()?;

            self.expect(TokenType::RParen)?;

            windows.push(NamedWindow {
                name: Identifier::new(name),
                spec: Over {
                    window_name: window_name.map(|n| Identifier::new(n)),
                    partition_by: partition_by.unwrap_or_default(),
                    order_by: order_by.map(|o| o.expressions).unwrap_or_default(),
                    frame,
                    alias: None,
                },
            });

            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        Ok(windows)
    }

    /// Parse query hint /*+ ... */
    fn parse_hint(&mut self) -> Result<Hint> {
        let token = self.advance();
        let hint_text = token.text.clone();

        // For now, parse as raw hint text
        // More sophisticated parsing can be added later
        let expressions = if hint_text.is_empty() {
            Vec::new()
        } else {
            vec![HintExpression::Raw(hint_text)]
        };

        Ok(Hint { expressions })
    }

    /// Parse SAMPLE / TABLESAMPLE / USING SAMPLE clause
    fn parse_sample_clause(&mut self) -> Result<Option<Sample>> {
        // Check for USING SAMPLE (DuckDB), SAMPLE, or TABLESAMPLE
        let is_using_sample = if self.check(TokenType::Using)
            && self.current + 1 < self.tokens.len()
            && self.tokens[self.current + 1].token_type == TokenType::Sample
        {
            self.advance(); // consume USING
            self.advance(); // consume SAMPLE
            true
        } else {
            false
        };

        let use_sample_keyword = if is_using_sample {
            // USING SAMPLE acts like SAMPLE
            true
        } else if self.match_token(TokenType::Sample) {
            true
        } else if self.match_token(TokenType::TableSample) {
            false
        } else {
            return Ok(None);
        };

        // Parse sampling method if specified (BERNOULLI, SYSTEM, BLOCK, ROW, RESERVOIR)
        let (method, method_before_size, explicit_method) =
            if self.match_token(TokenType::Bernoulli) {
                (SampleMethod::Bernoulli, true, true)
            } else if self.match_token(TokenType::System) {
                (SampleMethod::System, true, true)
            } else if self.match_token(TokenType::Block) {
                (SampleMethod::Block, true, true)
            } else if self.match_token(TokenType::Row) {
                (SampleMethod::Row, true, true)
            } else if self.check_identifier("RESERVOIR") {
                self.advance();
                (SampleMethod::Reservoir, true, true)
            } else {
                // Default to BERNOULLI for both SAMPLE and TABLESAMPLE
                // This matches Python SQLGlot's normalization behavior
                (SampleMethod::Bernoulli, false, false)
            };

        // Parse size (can be in parentheses)
        let has_paren = self.match_token(TokenType::LParen);

        // Check for BUCKET syntax: TABLESAMPLE (BUCKET 1 OUT OF 5 ON x)
        if self.match_identifier("BUCKET") {
            let bucket_numerator = self.parse_primary()?;
            self.match_identifier("OUT");
            self.match_token(TokenType::Of); // OF is a keyword token
            let bucket_denominator = self.parse_primary()?;
            let bucket_field = if self.match_token(TokenType::On) {
                Some(Box::new(self.parse_primary()?))
            } else {
                None
            };
            if has_paren {
                self.expect(TokenType::RParen)?;
            }
            return Ok(Some(Sample {
                method: SampleMethod::Bucket,
                size: bucket_numerator.clone(),
                seed: None,
                offset: None,
                unit_after_size: false,
                use_sample_keyword,
                explicit_method: true,     // BUCKET is always explicit
                method_before_size: false, // BUCKET appears inside parens
                use_seed_keyword: false,
                bucket_numerator: Some(Box::new(bucket_numerator)),
                bucket_denominator: Some(Box::new(bucket_denominator)),
                bucket_field,
                is_using_sample,
                is_percent: false,
                suppress_method_output: false,
            }));
        }

        // Use parse_unary to avoid consuming PERCENT as modulo operator
        let size = self.parse_unary()?;

        // Check for PERCENT/ROWS suffix after size (if not already part of the number)
        // Both "%" and "PERCENT" tokens map to TokenType::Percent - accept both as PERCENT modifier
        let (method, unit_after_size, is_percent) = if self.check(TokenType::Percent) {
            self.advance(); // consume PERCENT or %
                            // If method was already explicitly specified (e.g., SYSTEM), keep it
                            // PERCENT here is just the unit, not the sampling method
            if method_before_size {
                (method, true, true)
            } else {
                (SampleMethod::Percent, true, true)
            }
        } else if self.match_token(TokenType::Rows) {
            // If method was already explicitly specified, keep it
            if method_before_size {
                (method, true, false)
            } else {
                (SampleMethod::Row, true, false)
            }
        } else {
            // No explicit unit after size - preserve the original method
            (method, false, false)
        };

        if has_paren {
            self.expect(TokenType::RParen)?;
        }

        // DuckDB USING SAMPLE: method and optional seed can come in parens after size
        // e.g., "10 PERCENT (bernoulli)" or "10% (system, 377)"
        // DuckDB USING SAMPLE: method and optional seed can come in parens after size
        // e.g., "10 PERCENT (bernoulli)" or "10% (system, 377)"
        let (method, seed, use_seed_keyword, explicit_method) =
            if is_using_sample && self.check(TokenType::LParen) {
                self.advance(); // consume LParen
                                // Parse method name as identifier or keyword token
                                // BERNOULLI, SYSTEM, RESERVOIR can be tokenized as keywords, not identifiers
                let method_from_parens =
                    if self.check_identifier("BERNOULLI") || self.check(TokenType::Bernoulli) {
                        self.advance();
                        Some(SampleMethod::Bernoulli)
                    } else if self.check_identifier("SYSTEM") || self.check(TokenType::System) {
                        self.advance();
                        Some(SampleMethod::System)
                    } else if self.check_identifier("RESERVOIR") {
                        self.advance();
                        Some(SampleMethod::Reservoir)
                    } else {
                        None
                    };
                // Optional seed after comma
                let seed = if self.match_token(TokenType::Comma) {
                    Some(self.parse_expression()?)
                } else {
                    None
                };
                self.expect(TokenType::RParen)?;
                let final_method = method_from_parens.unwrap_or(method);
                (final_method, seed, false, true)
            } else {
                // Parse optional SEED / REPEATABLE
                let (seed, use_seed_keyword) = if self.match_token(TokenType::Seed) {
                    self.expect(TokenType::LParen)?;
                    let seed_value = self.parse_expression()?;
                    self.expect(TokenType::RParen)?;
                    (Some(seed_value), true)
                } else if self.match_token(TokenType::Repeatable) {
                    self.expect(TokenType::LParen)?;
                    let seed_value = self.parse_expression()?;
                    self.expect(TokenType::RParen)?;
                    (Some(seed_value), false)
                } else {
                    (None, false)
                };
                let explicit_method = explicit_method || unit_after_size;
                (method, seed, use_seed_keyword, explicit_method)
            };

        // For DuckDB USING SAMPLE: apply default methods
        // - bare number -> RESERVOIR, ROWS
        // - percent -> SYSTEM, PERCENT
        let (method, unit_after_size) = if is_using_sample && !explicit_method {
            // No explicit method - apply defaults
            (SampleMethod::Reservoir, false) // default: RESERVOIR with ROWS
        } else if is_using_sample && unit_after_size && !method_before_size {
            // Unit was specified after size (e.g., "10 PERCENT") but no method before
            // Check if method was set in post-parens
            if matches!(method, SampleMethod::Percent) {
                // "10%" or "10 PERCENT" without method -> SYSTEM
                (SampleMethod::System, true)
            } else if matches!(method, SampleMethod::Row) {
                // "50 ROWS" without method -> RESERVOIR
                (SampleMethod::Reservoir, true)
            } else {
                (method, unit_after_size)
            }
        } else {
            (method, unit_after_size)
        };

        // method_before_size: true for USING SAMPLE - we normalize to method-before-size format
        // e.g., "10 PERCENT (bernoulli)" becomes "BERNOULLI (10 PERCENT)"
        Ok(Some(Sample {
            method,
            size,
            seed,
            offset: None,
            unit_after_size,
            use_sample_keyword,
            explicit_method: true,    // For USING SAMPLE, always explicit
            method_before_size: true, // Normalize to method-before-size format
            use_seed_keyword,
            bucket_numerator: None,
            bucket_denominator: None,
            bucket_field: None,
            is_using_sample,
            is_percent,
            suppress_method_output: false,
        }))
    }

    /// Parse table-level TABLESAMPLE/SAMPLE: TABLESAMPLE/SAMPLE METHOD(size [PERCENT|ROWS])
    /// e.g., TABLESAMPLE RESERVOIR(20%), SAMPLE BERNOULLI(10 PERCENT), SAMPLE ROW(0)
    fn parse_table_level_sample(&mut self) -> Result<Option<Sample>> {
        // Accept both TABLESAMPLE and SAMPLE (Snowflake supports both)
        let use_sample_keyword = if self.match_token(TokenType::Sample) {
            true
        } else if self.match_token(TokenType::TableSample) {
            false
        } else {
            return Ok(None);
        };
        // Track which keyword was used for identity output
        let _ = use_sample_keyword; // Used below for is_using_sample field

        // Teradata: SAMPLE 5 or SAMPLE 0.33, .25, .1 (no parentheses)
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::Teradata)
        ) && use_sample_keyword
            && !self.check(TokenType::LParen)
        {
            let mut expressions = vec![self.parse_unary()?];
            while self.match_token(TokenType::Comma) {
                expressions.push(self.parse_unary()?);
            }
            let size = if expressions.len() == 1 {
                expressions.into_iter().next().unwrap()
            } else {
                Expression::Tuple(Box::new(Tuple { expressions }))
            };
            return Ok(Some(Sample {
                method: SampleMethod::Percent,
                size,
                seed: None,
                offset: None,
                unit_after_size: false,
                use_sample_keyword,
                explicit_method: false,
                method_before_size: false,
                use_seed_keyword: false,
                bucket_numerator: None,
                bucket_denominator: None,
                bucket_field: None,
                is_using_sample: false,
                is_percent: false,
                suppress_method_output: false,
            }));
        }

        // ClickHouse: SAMPLE 0.1 [OFFSET 0.2] (no parentheses)
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) && use_sample_keyword
            && !self.check(TokenType::LParen)
        {
            let size = self.parse_expression()?;
            let offset = if self.match_token(TokenType::Offset) {
                Some(self.parse_expression()?)
            } else {
                None
            };
            return Ok(Some(Sample {
                method: SampleMethod::Bernoulli,
                size,
                seed: None,
                offset,
                unit_after_size: false,
                use_sample_keyword,
                explicit_method: false,
                method_before_size: false,
                use_seed_keyword: false,
                bucket_numerator: None,
                bucket_denominator: None,
                bucket_field: None,
                is_using_sample: false,
                is_percent: false,
                suppress_method_output: false,
            }));
        }

        // Parse method name (optional for table-level TABLESAMPLE)
        let (method, explicit_method, method_before_size) = if self.check_identifier("RESERVOIR") {
            self.advance();
            (SampleMethod::Reservoir, true, true)
        } else if self.match_token(TokenType::Bernoulli) {
            (SampleMethod::Bernoulli, true, true)
        } else if self.match_token(TokenType::System) {
            (SampleMethod::System, true, true)
        } else if self.match_token(TokenType::Block) {
            (SampleMethod::Block, true, true)
        } else if self.match_token(TokenType::Row) {
            (SampleMethod::Row, true, true)
        } else {
            // No explicit method - default to Bernoulli internally but track as not explicit
            (SampleMethod::Bernoulli, false, false)
        };

        // Parse (size [PERCENT|ROWS])
        self.expect(TokenType::LParen)?;

        // Check for BUCKET syntax: TABLESAMPLE (BUCKET 1 OUT OF 5 [ON col])
        if self.match_identifier("BUCKET") {
            let bucket_numerator = self.parse_primary()?;
            self.match_identifier("OUT");
            self.match_token(TokenType::Of);
            let bucket_denominator = self.parse_primary()?;
            let bucket_field = if self.match_token(TokenType::On) {
                Some(Box::new(self.parse_primary()?))
            } else {
                None
            };
            self.expect(TokenType::RParen)?;
            return Ok(Some(Sample {
                method: SampleMethod::Bucket,
                size: bucket_numerator.clone(),
                seed: None,
                offset: None,
                unit_after_size: false,
                use_sample_keyword,
                explicit_method: true,
                method_before_size: false,
                use_seed_keyword: false,
                bucket_numerator: Some(Box::new(bucket_numerator)),
                bucket_denominator: Some(Box::new(bucket_denominator)),
                bucket_field,
                is_using_sample: false,
                is_percent: false,
                suppress_method_output: false,
            }));
        }

        let size = self.parse_unary()?;

        // Check for PERCENT/ROWS suffix or % symbol
        let (method, unit_after_size, is_percent) =
            if self.check(TokenType::Percent) && self.peek().text.to_uppercase() == "PERCENT" {
                self.advance();
                // If no explicit method, use Percent to represent "PERCENT" unit
                if explicit_method {
                    (method, true, true)
                } else {
                    (SampleMethod::Percent, true, true)
                }
            } else if self.match_token(TokenType::Rows) {
                // If no explicit method, use Row to represent "ROWS" unit
                if explicit_method {
                    (method, true, false)
                } else {
                    (SampleMethod::Row, true, false)
                }
            } else if self.check(TokenType::Percent) && self.peek().text == "%" {
                // 20% -> consume the %, treat as PERCENT unit
                self.advance();
                if explicit_method {
                    (method, true, true)
                } else {
                    (SampleMethod::Percent, true, true)
                }
            } else {
                (method, false, false)
            };

        self.expect(TokenType::RParen)?;

        // Optional SEED/REPEATABLE
        let (seed, use_seed_keyword) = if self.match_token(TokenType::Seed) {
            self.expect(TokenType::LParen)?;
            let seed_value = self.parse_expression()?;
            self.expect(TokenType::RParen)?;
            (Some(seed_value), true)
        } else if self.match_token(TokenType::Repeatable) {
            self.expect(TokenType::LParen)?;
            let seed_value = self.parse_expression()?;
            self.expect(TokenType::RParen)?;
            (Some(seed_value), false)
        } else {
            (None, false)
        };

        Ok(Some(Sample {
            method,
            size,
            seed,
            offset: None,
            unit_after_size,
            use_sample_keyword,
            explicit_method,
            method_before_size,
            use_seed_keyword,
            bucket_numerator: None,
            bucket_denominator: None,
            bucket_field: None,
            is_using_sample: false, // table-level uses TABLESAMPLE/SAMPLE keyword, not USING SAMPLE
            is_percent,
            suppress_method_output: false,
        }))
    }

    /// Parse set operations (UNION, INTERSECT, EXCEPT)
    fn parse_set_operation(&mut self, left: Expression) -> Result<Expression> {
        // Check for BigQuery set operation modifiers BEFORE the set operation keyword
        // Pattern: SELECT ... [INNER|LEFT|RIGHT|FULL] UNION/INTERSECT/EXCEPT ...
        let (side, kind) = self.parse_set_operation_side_kind();

        // Capture leading comments from the set operation keyword token (e.g., /*x*/ before UNION).
        // These comments appeared on a new line between the left SELECT and the set operation keyword.
        let set_op_leading_comments = if self.check(TokenType::Union)
            || self.check(TokenType::Intersect)
            || self.check(TokenType::Except)
        {
            self.current_leading_comments()
        } else {
            Vec::new()
        };

        // Wrap left expression with comments if needed
        let left = if !set_op_leading_comments.is_empty() {
            Expression::Annotated(Box::new(Annotated {
                this: left,
                trailing_comments: set_op_leading_comments,
            }))
        } else {
            left
        };

        if self.match_token(TokenType::Union) {
            let all = self.match_token(TokenType::All);
            let distinct = if !all {
                self.match_token(TokenType::Distinct)
            } else {
                false
            };

            // Parse STRICT CORRESPONDING, CORRESPONDING, BY NAME modifiers
            let (by_name, strict, corresponding, on_columns) =
                self.parse_set_operation_corresponding()?;

            // If CORRESPONDING (without STRICT) is present and no explicit side/kind, default kind to INNER
            // STRICT CORRESPONDING does NOT set kind to INNER
            let kind = if corresponding && !strict && side.is_none() && kind.is_none() {
                Some("INNER".to_string())
            } else {
                kind
            };

            let right = self.parse_select_or_paren_select()?;
            // Check for chained set operations first
            let mut result = Expression::Union(Box::new(Union {
                left,
                right,
                all,
                distinct,
                with: None,
                order_by: None,
                limit: None,
                offset: None,
                distribute_by: None,
                sort_by: None,
                cluster_by: None,
                by_name,
                side,
                kind,
                corresponding,
                strict,
                on_columns,
            }));
            result = self.parse_set_operation(result)?;
            // Parse ORDER BY, LIMIT, OFFSET for the outermost set operation
            self.parse_set_operation_modifiers(&mut result)?;
            Ok(result)
        } else if self.match_token(TokenType::Intersect) {
            let all = self.match_token(TokenType::All);
            let distinct = if !all {
                self.match_token(TokenType::Distinct)
            } else {
                false
            };

            // Parse STRICT CORRESPONDING, CORRESPONDING, BY NAME modifiers
            let (by_name, strict, corresponding, on_columns) =
                self.parse_set_operation_corresponding()?;

            // If CORRESPONDING (without STRICT) is present and no explicit side/kind, default kind to INNER
            // STRICT CORRESPONDING does NOT set kind to INNER
            let kind = if corresponding && !strict && side.is_none() && kind.is_none() {
                Some("INNER".to_string())
            } else {
                kind
            };

            let right = self.parse_select_or_paren_select()?;
            let mut result = Expression::Intersect(Box::new(Intersect {
                left,
                right,
                all,
                distinct,
                with: None,
                order_by: None,
                limit: None,
                offset: None,
                distribute_by: None,
                sort_by: None,
                cluster_by: None,
                by_name,
                side,
                kind,
                corresponding,
                strict,
                on_columns,
            }));
            result = self.parse_set_operation(result)?;
            self.parse_set_operation_modifiers(&mut result)?;
            Ok(result)
        } else if self.match_token(TokenType::Except) {
            let all = self.match_token(TokenType::All);
            let distinct = if !all {
                self.match_token(TokenType::Distinct)
            } else {
                false
            };

            // Parse STRICT CORRESPONDING, CORRESPONDING, BY NAME modifiers
            let (by_name, strict, corresponding, on_columns) =
                self.parse_set_operation_corresponding()?;

            // If CORRESPONDING (without STRICT) is present and no explicit side/kind, default kind to INNER
            // STRICT CORRESPONDING does NOT set kind to INNER
            let kind = if corresponding && !strict && side.is_none() && kind.is_none() {
                Some("INNER".to_string())
            } else {
                kind
            };

            let right = self.parse_select_or_paren_select()?;
            let mut result = Expression::Except(Box::new(Except {
                left,
                right,
                all,
                distinct,
                with: None,
                order_by: None,
                limit: None,
                offset: None,
                distribute_by: None,
                sort_by: None,
                cluster_by: None,
                by_name,
                side,
                kind,
                corresponding,
                strict,
                on_columns,
            }));
            result = self.parse_set_operation(result)?;
            self.parse_set_operation_modifiers(&mut result)?;
            Ok(result)
        } else if side.is_some() || kind.is_some() {
            // We parsed side/kind but didn't find a set operation - this is an error
            Err(self
                .parse_error("Expected UNION, INTERSECT, or EXCEPT after set operation modifier"))
        } else {
            Ok(left)
        }
    }

    /// Parse BigQuery set operation side (LEFT, RIGHT, FULL) and kind (INNER)
    /// These modifiers appear BEFORE the UNION/INTERSECT/EXCEPT keyword
    fn parse_set_operation_side_kind(&mut self) -> (Option<String>, Option<String>) {
        let mut side = None;
        let mut kind = None;

        // Check for side: LEFT, RIGHT, FULL (reusing join side tokens)
        if self.check(TokenType::Left)
            || self.check(TokenType::Right)
            || self.check(TokenType::Full)
        {
            // Only consume if followed by UNION/INTERSECT/EXCEPT (or INNER which would be followed by them)
            let saved = self.current;
            let side_token = self.advance();
            let side_text = side_token.text.to_uppercase();

            // Check if followed by set operation or INNER
            if self.check(TokenType::Union)
                || self.check(TokenType::Intersect)
                || self.check(TokenType::Except)
                || self.check(TokenType::Inner)
            {
                side = Some(side_text);
            } else {
                // Not a set operation modifier, backtrack
                self.current = saved;
                return (None, None);
            }
        }

        // Check for kind: INNER
        if self.check(TokenType::Inner) {
            let saved = self.current;
            self.advance(); // consume INNER

            // Check if followed by set operation
            if self.check(TokenType::Union)
                || self.check(TokenType::Intersect)
                || self.check(TokenType::Except)
            {
                kind = Some("INNER".to_string());
            } else {
                // Not a set operation modifier, backtrack
                self.current = saved;
                if side.is_some() {
                    // We already consumed a side token, need to backtrack that too
                    self.current = saved - 1;
                }
                return (None, None);
            }
        }

        (side, kind)
    }

    /// Parse CORRESPONDING/STRICT CORRESPONDING/BY NAME modifiers after ALL/DISTINCT
    /// Returns (by_name, strict, corresponding, on_columns)
    fn parse_set_operation_corresponding(&mut self) -> Result<(bool, bool, bool, Vec<Expression>)> {
        let mut by_name = false;
        let mut strict = false;
        let mut corresponding = false;
        let mut on_columns = Vec::new();

        // Check for BY NAME (DuckDB style)
        if self.match_token(TokenType::By) && self.match_identifier("NAME") {
            by_name = true;
        }
        // Check for STRICT CORRESPONDING (BigQuery style)
        else if self.match_identifier("STRICT") {
            if self.match_identifier("CORRESPONDING") {
                strict = true;
                corresponding = true;
            } else {
                // STRICT without CORRESPONDING - backtrack
                self.current -= 1;
            }
        }
        // Check for CORRESPONDING (BigQuery style)
        else if self.match_identifier("CORRESPONDING") {
            corresponding = true;
        }

        // If CORRESPONDING is set, check for BY (columns)
        if corresponding && self.match_token(TokenType::By) {
            self.expect(TokenType::LParen)?;
            on_columns = self
                .parse_identifier_list()?
                .into_iter()
                .map(|id| {
                    Expression::Column(Column {
                        name: id,
                        table: None,
                        join_mark: false,
                        trailing_comments: Vec::new(),
                        span: None,
                        inferred_type: None,
                    })
                })
                .collect();
            self.expect(TokenType::RParen)?;
        }

        Ok((by_name, strict, corresponding, on_columns))
    }

    /// Parse ORDER BY, LIMIT, OFFSET modifiers for set operations
    fn parse_set_operation_modifiers(&mut self, expr: &mut Expression) -> Result<()> {
        // Parse ORDER BY
        let order_by = if self.match_token(TokenType::Order) {
            self.expect(TokenType::By)?;
            Some(self.parse_order_by()?)
        } else {
            None
        };

        // Parse LIMIT
        let limit = if self.match_token(TokenType::Limit) {
            Some(Box::new(self.parse_expression()?))
        } else {
            None
        };

        // Parse OFFSET
        let offset = if self.match_token(TokenType::Offset) {
            Some(Box::new(self.parse_expression()?))
        } else {
            None
        };

        // Apply modifiers to the outermost set operation
        match expr {
            Expression::Union(ref mut union) => {
                if order_by.is_some() {
                    union.order_by = order_by;
                }
                if limit.is_some() {
                    union.limit = limit;
                }
                if offset.is_some() {
                    union.offset = offset;
                }
            }
            Expression::Intersect(ref mut intersect) => {
                if order_by.is_some() {
                    intersect.order_by = order_by;
                }
                if limit.is_some() {
                    intersect.limit = limit;
                }
                if offset.is_some() {
                    intersect.offset = offset;
                }
            }
            Expression::Except(ref mut except) => {
                if order_by.is_some() {
                    except.order_by = order_by;
                }
                if limit.is_some() {
                    except.limit = limit;
                }
                if offset.is_some() {
                    except.offset = offset;
                }
            }
            _ => {}
        }
        Ok(())
    }

    /// Parse either a SELECT statement or a parenthesized SELECT/set operation
    fn parse_select_or_paren_select(&mut self) -> Result<Expression> {
        if self.match_token(TokenType::LParen) {
            // Could be (SELECT ...) or ((SELECT ...) UNION ...) or (FROM ...) for DuckDB
            if self.check(TokenType::Select)
                || self.check(TokenType::With)
                || self.check(TokenType::From)
            {
                let query = self.parse_statement()?;
                self.expect(TokenType::RParen)?;
                // Handle optional alias after subquery: (SELECT 1) AS a
                let alias = if self.match_token(TokenType::As) {
                    Some(Identifier::new(self.expect_identifier()?))
                } else {
                    None
                };
                // Wrap in Subquery to preserve parentheses
                Ok(Expression::Subquery(Box::new(Subquery {
                    this: query,
                    alias,
                    column_aliases: Vec::new(),
                    order_by: None,
                    limit: None,
                    offset: None,
                    lateral: false,
                    modifiers_inside: false,
                    trailing_comments: Vec::new(),
                    distribute_by: None,
                    sort_by: None,
                    cluster_by: None,
                    inferred_type: None,
                })))
            } else if self.check(TokenType::LParen) {
                // Nested parentheses like ((SELECT ...))
                let inner = self.parse_select_or_paren_select()?;
                // Check for set operations inside the parens
                let result = self.parse_set_operation(inner)?;
                self.expect(TokenType::RParen)?;
                // Handle optional alias after subquery
                let alias = if self.match_token(TokenType::As) {
                    Some(Identifier::new(self.expect_identifier()?))
                } else {
                    None
                };
                // Wrap in Subquery to preserve parentheses
                Ok(Expression::Subquery(Box::new(Subquery {
                    this: result,
                    alias,
                    column_aliases: Vec::new(),
                    order_by: None,
                    limit: None,
                    offset: None,
                    lateral: false,
                    modifiers_inside: false,
                    trailing_comments: Vec::new(),
                    distribute_by: None,
                    sort_by: None,
                    cluster_by: None,
                    inferred_type: None,
                })))
            } else {
                Err(self.parse_error("Expected SELECT or ( after ("))
            }
        } else if self.check(TokenType::From) {
            // DuckDB FROM-first syntax without parentheses: ... UNION FROM t
            self.parse_from_first_query()
        } else if self.check(TokenType::With) {
            // WITH CTE as right-hand side of UNION/INTERSECT/EXCEPT
            self.parse_statement()
        } else {
            self.parse_select()
        }
    }

    /// Parse INSERT statement
    fn parse_insert(&mut self) -> Result<Expression> {
        let insert_token = self.expect(TokenType::Insert)?;
        let leading_comments = insert_token.comments;

        // Parse query hint /*+ ... */ if present (Oracle: INSERT /*+ APPEND */ INTO ...)
        let hint = if self.check(TokenType::Hint) {
            Some(self.parse_hint()?)
        } else {
            None
        };

        // Handle SQLite conflict action: INSERT OR ABORT|FAIL|IGNORE|REPLACE|ROLLBACK INTO
        let conflict_action = if self.match_token(TokenType::Or) {
            if self.match_identifier("ABORT") {
                Some("ABORT".to_string())
            } else if self.match_identifier("FAIL") {
                Some("FAIL".to_string())
            } else if self.match_token(TokenType::Ignore) {
                Some("IGNORE".to_string())
            } else if self.match_token(TokenType::Replace) {
                Some("REPLACE".to_string())
            } else if self.match_token(TokenType::Rollback) {
                Some("ROLLBACK".to_string())
            } else {
                return Err(self.parse_error(
                    "Expected ABORT, FAIL, IGNORE, REPLACE, or ROLLBACK after INSERT OR",
                ));
            }
        } else {
            None
        };

        // Handle INSERT IGNORE (MySQL)
        let ignore = conflict_action.is_none() && self.match_token(TokenType::Ignore);

        // Handle OVERWRITE for Hive/Spark: INSERT OVERWRITE TABLE ...
        let overwrite = self.match_token(TokenType::Overwrite);

        // Handle Oracle multi-table INSERT: INSERT ALL/FIRST ...
        // Must check before OVERWRITE handling since these are mutually exclusive
        if !overwrite && (self.match_token(TokenType::All) || self.match_token(TokenType::First)) {
            if let Some(multi_insert) = self.parse_multitable_inserts(leading_comments.clone())? {
                return Ok(multi_insert);
            }
        }

        // Handle INTO or TABLE (OVERWRITE requires TABLE, INTO is standard)
        // Also handle INSERT OVERWRITE [LOCAL] DIRECTORY 'path'
        let local_directory = overwrite && self.match_token(TokenType::Local);
        let is_directory = (overwrite || local_directory) && self.match_identifier("DIRECTORY");

        if is_directory {
            // INSERT OVERWRITE [LOCAL] DIRECTORY 'path' [ROW FORMAT ...] SELECT ...
            let path = self.expect_string()?;
            // Parse optional ROW FORMAT clause
            let row_format = if self.match_keywords(&[TokenType::Row, TokenType::Format]) {
                // ROW FORMAT DELIMITED ...
                let delimited = self.match_identifier("DELIMITED");
                let mut fields_terminated_by = None;
                let mut collection_items_terminated_by = None;
                let mut map_keys_terminated_by = None;
                let mut lines_terminated_by = None;
                let mut null_defined_as = None;

                // Parse the various TERMINATED BY clauses
                loop {
                    if self.match_identifier("FIELDS") || self.match_identifier("FIELD") {
                        self.match_identifier("TERMINATED");
                        self.match_token(TokenType::By);
                        fields_terminated_by = Some(self.expect_string()?);
                    } else if self.match_identifier("COLLECTION") {
                        self.match_identifier("ITEMS");
                        self.match_identifier("TERMINATED");
                        self.match_token(TokenType::By);
                        collection_items_terminated_by = Some(self.expect_string()?);
                    } else if self.match_identifier("MAP") {
                        self.match_identifier("KEYS");
                        self.match_identifier("TERMINATED");
                        self.match_token(TokenType::By);
                        map_keys_terminated_by = Some(self.expect_string()?);
                    } else if self.match_identifier("LINES") {
                        self.match_identifier("TERMINATED");
                        self.match_token(TokenType::By);
                        lines_terminated_by = Some(self.expect_string()?);
                    } else if self.match_token(TokenType::Null) {
                        self.match_identifier("DEFINED");
                        self.match_token(TokenType::As);
                        null_defined_as = Some(self.expect_string()?);
                    } else {
                        break;
                    }
                }

                Some(RowFormat {
                    delimited,
                    fields_terminated_by,
                    collection_items_terminated_by,
                    map_keys_terminated_by,
                    lines_terminated_by,
                    null_defined_as,
                })
            } else {
                None
            };

            // Parse optional STORED AS clause
            let stored_as = if self.match_identifier("STORED") {
                self.expect(TokenType::As)?;
                Some(self.expect_identifier()?)
            } else {
                None
            };

            // Parse the SELECT query
            let query = self.parse_statement()?;

            return Ok(Expression::Insert(Box::new(Insert {
                table: TableRef::new(""),
                columns: Vec::new(),
                values: Vec::new(),
                query: Some(query),
                overwrite,
                partition: Vec::new(),
                directory: Some(DirectoryInsert {
                    local: local_directory,
                    path,
                    row_format,
                    stored_as,
                }),
                returning: Vec::new(),
                output: None,
                on_conflict: None,
                leading_comments,
                if_exists: false,
                with: None,
                ignore,
                source_alias: None,
                alias: None,
                alias_explicit_as: false,
                default_values: false,
                by_name: false,
                conflict_action: conflict_action.clone(),
                is_replace: false,
                replace_where: None,
                source: None,
                hint: hint.clone(),
                function_target: None,
                partition_by: None,
                settings: Vec::new(),
            })));
        }

        if overwrite {
            // OVERWRITE is typically followed by TABLE
            self.match_token(TokenType::Table);
        } else {
            self.expect(TokenType::Into)?;
            // Optional TABLE keyword after INTO
            self.match_token(TokenType::Table);
        }

        // ClickHouse: INSERT INTO [TABLE] FUNCTION func_name(args...)
        let mut function_target: Option<Box<Expression>> = None;
        if self.match_token(TokenType::Function) {
            // Parse function call: func_name(args...)
            let func_name = self.expect_identifier_or_keyword()?;
            self.expect(TokenType::LParen)?;
            let args = if self.check(TokenType::RParen) {
                Vec::new()
            } else {
                self.parse_expression_list()?
            };
            self.expect(TokenType::RParen)?;
            function_target = Some(Box::new(Expression::Function(Box::new(Function {
                name: func_name,
                args,
                distinct: false,
                trailing_comments: Vec::new(),
                use_bracket_syntax: false,
                no_parens: false,
                quoted: false,
                span: None,
                inferred_type: None,
            }))));
        }

        let table_name = if function_target.is_some() {
            // For FUNCTION targets, use empty table name
            Identifier::new(String::new())
        } else {
            // Allow keywords (like TABLE) as table names in INSERT statements
            self.expect_identifier_or_keyword_with_quoted()?
        };
        // Handle qualified table names like a.b
        let table = if self.match_token(TokenType::Dot) {
            let schema = table_name;
            let name = self.expect_identifier_or_keyword_with_quoted()?;
            let trailing_comments = self.previous_trailing_comments();
            TableRef {
                name,
                schema: Some(schema),
                catalog: None,
                alias: None,
                alias_explicit_as: false,
                column_aliases: Vec::new(),
                trailing_comments,
                when: None,
                only: false,
                final_: false,
                table_sample: None,
                hints: Vec::new(),
                system_time: None,
                partitions: Vec::new(),
                identifier_func: None,
                changes: None,
                version: None,
                span: None,
            }
        } else {
            let trailing_comments = self.previous_trailing_comments();
            TableRef {
                name: table_name,
                schema: None,
                catalog: None,
                alias: None,
                alias_explicit_as: false,
                column_aliases: Vec::new(),
                when: None,
                only: false,
                final_: false,
                table_sample: None,
                hints: Vec::new(),
                system_time: None,
                trailing_comments,
                partitions: Vec::new(),
                identifier_func: None,
                changes: None,
                version: None,
                span: None,
            }
        };

        // Optional alias (PostgreSQL: INSERT INTO table AS t(...), Oracle: INSERT INTO table t ...)
        let (alias, alias_explicit_as) = if self.match_token(TokenType::As) {
            (Some(Identifier::new(self.expect_identifier()?)), true)
        } else if self.is_identifier_token()
            && !self.check(TokenType::Values)
            && !self.check(TokenType::Select)
            && !self.check(TokenType::Default)
            && !self.check(TokenType::By)
            && !self.check(TokenType::Partition)
            && !self.check(TokenType::Output)
            && !self.check(TokenType::If)
            && !self.check(TokenType::Replace)
            && !self.check(TokenType::Table)
            && !self.check(TokenType::LParen)
        {
            // Implicit alias without AS (e.g., INSERT INTO dest d VALUES ...)
            (Some(Identifier::new(self.expect_identifier()?)), false)
        } else {
            (None, false)
        };

        // Optional IF EXISTS (Hive)
        let if_exists = self.match_keywords(&[TokenType::If, TokenType::Exists]);

        // Optional REPLACE WHERE clause (Databricks): INSERT INTO a REPLACE WHERE cond VALUES ...
        let replace_where =
            if self.match_token(TokenType::Replace) && self.match_token(TokenType::Where) {
                Some(Box::new(self.parse_or()?))
            } else {
                None
            };

        // Optional PARTITION clause
        // ClickHouse: PARTITION BY expr (no parens)
        // Hive/Spark: PARTITION (col1 = val1, col2)
        let mut partition_by_expr: Option<Box<Expression>> = None;
        let partition = if self.check(TokenType::Partition) && self.check_next(TokenType::By) {
            // ClickHouse PARTITION BY expr
            self.advance(); // consume PARTITION
            self.advance(); // consume BY
            partition_by_expr = Some(Box::new(self.parse_expression()?));
            Vec::new()
        } else if self.match_token(TokenType::Partition) {
            self.expect(TokenType::LParen)?;
            let mut parts = Vec::new();
            loop {
                let col = Identifier::new(self.expect_identifier()?);
                let value = if self.match_token(TokenType::Eq) {
                    Some(self.parse_expression()?)
                } else {
                    None
                };
                parts.push((col, value));
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            self.expect(TokenType::RParen)?;
            parts
        } else {
            Vec::new()
        };

        // ClickHouse: SETTINGS key = val, ...
        let insert_settings = if self.match_token(TokenType::Settings) {
            let mut settings = Vec::new();
            loop {
                settings.push(self.parse_expression()?);
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            settings
        } else {
            Vec::new()
        };

        // Optional column list OR parenthesized subquery
        // We need to check if ( is followed by SELECT/WITH (subquery) or identifiers (column list)
        let columns = if self.check(TokenType::LParen) {
            // Look ahead to see if this is a subquery or column list
            if self
                .peek_nth(1)
                .map(|t| t.token_type == TokenType::Select || t.token_type == TokenType::With)
                .unwrap_or(false)
            {
                // This is a parenthesized subquery, not a column list
                Vec::new()
            } else if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && {
                // ClickHouse: INSERT INTO t (*), t(* EXCEPT ...), t(table.* EXCEPT ...), t(COLUMNS('pattern') EXCEPT ...)
                let peek1 = self.peek_nth(1).map(|t| t.token_type);
                peek1 == Some(TokenType::Star)
                    || (peek1 == Some(TokenType::Var)
                        && self.peek_nth(2).map(|t| t.token_type) == Some(TokenType::Dot)
                        && self.peek_nth(3).map(|t| t.token_type) == Some(TokenType::Star))
                    || (peek1 == Some(TokenType::Var)
                        && self
                            .peek_nth(1)
                            .map(|t| t.text.to_uppercase() == "COLUMNS")
                            .unwrap_or(false))
            } {
                // Consume balanced parens and skip entire column specification
                self.advance(); // consume (
                let mut depth = 1i32;
                while !self.is_at_end() && depth > 0 {
                    if self.check(TokenType::LParen) {
                        depth += 1;
                    }
                    if self.check(TokenType::RParen) {
                        depth -= 1;
                        if depth == 0 {
                            break;
                        }
                    }
                    self.advance();
                }
                self.expect(TokenType::RParen)?;
                Vec::new() // Treat as "all columns"
            } else {
                self.advance(); // consume (
                let cols = self.parse_identifier_list()?;
                self.expect(TokenType::RParen)?;
                cols
            }
        } else {
            Vec::new()
        };

        // Parse OUTPUT clause (TSQL)
        let output = if self.match_token(TokenType::Output) {
            Some(self.parse_output_clause()?)
        } else {
            None
        };

        // Check for BY NAME (DuckDB): INSERT INTO x BY NAME SELECT ...
        let by_name = self.match_token(TokenType::By) && self.match_identifier("NAME");

        // Check for DEFAULT VALUES (PostgreSQL)
        let default_values =
            self.match_token(TokenType::Default) && self.match_token(TokenType::Values);

        // VALUES or SELECT or TABLE source (Hive/Spark) or DEFAULT VALUES (already consumed above)
        let (values, query) = if default_values {
            // DEFAULT VALUES: no values or query
            (Vec::new(), None)
        } else if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) && self.check(TokenType::Format)
            && self.peek_nth(1).is_some_and(|t| {
                let upper = t.text.to_uppercase();
                upper != "VALUES"
                    && (t.token_type == TokenType::Var || t.token_type == TokenType::Identifier)
            })
        {
            // ClickHouse: FORMAT <format_name> followed by raw data (CSV, JSON, TSV, etc.)
            // Skip everything to next semicolon or end — the data is not SQL
            self.advance(); // consume FORMAT
            let format_name = self.advance().text.clone(); // consume format name
                                                           // Consume all remaining tokens until semicolon (raw data)
            while !self.is_at_end() && !self.check(TokenType::Semicolon) {
                self.advance();
            }
            // Store as empty values with the format name in the query as a command
            (
                Vec::new(),
                Some(Expression::Command(Box::new(crate::expressions::Command {
                    this: format!("FORMAT {}", format_name),
                }))),
            )
        } else if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) && self.match_text_seq(&["FORMAT", "VALUES"])
        {
            let mut all_values = Vec::new();

            loop {
                self.expect(TokenType::LParen)?;
                let row = self.parse_expression_list()?;
                self.expect(TokenType::RParen)?;
                all_values.push(row);

                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }

            (all_values, None)
        } else if self.match_token(TokenType::Values) {
            let mut all_values = Vec::new();

            // ClickHouse: INSERT INTO t VALUES; — empty VALUES (clientError expected)
            if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && (self.check(TokenType::Semicolon) || self.is_at_end())
            {
                // Return empty INSERT as Command to avoid needing all Insert fields
                return Ok(Expression::Command(Box::new(crate::expressions::Command {
                    this: "INSERT INTO VALUES".to_string(),
                })));
            }

            // ClickHouse: allow bare VALUES without parens: VALUES 1, 2, 3
            if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && !self.check(TokenType::LParen)
            {
                loop {
                    let val = self.parse_expression()?;
                    all_values.push(vec![val]);
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
            } else {
                loop {
                    self.expect(TokenType::LParen)?;
                    // ClickHouse: allow empty VALUES () — empty tuple
                    let row = if self.check(TokenType::RParen) {
                        Vec::new()
                    } else {
                        self.parse_values_expression_list()?
                    };
                    self.expect(TokenType::RParen)?;
                    all_values.push(row);

                    if !self.match_token(TokenType::Comma) {
                        // ClickHouse: allow tuples without commas: VALUES (1) (2) (3)
                        if matches!(
                            self.config.dialect,
                            Some(crate::dialects::DialectType::ClickHouse)
                        ) && self.check(TokenType::LParen)
                        {
                            continue;
                        }
                        break;
                    }
                    // ClickHouse: allow trailing comma after last tuple
                    if matches!(
                        self.config.dialect,
                        Some(crate::dialects::DialectType::ClickHouse)
                    ) && !self.check(TokenType::LParen)
                    {
                        break;
                    }
                }
            } // close else (parenthesized values)

            (all_values, None)
        } else if self.check(TokenType::Table) {
            // Hive/Spark: INSERT OVERWRITE TABLE target TABLE source
            // The TABLE keyword here indicates source table, not a subquery
            (Vec::new(), None)
        } else {
            (Vec::new(), Some(self.parse_statement()?))
        };

        // Parse source table (Hive/Spark): INSERT OVERWRITE TABLE target TABLE source
        let source = if self.match_token(TokenType::Table) {
            // Parse source table reference (similar to target table parsing)
            let source_name = self.expect_identifier_with_quoted()?;
            let source_table = if self.match_token(TokenType::Dot) {
                let schema = source_name;
                let name = self.expect_identifier_with_quoted()?;
                let trailing_comments = self.previous_trailing_comments();
                TableRef {
                    name,
                    schema: Some(schema),
                    catalog: None,
                    alias: None,
                    alias_explicit_as: false,
                    column_aliases: Vec::new(),
                    trailing_comments,
                    when: None,
                    only: false,
                    final_: false,
                    table_sample: None,
                    hints: Vec::new(),
                    system_time: None,
                    partitions: Vec::new(),
                    identifier_func: None,
                    changes: None,
                    version: None,
                    span: None,
                }
            } else {
                let trailing_comments = self.previous_trailing_comments();
                TableRef {
                    name: source_name,
                    schema: None,
                    catalog: None,
                    alias: None,
                    alias_explicit_as: false,
                    column_aliases: Vec::new(),
                    trailing_comments,
                    when: None,
                    only: false,
                    final_: false,
                    table_sample: None,
                    hints: Vec::new(),
                    system_time: None,
                    partitions: Vec::new(),
                    identifier_func: None,
                    changes: None,
                    version: None,
                    span: None,
                }
            };
            Some(Expression::Table(source_table))
        } else {
            None
        };

        // Parse optional AS alias after VALUES (MySQL: INSERT ... VALUES (...) AS new_data)
        let source_alias = if self.match_token(TokenType::As) {
            Some(Identifier::new(self.expect_identifier()?))
        } else {
            None
        };

        // Parse ON CONFLICT clause (PostgreSQL, SQLite) or ON DUPLICATE KEY UPDATE (MySQL)
        let on_conflict = if self.match_token(TokenType::On) {
            if self.match_identifier("CONFLICT") {
                Some(Box::new(self.parse_on_conflict()?))
            } else if self.match_identifier("DUPLICATE") {
                // MySQL: ON DUPLICATE KEY UPDATE
                self.expect(TokenType::Key)?;
                self.expect(TokenType::Update)?;

                // Parse the UPDATE SET expressions
                let mut sets = Vec::new();
                loop {
                    // Parse column = expression
                    let col_name = self.expect_identifier_with_quoted()?;
                    // Handle qualified column: table.column
                    let column = if self.match_token(TokenType::Dot) {
                        let col = self.expect_identifier_with_quoted()?;
                        Expression::Column(Column {
                            name: col,
                            table: Some(col_name),
                            join_mark: false,
                            trailing_comments: Vec::new(),
                            span: None,
                            inferred_type: None,
                        })
                    } else {
                        Expression::Identifier(col_name)
                    };
                    self.expect(TokenType::Eq)?;
                    let value = self.parse_expression()?;
                    sets.push(Expression::Eq(Box::new(BinaryOp {
                        left: column,
                        right: value,
                        left_comments: Vec::new(),
                        operator_comments: Vec::new(),
                        trailing_comments: Vec::new(),
                        inferred_type: None,
                    })));
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }

                Some(Box::new(Expression::OnConflict(Box::new(OnConflict {
                    duplicate: Some(Box::new(Expression::Boolean(BooleanLiteral {
                        value: true,
                    }))),
                    expressions: sets,
                    action: None,
                    conflict_keys: None,
                    index_predicate: None,
                    constraint: None,
                    where_: None,
                }))))
            } else {
                // Unexpected token after ON
                return Err(self.parse_error("Expected CONFLICT or DUPLICATE after ON"));
            }
        } else {
            None
        };

        // Parse RETURNING clause (PostgreSQL, SQLite)
        let returning = if self.match_token(TokenType::Returning) {
            self.parse_select_expressions()?
        } else {
            Vec::new()
        };

        Ok(Expression::Insert(Box::new(Insert {
            table,
            columns,
            values,
            query,
            overwrite,
            partition,
            directory: None,
            returning,
            output,
            on_conflict,
            leading_comments,
            if_exists,
            with: None,
            ignore,
            source_alias,
            alias,
            alias_explicit_as,
            default_values,
            by_name,
            conflict_action,
            is_replace: false,
            replace_where,
            source: source.map(Box::new),
            hint,
            function_target,
            partition_by: partition_by_expr,
            settings: insert_settings,
        })))
    }

    /// Parse ON CONFLICT clause for INSERT statements (PostgreSQL, SQLite)
    /// Syntax: ON CONFLICT [(conflict_target)] [WHERE predicate] DO NOTHING | DO UPDATE SET ...
    /// ON CONFLICT ON CONSTRAINT constraint_name DO ...
    fn parse_on_conflict(&mut self) -> Result<Expression> {
        // Check for ON CONSTRAINT variant
        let constraint =
            if self.match_token(TokenType::On) && self.match_token(TokenType::Constraint) {
                let name = self.expect_identifier()?;
                Some(Box::new(Expression::Identifier(Identifier::new(name))))
            } else {
                None
            };

        // Parse optional conflict target (column list)
        let conflict_keys = if constraint.is_none() && self.match_token(TokenType::LParen) {
            let keys = self.parse_expression_list()?;
            self.expect(TokenType::RParen)?;
            Some(Box::new(Expression::Tuple(Box::new(Tuple {
                expressions: keys,
            }))))
        } else {
            None
        };

        // Parse optional WHERE clause for conflict target
        let index_predicate = if self.match_token(TokenType::Where) {
            Some(Box::new(self.parse_expression()?))
        } else {
            None
        };

        // Parse DO NOTHING or DO UPDATE
        if !self.match_identifier("DO") {
            return Err(self.parse_error("Expected DO after ON CONFLICT"));
        }

        let action = if self.match_identifier("NOTHING") {
            // DO NOTHING
            Some(Box::new(Expression::Identifier(Identifier::new(
                "NOTHING".to_string(),
            ))))
        } else if self.match_token(TokenType::Update) {
            // DO UPDATE SET ...
            self.expect(TokenType::Set)?;
            let mut sets = Vec::new();
            loop {
                // Parse column = expression
                let col_name = self.expect_identifier_with_quoted()?;
                // Handle qualified column: table.column
                let column = if self.match_token(TokenType::Dot) {
                    let col = self.expect_identifier_with_quoted()?;
                    Expression::Column(Column {
                        name: col,
                        table: Some(col_name),
                        join_mark: false,
                        trailing_comments: Vec::new(),
                        span: None,
                        inferred_type: None,
                    })
                } else {
                    Expression::Identifier(col_name)
                };
                self.expect(TokenType::Eq)?;
                let value = self.parse_expression()?;
                sets.push(Expression::Eq(Box::new(BinaryOp {
                    left: column,
                    right: value,
                    left_comments: Vec::new(),
                    operator_comments: Vec::new(),
                    trailing_comments: Vec::new(),
                    inferred_type: None,
                })));
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            Some(Box::new(Expression::Tuple(Box::new(Tuple {
                expressions: sets,
            }))))
        } else {
            return Err(self.parse_error("Expected NOTHING or UPDATE after DO"));
        };

        // Parse optional WHERE clause for the UPDATE action
        let where_ = if self.match_token(TokenType::Where) {
            Some(Box::new(self.parse_expression()?))
        } else {
            None
        };

        Ok(Expression::OnConflict(Box::new(OnConflict {
            duplicate: None,
            expressions: Vec::new(),
            action,
            conflict_keys,
            index_predicate,
            constraint,
            where_,
        })))
    }

    /// Parse MySQL REPLACE [INTO] statement or REPLACE() function call
    fn parse_replace(&mut self) -> Result<Expression> {
        // Check if this is REPLACE() function call (REPLACE followed by '(')
        // or MySQL REPLACE INTO statement
        let replace_token = self.expect(TokenType::Replace)?;
        let leading_comments = replace_token.comments;

        if self.check(TokenType::LParen) {
            // This is a REPLACE() function call, parse as expression
            self.expect(TokenType::LParen)?;
            let args = self.parse_expression_list()?;
            self.expect(TokenType::RParen)?;
            return Ok(Expression::Function(Box::new(Function {
                name: "REPLACE".to_string(),
                args,
                distinct: false,
                trailing_comments: Vec::new(),
                use_bracket_syntax: false,
                no_parens: false,
                quoted: false,
                span: None,
                inferred_type: None,
            })));
        }

        // Teradata: REPLACE VIEW -> CREATE OR REPLACE VIEW
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::Teradata)
        ) && self.check(TokenType::View)
        {
            return self.parse_create_view(true, false, false, None, None, None, false);
        }

        // ClickHouse: REPLACE TABLE -> treat like CREATE OR REPLACE TABLE
        // Also handle REPLACE TEMPORARY TABLE
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) && (self.check(TokenType::Table) || self.check(TokenType::Temporary))
        {
            let temporary = self.match_token(TokenType::Temporary);
            return self.parse_create_table(true, temporary, leading_comments.clone(), None);
        }

        // ClickHouse: REPLACE DICTIONARY -> consume as Command
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) && (self.check(TokenType::Dictionary) || self.check_identifier("DICTIONARY"))
        {
            let mut parts = vec!["REPLACE".to_string()];
            let mut _paren_depth = 0i32;
            while !self.is_at_end() && !self.check(TokenType::Semicolon) {
                let token = self.advance();
                if token.token_type == TokenType::LParen {
                    _paren_depth += 1;
                }
                if token.token_type == TokenType::RParen {
                    _paren_depth -= 1;
                }
                let text = if token.token_type == TokenType::String {
                    format!("'{}'", token.text)
                } else if token.token_type == TokenType::QuotedIdentifier {
                    format!("\"{}\"", token.text)
                } else {
                    token.text.clone()
                };
                parts.push(text);
            }
            return Ok(Expression::Command(Box::new(crate::expressions::Command {
                this: parts.join(" "),
            })));
        }

        // Otherwise, this is MySQL/SQLite REPLACE INTO statement - parse similarly to INSERT
        self.match_token(TokenType::Into);

        let table_name = self.expect_identifier_or_safe_keyword_with_quoted()?;
        let table = if self.match_token(TokenType::Dot) {
            let second_name = self.expect_identifier_or_safe_keyword_with_quoted()?;
            TableRef {
                name: second_name,
                schema: Some(table_name),
                catalog: None,
                alias: None,
                alias_explicit_as: false,
                column_aliases: Vec::new(),
                trailing_comments: Vec::new(),
                when: None,
                only: false,
                final_: false,
                table_sample: None,
                hints: Vec::new(),
                system_time: None,
                partitions: Vec::new(),
                identifier_func: None,
                changes: None,
                version: None,
                span: None,
            }
        } else {
            TableRef::new(table_name.name)
        };

        // Parse optional column list
        let columns = if self.match_token(TokenType::LParen) {
            let mut cols = Vec::new();
            loop {
                if self.check(TokenType::RParen) {
                    break;
                }
                let col = self.expect_identifier_with_quoted()?;
                cols.push(col);
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            self.expect(TokenType::RParen)?;
            cols
        } else {
            Vec::new()
        };

        // Parse VALUES or SELECT query
        let mut values = Vec::new();
        let query = if self.match_token(TokenType::Values) {
            loop {
                self.expect(TokenType::LParen)?;
                let row = self.parse_expression_list()?;
                self.expect(TokenType::RParen)?;
                values.push(row);
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            None
        } else if !self.is_at_end() && !self.check(TokenType::Semicolon) {
            // SELECT or other statement as value source
            Some(self.parse_statement()?)
        } else {
            None
        };

        Ok(Expression::Insert(Box::new(Insert {
            table,
            columns,
            values,
            query,
            overwrite: false,
            partition: Vec::new(),
            directory: None,
            returning: Vec::new(),
            output: None,
            on_conflict: None,
            leading_comments,
            if_exists: false,
            with: None,
            ignore: false,
            source_alias: None,
            alias: None,
            alias_explicit_as: false,
            default_values: false,
            by_name: false,
            conflict_action: None,
            is_replace: true,
            replace_where: None,
            source: None,
            hint: None,
            function_target: None,
            partition_by: None,
            settings: Vec::new(),
        })))
    }

    /// Parse UPDATE statement
    fn parse_update(&mut self) -> Result<Expression> {
        let update_token = self.expect(TokenType::Update)?;
        let leading_comments = update_token.comments;

        // TSQL: UPDATE STATISTICS table_name - parse as Command
        if self.check_identifier("STATISTICS") {
            let mut parts = vec!["UPDATE".to_string()];
            while !self.is_at_end() && !self.check(TokenType::Semicolon) {
                parts.push(self.advance().text);
            }
            return Ok(Expression::Command(Box::new(Command {
                this: parts.join(" "),
            })));
        }

        // Parse table name (can be qualified: db.table_name)
        let first_name = self.expect_identifier_with_quoted()?;
        let mut table = if self.match_token(TokenType::Dot) {
            let second_name = self.expect_identifier_with_quoted()?;
            // Check for three-part name (catalog.schema.table)
            if self.match_token(TokenType::Dot) {
                let table_name = self.expect_identifier_with_quoted()?;
                TableRef {
                    name: table_name,
                    schema: Some(second_name),
                    catalog: Some(first_name),
                    alias: None,
                    alias_explicit_as: false,
                    column_aliases: Vec::new(),
                    trailing_comments: Vec::new(),
                    when: None,
                    only: false,
                    final_: false,
                    table_sample: None,
                    hints: Vec::new(),
                    system_time: None,
                    partitions: Vec::new(),
                    identifier_func: None,
                    changes: None,
                    version: None,
                    span: None,
                }
            } else {
                TableRef {
                    name: second_name,
                    schema: Some(first_name),
                    catalog: None,
                    alias: None,
                    alias_explicit_as: false,
                    column_aliases: Vec::new(),
                    trailing_comments: Vec::new(),
                    when: None,
                    only: false,
                    final_: false,
                    table_sample: None,
                    hints: Vec::new(),
                    system_time: None,
                    partitions: Vec::new(),
                    identifier_func: None,
                    changes: None,
                    version: None,
                    span: None,
                }
            }
        } else {
            TableRef::from_identifier(first_name)
        };
        table.trailing_comments = self.previous_trailing_comments();

        // Optional alias (with or without AS)
        if self.match_token(TokenType::As) {
            table.alias = Some(self.expect_identifier_with_quoted()?);
            table.alias_explicit_as = true;
        } else if self.is_identifier_token() && !self.check(TokenType::Set) {
            // Implicit alias (table t SET ...)
            table.alias = Some(self.expect_identifier_with_quoted()?);
            table.alias_explicit_as = false;
        }

        // Handle multi-table UPDATE syntax: UPDATE t1, t2, t3 LEFT JOIN t4 ON ... SET ...
        // Capture additional tables
        let mut extra_tables = Vec::new();
        while self.match_token(TokenType::Comma) {
            // Parse additional table name
            let first_name = self.expect_identifier_with_quoted()?;
            let mut extra_table = if self.match_token(TokenType::Dot) {
                let second_name = self.expect_identifier_with_quoted()?;
                if self.match_token(TokenType::Dot) {
                    let table_name = self.expect_identifier_with_quoted()?;
                    TableRef {
                        name: table_name,
                        schema: Some(second_name),
                        catalog: Some(first_name),
                        alias: None,
                        alias_explicit_as: false,
                        column_aliases: Vec::new(),
                        trailing_comments: Vec::new(),
                        when: None,
                        only: false,
                        final_: false,
                        table_sample: None,
                        hints: Vec::new(),
                        system_time: None,
                        partitions: Vec::new(),
                        identifier_func: None,
                        changes: None,
                        version: None,
                        span: None,
                    }
                } else {
                    TableRef {
                        name: second_name,
                        schema: Some(first_name),
                        catalog: None,
                        alias: None,
                        alias_explicit_as: false,
                        column_aliases: Vec::new(),
                        trailing_comments: Vec::new(),
                        when: None,
                        only: false,
                        final_: false,
                        table_sample: None,
                        hints: Vec::new(),
                        system_time: None,
                        partitions: Vec::new(),
                        identifier_func: None,
                        changes: None,
                        version: None,
                        span: None,
                    }
                }
            } else {
                TableRef::from_identifier(first_name)
            };
            // Optional alias
            if self.match_token(TokenType::As) {
                extra_table.alias = Some(self.expect_identifier_with_quoted()?);
                extra_table.alias_explicit_as = true;
            } else if self.is_identifier_token()
                && !self.check(TokenType::Set)
                && !self.check_keyword()
            {
                extra_table.alias = Some(self.expect_identifier_with_quoted()?);
                extra_table.alias_explicit_as = false;
            }
            extra_tables.push(extra_table);
        }

        // Handle JOINs before SET
        let mut table_joins = Vec::new();
        while let Some((kind, _, use_inner_keyword, use_outer_keyword, _join_hint)) =
            self.try_parse_join_kind()
        {
            if self.check(TokenType::Join) {
                self.advance(); // consume JOIN
            }
            // Parse joined table
            let first_name = self.expect_identifier_with_quoted()?;
            let mut join_table = if self.match_token(TokenType::Dot) {
                let second_name = self.expect_identifier_with_quoted()?;
                if self.match_token(TokenType::Dot) {
                    let table_name = self.expect_identifier_with_quoted()?;
                    TableRef {
                        name: table_name,
                        schema: Some(second_name),
                        catalog: Some(first_name),
                        alias: None,
                        alias_explicit_as: false,
                        column_aliases: Vec::new(),
                        trailing_comments: Vec::new(),
                        when: None,
                        only: false,
                        final_: false,
                        table_sample: None,
                        hints: Vec::new(),
                        system_time: None,
                        partitions: Vec::new(),
                        identifier_func: None,
                        changes: None,
                        version: None,
                        span: None,
                    }
                } else {
                    TableRef {
                        name: second_name,
                        schema: Some(first_name),
                        catalog: None,
                        alias: None,
                        alias_explicit_as: false,
                        column_aliases: Vec::new(),
                        trailing_comments: Vec::new(),
                        when: None,
                        only: false,
                        final_: false,
                        table_sample: None,
                        hints: Vec::new(),
                        system_time: None,
                        partitions: Vec::new(),
                        changes: None,
                        version: None,
                        identifier_func: None,
                        span: None,
                    }
                }
            } else {
                TableRef::from_identifier(first_name)
            };
            // Optional alias
            if self.match_token(TokenType::As) {
                join_table.alias = Some(self.expect_identifier_with_quoted()?);
                join_table.alias_explicit_as = true;
            } else if self.is_identifier_token()
                && !self.check(TokenType::On)
                && !self.check(TokenType::Set)
            {
                join_table.alias = Some(self.expect_identifier_with_quoted()?);
                join_table.alias_explicit_as = false;
            }
            // ON clause
            let on_condition = if self.match_token(TokenType::On) {
                Some(self.parse_expression()?)
            } else {
                None
            };
            table_joins.push(Join {
                this: Expression::Table(join_table),
                on: on_condition,
                using: Vec::new(),
                kind,
                use_inner_keyword,
                use_outer_keyword,
                deferred_condition: false,
                join_hint: None,
                match_condition: None,
                pivots: Vec::new(),
                comments: Vec::new(),
                nesting_group: 0,
                directed: false,
            });
        }

        // Snowflake syntax: UPDATE table FROM (source) SET ... WHERE ...
        // Check if FROM comes before SET
        let (from_before_set, early_from_clause, early_from_joins) =
            if self.match_token(TokenType::From) {
                let from_clause = self.parse_from()?;
                let from_joins = self.parse_joins()?;
                (true, Some(from_clause), from_joins)
            } else {
                (false, None, Vec::new())
            };

        self.expect(TokenType::Set)?;

        let mut set = Vec::new();
        loop {
            // Column can be qualified for multi-table UPDATE (e.g., a.id = 1)
            // Use safe keyword variant to allow keywords like 'exists' as column names (ClickHouse)
            let mut col_ident = self.expect_identifier_or_safe_keyword_with_quoted()?;
            while self.match_token(TokenType::Dot) {
                let part = self.expect_identifier_or_safe_keyword_with_quoted()?;
                // For qualified columns, preserve both parts
                col_ident = Identifier {
                    name: format!("{}.{}", col_ident.name, part.name),
                    quoted: col_ident.quoted || part.quoted,
                    trailing_comments: Vec::new(),
                    span: None,
                };
            }
            self.expect(TokenType::Eq)?;
            let value = self.parse_expression()?;
            set.push((col_ident, value));

            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        // Parse OUTPUT clause (TSQL)
        let output = if self.match_token(TokenType::Output) {
            Some(self.parse_output_clause()?)
        } else {
            None
        };

        // Parse FROM clause (PostgreSQL, SQL Server, Snowflake) - only if not already parsed before SET
        let (from_clause, from_joins) = if from_before_set {
            (early_from_clause, early_from_joins)
        } else if self.match_token(TokenType::From) {
            let from_clause = Some(self.parse_from()?);
            let from_joins = self.parse_joins()?;
            (from_clause, from_joins)
        } else {
            (None, Vec::new())
        };

        let where_clause = if self.match_token(TokenType::Where) {
            Some(Where {
                this: self.parse_expression()?,
            })
        } else {
            None
        };

        // Parse RETURNING clause (PostgreSQL, SQLite)
        let returning = if self.match_token(TokenType::Returning) {
            self.parse_select_expressions()?
        } else {
            Vec::new()
        };

        // Parse ORDER BY clause (MySQL)
        let order_by = if self.match_keywords(&[TokenType::Order, TokenType::By]) {
            Some(self.parse_order_by()?)
        } else {
            None
        };

        // Parse LIMIT clause (MySQL)
        let limit = if self.match_token(TokenType::Limit) {
            Some(self.parse_expression()?)
        } else {
            None
        };

        Ok(Expression::Update(Box::new(Update {
            table,
            extra_tables,
            table_joins,
            set,
            from_clause,
            from_joins,
            where_clause,
            returning,
            output,
            with: None,
            leading_comments,
            limit,
            order_by,
            from_before_set,
        })))
    }

    /// Parse DELETE statement
    /// Handles:
    /// - Standard: DELETE FROM t WHERE ...
    /// - PostgreSQL USING: DELETE FROM t USING s WHERE ... RETURNING a
    /// - DuckDB USING: DELETE FROM t USING (VALUES ...) AS t1 WHERE ...
    /// - MySQL multi-table: DELETE t1 FROM t1 JOIN t2 ON ... WHERE ...
    /// - MySQL multi-table: DELETE t1, t2 FROM t1 JOIN t2 JOIN t3 WHERE ...
    /// - MySQL USING: DELETE FROM t1, t2 USING t1 JOIN t2 JOIN t3 WHERE ...
    /// - MySQL FORCE INDEX: DELETE FROM t FORCE INDEX (idx) WHERE ...
    fn parse_delete(&mut self) -> Result<Expression> {
        let delete_token = self.expect(TokenType::Delete)?;
        let leading_comments = delete_token.comments;

        // Check if FROM is present. If not, this is MySQL multi-table: DELETE t1, t2 FROM ...
        // or TSQL: DELETE x OUTPUT x.a FROM z
        let mut tables = Vec::new();
        let mut early_output = None;
        let _has_from = if self.check(TokenType::From) {
            self.advance(); // consume FROM
            true
        } else {
            // MySQL multi-table: DELETE t1[, t2, ...] FROM ...
            // or TSQL: DELETE x OUTPUT x.a FROM z
            // or BigQuery/generic: DELETE table WHERE ... (no FROM required)
            // Parse target table list (supporting dotted names)
            loop {
                let tref = self.parse_table_ref()?;
                tables.push(tref);
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            // TSQL: OUTPUT clause can appear before FROM
            if self.match_token(TokenType::Output) {
                early_output = Some(self.parse_output_clause()?);
            }
            if self.check(TokenType::From) {
                self.advance(); // consume FROM
                true
            } else {
                // BigQuery-style: DELETE table WHERE ... (no FROM)
                false
            }
        };

        // Now parse the main table after FROM (or use from no-FROM path)
        let table = if _has_from {
            // Parse the main table(s) after FROM
            // Use parse_table_ref() to handle dotted names like db.table
            self.parse_table_ref()?
        } else {
            // BigQuery-style: table was already parsed into `tables`
            // Move it out to be the main table
            if !tables.is_empty() {
                tables.remove(0)
            } else {
                return Err(self.parse_error("Expected table name in DELETE statement"));
            }
        };

        // ClickHouse: ON CLUSTER clause
        let on_cluster = self.parse_on_cluster_clause()?;

        // Check for additional tables after the first: DELETE FROM t1, t2 USING ...
        let mut extra_from_tables = Vec::new();
        if _has_from
            && tables.is_empty()
            && self.check(TokenType::Comma)
            && !self.check(TokenType::Where)
        {
            // Could be multi-table: DELETE FROM t1, t2 USING ...
            // Check ahead if this is followed by USING or more tables
            while self.match_token(TokenType::Comma) {
                let extra_name = self.expect_identifier_with_quoted()?;
                let extra_ref = TableRef::from_identifier(extra_name);
                extra_from_tables.push(extra_ref);
            }
        }

        // If we had DELETE FROM t1, t2 USING ..., the tables field stores t1, t2
        let mut tables_from_using = false;
        if !extra_from_tables.is_empty() {
            // The main table + extra tables form the multi-table target
            tables.push(table.clone());
            tables.append(&mut extra_from_tables);
            tables_from_using = true;
        }

        // Check for FORCE INDEX hint (MySQL): DELETE FROM t FORCE INDEX (idx)
        let force_index = if self.match_text_seq(&["FORCE", "INDEX"]) {
            self.expect(TokenType::LParen)?;
            let idx_name = self.expect_identifier_with_quoted()?;
            self.expect(TokenType::RParen)?;
            Some(idx_name.name)
        } else {
            None
        };

        // Check for optional alias (with or without AS)
        let (alias, alias_explicit_as) = if force_index.is_none() && self.match_token(TokenType::As)
        {
            (Some(self.expect_identifier_with_quoted()?), true)
        } else if force_index.is_none()
            && self.is_identifier_token()
            && !self.check(TokenType::Using)
            && !self.check(TokenType::Where)
            && !self.check(TokenType::Inner)
            && !self.check(TokenType::Left)
            && !self.check(TokenType::Right)
            && !self.check(TokenType::Cross)
            && !self.check(TokenType::Full)
            && !self.check(TokenType::Join)
            && !self.check_identifier("FORCE")
        {
            (Some(self.expect_identifier_with_quoted()?), false)
        } else {
            (None, false)
        };

        // Parse JOINs for MySQL multi-table: DELETE t1 FROM t1 LEFT JOIN t2 ON ...
        let mut joins = self.parse_joins()?;

        // Parse USING clause (PostgreSQL/DuckDB/MySQL)
        let mut using = Vec::new();
        if self.match_token(TokenType::Using) {
            loop {
                // Check for subquery: USING (SELECT ...) AS ... or (VALUES ...) AS ...
                if self.check(TokenType::LParen) {
                    // Check if next token after ( is VALUES
                    let is_values = self.current + 1 < self.tokens.len()
                        && self.tokens[self.current + 1].token_type == TokenType::Values;
                    let subquery = if is_values {
                        // Parse (VALUES ...) as parenthesized VALUES
                        self.advance(); // consume (
                        let values = self.parse_values()?;
                        self.expect(TokenType::RParen)?;
                        Expression::Paren(Box::new(Paren {
                            this: values,
                            trailing_comments: Vec::new(),
                        }))
                    } else {
                        // Parse as subquery (SELECT ...) or other expression
                        self.parse_primary()?
                    };
                    // Parse alias
                    let using_alias = if self.match_token(TokenType::As) {
                        let alias_name = self.expect_identifier_with_quoted()?;
                        // Check for column aliases: AS name(col1, col2)
                        let col_aliases = if self.match_token(TokenType::LParen) {
                            let aliases = self.parse_identifier_list()?;
                            self.expect(TokenType::RParen)?;
                            aliases
                        } else {
                            Vec::new()
                        };
                        Some((alias_name, col_aliases))
                    } else {
                        None
                    };
                    // Create a TableRef from the subquery with alias
                    let mut tref = TableRef::new("");
                    if let Some((alias_name, col_aliases)) = using_alias {
                        tref.alias = Some(alias_name);
                        tref.alias_explicit_as = true;
                        tref.column_aliases = col_aliases;
                    }
                    // Store the subquery in the table reference using hints (as a hack)
                    // Actually, we need a better approach - use the table ref hints to store the subquery
                    tref.hints = vec![subquery];
                    using.push(tref);
                } else {
                    let using_table = self.expect_identifier_with_quoted()?;
                    let mut using_ref = TableRef::from_identifier(using_table);

                    // Check for JOINs: USING t1 INNER JOIN t2 INNER JOIN t3
                    if self.check_join_keyword() {
                        // Parse JOINs as part of USING
                        using.push(using_ref);
                        let mut using_joins = self.parse_joins()?;
                        joins.append(&mut using_joins);
                        break;
                    }

                    // Optional alias for using table
                    if self.match_token(TokenType::As) {
                        using_ref.alias = Some(self.expect_identifier_with_quoted()?);
                        using_ref.alias_explicit_as = true;
                    } else if self.is_identifier_token()
                        && !self.check(TokenType::Comma)
                        && !self.check(TokenType::Where)
                    {
                        using_ref.alias = Some(self.expect_identifier_with_quoted()?);
                    }
                    using.push(using_ref);
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
        }

        // ClickHouse: IN PARTITION 'partition_id' clause before WHERE
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) && self.check(TokenType::In)
            && self
                .peek_nth(1)
                .is_some_and(|t| t.text.eq_ignore_ascii_case("PARTITION"))
        {
            self.advance(); // consume IN
            self.advance(); // consume PARTITION
                            // Consume partition expression (string or identifier)
            let _partition = self.parse_primary()?;
        }

        // Parse OUTPUT clause (TSQL) - may have been parsed early (before FROM)
        let output = if early_output.is_some() {
            early_output
        } else if self.match_token(TokenType::Output) {
            Some(self.parse_output_clause()?)
        } else {
            None
        };

        let where_clause = if self.match_token(TokenType::Where) {
            Some(Where {
                this: self.parse_expression()?,
            })
        } else {
            None
        };

        // Parse ORDER BY clause (MySQL)
        let order_by = if self.match_keywords(&[TokenType::Order, TokenType::By]) {
            Some(self.parse_order_by()?)
        } else {
            None
        };

        // Parse LIMIT clause (MySQL)
        let limit = if self.match_token(TokenType::Limit) {
            Some(self.parse_expression()?)
        } else {
            None
        };

        // Parse RETURNING clause (PostgreSQL)
        let returning = if self.match_token(TokenType::Returning) {
            self.parse_select_expressions()?
        } else {
            Vec::new()
        };

        Ok(Expression::Delete(Box::new(Delete {
            table,
            on_cluster,
            alias,
            alias_explicit_as,
            using,
            where_clause,
            output,
            leading_comments,
            with: None,
            limit,
            order_by,
            returning,
            tables,
            tables_from_using,
            joins,
            force_index,
            no_from: !_has_from,
        })))
    }

    // ==================== DDL Parsing ====================

    /// Parse a CREATE statement
    fn parse_create(&mut self) -> Result<Expression> {
        let create_pos = self.current; // position of CREATE token
        let create_token = self.expect(TokenType::Create)?;
        let leading_comments = create_token.comments;

        // Handle OR REPLACE
        let or_replace = self.match_keywords(&[TokenType::Or, TokenType::Replace]);

        // Handle TEMPORARY
        let temporary = self.match_token(TokenType::Temporary);

        // Handle MATERIALIZED
        let materialized = self.match_token(TokenType::Materialized);

        // Parse MySQL-specific CREATE VIEW options: ALGORITHM, DEFINER, SQL SECURITY
        // CREATE ALGORITHM=... DEFINER=... SQL SECURITY DEFINER VIEW ...
        let mut algorithm: Option<String> = None;
        let mut definer: Option<String> = None;
        let mut security: Option<FunctionSecurity> = None;

        while self.match_identifier("ALGORITHM")
            || self.match_identifier("DEFINER")
            || self.match_identifier("SQL")
        {
            let option_name = self.previous().text.to_uppercase();

            if option_name == "ALGORITHM" && self.match_token(TokenType::Eq) {
                // ALGORITHM=UNDEFINED|MERGE|TEMPTABLE
                let value = self.expect_identifier_or_keyword()?;
                algorithm = Some(value.to_uppercase());
            } else if option_name == "DEFINER" && self.match_token(TokenType::Eq) {
                // DEFINER=user@host (can include @ and %)
                let mut definer_value = String::new();
                while !self.is_at_end()
                    && !self.check(TokenType::View)
                    && !self.check_identifier("ALGORITHM")
                    && !self.check_identifier("DEFINER")
                    && !self.check_identifier("SQL")
                    && !self.check_identifier("SECURITY")
                {
                    definer_value.push_str(&self.advance().text);
                }
                definer = Some(definer_value);
            } else if option_name == "SQL" && self.match_identifier("SECURITY") {
                // SQL SECURITY DEFINER/INVOKER
                if self.match_identifier("DEFINER") {
                    security = Some(FunctionSecurity::Definer);
                } else if self.match_identifier("INVOKER") {
                    security = Some(FunctionSecurity::Invoker);
                }
            }
        }

        // Handle SECURE modifier for VIEW (Snowflake)
        let secure = self.match_identifier("SECURE");

        // Handle table modifiers: DYNAMIC, ICEBERG, EXTERNAL, HYBRID, TRANSIENT (Snowflake), UNLOGGED (PostgreSQL)
        let mut table_modifier: Option<String> = if self.check_identifier("DYNAMIC") {
            self.advance();
            Some("DYNAMIC".to_string())
        } else if self.check_identifier("ICEBERG") {
            self.advance();
            Some("ICEBERG".to_string())
        } else if self.check_identifier("EXTERNAL") {
            self.advance();
            Some("EXTERNAL".to_string())
        } else if self.check_identifier("HYBRID") {
            self.advance();
            Some("HYBRID".to_string())
        } else if self.check_identifier("TRANSIENT") {
            self.advance();
            Some("TRANSIENT".to_string())
        } else if self.check_identifier("UNLOGGED") {
            self.advance();
            Some("UNLOGGED".to_string())
        } else if self.check_identifier("DICTIONARY") {
            self.advance();
            Some("DICTIONARY".to_string())
        } else if self.check(TokenType::Dictionary) {
            self.advance();
            Some("DICTIONARY".to_string())
        } else {
            None
        };

        // Teradata: SET/MULTISET/VOLATILE/GLOBAL TEMPORARY modifiers before TABLE
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::Teradata)
        ) {
            let mut parts = Vec::new();
            loop {
                if self.match_token(TokenType::Set) {
                    parts.push(self.previous().text.to_uppercase());
                } else if self.match_identifier("MULTISET") {
                    parts.push(self.previous().text.to_uppercase());
                } else if self.match_identifier("VOLATILE") {
                    parts.push(self.previous().text.to_uppercase());
                } else if self.match_identifier("GLOBAL") {
                    parts.push(self.previous().text.to_uppercase());
                } else if self.match_token(TokenType::Temporary) {
                    parts.push(self.previous().text.to_uppercase());
                } else {
                    break;
                }
            }
            if !parts.is_empty() {
                table_modifier = Some(parts.join(" "));
            }
        }

        if table_modifier.as_deref() == Some("DICTIONARY") {
            return self.parse_create_table(
                or_replace,
                temporary,
                leading_comments,
                table_modifier.as_deref(),
            );
        }

        match self.peek().token_type {
            TokenType::Table => {
                // Check if this is CREATE TABLE FUNCTION (BigQuery)
                if self.current + 1 < self.tokens.len()
                    && self.tokens[self.current + 1].token_type == TokenType::Function
                {
                    self.advance(); // consume TABLE
                    return self.parse_create_function(or_replace, temporary, true);
                }
                let modifier = if materialized {
                    Some("MATERIALIZED")
                } else {
                    table_modifier.as_deref()
                };
                self.parse_create_table(or_replace, temporary, leading_comments, modifier)
            }
            TokenType::Dictionary => {
                self.parse_create_table(or_replace, temporary, leading_comments, Some("DICTIONARY"))
            }
            TokenType::View => self.parse_create_view(
                or_replace,
                materialized,
                temporary,
                algorithm,
                definer,
                security,
                secure,
            ),
            TokenType::Unique => {
                self.advance(); // consume UNIQUE
                                // Check for CLUSTERED/NONCLUSTERED after UNIQUE (TSQL)
                let clustered = if self.check_identifier("CLUSTERED") {
                    self.advance();
                    Some("CLUSTERED".to_string())
                } else if self.check_identifier("NONCLUSTERED") {
                    self.advance();
                    Some("NONCLUSTERED".to_string())
                } else {
                    None
                };
                // Check for COLUMNSTORE (TSQL: CREATE UNIQUE NONCLUSTERED COLUMNSTORE INDEX)
                if self.check_identifier("COLUMNSTORE") {
                    self.advance();
                    // Prepend COLUMNSTORE to clustered
                    let clustered = clustered
                        .map(|c| format!("{} COLUMNSTORE", c))
                        .or_else(|| Some("COLUMNSTORE".to_string()));
                    self.parse_create_index_with_clustered(true, clustered)
                } else {
                    self.parse_create_index_with_clustered(true, clustered)
                }
            }
            TokenType::Index => self.parse_create_index_with_clustered(false, None),
            TokenType::Schema => self.parse_create_schema(leading_comments),
            TokenType::Database => self.parse_create_database(),
            TokenType::Function => self.parse_create_function(or_replace, temporary, false),
            TokenType::Procedure => self.parse_create_procedure(or_replace),
            TokenType::Sequence => self.parse_create_sequence(temporary, or_replace),
            TokenType::Trigger => self.parse_create_trigger(or_replace, false, create_pos),
            TokenType::Constraint => {
                self.advance(); // consume CONSTRAINT
                self.parse_create_trigger(or_replace, true, create_pos)
            }
            TokenType::Type => self.parse_create_type(),
            TokenType::Domain => self.parse_create_domain(),
            _ => {
                // Handle TSQL CLUSTERED/NONCLUSTERED [COLUMNSTORE] INDEX
                if self.check_identifier("CLUSTERED") || self.check_identifier("NONCLUSTERED") {
                    let clustered_text = self.advance().text.to_uppercase();
                    // Check for COLUMNSTORE after CLUSTERED/NONCLUSTERED
                    let clustered = if self.check_identifier("COLUMNSTORE") {
                        self.advance();
                        Some(format!("{} COLUMNSTORE", clustered_text))
                    } else {
                        Some(clustered_text)
                    };
                    return self.parse_create_index_with_clustered(false, clustered);
                }
                // Handle TSQL COLUMNSTORE INDEX (without CLUSTERED/NONCLUSTERED prefix)
                if self.check_identifier("COLUMNSTORE") && {
                    let pos = self.current;
                    let result = pos + 1 < self.tokens.len()
                        && self.tokens[pos + 1].token_type == TokenType::Index;
                    result
                } {
                    self.advance(); // consume COLUMNSTORE
                                    // COLUMNSTORE without prefix implies NONCLUSTERED
                    return self.parse_create_index_with_clustered(
                        false,
                        Some("NONCLUSTERED COLUMNSTORE".to_string()),
                    );
                }
                // Handle identifiers that aren't keywords: TAG, STAGE, STREAM, etc.
                if self.check_identifier("TAG") {
                    return self.parse_create_tag(or_replace);
                }
                if self.check_identifier("STAGE") {
                    return self.parse_create_stage(or_replace, temporary);
                }
                if self.check_identifier("STREAM") {
                    return self.parse_create_stream(or_replace);
                }
                if (self.check_identifier("FILE") || self.check(TokenType::File)) && {
                    let next = self.current + 1;
                    next < self.tokens.len()
                        && (self.tokens[next].text.eq_ignore_ascii_case("FORMAT"))
                } {
                    return self.parse_create_file_format(or_replace, temporary);
                }
                // Fall back to Raw for unrecognized CREATE targets
                // (e.g., CREATE WAREHOUSE, CREATE STREAMLIT, CREATE STORAGE INTEGRATION, etc.)
                {
                    let start = self.current;
                    while !self.is_at_end() && !self.check(TokenType::Semicolon) {
                        self.advance();
                    }
                    let sql = self.tokens_to_sql(start, self.current);
                    let mut prefix = String::from("CREATE");
                    if or_replace {
                        prefix.push_str(" OR REPLACE");
                    }
                    if temporary {
                        prefix.push_str(" TEMPORARY");
                    }
                    if materialized {
                        prefix.push_str(" MATERIALIZED");
                    }
                    prefix.push(' ');
                    prefix.push_str(&sql);
                    Ok(Expression::Raw(Raw { sql: prefix }))
                }
            }
        }
    }

    /// Parse CREATE TABLE
    fn parse_create_table(
        &mut self,
        or_replace: bool,
        temporary: bool,
        leading_comments: Vec<String>,
        table_modifier: Option<&str>,
    ) -> Result<Expression> {
        if table_modifier == Some("DICTIONARY") {
            let _ = self.match_token(TokenType::Dictionary);
        } else {
            self.expect(TokenType::Table)?;
        }

        // Handle IF NOT EXISTS
        let if_not_exists =
            self.match_keywords(&[TokenType::If, TokenType::Not, TokenType::Exists]);

        let is_special_modifier = matches!(
            table_modifier,
            Some(
                "DYNAMIC"
                    | "ICEBERG"
                    | "EXTERNAL"
                    | "HYBRID"
                    | "UNLOGGED"
                    | "DICTIONARY"
                    | "MATERIALIZED"
            )
        ) || (table_modifier.is_some()
            && matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::Teradata)
            ));
        let is_clickhouse = matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        );

        // Parse table name
        let name = self.parse_table_ref()?;

        // ClickHouse: UUID 'xxx' clause after table name
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) && self.check_identifier("UUID")
        {
            self.advance(); // consume UUID
            let _ = self.advance(); // consume UUID string value
        }

        // ClickHouse: ON CLUSTER clause
        let on_cluster = self.parse_on_cluster_clause()?;

        // Teradata: options after name before column list
        let teradata_post_name_options = if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::Teradata)
        ) {
            self.parse_teradata_post_name_options()
        } else {
            Vec::new()
        };

        // Handle PARTITION OF parent_table [(column_defs)] [FOR VALUES spec | DEFAULT] [PARTITION BY ...]
        if self.match_keywords(&[TokenType::Partition, TokenType::Of]) {
            return self.parse_create_table_partition_of(
                name,
                if_not_exists,
                temporary,
                or_replace,
                table_modifier,
                leading_comments,
            );
        }

        // ClickHouse: EMPTY AS source_table — create empty table from source
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) && self.check_identifier("EMPTY")
        {
            if self.check_next(TokenType::As) {
                self.advance(); // consume EMPTY
                self.advance(); // consume AS
                                // Consume rest as Command
                let start = self.current;
                while !self.is_at_end() && !self.check(TokenType::Semicolon) {
                    self.advance();
                }
                let rest_sql = self.tokens_to_sql(start, self.current);
                let mut prefix = String::from("CREATE TABLE");
                if if_not_exists {
                    prefix.push_str(" IF NOT EXISTS");
                }
                prefix.push(' ');
                prefix.push_str(&name.name.name);
                prefix.push_str(" EMPTY AS ");
                prefix.push_str(&rest_sql);
                return Ok(Expression::Raw(Raw { sql: prefix }));
            }
        }

        // Handle [SHALLOW | DEEP] CLONE source_table [AT(...) | BEFORE(...)]
        // Databricks/Delta Lake uses SHALLOW CLONE / DEEP CLONE
        // Snowflake uses just CLONE (which is equivalent to DEEP CLONE)
        let shallow_clone = self.check_identifier("SHALLOW");
        let deep_clone = self.check_identifier("DEEP");
        if shallow_clone || deep_clone {
            self.advance(); // consume SHALLOW or DEEP
        }
        // Also handle COPY (BigQuery: CREATE TABLE ... COPY source_table)
        // But NOT "COPY GRANTS" which is a Snowflake property
        let is_copy = self.check(TokenType::Copy) && !self.check_next_identifier("GRANTS");
        if self.check_identifier("CLONE") || is_copy {
            self.advance(); // consume CLONE or COPY
                            // ClickHouse: CLONE AS source_table (AS is part of the syntax, not an alias)
            if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) {
                let _ = self.match_token(TokenType::As);
            }
            let source = self.parse_table_ref()?;
            // Parse optional AT or BEFORE time travel clause
            // Note: BEFORE is a keyword token, AT is an identifier
            let at_clause = if self.match_identifier("AT") || self.match_token(TokenType::Before) {
                let keyword = self.previous().text.to_uppercase();
                self.expect(TokenType::LParen)?;
                // Parse the content: OFFSET => value or TIMESTAMP => value
                let mut result = format!("{} (", keyword);
                let mut prev_token_type: Option<TokenType> = None;
                let mut paren_depth = 1;
                while !self.is_at_end() && paren_depth > 0 {
                    let token = self.advance();
                    if token.token_type == TokenType::LParen {
                        paren_depth += 1;
                    } else if token.token_type == TokenType::RParen {
                        paren_depth -= 1;
                        if paren_depth == 0 {
                            break;
                        }
                    }
                    let needs_space = !result.ends_with('(')
                        && prev_token_type != Some(TokenType::Arrow)
                        && prev_token_type != Some(TokenType::Dash)
                        && prev_token_type != Some(TokenType::LParen)
                        && prev_token_type != Some(TokenType::Comma) // comma already adds trailing space
                        && token.token_type != TokenType::LParen; // no space before (
                    if needs_space
                        && token.token_type != TokenType::RParen
                        && token.token_type != TokenType::Comma
                    {
                        result.push(' ');
                    }
                    // Properly quote string literals
                    if token.token_type == TokenType::String {
                        result.push('\'');
                        result.push_str(&token.text.replace('\'', "''"));
                        result.push('\'');
                    } else {
                        result.push_str(&token.text);
                    }
                    if token.token_type == TokenType::Arrow || token.token_type == TokenType::Comma
                    {
                        result.push(' ');
                    }
                    prev_token_type = Some(token.token_type);
                }
                result.push(')');
                Some(Expression::Raw(Raw { sql: result }))
            } else {
                None
            };
            // Return the CLONE table immediately
            return Ok(Expression::CreateTable(Box::new(CreateTable {
                name,
                on_cluster: on_cluster.clone(),
                columns: Vec::new(),
                constraints: Vec::new(),
                if_not_exists,
                temporary,
                or_replace,
                table_modifier: table_modifier.map(|s| s.to_string()),
                as_select: None,
                as_select_parenthesized: false,
                on_commit: None,
                clone_source: Some(source),
                clone_at_clause: at_clause,
                shallow_clone,
                is_copy,
                leading_comments,
                with_properties: Vec::new(),
                teradata_post_name_options: teradata_post_name_options.clone(),
                with_data: None,
                with_statistics: None,
                teradata_indexes: Vec::new(),
                with_cte: None,
                properties: Vec::new(),
                partition_of: None,
                post_table_properties: Vec::new(),
                mysql_table_options: Vec::new(),
                inherits: Vec::new(),
                on_property: None,
                copy_grants: false,
                using_template: None,
                rollup: None,
            })));
        }

        // Handle WITH properties before columns/AS (e.g., CREATE TABLE z WITH (FORMAT='parquet') AS SELECT 1)
        let with_properties = if self.match_token(TokenType::With) {
            self.parse_with_properties()?
        } else {
            Vec::new()
        };

        // Snowflake: COPY GRANTS clause (before column list or AS)
        let copy_grants = self.match_text_seq(&["COPY", "GRANTS"]);

        // Snowflake: USING TEMPLATE (expr) - allows schema inference from a query
        let using_template = if self.match_text_seq(&["USING", "TEMPLATE"]) {
            Some(Box::new(self.parse_primary()?))
        } else {
            None
        };

        // If we have USING TEMPLATE, return early since it replaces AS SELECT
        if using_template.is_some() {
            return Ok(Expression::CreateTable(Box::new(CreateTable {
                name,
                on_cluster: on_cluster.clone(),
                columns: Vec::new(),
                constraints: Vec::new(),
                if_not_exists,
                temporary,
                or_replace,
                table_modifier: table_modifier.map(|s| s.to_string()),
                as_select: None,
                as_select_parenthesized: false,
                on_commit: None,
                clone_source: None,
                clone_at_clause: None,
                shallow_clone: false,
                is_copy: false,
                leading_comments,
                with_properties,
                teradata_post_name_options: teradata_post_name_options.clone(),
                with_data: None,
                with_statistics: None,
                teradata_indexes: Vec::new(),
                with_cte: None,
                properties: Vec::new(),
                partition_of: None,
                post_table_properties: Vec::new(),
                mysql_table_options: Vec::new(),
                inherits: Vec::new(),
                on_property: None,
                copy_grants,
                using_template,
                rollup: None,
            })));
        }

        // Redshift: Parse DISTKEY, SORTKEY, DISTSTYLE, BACKUP before AS SELECT (CTAS without columns)
        // This handles: CREATE TABLE t BACKUP YES|NO AS SELECT ...
        let mut redshift_ctas_properties: Vec<Expression> = Vec::new();
        loop {
            if self.match_identifier("DISTKEY") {
                // DISTKEY(column)
                if self.match_token(TokenType::LParen) {
                    let col = self.expect_identifier()?;
                    self.expect(TokenType::RParen)?;
                    redshift_ctas_properties.push(Expression::DistKeyProperty(Box::new(
                        DistKeyProperty {
                            this: Box::new(Expression::Column(Column {
                                name: Identifier::new(col),
                                table: None,
                                join_mark: false,
                                trailing_comments: Vec::new(),
                                span: None,
                                inferred_type: None,
                            })),
                        },
                    )));
                }
            } else if self.check_identifier("COMPOUND") || self.check_identifier("INTERLEAVED") {
                // COMPOUND SORTKEY(col, ...) or INTERLEAVED SORTKEY(col, ...)
                let modifier = self.advance().text.to_uppercase();
                if self.match_identifier("SORTKEY") && self.match_token(TokenType::LParen) {
                    let mut cols = Vec::new();
                    loop {
                        let col = self.expect_identifier()?;
                        cols.push(Expression::Column(Column {
                            name: Identifier::new(col),
                            table: None,
                            join_mark: false,
                            trailing_comments: Vec::new(),
                            span: None,
                            inferred_type: None,
                        }));
                        if !self.match_token(TokenType::Comma) {
                            break;
                        }
                    }
                    self.expect(TokenType::RParen)?;
                    let compound_value = if modifier == "COMPOUND" {
                        Some(Box::new(Expression::Boolean(BooleanLiteral {
                            value: true,
                        })))
                    } else {
                        None
                    };
                    redshift_ctas_properties.push(Expression::SortKeyProperty(Box::new(
                        SortKeyProperty {
                            this: Box::new(Expression::Tuple(Box::new(Tuple {
                                expressions: cols,
                            }))),
                            compound: compound_value,
                        },
                    )));
                }
            } else if self.match_identifier("SORTKEY") {
                // SORTKEY(column, ...)
                if self.match_token(TokenType::LParen) {
                    let mut cols = Vec::new();
                    loop {
                        let col = self.expect_identifier()?;
                        cols.push(Expression::Column(Column {
                            name: Identifier::new(col),
                            table: None,
                            join_mark: false,
                            trailing_comments: Vec::new(),
                            span: None,
                            inferred_type: None,
                        }));
                        if !self.match_token(TokenType::Comma) {
                            break;
                        }
                    }
                    self.expect(TokenType::RParen)?;
                    redshift_ctas_properties.push(Expression::SortKeyProperty(Box::new(
                        SortKeyProperty {
                            this: Box::new(Expression::Tuple(Box::new(Tuple {
                                expressions: cols,
                            }))),
                            compound: None,
                        },
                    )));
                }
            } else if self.match_identifier("DISTSTYLE") {
                // DISTSTYLE ALL|EVEN|AUTO|KEY
                if self.match_texts(&["ALL", "EVEN", "AUTO", "KEY"]) {
                    let style = self.previous().text.to_uppercase();
                    redshift_ctas_properties.push(Expression::DistStyleProperty(Box::new(
                        DistStyleProperty {
                            this: Box::new(Expression::Var(Box::new(Var { this: style }))),
                        },
                    )));
                }
            } else if self.match_identifier("BACKUP") {
                // BACKUP YES|NO
                if self.match_texts(&["YES", "NO"]) {
                    let value = self.previous().text.to_uppercase();
                    redshift_ctas_properties.push(Expression::BackupProperty(Box::new(
                        BackupProperty {
                            this: Box::new(Expression::Var(Box::new(Var { this: value }))),
                        },
                    )));
                }
            } else {
                break;
            }
        }

        // Check for AS SELECT (CTAS)
        if self.match_token(TokenType::As) {
            // ClickHouse: CREATE TABLE t AS other_table [ENGINE = ...] — copy structure from another table
            // Also: CREATE TABLE t AS func_name(args...) — table from function (e.g., remote, merge)
            // Detect when AS is followed by an identifier (not SELECT/WITH/LParen)
            if is_clickhouse
                && !self.check(TokenType::Select)
                && !self.check(TokenType::With)
                && !self.check(TokenType::LParen)
                && (self.is_identifier_token() || self.is_safe_keyword_as_identifier())
            {
                // Check if this is AS func_name(...) — table function
                let is_table_func = self.current + 1 < self.tokens.len()
                    && self.tokens[self.current + 1].token_type == TokenType::LParen;
                let source = if is_table_func {
                    // Parse as expression to consume function call with arguments
                    self.parse_primary()?;
                    let mut table_properties: Vec<Expression> = Vec::new();
                    self.parse_clickhouse_table_properties(&mut table_properties)?;
                    return Ok(Expression::CreateTable(Box::new(CreateTable {
                        name,
                        on_cluster: on_cluster.clone(),
                        columns: Vec::new(),
                        constraints: Vec::new(),
                        if_not_exists,
                        temporary,
                        or_replace,
                        table_modifier: table_modifier.map(|s| s.to_string()),
                        as_select: None,
                        as_select_parenthesized: false,
                        on_commit: None,
                        clone_source: None,
                        clone_at_clause: None,
                        shallow_clone: false,
                        is_copy: false,
                        leading_comments,
                        with_properties,
                        teradata_post_name_options: teradata_post_name_options.clone(),
                        with_data: None,
                        with_statistics: None,
                        teradata_indexes: Vec::new(),
                        with_cte: None,
                        properties: table_properties,
                        partition_of: None,
                        post_table_properties: redshift_ctas_properties,
                        mysql_table_options: Vec::new(),
                        inherits: Vec::new(),
                        on_property: None,
                        copy_grants,
                        using_template: None,
                        rollup: None,
                    })));
                } else {
                    self.parse_table_ref()?
                };
                // Parse ClickHouse table properties after the source table
                let mut table_properties: Vec<Expression> = Vec::new();
                self.parse_clickhouse_table_properties(&mut table_properties)?;
                return Ok(Expression::CreateTable(Box::new(CreateTable {
                    name,
                    on_cluster: on_cluster.clone(),
                    columns: Vec::new(),
                    constraints: Vec::new(),
                    if_not_exists,
                    temporary,
                    or_replace,
                    table_modifier: table_modifier.map(|s| s.to_string()),
                    as_select: None,
                    as_select_parenthesized: false,
                    on_commit: None,
                    clone_source: Some(source),
                    clone_at_clause: None,
                    shallow_clone: false,
                    is_copy: false,
                    leading_comments,
                    with_properties,
                    teradata_post_name_options: teradata_post_name_options.clone(),
                    with_data: None,
                    with_statistics: None,
                    teradata_indexes: Vec::new(),
                    with_cte: None,
                    properties: table_properties,
                    partition_of: None,
                    post_table_properties: redshift_ctas_properties,
                    mysql_table_options: Vec::new(),
                    inherits: Vec::new(),
                    on_property: None,
                    copy_grants,
                    using_template: None,
                    rollup: None,
                })));
            }

            // The query can be:
            // - SELECT ... (simple case)
            // - (SELECT 1) UNION ALL (SELECT 2) (set operations)
            // - (WITH cte AS (SELECT 1) SELECT * FROM cte) (CTE in parens)
            let mut as_select_parenthesized = self.check(TokenType::LParen);
            let query = if as_select_parenthesized {
                // Parenthesized query - parse as expression which handles subqueries
                // Note: parse_primary will consume set operations like UNION internally
                let subquery = self.parse_primary()?;
                // If parse_primary returned a set operation, the outer parens weren't wrapping
                // the entire expression - they were part of the operands
                if matches!(
                    &subquery,
                    Expression::Union(_) | Expression::Intersect(_) | Expression::Except(_)
                ) {
                    as_select_parenthesized = false;
                    subquery
                } else {
                    // Just a parenthesized query without set ops
                    // Keep the Subquery wrapper if it has limit/offset/order_by
                    if let Expression::Subquery(ref sq) = subquery {
                        if sq.limit.is_some() || sq.offset.is_some() || sq.order_by.is_some() {
                            // Keep the Subquery to preserve the modifiers
                            subquery
                        } else {
                            // Extract the inner query
                            if let Expression::Subquery(sq) = subquery {
                                sq.this
                            } else {
                                subquery
                            }
                        }
                    } else if let Expression::Paren(p) = subquery {
                        p.this
                    } else {
                        subquery
                    }
                }
            } else if self.check(TokenType::With) {
                // Handle WITH ... SELECT ...
                self.parse_statement()?
            } else {
                self.parse_select()?
            };

            // Parse any trailing Teradata options like "WITH DATA", "NO PRIMARY INDEX", etc.
            let (with_data, with_statistics, teradata_indexes) =
                self.parse_teradata_table_options();
            let on_commit = if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::Teradata)
            ) && self.check(TokenType::On)
                && self.check_next(TokenType::Commit)
            {
                self.advance(); // ON
                self.advance(); // COMMIT
                if self.match_keywords(&[TokenType::Preserve, TokenType::Rows]) {
                    Some(OnCommit::PreserveRows)
                } else if self.match_keywords(&[TokenType::Delete, TokenType::Rows]) {
                    Some(OnCommit::DeleteRows)
                } else {
                    return Err(
                        self.parse_error("Expected PRESERVE ROWS or DELETE ROWS after ON COMMIT")
                    );
                }
            } else {
                None
            };

            return Ok(Expression::CreateTable(Box::new(CreateTable {
                name,
                on_cluster: on_cluster.clone(),
                columns: Vec::new(),
                constraints: Vec::new(),
                if_not_exists,
                temporary,
                or_replace,
                table_modifier: table_modifier.map(|s| s.to_string()),
                as_select: Some(query),
                as_select_parenthesized,
                on_commit,
                clone_source: None,
                clone_at_clause: None,
                shallow_clone: false,
                is_copy: false,
                leading_comments,
                with_properties,
                teradata_post_name_options: teradata_post_name_options.clone(),
                with_data,
                with_statistics,
                teradata_indexes,
                with_cte: None,
                properties: Vec::new(),
                partition_of: None,
                post_table_properties: redshift_ctas_properties,
                mysql_table_options: Vec::new(),
                inherits: Vec::new(),
                on_property: None,
                copy_grants,
                using_template: None,
                rollup: None,
            })));
        }

        // ClickHouse: allow table properties/AS SELECT without a column list
        if is_clickhouse && !self.check(TokenType::LParen) {
            let starts_props = self.check_identifier("ENGINE")
                || self.check(TokenType::Order)
                || self.check(TokenType::Sample)
                || self.check(TokenType::Settings)
                || self.check(TokenType::Comment)
                || self.check(TokenType::As);

            if starts_props {
                let mut table_properties: Vec<Expression> = Vec::new();
                self.parse_clickhouse_table_properties(&mut table_properties)?;

                let as_select = if self.match_token(TokenType::As) {
                    Some(self.parse_statement()?)
                } else {
                    None
                };
                let as_select_parenthesized = as_select.is_some();

                if as_select.is_some() {
                    self.parse_clickhouse_table_properties(&mut table_properties)?;
                }

                return Ok(Expression::CreateTable(Box::new(CreateTable {
                    name,
                    on_cluster: on_cluster.clone(),
                    columns: Vec::new(),
                    constraints: Vec::new(),
                    if_not_exists,
                    temporary,
                    or_replace,
                    table_modifier: table_modifier.map(|s| s.to_string()),
                    as_select,
                    as_select_parenthesized,
                    on_commit: None,
                    clone_source: None,
                    clone_at_clause: None,
                    shallow_clone: false,
                    is_copy: false,
                    leading_comments,
                    with_properties,
                    teradata_post_name_options: teradata_post_name_options.clone(),
                    with_data: None,
                    with_statistics: None,
                    teradata_indexes: Vec::new(),
                    with_cte: None,
                    properties: table_properties,
                    partition_of: None,
                    post_table_properties: Vec::new(),
                    mysql_table_options: Vec::new(),
                    inherits: Vec::new(),
                    on_property: None,
                    copy_grants,
                    using_template: None,
                    rollup: None,
                })));
            }
        }

        // For DYNAMIC/ICEBERG/EXTERNAL tables, columns might be optional (use AS SELECT or other syntax)
        // Check if we have a left paren for columns or if we're going straight to options
        if !self.check(TokenType::LParen) && is_special_modifier {
            // No columns - parse options and AS SELECT
            let mut extra_options = Vec::new();
            // Parse key=value options until AS or end
            // Note: WAREHOUSE is a keyword token type, so check for it explicitly
            while !self.is_at_end()
                && !self.check(TokenType::As)
                && !self.check(TokenType::Semicolon)
            {
                if self.is_identifier_token()
                    || self.is_safe_keyword_as_identifier()
                    || self.check(TokenType::Warehouse)
                {
                    let key = self.advance().text;
                    if self.match_token(TokenType::Eq) {
                        // Capture value
                        let value = if self.check(TokenType::String) {
                            let v = format!("'{}'", self.peek().text);
                            self.advance();
                            v
                        } else if self.is_identifier_token() || self.is_safe_keyword_as_identifier()
                        {
                            self.advance().text
                        } else {
                            break;
                        };
                        extra_options.push((key, value));
                    } else {
                        // Just a keyword without value (like WAREHOUSE mywh)
                        if self.is_identifier_token() || self.is_safe_keyword_as_identifier() {
                            let value = self.advance().text;
                            extra_options.push((key, value));
                        }
                    }
                } else {
                    break;
                }
            }
            // Check for AS SELECT
            let as_select = if self.match_token(TokenType::As) {
                Some(self.parse_statement()?)
            } else {
                None
            };
            return Ok(Expression::CreateTable(Box::new(CreateTable {
                name,
                on_cluster: on_cluster.clone(),
                columns: Vec::new(),
                constraints: Vec::new(),
                if_not_exists,
                temporary,
                or_replace,
                table_modifier: table_modifier.map(|s| s.to_string()),
                as_select,
                as_select_parenthesized: false,
                on_commit: None,
                clone_source: None,
                clone_at_clause: None,
                shallow_clone: false,
                is_copy: false,
                leading_comments,
                with_properties: extra_options,
                teradata_post_name_options: teradata_post_name_options.clone(),
                with_data: None,
                with_statistics: None,
                teradata_indexes: Vec::new(),
                with_cte: None,
                properties: Vec::new(),
                partition_of: None,
                post_table_properties: Vec::new(),
                mysql_table_options: Vec::new(),
                inherits: Vec::new(),
                on_property: None,
                copy_grants,
                using_template: None,
                rollup: None,
            })));
        }

        // MySQL: CREATE TABLE A LIKE B (without parentheses)
        if self.check(TokenType::Like) {
            self.advance(); // consume LIKE
            let source_ref = self.parse_table_ref()?;
            return Ok(Expression::CreateTable(Box::new(CreateTable {
                name,
                on_cluster: on_cluster.clone(),
                columns: Vec::new(),
                constraints: vec![TableConstraint::Like {
                    source: source_ref,
                    options: Vec::new(),
                }],
                if_not_exists,
                temporary,
                or_replace,
                table_modifier: table_modifier.map(|s| s.to_string()),
                as_select: None,
                as_select_parenthesized: false,
                on_commit: None,
                clone_source: None,
                clone_at_clause: None,
                shallow_clone: false,
                is_copy: false,
                leading_comments,
                with_properties,
                teradata_post_name_options: teradata_post_name_options.clone(),
                with_data: None,
                with_statistics: None,
                teradata_indexes: Vec::new(),
                with_cte: None,
                properties: Vec::new(),
                partition_of: None,
                post_table_properties: Vec::new(),
                mysql_table_options: Vec::new(),
                inherits: Vec::new(),
                on_property: None,
                copy_grants,
                using_template: None,
                rollup: None,
            })));
        }

        // Snowflake: CREATE TABLE a TAG (key='value', ...) without column definitions
        if self.match_keyword("TAG")
            || (self.match_token(TokenType::With) && self.match_keyword("TAG"))
        {
            let tags = self.parse_tags()?;
            return Ok(Expression::CreateTable(Box::new(CreateTable {
                name,
                on_cluster: on_cluster.clone(),
                columns: Vec::new(),
                constraints: vec![TableConstraint::Tags(tags)],
                if_not_exists,
                temporary,
                or_replace,
                table_modifier: table_modifier.map(|s| s.to_string()),
                as_select: None,
                as_select_parenthesized: false,
                on_commit: None,
                clone_source: None,
                clone_at_clause: None,
                shallow_clone: false,
                is_copy: false,
                leading_comments,
                with_properties,
                teradata_post_name_options: teradata_post_name_options.clone(),
                with_data: None,
                with_statistics: None,
                teradata_indexes: Vec::new(),
                with_cte: None,
                properties: Vec::new(),
                partition_of: None,
                post_table_properties: Vec::new(),
                mysql_table_options: Vec::new(),
                inherits: Vec::new(),
                on_property: None,
                copy_grants,
                using_template: None,
                rollup: None,
            })));
        }

        // Hive/Spark/Databricks: CREATE TABLE t TBLPROPERTIES (...) without column definitions
        // Check for Hive-style table properties before expecting column definitions
        if self.check_identifier("TBLPROPERTIES")
            || self.check_identifier("LOCATION")
            || self.check_identifier("STORED")
            || self.check(TokenType::Row)
            || self.check(TokenType::Using)
            || self.check_identifier("CLUSTERED")
            || self.check_identifier("PARTITIONED")
            || self.check_identifier("COMMENT")
        {
            // Parse Hive table properties without column definitions
            let hive_properties = self.parse_hive_table_properties()?;

            // Check for AS SELECT (CTAS) after properties
            let as_select = if self.match_token(TokenType::As) {
                Some(self.parse_statement()?)
            } else {
                None
            };

            return Ok(Expression::CreateTable(Box::new(CreateTable {
                name,
                on_cluster: on_cluster.clone(),
                columns: Vec::new(),
                constraints: Vec::new(),
                if_not_exists,
                temporary,
                or_replace,
                table_modifier: table_modifier.map(|s| s.to_string()),
                as_select,
                as_select_parenthesized: false,
                on_commit: None,
                clone_source: None,
                clone_at_clause: None,
                shallow_clone: false,
                is_copy: false,
                leading_comments,
                with_properties,
                teradata_post_name_options: teradata_post_name_options.clone(),
                with_data: None,
                with_statistics: None,
                teradata_indexes: Vec::new(),
                with_cte: None,
                properties: hive_properties,
                partition_of: None,
                post_table_properties: Vec::new(),
                mysql_table_options: Vec::new(),
                inherits: Vec::new(),
                on_property: None,
                copy_grants,
                using_template: None,
                rollup: None,
            })));
        }

        // Check if (SELECT ...) or (WITH ...) follows - this is CTAS without explicit AS keyword
        if self.check(TokenType::LParen) {
            let saved = self.current;
            self.advance(); // consume (
            let is_ctas = self.check(TokenType::Select) || self.check(TokenType::With);
            self.current = saved;
            if is_ctas {
                // Parse as subquery
                let subquery = self.parse_primary()?;
                let query = if let Expression::Subquery(sq) = subquery {
                    sq.this
                } else if let Expression::Paren(p) = subquery {
                    p.this
                } else {
                    subquery
                };
                return Ok(Expression::CreateTable(Box::new(CreateTable {
                    name,
                    on_cluster: on_cluster.clone(),
                    columns: Vec::new(),
                    constraints: Vec::new(),
                    if_not_exists,
                    temporary,
                    or_replace,
                    table_modifier: table_modifier.map(|s| s.to_string()),
                    as_select: Some(query),
                    as_select_parenthesized: true,
                    on_commit: None,
                    clone_source: None,
                    clone_at_clause: None,
                    shallow_clone: false,
                    is_copy: false,
                    leading_comments,
                    with_properties,
                    teradata_post_name_options: teradata_post_name_options.clone(),
                    with_data: None,
                    with_statistics: None,
                    teradata_indexes: Vec::new(),
                    with_cte: None,
                    properties: Vec::new(),
                    partition_of: None,
                    post_table_properties: Vec::new(),
                    mysql_table_options: Vec::new(),
                    inherits: Vec::new(),
                    on_property: None,
                    copy_grants,
                    using_template: None,
                    rollup: None,
                })));
            }
        }

        // BigQuery (and others): CREATE TABLE t PARTITION BY ... CLUSTER BY ... OPTIONS(...) AS (SELECT ...)
        // When there are no column definitions, skip straight to property/AS parsing
        let no_column_defs = !self.check(TokenType::LParen)
            && (self.check(TokenType::Partition)
                || self.check(TokenType::PartitionBy)
                || self.check(TokenType::Cluster)
                || self.check_identifier("OPTIONS")
                || self.check(TokenType::As));

        // Parse column definitions
        if !no_column_defs {
            self.expect(TokenType::LParen)?;
        }

        // For DYNAMIC TABLE, column list contains only names without types
        // e.g., CREATE DYNAMIC TABLE t (col1, col2, col3) TARGET_LAG=... AS SELECT ...
        let (columns, constraints) = if no_column_defs {
            (Vec::new(), Vec::new())
        } else if table_modifier == Some("DYNAMIC") {
            // Check if this looks like a simple column name list (just identifiers separated by commas)
            // by peeking ahead - if next token after identifier is comma or rparen, it's a name-only list
            let saved = self.current;
            let is_name_only_list =
                if self.is_identifier_token() || self.is_safe_keyword_as_identifier() {
                    self.advance();
                    let result = self.check(TokenType::Comma) || self.check(TokenType::RParen);
                    self.current = saved;
                    result
                } else {
                    false
                };

            if is_name_only_list {
                // Parse column names without types
                let mut cols = Vec::new();
                loop {
                    let name = self.expect_identifier_or_safe_keyword_with_quoted()?;
                    // Create a column def with an empty/placeholder type
                    let mut col_def = ColumnDef::new(
                        name.name.clone(),
                        DataType::Custom {
                            name: String::new(),
                        },
                    );
                    col_def.name = name;
                    cols.push(col_def);
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
                (cols, Vec::new())
            } else {
                // Regular column definitions with types
                self.parse_column_definitions()?
            }
        } else {
            self.parse_column_definitions()?
        };

        if !no_column_defs {
            self.expect(TokenType::RParen)?;
        }

        // Parse COMMENT before WITH properties (Presto: CREATE TABLE x (...) COMMENT 'text' WITH (...))
        let pre_with_comment = if self.check(TokenType::Comment) {
            let saved = self.current;
            self.advance(); // consume COMMENT
            if self.check(TokenType::String) {
                let comment_text = self.advance().text.clone();
                Some(comment_text)
            } else {
                self.current = saved;
                None
            }
        } else {
            None
        };

        // Handle WITH properties after columns (e.g., CREATE TABLE z (z INT) WITH (...))
        // But skip if this is WITH(SYSTEM_VERSIONING=...) which is handled by parse_post_table_properties
        let with_properties_after = if self.check(TokenType::With) {
            // Lookahead: check if this is WITH(SYSTEM_VERSIONING=...)
            let saved = self.current;
            self.advance(); // consume WITH
            let is_system_versioning = if self.check(TokenType::LParen) {
                let saved2 = self.current;
                self.advance(); // consume (
                let result = self.check_identifier("SYSTEM_VERSIONING");
                self.current = saved2; // retreat to before (
                result
            } else {
                false
            };
            if is_system_versioning {
                // Retreat back before WITH, let parse_post_table_properties handle it
                self.current = saved;
                Vec::new()
            } else {
                // Normal WITH properties parsing
                self.parse_with_properties()?
            }
        } else {
            Vec::new()
        };

        // Combine properties from before and after columns
        let mut all_with_properties = with_properties;
        all_with_properties.extend(with_properties_after);

        // For DYNAMIC/ICEBERG/EXTERNAL tables with columns, parse Snowflake-specific options
        // like TARGET_LAG, WAREHOUSE, CATALOG, EXTERNAL_VOLUME, LOCATION etc.
        if is_special_modifier {
            while !self.is_at_end()
                && !self.check(TokenType::As)
                && !self.check(TokenType::Semicolon)
            {
                // Check for known Snowflake table options (WAREHOUSE is a keyword, others are identifiers)
                // These are Snowflake-style options that use KEY=VALUE or KEY VALUE (without =)
                // Hive-style LOCATION/TBLPROPERTIES (without =) should NOT be matched here
                let is_snowflake_option = self.check(TokenType::Warehouse)
                    || self.check_identifier("TARGET_LAG")
                    || self.check_identifier("CATALOG")
                    || self.check_identifier("EXTERNAL_VOLUME")
                    || self.check_identifier("BASE_LOCATION")
                    || self.check_identifier("REFRESH_MODE")
                    || self.check_identifier("INITIALIZE")
                    || self.check_identifier("DATA_RETENTION_TIME_IN_DAYS")
                    || self.check_identifier("LOCATION")
                    || self.check_identifier("PARTITION")
                    || self.check_identifier("FILE_FORMAT")
                    || self.check_identifier("AUTO_REFRESH");
                if is_snowflake_option {
                    // Save position before consuming key - we might need to retreat for Hive-style syntax
                    let saved = self.current;
                    let key = self.advance().text;
                    if self.match_token(TokenType::Eq) {
                        // Capture value - could be string, identifier, stage path @..., keyword, or parenthesized options
                        let value = if self.check(TokenType::LParen) {
                            // Parenthesized option list like file_format = (type = parquet compression = gzip)
                            self.advance(); // consume (
                            let mut options = String::from("(");
                            let mut depth = 1;
                            while !self.is_at_end() && depth > 0 {
                                let tok = self.advance();
                                if tok.token_type == TokenType::LParen {
                                    depth += 1;
                                } else if tok.token_type == TokenType::RParen {
                                    depth -= 1;
                                }
                                // Add space before tokens that need it (not after open paren, not before close paren)
                                if !options.ends_with('(')
                                    && !options.ends_with(' ')
                                    && tok.token_type != TokenType::RParen
                                {
                                    options.push(' ');
                                }
                                options.push_str(&tok.text);
                            }
                            options
                        } else if self.check(TokenType::String) {
                            let v = format!("'{}'", self.peek().text);
                            self.advance();
                            v
                        } else if self.check(TokenType::DAt) {
                            // Stage path like @s1/logs/
                            self.advance(); // consume @
                            let mut path = String::from("@");
                            if self.is_identifier_token() || self.is_safe_keyword_as_identifier() {
                                path.push_str(&self.advance().text);
                            }
                            // Parse path segments, but stop before Snowflake option keywords
                            while self.check(TokenType::Slash) {
                                // Peek ahead to see if next identifier is a Snowflake option keyword
                                if self.current + 1 < self.tokens.len() {
                                    let next = &self.tokens[self.current + 1];
                                    let next_text_upper = next.text.to_uppercase();
                                    if next_text_upper == "FILE_FORMAT"
                                        || next_text_upper == "PARTITION_TYPE"
                                        || next_text_upper == "AUTO_REFRESH"
                                        || next_text_upper == "LOCATION"
                                        || next_text_upper == "PARTITION"
                                        || next_text_upper == "WAREHOUSE"
                                    {
                                        // Consume the trailing slash before the keyword
                                        self.advance();
                                        path.push('/');
                                        break;
                                    }
                                }
                                self.advance();
                                path.push('/');
                                if self.is_identifier_token()
                                    || self.is_safe_keyword_as_identifier()
                                {
                                    path.push_str(&self.advance().text);
                                }
                            }
                            path
                        } else if self.check(TokenType::Var) && self.peek().text.starts_with('@') {
                            // Stage path tokenized as Var (e.g., @s2/logs/)
                            // When @ is followed by alphanumeric, tokenizer creates a Var token
                            let mut path = self.advance().text;
                            // Parse path segments, but stop before Snowflake option keywords
                            while self.check(TokenType::Slash) {
                                // Peek ahead to see if next identifier is a Snowflake option keyword
                                if self.current + 1 < self.tokens.len() {
                                    let next = &self.tokens[self.current + 1];
                                    let next_text_upper = next.text.to_uppercase();
                                    if next_text_upper == "FILE_FORMAT"
                                        || next_text_upper == "PARTITION_TYPE"
                                        || next_text_upper == "AUTO_REFRESH"
                                        || next_text_upper == "LOCATION"
                                        || next_text_upper == "PARTITION"
                                        || next_text_upper == "WAREHOUSE"
                                    {
                                        // Consume the trailing slash before the keyword
                                        self.advance();
                                        path.push('/');
                                        break;
                                    }
                                }
                                self.advance();
                                path.push('/');
                                if self.is_identifier_token()
                                    || self.is_safe_keyword_as_identifier()
                                {
                                    path.push_str(&self.advance().text);
                                }
                            }
                            path
                        } else if self.check(TokenType::Warehouse) {
                            self.advance().text
                        } else if self.is_identifier_token() || self.is_safe_keyword_as_identifier()
                        {
                            self.advance().text
                        } else {
                            // No valid value after =, retreat and let Hive parsing try
                            self.current = saved;
                            break;
                        };
                        all_with_properties.push((key, value));
                    } else if self.is_identifier_token()
                        || self.is_safe_keyword_as_identifier()
                        || self.check(TokenType::Warehouse)
                    {
                        // WAREHOUSE mywh (without =)
                        let value = self.advance().text;
                        all_with_properties.push((key, value));
                    } else {
                        // Not a Snowflake-style option (e.g., Hive LOCATION 'path' without =)
                        // Retreat and let Hive parsing try
                        self.current = saved;
                        break;
                    }
                } else {
                    break;
                }
            }
        }

        // Parse MySQL table options: ENGINE=val, AUTO_INCREMENT=val, DEFAULT CHARSET=val, etc.
        let mysql_table_options = if is_clickhouse {
            Vec::new()
        } else {
            self.parse_mysql_table_options()
        };

        // Parse StarRocks ROLLUP property: ROLLUP (r1(col1, col2), r2(col1))
        let rollup = if self.match_token(TokenType::Rollup) {
            self.expect(TokenType::LParen)?;
            let mut indices = Vec::new();
            loop {
                let name = self.expect_identifier_or_keyword_with_quoted()?;
                let cols = if self.match_token(TokenType::LParen) {
                    let mut col_list = Vec::new();
                    loop {
                        col_list.push(self.expect_identifier_or_keyword_with_quoted()?);
                        if !self.match_token(TokenType::Comma) {
                            break;
                        }
                    }
                    self.expect(TokenType::RParen)?;
                    col_list
                } else {
                    Vec::new()
                };
                indices.push(crate::expressions::RollupIndex {
                    name,
                    expressions: cols,
                });
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            self.expect(TokenType::RParen)?;
            Some(crate::expressions::RollupProperty {
                expressions: indices,
            })
        } else {
            None
        };

        // Parse Hive table properties: ROW FORMAT, STORED AS/BY, LOCATION, TBLPROPERTIES
        let hive_properties = self.parse_hive_table_properties()?;
        let is_teradata = matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::Teradata)
        );

        // Handle ON COMMIT PRESERVE ROWS or ON COMMIT DELETE ROWS
        // Also handle TSQL ON filegroup or ON filegroup (partition_column)
        let (mut on_commit, on_property) = if is_teradata {
            (None, None)
        } else if self.match_token(TokenType::On) {
            if self.match_token(TokenType::Commit) {
                if self.match_keywords(&[TokenType::Preserve, TokenType::Rows]) {
                    (Some(OnCommit::PreserveRows), None)
                } else if self.match_keywords(&[TokenType::Delete, TokenType::Rows]) {
                    (Some(OnCommit::DeleteRows), None)
                } else {
                    return Err(
                        self.parse_error("Expected PRESERVE ROWS or DELETE ROWS after ON COMMIT")
                    );
                }
            } else {
                // TSQL: ON filegroup or ON filegroup (partition_column)
                // Parse filegroup name as schema which allows filegroup(column) syntax
                let filegroup = self.parse_schema_identifier()?;
                (
                    None,
                    Some(OnProperty {
                        this: Box::new(filegroup),
                    }),
                )
            }
        } else {
            (None, None)
        };

        // Parse table properties like DEFAULT COLLATE (BigQuery)
        let mut table_properties = hive_properties;

        // If COMMENT was found before WITH, add it to table_properties as SchemaCommentProperty
        if let Some(comment_text) = pre_with_comment {
            table_properties.push(Expression::SchemaCommentProperty(Box::new(
                SchemaCommentProperty {
                    this: Box::new(Expression::Literal(Literal::String(comment_text))),
                },
            )));
        }

        if self.match_token(TokenType::Default) && self.match_token(TokenType::Collate) {
            let collation = self.parse_primary()?;
            table_properties.push(Expression::CollateProperty(Box::new(CollateProperty {
                this: Box::new(collation),
                default: Some(Box::new(Expression::Boolean(BooleanLiteral {
                    value: true,
                }))),
            })));
        }

        // BigQuery: OPTIONS (key=value, ...) on table - comes after column definitions
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::BigQuery)
        ) {
            if let Some(options_property) = self.parse_bigquery_options_property()? {
                table_properties.push(options_property);
            }
        } else if self.match_identifier("OPTIONS") {
            let options = self.parse_options_list()?;
            table_properties.push(Expression::Properties(Box::new(Properties {
                expressions: options,
            })));
        }

        // Doris/StarRocks: PROPERTIES ('key'='value', ...) - comes after column definitions
        let is_doris_starrocks = matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::Doris)
                | Some(crate::dialects::DialectType::StarRocks)
        );
        if is_doris_starrocks && self.match_identifier("PROPERTIES") {
            // Use parse_options_list which handles 'key'='value' format
            let props = self.parse_options_list()?;
            if !props.is_empty() {
                table_properties.push(Expression::Properties(Box::new(Properties {
                    expressions: props,
                })));
            }
        }

        // Redshift: Parse DISTKEY, SORTKEY, DISTSTYLE, BACKUP after column definitions
        // These can appear in any order and multiple times
        loop {
            if self.match_identifier("DISTKEY") {
                // DISTKEY(column)
                if let Some(distkey) = self.parse_distkey()? {
                    table_properties.push(distkey);
                }
            } else if self.match_text_seq(&["COMPOUND", "SORTKEY"]) {
                // COMPOUND SORTKEY(col1, col2, ...)
                if let Some(sortkey) = self.parse_sortkey()? {
                    // Set compound flag
                    if let Expression::SortKeyProperty(mut skp) = sortkey {
                        skp.compound = Some(Box::new(Expression::Boolean(BooleanLiteral {
                            value: true,
                        })));
                        table_properties.push(Expression::SortKeyProperty(skp));
                    }
                }
            } else if self.match_identifier("SORTKEY") {
                // SORTKEY(col1, col2, ...)
                if let Some(sortkey) = self.parse_sortkey()? {
                    table_properties.push(sortkey);
                }
            } else if self.match_identifier("DISTSTYLE") {
                // DISTSTYLE ALL|EVEN|AUTO|KEY
                if self.match_texts(&["ALL", "EVEN", "AUTO", "KEY"]) {
                    let style = self.previous().text.to_uppercase();
                    table_properties.push(Expression::DistStyleProperty(Box::new(
                        DistStyleProperty {
                            this: Box::new(Expression::Var(Box::new(Var { this: style }))),
                        },
                    )));
                }
            } else if self.match_identifier("BACKUP") {
                // BACKUP YES|NO
                if self.match_texts(&["YES", "NO"]) {
                    let value = self.previous().text.to_uppercase();
                    table_properties.push(Expression::BackupProperty(Box::new(BackupProperty {
                        this: Box::new(Expression::Var(Box::new(Var { this: value }))),
                    })));
                }
            } else {
                break;
            }
        }

        // Teradata: PRIMARY/UNIQUE/INDEX and PARTITION BY clauses after columns
        if is_teradata {
            loop {
                // Consume optional comma separator between index specs (only if followed by an index keyword)
                if self.check(TokenType::Comma) {
                    let saved_comma = self.current;
                    self.advance(); // consume comma
                    let is_index_keyword = self.check(TokenType::Unique)
                        || self.check(TokenType::PrimaryKey)
                        || self.check(TokenType::Index)
                        || self.check(TokenType::No);
                    if !is_index_keyword {
                        self.current = saved_comma; // retreat
                    }
                }
                if self.match_token(TokenType::Unique) {
                    let primary = self.match_token(TokenType::PrimaryKey);
                    let amp = self.match_identifier("AMP");
                    self.match_token(TokenType::Index);
                    let params = if self.match_token(TokenType::LParen) {
                        let cols = self.parse_identifier_list()?;
                        self.expect(TokenType::RParen)?;
                        cols.into_iter()
                            .map(|id| {
                                Expression::Column(Column {
                                    name: id,
                                    table: None,
                                    join_mark: false,
                                    trailing_comments: Vec::new(),
                                    span: None,
                                    inferred_type: None,
                                })
                            })
                            .collect()
                    } else {
                        Vec::new()
                    };
                    table_properties.push(Expression::Index(Box::new(Index {
                        this: None,
                        table: None,
                        unique: true,
                        primary: if primary {
                            Some(Box::new(Expression::Boolean(BooleanLiteral {
                                value: true,
                            })))
                        } else {
                            None
                        },
                        amp: if amp {
                            Some(Box::new(Expression::Boolean(BooleanLiteral {
                                value: true,
                            })))
                        } else {
                            None
                        },
                        params,
                    })));
                    continue;
                }
                if self.match_token(TokenType::PrimaryKey) {
                    let amp = self.match_identifier("AMP");
                    self.match_token(TokenType::Index);
                    let params = if self.match_token(TokenType::LParen) {
                        let cols = self.parse_identifier_list()?;
                        self.expect(TokenType::RParen)?;
                        cols.into_iter()
                            .map(|id| {
                                Expression::Column(Column {
                                    name: id,
                                    table: None,
                                    join_mark: false,
                                    trailing_comments: Vec::new(),
                                    span: None,
                                    inferred_type: None,
                                })
                            })
                            .collect()
                    } else {
                        Vec::new()
                    };
                    table_properties.push(Expression::Index(Box::new(Index {
                        this: None,
                        table: None,
                        unique: false,
                        primary: Some(Box::new(Expression::Boolean(BooleanLiteral {
                            value: true,
                        }))),
                        amp: if amp {
                            Some(Box::new(Expression::Boolean(BooleanLiteral {
                                value: true,
                            })))
                        } else {
                            None
                        },
                        params,
                    })));
                    continue;
                }
                if self.match_token(TokenType::Index) {
                    let params = if self.match_token(TokenType::LParen) {
                        let cols = self.parse_identifier_list()?;
                        self.expect(TokenType::RParen)?;
                        cols.into_iter()
                            .map(|id| {
                                Expression::Column(Column {
                                    name: id,
                                    table: None,
                                    join_mark: false,
                                    trailing_comments: Vec::new(),
                                    span: None,
                                    inferred_type: None,
                                })
                            })
                            .collect()
                    } else {
                        Vec::new()
                    };
                    table_properties.push(Expression::Index(Box::new(Index {
                        this: None,
                        table: None,
                        unique: false,
                        primary: None,
                        amp: None,
                        params,
                    })));
                    continue;
                }
                if self.match_keywords(&[TokenType::Partition, TokenType::By]) {
                    let expr = self.parse_primary()?;
                    table_properties.push(Expression::PartitionedByProperty(Box::new(
                        PartitionedByProperty {
                            this: Box::new(expr),
                        },
                    )));
                    continue;
                }
                break;
            }

            if on_commit.is_none()
                && self.check(TokenType::On)
                && self.check_next(TokenType::Commit)
            {
                self.advance(); // ON
                self.advance(); // COMMIT
                if self.match_keywords(&[TokenType::Preserve, TokenType::Rows]) {
                    on_commit = Some(OnCommit::PreserveRows);
                } else if self.match_keywords(&[TokenType::Delete, TokenType::Rows]) {
                    on_commit = Some(OnCommit::DeleteRows);
                } else {
                    return Err(
                        self.parse_error("Expected PRESERVE ROWS or DELETE ROWS after ON COMMIT")
                    );
                }
            }
        }

        // ClickHouse: table properties after column definitions
        if is_clickhouse {
            self.parse_clickhouse_table_properties(&mut table_properties)?;
        }

        // ClickHouse: EMPTY AS SELECT
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) && self.match_identifier("EMPTY")
        {
            table_properties.push(Expression::Var(Box::new(Var {
                this: "EMPTY".to_string(),
            })));
        }

        // Handle AS SELECT after columns/WITH (CTAS with column definitions)
        // When there are no column definitions, AS comes after PARTITION BY/CLUSTER BY/OPTIONS
        let as_select = if !no_column_defs && self.match_token(TokenType::As) {
            Some(self.parse_statement()?)
        } else {
            None
        };

        if is_clickhouse && as_select.is_some() {
            self.parse_clickhouse_table_properties(&mut table_properties)?;
        }

        // Parse PARTITION BY RANGE/LIST/HASH(columns) for regular CREATE TABLE
        let is_bigquery = matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::BigQuery)
        );
        if !is_teradata && (self.check(TokenType::Partition) || self.check(TokenType::PartitionBy))
        {
            let parsed_bigquery_partition = if is_bigquery {
                if let Some(partition_property) = self.parse_bigquery_partition_by_property()? {
                    table_properties.push(partition_property);
                    true
                } else {
                    false
                }
            } else {
                false
            };

            if !parsed_bigquery_partition {
                let saved = self.current;
                let is_partition_by = if self.match_token(TokenType::PartitionBy) {
                    true
                } else if self.match_token(TokenType::Partition) {
                    self.match_token(TokenType::By)
                } else {
                    false
                };
                if is_partition_by {
                    let partition_kind = if self.check(TokenType::Range) {
                        self.advance();
                        Some("RANGE".to_string())
                    } else if self.check(TokenType::List) {
                        self.advance();
                        Some("LIST".to_string())
                    } else if (self.check(TokenType::Identifier) || self.check(TokenType::Var))
                        && self.check_next(TokenType::LParen)
                    {
                        // Only treat identifier as partition method (like HASH) if followed by (
                        Some(self.advance().text.to_uppercase())
                    } else {
                        // No explicit partition method (RANGE/LIST/HASH), just PARTITION BY (cols)
                        None
                    };

                    // StarRocks/Doris: PARTITION BY func(), col (bare expressions without RANGE/LIST)
                    // When the partition_kind was consumed as an identifier that's actually a function call
                    // and the content after the parenthesized args includes a comma, it's a bare expression list
                    if is_doris_starrocks
                        && partition_kind.is_some()
                        && !matches!(
                            partition_kind.as_deref(),
                            Some("RANGE") | Some("LIST") | Some("HASH") | Some("KEY")
                        )
                    {
                        // Backtrack: re-parse as bare PARTITION BY with comma-separated expressions
                        let func_name = partition_kind.unwrap();
                        let mut raw_sql = format!("PARTITION BY {}", func_name);
                        // Helper closure for consuming parenthesized content with proper spacing
                        fn consume_parens(parser: &mut Parser, raw_sql: &mut String) {
                            if !parser.check(TokenType::LParen) {
                                return;
                            }
                            parser.advance();
                            raw_sql.push('(');
                            let mut depth = 1;
                            let mut last_type: Option<TokenType> = None;
                            while !parser.is_at_end() && depth > 0 {
                                let tok = parser.advance();
                                if tok.token_type == TokenType::LParen {
                                    depth += 1;
                                } else if tok.token_type == TokenType::RParen {
                                    depth -= 1;
                                    if depth == 0 {
                                        break;
                                    }
                                }
                                // Add space after commas
                                if matches!(last_type, Some(TokenType::Comma)) {
                                    raw_sql.push(' ');
                                }
                                if tok.token_type == TokenType::String {
                                    raw_sql.push('\'');
                                    raw_sql.push_str(&tok.text);
                                    raw_sql.push('\'');
                                } else {
                                    raw_sql.push_str(&tok.text);
                                }
                                last_type = Some(tok.token_type.clone());
                            }
                            raw_sql.push(')');
                        }
                        consume_parens(self, &mut raw_sql);
                        // Consume more comma-separated expressions
                        while self.match_token(TokenType::Comma) {
                            raw_sql.push_str(", ");
                            let tok = self.advance();
                            raw_sql.push_str(&tok.text);
                            consume_parens(self, &mut raw_sql);
                        }
                        table_properties.push(Expression::Raw(Raw { sql: raw_sql }));
                    } else
                    // For Doris/StarRocks/MySQL RANGE/LIST, use structured parsing
                    if (is_doris_starrocks
                        || matches!(
                            self.config.dialect,
                            Some(crate::dialects::DialectType::MySQL)
                                | Some(crate::dialects::DialectType::SingleStore)
                                | Some(crate::dialects::DialectType::TiDB)
                        ))
                        && matches!(partition_kind.as_deref(), Some("RANGE") | Some("LIST"))
                    {
                        let partition_expr = self.parse_doris_partition_by_range_or_list(
                            partition_kind
                                .as_ref()
                                .map(|s| s.as_str())
                                .unwrap_or("RANGE"),
                        )?;
                        table_properties.push(partition_expr);
                    } else {
                        // Generic raw SQL parsing for other dialects
                        let no_partition_kind = partition_kind.is_none();
                        let mut raw_sql = match partition_kind {
                            Some(kind) => format!("PARTITION BY {}", kind),
                            None => "PARTITION BY ".to_string(),
                        };
                        if self.check(TokenType::LParen) {
                            self.advance();
                            raw_sql.push('(');
                            let mut depth = 1;
                            let mut last_tok_type: Option<TokenType> = None;
                            while !self.is_at_end() && depth > 0 {
                                let tok = self.advance();
                                if tok.token_type == TokenType::LParen {
                                    depth += 1;
                                } else if tok.token_type == TokenType::RParen {
                                    depth -= 1;
                                    if depth == 0 {
                                        break;
                                    }
                                }
                                // Add space before token if needed for proper formatting
                                let needs_space = match (&last_tok_type, &tok.token_type) {
                                    // Add space after comma
                                    (Some(TokenType::Comma), _) => true,
                                    // Add space after identifiers/keywords before other identifiers/keywords
                                    (Some(TokenType::Identifier), TokenType::Identifier) => true,
                                    _ => false,
                                };
                                if needs_space {
                                    raw_sql.push(' ');
                                }
                                // Handle string literals - preserve quotes
                                if tok.token_type == TokenType::String {
                                    raw_sql.push('\'');
                                    raw_sql.push_str(&tok.text);
                                    raw_sql.push('\'');
                                } else {
                                    raw_sql.push_str(&tok.text);
                                }
                                last_tok_type = Some(tok.token_type.clone());
                            }
                            raw_sql.push(')');
                        } else if no_partition_kind {
                            // Bare PARTITION BY expression list without a partition method
                            let mut first = true;
                            while !self.is_at_end()
                                && !self.check(TokenType::Cluster)
                                && !self.check(TokenType::As)
                                && !self.check(TokenType::Semicolon)
                                && !self.check(TokenType::RParen)
                                && !self.check_identifier("OPTIONS")
                            {
                                if !first {
                                    raw_sql.push_str(", ");
                                }
                                first = false;
                                let tok = self.advance();
                                raw_sql.push_str(&tok.text);
                                // Handle function calls: PARTITION BY DATE(col)
                                if self.check(TokenType::LParen) {
                                    self.advance();
                                    raw_sql.push('(');
                                    let mut depth = 1;
                                    while !self.is_at_end() && depth > 0 {
                                        let t = self.advance();
                                        if t.token_type == TokenType::LParen {
                                            depth += 1;
                                        } else if t.token_type == TokenType::RParen {
                                            depth -= 1;
                                            if depth == 0 {
                                                break;
                                            }
                                        }
                                        raw_sql.push_str(&t.text);
                                    }
                                    raw_sql.push(')');
                                }
                                if !self.match_token(TokenType::Comma) {
                                    break;
                                }
                            }
                        }
                        table_properties.push(Expression::Raw(Raw { sql: raw_sql }));
                    }
                } else {
                    self.current = saved;
                }
            }
        }

        // Parse CLUSTER BY (BigQuery) after PARTITION BY
        if is_bigquery {
            if let Some(cluster_property) = self.parse_bigquery_cluster_by_property()? {
                table_properties.push(cluster_property);
            }
        } else if self.match_keywords(&[TokenType::Cluster, TokenType::By]) {
            let mut cluster_names = Vec::new();
            loop {
                let name = self.expect_identifier_or_keyword()?;
                cluster_names.push(name);
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            table_properties.push(Expression::Raw(Raw {
                sql: format!("CLUSTER BY {}", cluster_names.join(", ")),
            }));
        }

        // No-column-defs path: OPTIONS and AS SELECT come after PARTITION BY / CLUSTER BY
        if no_column_defs {
            if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::BigQuery)
            ) {
                if let Some(options_property) = self.parse_bigquery_options_property()? {
                    table_properties.push(options_property);
                }
            } else if self.match_identifier("OPTIONS") {
                let options = self.parse_options_list()?;
                table_properties.push(Expression::Properties(Box::new(Properties {
                    expressions: options,
                })));
            }
        }

        let as_select = if no_column_defs && self.match_token(TokenType::As) {
            Some(self.parse_statement()?)
        } else {
            as_select
        };

        // For EXTERNAL tables, parse additional Snowflake options that may come after PARTITION BY
        // (location=@s2/logs/, partition_type = user_specified, file_format = (...), etc.)
        if is_special_modifier {
            while !self.is_at_end()
                && !self.check(TokenType::As)
                && !self.check(TokenType::Semicolon)
            {
                let is_snowflake_option = self.check(TokenType::Warehouse)
                    || self.check_identifier("TARGET_LAG")
                    || self.check_identifier("CATALOG")
                    || self.check_identifier("EXTERNAL_VOLUME")
                    || self.check_identifier("BASE_LOCATION")
                    || self.check_identifier("REFRESH_MODE")
                    || self.check_identifier("INITIALIZE")
                    || self.check_identifier("DATA_RETENTION_TIME_IN_DAYS")
                    || self.check_identifier("LOCATION")
                    || self.check_identifier("PARTITION_TYPE")
                    || self.check_identifier("FILE_FORMAT")
                    || self.check_identifier("AUTO_REFRESH");
                if is_snowflake_option {
                    let key = self.advance().text;
                    if self.match_token(TokenType::Eq) {
                        let value = if self.check(TokenType::LParen) {
                            // Parenthesized option list
                            self.advance();
                            let mut options = String::from("(");
                            let mut depth = 1;
                            while !self.is_at_end() && depth > 0 {
                                let tok = self.advance();
                                if tok.token_type == TokenType::LParen {
                                    depth += 1;
                                } else if tok.token_type == TokenType::RParen {
                                    depth -= 1;
                                }
                                if !options.ends_with('(')
                                    && !options.ends_with(' ')
                                    && tok.token_type != TokenType::RParen
                                {
                                    options.push(' ');
                                }
                                options.push_str(&tok.text);
                            }
                            options
                        } else if self.check(TokenType::String) {
                            let v = format!("'{}'", self.peek().text);
                            self.advance();
                            v
                        } else if self.check(TokenType::DAt) {
                            // Stage path like @s1/logs/
                            self.advance();
                            let mut path = String::from("@");
                            if self.is_identifier_token() || self.is_safe_keyword_as_identifier() {
                                path.push_str(&self.advance().text);
                            }
                            while self.check(TokenType::Slash) {
                                if self.current + 1 < self.tokens.len() {
                                    let next = &self.tokens[self.current + 1];
                                    let next_text_upper = next.text.to_uppercase();
                                    if next_text_upper == "FILE_FORMAT"
                                        || next_text_upper == "PARTITION_TYPE"
                                        || next_text_upper == "AUTO_REFRESH"
                                        || next_text_upper == "LOCATION"
                                        || next_text_upper == "PARTITION"
                                        || next_text_upper == "WAREHOUSE"
                                    {
                                        self.advance();
                                        path.push('/');
                                        break;
                                    }
                                }
                                self.advance();
                                path.push('/');
                                if self.is_identifier_token()
                                    || self.is_safe_keyword_as_identifier()
                                {
                                    path.push_str(&self.advance().text);
                                }
                            }
                            path
                        } else if self.check(TokenType::Var) && self.peek().text.starts_with('@') {
                            let mut path = self.advance().text;
                            while self.check(TokenType::Slash) {
                                if self.current + 1 < self.tokens.len() {
                                    let next = &self.tokens[self.current + 1];
                                    let next_text_upper = next.text.to_uppercase();
                                    if next_text_upper == "FILE_FORMAT"
                                        || next_text_upper == "PARTITION_TYPE"
                                        || next_text_upper == "AUTO_REFRESH"
                                        || next_text_upper == "LOCATION"
                                        || next_text_upper == "PARTITION"
                                        || next_text_upper == "WAREHOUSE"
                                    {
                                        self.advance();
                                        path.push('/');
                                        break;
                                    }
                                }
                                self.advance();
                                path.push('/');
                                if self.is_identifier_token()
                                    || self.is_safe_keyword_as_identifier()
                                {
                                    path.push_str(&self.advance().text);
                                }
                            }
                            path
                        } else if self.check(TokenType::Warehouse) {
                            self.advance().text
                        } else if self.is_identifier_token() || self.is_safe_keyword_as_identifier()
                        {
                            self.advance().text
                        } else {
                            break;
                        };
                        all_with_properties.push((key, value));
                    } else if self.is_identifier_token()
                        || self.is_safe_keyword_as_identifier()
                        || self.check(TokenType::Warehouse)
                    {
                        let value = self.advance().text;
                        all_with_properties.push((key, value));
                    }
                } else {
                    break;
                }
            }
        }

        // Parse TSQL table-level WITH(SYSTEM_VERSIONING=ON(...)) after columns
        // This is different from the earlier WITH properties parsing.
        // TSQL uses WITH(...) after columns for system versioning.
        let post_table_properties = self.parse_post_table_properties()?;

        // PostgreSQL: INHERITS (parent1, parent2, ...)
        let inherits = if self.match_identifier("INHERITS") {
            self.expect(TokenType::LParen)?;
            let mut parents = Vec::new();
            loop {
                parents.push(self.parse_table_ref()?);
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            self.expect(TokenType::RParen)?;
            parents
        } else {
            Vec::new()
        };

        Ok(Expression::CreateTable(Box::new(CreateTable {
            name,
            on_cluster,
            columns,
            constraints,
            if_not_exists,
            temporary,
            or_replace,
            table_modifier: table_modifier.map(|s| s.to_string()),
            as_select,
            as_select_parenthesized: false,
            on_commit,
            clone_source: None,
            clone_at_clause: None,
            shallow_clone: false,
            is_copy: false,
            leading_comments,
            with_properties: all_with_properties,
            teradata_post_name_options: teradata_post_name_options.clone(),
            with_data: None,
            with_statistics: None,
            teradata_indexes: Vec::new(),
            with_cte: None,
            properties: table_properties,
            partition_of: None,
            post_table_properties,
            mysql_table_options,
            inherits,
            on_property,
            copy_grants,
            using_template: None,
            rollup,
        })))
    }

    /// Parse CREATE TABLE ... PARTITION OF parent_table [(cols)] [FOR VALUES spec | DEFAULT] [PARTITION BY ...]
    fn parse_create_table_partition_of(
        &mut self,
        name: TableRef,
        if_not_exists: bool,
        temporary: bool,
        or_replace: bool,
        table_modifier: Option<&str>,
        leading_comments: Vec<String>,
    ) -> Result<Expression> {
        // Parse parent table name
        let parent_table = self.parse_table_ref()?;

        // Optionally parse column constraints in parens: (unitsales DEFAULT 0) or (CONSTRAINT ...)
        // This must come before FOR VALUES or DEFAULT. We distinguish from other uses
        // by checking if the first token after LParen is CONSTRAINT or an identifier
        // that is not a string literal.
        let (columns, constraints) = if self.check(TokenType::LParen) {
            // Peek ahead: current is LParen, current+1 is first token inside parens
            let first_inside = self.current + 1;
            // Check if this is a partition column specification: (colname DEFAULT value)
            // Column names tokenize as Var (unquoted) or QuotedIdentifier (quoted)
            let is_column_defs = first_inside < self.tokens.len()
                && (self.tokens[first_inside].token_type == TokenType::Constraint
                    || ((self.tokens[first_inside].token_type == TokenType::Var
                        || self.tokens[first_inside].token_type == TokenType::QuotedIdentifier
                        || self.tokens[first_inside].token_type == TokenType::Identifier)
                        && first_inside + 1 < self.tokens.len()
                        && self.tokens[first_inside + 1].token_type == TokenType::Default));

            if is_column_defs {
                self.advance(); // consume LParen
                                // Use special parsing for partition column specs - they don't have data types,
                                // just column names with constraint overrides like DEFAULT
                let (cols, constrs) = self.parse_partition_column_specs()?;
                self.expect(TokenType::RParen)?;
                (cols, constrs)
            } else {
                (Vec::new(), Vec::new())
            }
        } else {
            (Vec::new(), Vec::new())
        };

        // Parse DEFAULT or FOR VALUES spec
        let partition_bound: Expression = if self.match_token(TokenType::Default) {
            // DEFAULT partition
            Expression::Var(Box::new(Var {
                this: "DEFAULT".to_string(),
            }))
        } else if self.match_token(TokenType::For) {
            // FOR VALUES ...
            self.expect(TokenType::Values)?;
            self.parse_partition_bound_spec()?
        } else {
            // Neither DEFAULT nor FOR VALUES - could be an error
            // but we'll be lenient and just create a DEFAULT
            Expression::Var(Box::new(Var {
                this: "DEFAULT".to_string(),
            }))
        };

        let partition_of_expr =
            Expression::PartitionedOfProperty(Box::new(PartitionedOfProperty {
                this: Box::new(Expression::Table(parent_table)),
                expression: Box::new(partition_bound),
            }));

        // Optionally parse trailing PARTITION BY RANGE/LIST/HASH(columns)
        let mut table_properties: Vec<Expression> = Vec::new();
        if self.match_token(TokenType::Partition) || self.match_token(TokenType::PartitionBy) {
            // Could be PARTITION BY or just PartitionBy token
            if self.previous().token_type == TokenType::Partition {
                self.expect(TokenType::By)?;
            }
            // Parse RANGE/LIST/HASH(columns)
            let partition_kind = if self.check(TokenType::Identifier) || self.check(TokenType::Var)
            {
                let kind_text = self.advance().text.to_uppercase();
                kind_text
            } else if self.check(TokenType::Range) {
                self.advance();
                "RANGE".to_string()
            } else if self.check(TokenType::List) {
                self.advance();
                "LIST".to_string()
            } else {
                "RANGE".to_string()
            };
            // Parse (columns)
            let mut raw_sql = format!("PARTITION BY {}", partition_kind);
            if self.check(TokenType::LParen) {
                self.advance(); // consume LParen
                raw_sql.push('(');
                let mut depth = 1;
                while !self.is_at_end() && depth > 0 {
                    let tok = self.advance();
                    if tok.token_type == TokenType::LParen {
                        depth += 1;
                    } else if tok.token_type == TokenType::RParen {
                        depth -= 1;
                        if depth == 0 {
                            break;
                        }
                    }
                    raw_sql.push_str(&tok.text);
                }
                raw_sql.push(')');
            }
            table_properties.push(Expression::Raw(Raw { sql: raw_sql }));
        }

        Ok(Expression::CreateTable(Box::new(CreateTable {
            name,
            on_cluster: None,
            columns,
            constraints,
            if_not_exists,
            temporary,
            or_replace,
            table_modifier: table_modifier.map(|s| s.to_string()),
            as_select: None,
            as_select_parenthesized: false,
            on_commit: None,
            clone_source: None,
            clone_at_clause: None,
            shallow_clone: false,
            is_copy: false,
            leading_comments,
            with_properties: Vec::new(),
            teradata_post_name_options: Vec::new(),
            with_data: None,
            with_statistics: None,
            teradata_indexes: Vec::new(),
            with_cte: None,
            properties: table_properties,
            partition_of: Some(partition_of_expr),
            post_table_properties: Vec::new(),
            mysql_table_options: Vec::new(),
            inherits: Vec::new(),
            on_property: None,
            copy_grants: false,
            using_template: None,
            rollup: None,
        })))
    }

    /// Parse partition bound spec for PARTITION OF: IN (...), FROM (...) TO (...), or WITH (MODULUS n, REMAINDER n)
    fn parse_partition_bound_spec(&mut self) -> Result<Expression> {
        if self.match_token(TokenType::In) {
            // IN (val, val, ...)
            self.expect(TokenType::LParen)?;
            let mut values = Vec::new();
            loop {
                let val = self.parse_expression()?;
                values.push(val);
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            self.expect(TokenType::RParen)?;
            // Use Tuple for multiple values (generator strips parens for partition bounds)
            let this_expr = if values.len() == 1 {
                values.into_iter().next().unwrap()
            } else {
                Expression::Tuple(Box::new(Tuple {
                    expressions: values,
                }))
            };
            Ok(Expression::PartitionBoundSpec(Box::new(
                PartitionBoundSpec {
                    this: Some(Box::new(this_expr)),
                    expression: None,
                    from_expressions: None,
                    to_expressions: None,
                },
            )))
        } else if self.match_token(TokenType::From) {
            // FROM (val, ...) TO (val, ...)
            self.expect(TokenType::LParen)?;
            let mut from_vals = Vec::new();
            loop {
                let val = self.parse_partition_bound_value()?;
                from_vals.push(val);
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            self.expect(TokenType::RParen)?;

            self.expect(TokenType::To)?;
            self.expect(TokenType::LParen)?;
            let mut to_vals = Vec::new();
            loop {
                let val = self.parse_partition_bound_value()?;
                to_vals.push(val);
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            self.expect(TokenType::RParen)?;

            let from_expr = if from_vals.len() == 1 {
                from_vals.into_iter().next().unwrap()
            } else {
                Expression::Tuple(Box::new(Tuple {
                    expressions: from_vals,
                }))
            };
            let to_expr = if to_vals.len() == 1 {
                to_vals.into_iter().next().unwrap()
            } else {
                Expression::Tuple(Box::new(Tuple {
                    expressions: to_vals,
                }))
            };

            Ok(Expression::PartitionBoundSpec(Box::new(
                PartitionBoundSpec {
                    this: None,
                    expression: None,
                    from_expressions: Some(Box::new(from_expr)),
                    to_expressions: Some(Box::new(to_expr)),
                },
            )))
        } else if self.match_token(TokenType::With) {
            // WITH (MODULUS n, REMAINDER n)
            self.expect(TokenType::LParen)?;
            self.match_text_seq(&["MODULUS"]);
            let modulus = self.parse_expression()?;
            self.expect(TokenType::Comma)?;
            self.match_text_seq(&["REMAINDER"]);
            let remainder = self.parse_expression()?;
            self.expect(TokenType::RParen)?;

            Ok(Expression::PartitionBoundSpec(Box::new(
                PartitionBoundSpec {
                    this: Some(Box::new(modulus)),
                    expression: Some(Box::new(remainder)),
                    from_expressions: None,
                    to_expressions: None,
                },
            )))
        } else {
            Err(self.parse_error("Expected IN, FROM, or WITH after FOR VALUES in PARTITION OF"))
        }
    }

    /// Parse a single partition bound value (number, string, MINVALUE, MAXVALUE)
    fn parse_partition_bound_value(&mut self) -> Result<Expression> {
        if self.match_token(TokenType::Minvalue) {
            Ok(Expression::Var(Box::new(Var {
                this: "MINVALUE".to_string(),
            })))
        } else if self.match_token(TokenType::Maxvalue) {
            Ok(Expression::Var(Box::new(Var {
                this: "MAXVALUE".to_string(),
            })))
        } else {
            self.parse_expression()
        }
    }

    /// Parse column specifications for PostgreSQL PARTITION OF syntax.
    /// Unlike regular column definitions, these don't have data types - just column names
    /// with constraint overrides like DEFAULT, NOT NULL, or table-level CONSTRAINT clauses.
    /// Example: (unitsales DEFAULT 0) or (CONSTRAINT check_date CHECK (logdate >= '2016-07-01'))
    fn parse_partition_column_specs(&mut self) -> Result<(Vec<ColumnDef>, Vec<TableConstraint>)> {
        let mut columns = Vec::new();
        let mut constraints = Vec::new();

        loop {
            // Check for table-level constraint (CONSTRAINT name ...)
            if self.check(TokenType::Constraint) {
                constraints.push(self.parse_table_constraint()?);
            } else if self.check(TokenType::PrimaryKey)
                || self.check(TokenType::ForeignKey)
                || self.check(TokenType::Unique)
                || self.check(TokenType::Check)
                || self.check(TokenType::Exclude)
            {
                constraints.push(self.parse_table_constraint()?);
            } else {
                // Parse column name with optional constraints (no data type)
                columns.push(self.parse_partition_column_spec()?);
            }

            if !self.match_token(TokenType::Comma) {
                break;
            }
            // ClickHouse allows a trailing comma before the closing ')'
            if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && self.check(TokenType::RParen)
            {
                break;
            }
        }

        Ok((columns, constraints))
    }

    /// Parse a single partition column specification: column_name [DEFAULT value] [NOT NULL] [NULL] [WITH OPTIONS ...]
    fn parse_partition_column_spec(&mut self) -> Result<ColumnDef> {
        // Parse column name
        let name = self.expect_identifier_or_safe_keyword_with_quoted()?;

        // Create column def with Unknown data type (data type comes from parent table)
        let mut col_def = ColumnDef::new(name.name.clone(), DataType::Unknown);
        col_def.name = name;

        // Parse column constraints (no data type expected)
        loop {
            if self.match_token(TokenType::Default) {
                // DEFAULT value
                let default_val = self.parse_expression()?;
                col_def.default = Some(default_val.clone());
                col_def
                    .constraints
                    .push(ColumnConstraint::Default(default_val));
                col_def.constraint_order.push(ConstraintType::Default);
            } else if self.match_keywords(&[TokenType::Not, TokenType::Null]) {
                col_def.nullable = Some(false);
                col_def.constraint_order.push(ConstraintType::NotNull);
            } else if self.match_token(TokenType::Null) {
                col_def.nullable = Some(true);
                col_def.constraint_order.push(ConstraintType::Null);
            } else if self.match_token(TokenType::Constraint) {
                // Inline CONSTRAINT name ... for this column
                let constraint_name = self.expect_identifier_or_safe_keyword()?;
                if self.match_keywords(&[TokenType::Not, TokenType::Null]) {
                    col_def.nullable = Some(false);
                    col_def.not_null_constraint_name = Some(constraint_name);
                    col_def.constraint_order.push(ConstraintType::NotNull);
                } else if self.match_token(TokenType::Check) {
                    col_def.check_constraint_name = Some(constraint_name);
                    if self.match_token(TokenType::LParen) {
                        let check_expr = self.parse_expression()?;
                        self.expect(TokenType::RParen)?;
                        col_def
                            .constraints
                            .push(ColumnConstraint::Check(check_expr));
                    }
                    col_def.constraint_order.push(ConstraintType::Check);
                } else if self.match_token(TokenType::Default) {
                    let default_val = self.parse_expression()?;
                    col_def.default = Some(default_val.clone());
                    col_def
                        .constraints
                        .push(ColumnConstraint::Default(default_val));
                    col_def.constraint_order.push(ConstraintType::Default);
                }
            } else if self.match_text_seq(&["WITH", "OPTIONS"]) {
                // PostgreSQL: WITH OPTIONS allows specifying more options
                // For now, just skip this - it's rarely used
                break;
            } else {
                break;
            }
        }

        Ok(col_def)
    }

    /// Parse WITH properties for CREATE TABLE (e.g., WITH (FORMAT='parquet', x='2'))
    /// Returns a list of (key, value) pairs
    fn parse_with_properties(&mut self) -> Result<Vec<(String, String)>> {
        self.expect(TokenType::LParen)?;
        let mut properties = Vec::new();

        loop {
            if self.check(TokenType::RParen) {
                break;
            }

            // Parse property name (can be keywords like FORMAT, TABLE_FORMAT)
            let mut key = self.expect_identifier_or_keyword()?;

            // Handle multi-word keys like "PARTITIONED BY" -> "PARTITIONED_BY"
            if key.to_uppercase() == "PARTITIONED" && self.check(TokenType::By) {
                self.advance(); // consume BY
                key = "PARTITIONED_BY".to_string();
            }

            // Expect = or special case for PARTITIONED_BY=(...)
            self.expect(TokenType::Eq)?;

            // Parse property value - can be string, identifier, or parenthesized expression
            let value = if self.check(TokenType::String) {
                // Store string with quotes to preserve format
                let val = format!("'{}'", self.peek().text);
                self.advance();
                val
            } else if self.match_token(TokenType::LParen) {
                // Handle PARTITIONED_BY=(x INT, y INT) or similar
                let mut depth = 1;
                let mut result = String::from("(");
                let mut need_space = false;
                while !self.is_at_end() && depth > 0 {
                    if self.check(TokenType::LParen) {
                        depth += 1;
                    } else if self.check(TokenType::RParen) {
                        depth -= 1;
                        if depth == 0 {
                            break;
                        }
                    }
                    let token = self.peek();
                    let text = &token.text;
                    let token_type = token.token_type;

                    // Determine if we need a space before this token
                    let is_punctuation = matches!(
                        token_type,
                        TokenType::Comma | TokenType::LParen | TokenType::RParen
                    );
                    if need_space && !is_punctuation {
                        result.push(' ');
                    }

                    result.push_str(text);

                    // Determine if we need a space after this token
                    need_space = token_type == TokenType::Comma
                        || (!is_punctuation
                            && !matches!(
                                token_type,
                                TokenType::LParen | TokenType::RParen | TokenType::Comma
                            ));
                    self.advance();
                }
                self.expect(TokenType::RParen)?;
                result.push(')');
                result
            } else if self.check_identifier("ARRAY")
                && self
                    .peek_nth(1)
                    .is_some_and(|t| t.token_type == TokenType::LBracket)
            {
                // Handle ARRAY['value', 'value', ...] syntax (Athena/Presto)
                let mut result = self.advance().text.clone(); // consume ARRAY
                self.expect(TokenType::LBracket)?;
                result.push('[');
                let mut first = true;
                while !self.is_at_end() && !self.check(TokenType::RBracket) {
                    if !first {
                        if self.match_token(TokenType::Comma) {
                            result.push_str(", ");
                        } else {
                            break;
                        }
                    }
                    first = false;
                    // Parse array element (usually a string)
                    if self.check(TokenType::String) {
                        result.push('\'');
                        result.push_str(&self.advance().text);
                        result.push('\'');
                    } else if self.is_identifier_token() {
                        result.push_str(&self.advance().text);
                    } else {
                        break;
                    }
                }
                self.expect(TokenType::RBracket)?;
                result.push(']');
                result
            } else if self.check(TokenType::Number) {
                // Numeric value (e.g., bucket_count=64)
                self.advance().text.clone()
            } else {
                // Just an identifier or keyword (e.g., allow_page_locks=on)
                self.expect_identifier_or_keyword()?
            };

            properties.push((key, value));

            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        self.expect(TokenType::RParen)?;
        Ok(properties)
    }

    /// Parse column definitions and table constraints
    fn parse_column_definitions(&mut self) -> Result<(Vec<ColumnDef>, Vec<TableConstraint>)> {
        let mut columns = Vec::new();
        let mut constraints = Vec::new();

        loop {
            if self.check(TokenType::RParen) {
                break;
            }
            // Check for LIKE clause (PostgreSQL)
            if self.check(TokenType::Like) {
                constraints.push(self.parse_like_clause()?);
            }
            // Check for table-level constraint
            // For CHECK, only treat as constraint if followed by '(' (or in ClickHouse where parens are optional).
            // Otherwise, 'check' is a column name (e.g., CREATE TABLE t (check INT)).
            else if self.check(TokenType::Constraint)
                || self.check(TokenType::PrimaryKey)
                || self.check(TokenType::ForeignKey)
                || self.check(TokenType::Unique)
                || (self.check(TokenType::Check)
                    && (self
                        .peek_nth(1)
                        .map_or(false, |t| t.token_type == TokenType::LParen)
                        || matches!(
                            self.config.dialect,
                            Some(crate::dialects::DialectType::ClickHouse)
                        )))
                || self.check(TokenType::Exclude)
            {
                constraints.push(self.parse_table_constraint()?);
            } else if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && self.check(TokenType::Index)
            {
                // ClickHouse: INDEX name expr TYPE type_func(args) GRANULARITY n
                self.advance(); // consume INDEX
                let name = self.expect_identifier_or_keyword_with_quoted()?;
                // Use parse_conjunction to handle comparisons like c0 < (SELECT _table)
                let expression = self.parse_conjunction()?.ok_or_else(|| {
                    self.parse_error("Expected expression in ClickHouse INDEX definition")
                })?;
                let index_type = if self.match_token(TokenType::Type) {
                    // Parse function or identifier for type (e.g., bloom_filter(0.001), set(100), minmax)
                    // Handle keywords like 'set' that are tokenized as TokenType::Set
                    if let Some(func) = self.parse_function()? {
                        Some(Box::new(func))
                    } else if !self.check(TokenType::Identifier)
                        && !self.check(TokenType::Var)
                        && !self.is_at_end()
                    {
                        // Handle keywords as index type names (e.g., set, minmax)
                        let type_name = self.advance().text.clone();
                        if self.check(TokenType::LParen) {
                            // It's a function call like set(100)
                            self.advance(); // consume (
                            let mut args = Vec::new();
                            if !self.check(TokenType::RParen) {
                                args.push(self.parse_expression()?);
                                while self.match_token(TokenType::Comma) {
                                    args.push(self.parse_expression()?);
                                }
                            }
                            self.expect(TokenType::RParen)?;
                            Some(Box::new(Expression::Function(Box::new(Function::new(
                                type_name, args,
                            )))))
                        } else {
                            // Just an identifier
                            Some(Box::new(Expression::Identifier(Identifier::new(type_name))))
                        }
                    } else if let Some(id) = self.parse_id_var()? {
                        Some(Box::new(id))
                    } else {
                        None
                    }
                } else {
                    None
                };
                let granularity = if self.match_identifier("GRANULARITY") {
                    let gran_val = self.parse_expression()?;
                    Some(Box::new(gran_val))
                } else {
                    None
                };
                constraints.push(TableConstraint::Index {
                    name: Some(name),
                    columns: Vec::new(),
                    kind: None,
                    modifiers: ConstraintModifiers::default(),
                    use_key_keyword: false,
                    expression: Some(Box::new(expression)),
                    index_type,
                    granularity,
                });
            } else if !matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && (self.check(TokenType::Index)
                || self.check(TokenType::Key)
                || self.check_identifier("FULLTEXT")
                || self.check_identifier("SPATIAL"))
            {
                // INDEX/KEY constraint (MySQL). Guard KEY <type> as a normal column definition
                // (e.g. ClickHouse: `key UInt64`).
                let looks_like_key_constraint = if self.check(TokenType::Key) {
                    self.check_next(TokenType::LParen)
                        || ((self.check_next(TokenType::Identifier)
                            || self.check_next(TokenType::Var)
                            || self.check_next(TokenType::QuotedIdentifier))
                            && self.current + 2 < self.tokens.len()
                            && self.tokens[self.current + 2].token_type == TokenType::LParen)
                } else {
                    true
                };

                if looks_like_key_constraint {
                    constraints.push(self.parse_index_table_constraint()?);
                } else {
                    columns.push(self.parse_column_def()?);
                }
            } else if self.check_identifier("PERIOD") {
                // TSQL: PERIOD FOR SYSTEM_TIME (start_col, end_col)
                if let Some(period_constraint) =
                    self.parse_period_for_system_time_table_constraint()?
                {
                    constraints.push(period_constraint);
                } else {
                    // Not actually PERIOD FOR SYSTEM_TIME, treat as column definition
                    columns.push(self.parse_column_def()?);
                }
            } else if self.check_identifier("INITIALLY") {
                // PostgreSQL: INITIALLY DEFERRED / INITIALLY IMMEDIATE as table-level setting
                self.advance(); // consume INITIALLY
                if self.match_identifier("DEFERRED") {
                    constraints.push(TableConstraint::InitiallyDeferred { deferred: true });
                } else if self.match_identifier("IMMEDIATE") {
                    constraints.push(TableConstraint::InitiallyDeferred { deferred: false });
                } else {
                    return Err(self.parse_error("Expected DEFERRED or IMMEDIATE after INITIALLY"));
                }
            } else if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && self.check_identifier("PROJECTION")
            {
                // ClickHouse: PROJECTION name (SELECT ...) or PROJECTION name INDEX expr TYPE type_name
                self.advance(); // consume PROJECTION
                let name = self.expect_identifier_or_keyword_with_quoted()?;
                if self.match_token(TokenType::LParen) {
                    let expression = self.parse_statement()?;
                    self.expect(TokenType::RParen)?;
                    // ClickHouse: PROJECTION name (SELECT ...) WITH SETTINGS (key=value, ...)
                    if self.check(TokenType::With)
                        && self.current + 1 < self.tokens.len()
                        && self.tokens[self.current + 1].token_type == TokenType::Settings
                    {
                        self.advance(); // consume WITH
                        self.advance(); // consume SETTINGS
                        if self.match_token(TokenType::LParen) {
                            // Consume key=value pairs
                            loop {
                                if self.check(TokenType::RParen) {
                                    break;
                                }
                                if self.is_identifier_token()
                                    || self.is_safe_keyword_as_identifier()
                                {
                                    self.advance(); // key
                                }
                                if self.match_token(TokenType::Eq) {
                                    let _ = self.parse_primary()?; // value
                                }
                                if !self.match_token(TokenType::Comma) {
                                    break;
                                }
                            }
                            self.expect(TokenType::RParen)?;
                        }
                    }
                    constraints.push(TableConstraint::Projection { name, expression });
                } else if self.match_token(TokenType::Index) {
                    // PROJECTION name INDEX expr TYPE type_name
                    let expr = self.parse_bitwise()?.ok_or_else(|| {
                        self.parse_error(
                            "Expected expression in ClickHouse PROJECTION INDEX definition",
                        )
                    })?;
                    let type_str = if self.match_token(TokenType::Type) {
                        if !self.is_at_end()
                            && !self.check(TokenType::Comma)
                            && !self.check(TokenType::RParen)
                        {
                            self.advance().text.clone()
                        } else {
                            String::new()
                        }
                    } else {
                        String::new()
                    };
                    let raw_sql = if type_str.is_empty() {
                        format!("INDEX {} ", expr)
                    } else {
                        format!("INDEX {} TYPE {}", expr, type_str)
                    };
                    constraints.push(TableConstraint::Projection {
                        name,
                        expression: Expression::Raw(Raw { sql: raw_sql }),
                    });
                } else {
                    constraints.push(TableConstraint::Projection {
                        name,
                        expression: Expression::Null(Null),
                    });
                }
            } else {
                // Parse column definition
                columns.push(self.parse_column_def()?);
            }

            if !self.match_token(TokenType::Comma) {
                break;
            }
            // ClickHouse: allow trailing comma before closing paren
            if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && self.check(TokenType::RParen)
            {
                break;
            }
        }

        Ok((columns, constraints))
    }

    /// Parse LIKE clause in CREATE TABLE: LIKE source_table [INCLUDING|EXCLUDING options]
    fn parse_like_clause(&mut self) -> Result<TableConstraint> {
        self.expect(TokenType::Like)?;
        let source = self.parse_table_ref()?;
        let mut options = Vec::new();

        // Parse optional INCLUDING/EXCLUDING modifiers
        loop {
            if self.match_identifier("INCLUDING") {
                let prop = self.expect_identifier_or_keyword()?.to_uppercase();
                options.push((LikeOptionAction::Including, prop));
            } else if self.match_identifier("EXCLUDING") {
                let prop = self.expect_identifier_or_keyword()?.to_uppercase();
                options.push((LikeOptionAction::Excluding, prop));
            } else {
                break;
            }
        }

        Ok(TableConstraint::Like { source, options })
    }

    /// Parse a single column definition
    fn parse_column_def(&mut self) -> Result<ColumnDef> {
        // Column names can be keywords like 'end', 'truncate', 'view', etc.
        // ClickHouse allows any keyword as column name (from, select, etc.)
        let mut name = if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) {
            self.expect_identifier_or_keyword_with_quoted()?
        } else {
            self.expect_identifier_or_safe_keyword_with_quoted()?
        };
        // ClickHouse: Nested column names like n.b for Nested() columns
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) {
            while self.match_token(TokenType::Dot) {
                let sub = self.expect_identifier_or_safe_keyword_with_quoted()?;
                name = Identifier {
                    name: format!("{}.{}", name.name, sub.name),
                    quoted: name.quoted,
                    trailing_comments: sub.trailing_comments,
                    span: None,
                };
            }
        }

        // TSQL computed columns have no data type: column_name AS (expression) [PERSISTED]
        // Check if AS follows immediately (no data type)
        if self.check(TokenType::As) {
            let mut col_def = ColumnDef::new(
                name.name.clone(),
                DataType::Custom {
                    name: String::new(),
                },
            );
            col_def.name = name;
            // Consume AS and parse computed column expression
            self.advance(); // consume AS
            if self.check(TokenType::LParen) {
                self.parse_as_computed_column(&mut col_def)?;
            }
            return Ok(col_def);
        }

        // SQLite allows column definitions without types: CREATE TABLE t (x, y)
        // ClickHouse allows typeless columns with DEFAULT/MATERIALIZED/ALIAS/EPHEMERAL
        // Check if the next token indicates no type (comma, rparen, or constraint keyword)
        let no_type = self.check(TokenType::Comma)
            || self.check(TokenType::RParen)
            || (matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && (self.check(TokenType::Default)
                || self.check(TokenType::Materialized)
                || self.check_identifier("ALIAS")
                || self.check_identifier("EPHEMERAL")));
        let data_type = if no_type {
            // No type specified - use empty custom type
            DataType::Custom {
                name: String::new(),
            }
        } else {
            self.parse_data_type()?
        };

        let mut col_def = ColumnDef::new(name.name.clone(), data_type);
        col_def.name = name;
        col_def.no_type = no_type;

        // Parse MySQL type modifiers (UNSIGNED, ZEROFILL)
        // These come after the data type but before other constraints
        while self.match_identifier("UNSIGNED")
            || self.match_identifier("ZEROFILL")
            || self.match_identifier("SIGNED")
        {
            let modifier = self.previous().text.to_uppercase();
            if modifier == "UNSIGNED" {
                col_def.unsigned = true;
            } else if modifier == "ZEROFILL" {
                col_def.zerofill = true;
            }
            // SIGNED is the default, no action needed
        }

        // BigQuery: OPTIONS (key=value, ...) on column - comes right after type
        if self.match_identifier("OPTIONS") {
            col_def.options = self.parse_options_list()?;
        }

        // Parse column constraints
        loop {
            if self.match_keywords(&[TokenType::Not, TokenType::Null]) {
                col_def.nullable = Some(false);
                col_def.constraint_order.push(ConstraintType::NotNull);
            } else if self.match_token(TokenType::Null) {
                col_def.nullable = Some(true);
                col_def.constraint_order.push(ConstraintType::Null);
            } else if self.match_keywords(&[TokenType::PrimaryKey, TokenType::Key]) {
                // Handle PRIMARY KEY [ASC|DESC]
                col_def.primary_key = true;
                // Capture ASC/DESC after PRIMARY KEY
                if self.match_token(TokenType::Asc) {
                    col_def.primary_key_order = Some(SortOrder::Asc);
                } else if self.match_token(TokenType::Desc) {
                    col_def.primary_key_order = Some(SortOrder::Desc);
                }
                col_def.constraint_order.push(ConstraintType::PrimaryKey);
            } else if self.match_token(TokenType::Constraint) {
                // Inline CONSTRAINT name ... (e.g., CONSTRAINT fk_name REFERENCES ...)
                let constraint_name = self.expect_identifier()?;
                // After constraint name, expect REFERENCES, PRIMARY KEY, UNIQUE, CHECK, NOT NULL, NULL, etc.
                if self.match_token(TokenType::References) {
                    let mut fk_ref = self.parse_foreign_key_ref()?;
                    fk_ref.constraint_name = Some(constraint_name);
                    col_def
                        .constraints
                        .push(ColumnConstraint::References(fk_ref));
                    col_def.constraint_order.push(ConstraintType::References);
                } else if self.match_keywords(&[TokenType::PrimaryKey, TokenType::Key]) {
                    col_def.primary_key = true;
                    col_def.primary_key_constraint_name = Some(constraint_name);
                    col_def.constraint_order.push(ConstraintType::PrimaryKey);
                } else if self.match_token(TokenType::Unique) {
                    col_def.unique = true;
                    col_def.unique_constraint_name = Some(constraint_name);
                    // Check for NULLS NOT DISTINCT (PostgreSQL 15+ feature)
                    if self.match_text_seq(&["NULLS", "NOT", "DISTINCT"]) {
                        col_def.unique_nulls_not_distinct = true;
                    }
                    col_def.constraint_order.push(ConstraintType::Unique);
                } else if self.match_keywords(&[TokenType::Not, TokenType::Null]) {
                    col_def.nullable = Some(false);
                    col_def.not_null_constraint_name = Some(constraint_name);
                    col_def.constraint_order.push(ConstraintType::NotNull);
                } else if self.match_token(TokenType::Check) {
                    col_def.check_constraint_name = Some(constraint_name);
                    // Parse CHECK constraint expression
                    if self.match_token(TokenType::LParen) {
                        let check_expr = self.parse_expression()?;
                        self.expect(TokenType::RParen)?;
                        col_def
                            .constraints
                            .push(ColumnConstraint::Check(check_expr));
                    } else if matches!(
                        self.config.dialect,
                        Some(crate::dialects::DialectType::ClickHouse)
                    ) {
                        // ClickHouse: CHECK expr without parens
                        let check_expr = self.parse_or()?;
                        col_def
                            .constraints
                            .push(ColumnConstraint::Check(check_expr));
                    }
                    col_def.constraint_order.push(ConstraintType::Check);
                }
            } else if self.match_token(TokenType::Unique) {
                col_def.unique = true;
                // Check for NULLS NOT DISTINCT (PostgreSQL 15+ feature)
                if self.match_text_seq(&["NULLS", "NOT", "DISTINCT"]) {
                    col_def.unique_nulls_not_distinct = true;
                }
                col_def.constraint_order.push(ConstraintType::Unique);
            } else if self.match_token(TokenType::Check) {
                // Standalone CHECK (expr) constraint (without CONSTRAINT name)
                if self.match_token(TokenType::LParen) {
                    let check_expr = self.parse_expression()?;
                    self.expect(TokenType::RParen)?;
                    col_def
                        .constraints
                        .push(ColumnConstraint::Check(check_expr));
                    col_def.constraint_order.push(ConstraintType::Check);
                } else if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) {
                    // ClickHouse: CHECK expr without parens
                    let check_expr = self.parse_or()?;
                    col_def
                        .constraints
                        .push(ColumnConstraint::Check(check_expr));
                    col_def.constraint_order.push(ConstraintType::Check);
                }
            } else if self.match_token(TokenType::AutoIncrement) || self.match_keyword("IDENTITY") {
                col_def.auto_increment = true;
                col_def.constraint_order.push(ConstraintType::AutoIncrement);
                // Handle IDENTITY/AUTOINCREMENT options: START n INCREMENT m [ORDER|NOORDER] or (start, increment)
                if self.match_keyword("START") {
                    col_def.auto_increment_start = Some(Box::new(self.parse_primary()?));
                    if self.match_keyword("INCREMENT") {
                        col_def.auto_increment_increment = Some(Box::new(self.parse_primary()?));
                    }
                    // Snowflake: ORDER or NOORDER option
                    if self.match_token(TokenType::Order) {
                        col_def.auto_increment_order = Some(true);
                    } else if self.match_identifier("NOORDER") {
                        col_def.auto_increment_order = Some(false);
                    }
                } else if self.match_token(TokenType::LParen) {
                    // IDENTITY(start, increment) or AUTOINCREMENT(start, increment)
                    col_def.auto_increment_start = Some(Box::new(self.parse_primary()?));
                    if self.match_token(TokenType::Comma) {
                        col_def.auto_increment_increment = Some(Box::new(self.parse_primary()?));
                    }
                    self.expect(TokenType::RParen)?;
                }
            } else if self.match_token(TokenType::Default) {
                // ClickHouse: DEFAULT expressions can be complex (today(), a + 1, cond ? x : y, etc.)
                col_def.default = if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) {
                    Some(self.parse_expression()?)
                } else {
                    Some(self.parse_unary()?)
                };
                col_def.constraint_order.push(ConstraintType::Default);
            } else if self.match_keywords(&[TokenType::ForeignKey, TokenType::Key]) {
                // Snowflake/SQL Server: FOREIGN KEY REFERENCES table(columns)
                // The FOREIGN KEY keywords are followed by REFERENCES
                self.expect(TokenType::References)?;
                let mut fk_ref = self.parse_foreign_key_ref()?;
                fk_ref.has_foreign_key_keywords = true;
                col_def
                    .constraints
                    .push(ColumnConstraint::References(fk_ref));
                col_def.constraint_order.push(ConstraintType::References);
            } else if self.match_token(TokenType::References) {
                let fk_ref = self.parse_foreign_key_ref()?;
                col_def
                    .constraints
                    .push(ColumnConstraint::References(fk_ref));
                col_def.constraint_order.push(ConstraintType::References);
            } else if self.match_token(TokenType::Generated) {
                // GENERATED [BY DEFAULT [ON NULL] | ALWAYS] AS ...
                // Could be: AS IDENTITY, AS (expr) STORED|VIRTUAL, AS ROW START|END
                self.parse_generated_column_constraint(&mut col_def)?;
            } else if self.match_token(TokenType::Collate) {
                // COLLATE collation_name (may be quoted like "de_DE")
                // Also handle dotted names like pg_catalog."default"
                let mut collation = self.expect_identifier_or_keyword_with_quoted()?;
                // Check for dotted collation names: pg_catalog."default"
                while self.match_token(TokenType::Dot) {
                    let next = self.expect_identifier_or_keyword_with_quoted()?;
                    let sep = if next.quoted {
                        format!("{}.\"{}\"", collation.name, next.name)
                    } else {
                        format!("{}.{}", collation.name, next.name)
                    };
                    collation = Identifier {
                        name: sep,
                        quoted: false,
                        trailing_comments: Vec::new(),
                        span: None,
                    };
                }
                col_def
                    .constraints
                    .push(ColumnConstraint::Collate(collation));
                col_def.constraint_order.push(ConstraintType::Collate);
            } else if self.match_token(TokenType::Comment) {
                // COMMENT 'comment text'
                let comment_text = self.expect_string()?;
                col_def
                    .constraints
                    .push(ColumnConstraint::Comment(comment_text));
                col_def.constraint_order.push(ConstraintType::Comment);
            } else if self.match_keywords(&[TokenType::On, TokenType::Update]) {
                // MySQL: ON UPDATE expression (e.g., ON UPDATE CURRENT_TIMESTAMP)
                let expr = self.parse_unary()?;
                col_def.on_update = Some(expr);
                col_def.constraint_order.push(ConstraintType::OnUpdate);
            } else if self.match_identifier("ENCODE") {
                // Redshift: ENCODE encoding_type (e.g., ZSTD, DELTA, LZO, etc.)
                let encoding = self.expect_identifier_or_keyword()?;
                col_def.encoding = Some(encoding);
                col_def.constraint_order.push(ConstraintType::Encode);
            } else if !matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && self.match_token(TokenType::Format)
            {
                // Teradata: FORMAT 'pattern' (not ClickHouse — FORMAT there is statement-level)
                let format_str = self.expect_string()?;
                col_def.format = Some(format_str);
            } else if self.match_identifier("TITLE") {
                // Teradata: TITLE 'title'
                let title_str = self.expect_string()?;
                col_def.title = Some(title_str);
            } else if self.match_identifier("INLINE") {
                // Teradata: INLINE LENGTH n
                self.match_identifier("LENGTH");
                let length = self.expect_number()?;
                col_def.inline_length = Some(length as u64);
            } else if self.match_identifier("COMPRESS") {
                // Teradata: COMPRESS or COMPRESS (values) or COMPRESS 'value'
                if self.match_token(TokenType::LParen) {
                    let values = self.parse_expression_list()?;
                    self.expect(TokenType::RParen)?;
                    col_def.compress = Some(values);
                } else if self.check(TokenType::String) {
                    // COMPRESS 'value'
                    let value = self.parse_primary()?;
                    col_def.compress = Some(vec![value]);
                } else {
                    // COMPRESS without values
                    col_def.compress = Some(Vec::new());
                }
            } else if self.match_identifier("CHARACTER") {
                // Teradata: CHARACTER SET name
                self.match_token(TokenType::Set);
                let charset = self.expect_identifier_or_keyword()?;
                col_def.character_set = Some(charset);
            } else if self.match_identifier("UPPERCASE") {
                // Teradata: UPPERCASE
                col_def.uppercase = true;
            } else if self.match_identifier("CASESPECIFIC") {
                // Teradata: CASESPECIFIC
                col_def.casespecific = Some(true);
            } else if self.match_text_seq(&["NOT", "FOR", "REPLICATION"]) {
                // TSQL: NOT FOR REPLICATION - skip this modifier (not preserved in output for non-TSQL)
                col_def.not_for_replication = true;
            } else if self.match_token(TokenType::Not) && self.match_identifier("CASESPECIFIC") {
                // Teradata: NOT CASESPECIFIC
                col_def.casespecific = Some(false);
            } else if self.match_keyword("TAG")
                || (self.match_token(TokenType::With) && self.match_keyword("TAG"))
            {
                // Snowflake: TAG (key='value', ...) or WITH TAG (key='value', ...)
                let tags = self.parse_tags()?;
                col_def.constraints.push(ColumnConstraint::Tags(tags));
                col_def.constraint_order.push(ConstraintType::Tags);
            } else if self.match_token(TokenType::As) {
                // Computed column: AS (expression) [STORED|VIRTUAL|PERSISTED] [NOT NULL]
                // TSQL: AS (expression) [PERSISTED] [NOT NULL]
                // MySQL shorthand: AS (expression) [STORED|VIRTUAL]
                // Also: Snowflake External Table virtual column expression
                if self.check(TokenType::LParen) {
                    self.parse_as_computed_column(&mut col_def)?;
                }
            } else if self.match_identifier("CODEC") {
                // ClickHouse: CODEC(LZ4HC(9), ZSTD, DELTA)
                self.expect(TokenType::LParen)?;
                let start = self.current;
                let mut depth = 1;
                while !self.is_at_end() && depth > 0 {
                    if self.check(TokenType::LParen) {
                        depth += 1;
                    }
                    if self.check(TokenType::RParen) {
                        depth -= 1;
                        if depth == 0 {
                            break;
                        }
                    }
                    self.advance();
                }
                let codec_text = self.tokens_to_sql(start, self.current);
                self.expect(TokenType::RParen)?;
                col_def.codec = Some(codec_text);
            } else if self.match_identifier("STATISTICS") {
                // ClickHouse: STATISTICS(tdigest, minmax, uniq, ...)
                self.expect(TokenType::LParen)?;
                let mut depth = 1;
                while !self.is_at_end() && depth > 0 {
                    if self.check(TokenType::LParen) {
                        depth += 1;
                    }
                    if self.check(TokenType::RParen) {
                        depth -= 1;
                        if depth == 0 {
                            break;
                        }
                    }
                    self.advance();
                }
                self.expect(TokenType::RParen)?;
                // Statistics info is stored but we don't need it for transpilation
            } else if self.match_identifier("EPHEMERAL") {
                // ClickHouse: EPHEMERAL [expr] [type]
                // EPHEMERAL can optionally be followed by an expression, then optionally a data type
                if !self.check(TokenType::Comma)
                    && !self.check(TokenType::RParen)
                    && !self.is_at_end()
                    && !self.check_identifier("CODEC")
                    && !self.check_identifier("TTL")
                    && !self.check(TokenType::Comment)
                {
                    let expr = self.parse_bitwise()?.unwrap_or(Expression::Null(Null));
                    col_def.ephemeral = Some(Some(Box::new(expr)));
                    // ClickHouse: type can follow EPHEMERAL expression (e.g., b EPHEMERAL 'a' String)
                    if col_def.no_type
                        && !self.check(TokenType::Comma)
                        && !self.check(TokenType::RParen)
                        && !self.is_at_end()
                        && !self.check_identifier("CODEC")
                        && !self.check_identifier("TTL")
                        && !self.check(TokenType::Comment)
                    {
                        col_def.data_type = self.parse_data_type()?;
                        col_def.no_type = false;
                    }
                } else {
                    col_def.ephemeral = Some(None);
                }
            } else if self.check(TokenType::Materialized) && !self.check_next(TokenType::View) {
                // ClickHouse: MATERIALIZED expr (but not MATERIALIZED VIEW)
                self.advance(); // consume MATERIALIZED
                let expr = self.parse_or()?;
                col_def.materialized_expr = Some(Box::new(expr));
            } else if self.match_identifier("ALIAS") {
                // ClickHouse: ALIAS expr
                let expr = self.parse_or()?;
                col_def.alias_expr = Some(Box::new(expr));
            } else if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && self.check_identifier("EXPRESSION")
            {
                // ClickHouse dictionary column: EXPRESSION expr
                self.advance(); // consume EXPRESSION
                let expr = self.parse_or()?;
                col_def.materialized_expr = Some(Box::new(expr));
            } else if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && (self.match_identifier("HIERARCHICAL")
                || self.match_identifier("IS_OBJECT_ID")
                || self.match_identifier("INJECTIVE")
                || self.match_identifier("BIDIRECTIONAL"))
            {
                // ClickHouse dictionary column attributes: HIERARCHICAL, IS_OBJECT_ID, INJECTIVE, BIDIRECTIONAL
                // These are flag-like attributes with no value, just skip them
            } else if self.match_identifier("TTL") {
                // ClickHouse: TTL expr
                let expr = self.parse_expression()?;
                col_def.ttl_expr = Some(Box::new(expr));
            } else if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && self.check(TokenType::Settings)
                && self.check_next(TokenType::LParen)
            {
                // ClickHouse: SETTINGS (key = value, ...) on column definition
                // Only match parenthesized form; non-parenthesized SETTINGS is statement-level
                self.advance(); // consume SETTINGS
                self.expect(TokenType::LParen)?;
                let mut depth = 1i32;
                while !self.is_at_end() && depth > 0 {
                    if self.check(TokenType::LParen) {
                        depth += 1;
                    }
                    if self.check(TokenType::RParen) {
                        depth -= 1;
                        if depth == 0 {
                            break;
                        }
                    }
                    self.advance();
                }
                self.expect(TokenType::RParen)?;
            } else {
                // Skip unknown column modifiers (DEFERRABLE, CHARACTER SET, etc.)
                // to allow parsing to continue
                if self.skip_column_modifier() {
                    continue;
                }
                break;
            }
        }

        Ok(col_def)
    }

    /// Skip optional column modifiers that we don't need to preserve
    fn skip_column_modifier(&mut self) -> bool {
        // NOT DEFERRABLE, NOT CASESPECIFIC - handle NOT followed by specific keywords
        // (NOT NULL is handled earlier in the constraint loop)
        if self.check(TokenType::Not) {
            // Check what follows NOT
            if self.check_next_identifier("DEFERRABLE")
                || self.check_next_identifier("CASESPECIFIC")
            {
                self.advance(); // consume NOT
                self.advance(); // consume DEFERRABLE/CASESPECIFIC
                return true;
            }
        }
        // DEFERRABLE / NOT DEFERRABLE / INITIALLY DEFERRED / INITIALLY IMMEDIATE
        if self.match_identifier("DEFERRABLE")
            || self.match_identifier("DEFERRED")
            || self.match_identifier("IMMEDIATE")
        {
            return true;
        }
        // CHARACTER SET name
        if self.match_identifier("CHARACTER") {
            self.match_token(TokenType::Set);
            // Consume charset name (can be multiple parts like LATIN, utf8_bin, etc.)
            let _ = self.match_token(TokenType::Var) || self.match_token(TokenType::Identifier);
            return true;
        }
        // UPPERCASE, CASESPECIFIC
        if self.match_identifier("UPPERCASE") || self.match_identifier("CASESPECIFIC") {
            return true;
        }
        // Note: COMPRESS, FORMAT, TITLE, and INLINE LENGTH are now properly parsed and stored in ColumnDef
        false
    }

    /// Parse Teradata-specific table options after CREATE TABLE AS
    /// Returns (with_data, with_statistics, teradata_indexes)
    fn parse_teradata_table_options(&mut self) -> (Option<bool>, Option<bool>, Vec<TeradataIndex>) {
        let mut with_data = None;
        let mut with_statistics = None;
        let mut teradata_indexes = Vec::new();

        loop {
            // WITH DATA [AND STATISTICS] / WITH NO DATA [AND NO STATISTICS]
            if self.match_token(TokenType::With) {
                let no = self.match_token(TokenType::No); // optional NO
                self.match_identifier("DATA");
                with_data = Some(!no); // WITH DATA = true, WITH NO DATA = false
                                       // Optional AND [NO] STATISTICS
                if self.match_token(TokenType::And) {
                    let no_stats = self.match_token(TokenType::No); // optional NO
                    self.match_identifier("STATISTICS");
                    with_statistics = Some(!no_stats); // AND STATISTICS = true, AND NO STATISTICS = false
                }
                continue;
            }
            // NO PRIMARY INDEX
            if self.match_token(TokenType::No) {
                self.match_token(TokenType::PrimaryKey);
                self.match_token(TokenType::Index);
                teradata_indexes.push(TeradataIndex {
                    kind: TeradataIndexKind::NoPrimary,
                    name: None,
                    columns: Vec::new(),
                });
                // Consume optional comma separator between index specs
                self.match_token(TokenType::Comma);
                continue;
            }
            // PRIMARY AMP INDEX / PRIMARY INDEX
            if self.match_token(TokenType::PrimaryKey) {
                let is_amp = self.match_identifier("AMP");
                self.match_token(TokenType::Index);
                // Optional index name
                let name = if self.is_identifier_token() && !self.check(TokenType::LParen) {
                    Some(self.advance().text)
                } else {
                    None
                };
                // Optional column list
                let columns = if self.match_token(TokenType::LParen) {
                    let cols = self.parse_identifier_list_raw();
                    self.match_token(TokenType::RParen);
                    cols
                } else {
                    Vec::new()
                };
                teradata_indexes.push(TeradataIndex {
                    kind: if is_amp {
                        TeradataIndexKind::PrimaryAmp
                    } else {
                        TeradataIndexKind::Primary
                    },
                    name,
                    columns,
                });
                // Consume optional comma separator between index specs
                self.match_token(TokenType::Comma);
                continue;
            }
            // UNIQUE [PRIMARY] INDEX
            if self.match_token(TokenType::Unique) {
                let is_primary = self.match_token(TokenType::PrimaryKey);
                self.match_token(TokenType::Index);
                // Optional index name
                let name = if self.is_identifier_token() {
                    Some(self.advance().text)
                } else {
                    None
                };
                // Optional column list
                let columns = if self.match_token(TokenType::LParen) {
                    let cols = self.parse_identifier_list_raw();
                    self.match_token(TokenType::RParen);
                    cols
                } else {
                    Vec::new()
                };
                teradata_indexes.push(TeradataIndex {
                    kind: if is_primary {
                        TeradataIndexKind::UniquePrimary
                    } else {
                        TeradataIndexKind::Unique
                    },
                    name,
                    columns,
                });
                // Consume optional comma separator between index specs
                self.match_token(TokenType::Comma);
                continue;
            }
            // Plain INDEX (non-primary, non-unique)
            if self.match_token(TokenType::Index) {
                // Optional index name
                let name = if self.is_identifier_token() && !self.check(TokenType::LParen) {
                    Some(self.advance().text)
                } else {
                    None
                };
                // Optional column list
                let columns = if self.match_token(TokenType::LParen) {
                    let cols = self.parse_identifier_list_raw();
                    self.match_token(TokenType::RParen);
                    cols
                } else {
                    Vec::new()
                };
                teradata_indexes.push(TeradataIndex {
                    kind: TeradataIndexKind::Secondary,
                    name,
                    columns,
                });
                // Consume optional comma separator between index specs
                self.match_token(TokenType::Comma);
                continue;
            }
            break;
        }

        (with_data, with_statistics, teradata_indexes)
    }

    /// Parse Teradata table options after name before column list (comma-separated)
    fn parse_teradata_post_name_options(&mut self) -> Vec<String> {
        // Options begin with a comma after the table name.
        if !self.match_token(TokenType::Comma) {
            return Vec::new();
        }

        let mut options = Vec::new();
        let mut current_tokens: Vec<(String, TokenType)> = Vec::new();
        let mut paren_depth = 0;
        let mut in_value = false;

        while !self.is_at_end() {
            if self.check(TokenType::LParen) && paren_depth == 0 {
                if !in_value {
                    // Column list begins
                    break;
                }
                let mut is_terminal = false;
                if let Some((last_text, last_type)) = current_tokens.last() {
                    let last_upper = last_text.to_uppercase();
                    is_terminal = matches!(last_type, TokenType::Number | TokenType::String)
                        || matches!(
                            last_upper.as_str(),
                            "ON" | "OFF"
                                | "DEFAULT"
                                | "NEVER"
                                | "ALWAYS"
                                | "MINIMUM"
                                | "MAXIMUM"
                                | "BYTES"
                                | "KBYTES"
                                | "KILOBYTES"
                                | "PERCENT"
                        );
                }
                if is_terminal {
                    break;
                }
            }

            let token = self.advance();

            match token.token_type {
                TokenType::LParen => {
                    paren_depth += 1;
                }
                TokenType::RParen => {
                    if paren_depth > 0 {
                        paren_depth -= 1;
                        if paren_depth == 0 && in_value {
                            in_value = false;
                        }
                    }
                }
                TokenType::Eq => {
                    if paren_depth == 0 {
                        in_value = true;
                    }
                }
                TokenType::Comma => {
                    if paren_depth == 0 {
                        let option = self.join_teradata_option_tokens(current_tokens);
                        if !option.is_empty() {
                            options.push(option);
                        }
                        current_tokens = Vec::new();
                        in_value = false;
                        continue;
                    }
                }
                _ => {}
            }

            let text = if token.token_type == TokenType::QuotedIdentifier {
                let quote_char = if self.config.dialect == Some(crate::dialects::DialectType::MySQL)
                    || self.config.dialect == Some(crate::dialects::DialectType::SingleStore)
                    || self.config.dialect == Some(crate::dialects::DialectType::Doris)
                    || self.config.dialect == Some(crate::dialects::DialectType::StarRocks)
                {
                    '`'
                } else {
                    '"'
                };
                format!("{}{}{}", quote_char, token.text, quote_char)
            } else if token.token_type == TokenType::String {
                format!("'{}'", token.text)
            } else {
                token.text.clone()
            };

            let mut join_type = token.token_type;
            if join_type == TokenType::Percent && token.text.eq_ignore_ascii_case("PERCENT") {
                // Treat PERCENT as an identifier to preserve spacing (e.g., "1 PERCENT")
                join_type = TokenType::Identifier;
            }
            current_tokens.push((text, join_type));
        }

        if !current_tokens.is_empty() {
            let option = self.join_teradata_option_tokens(current_tokens);
            if !option.is_empty() {
                options.push(option);
            }
        }

        options
    }

    /// Parse identifier list for Teradata indexes, returning raw strings
    fn parse_identifier_list_raw(&mut self) -> Vec<String> {
        let mut identifiers = Vec::new();
        loop {
            if self.is_identifier_token() || self.is_identifier_or_keyword_token() {
                identifiers.push(self.advance().text);
            }
            if !self.match_token(TokenType::Comma) {
                break;
            }
        }
        identifiers
    }

    /// Parse GENERATED column constraint after GENERATED token has been consumed.
    /// Handles three forms:
    /// 1. GENERATED [BY DEFAULT | ALWAYS] AS IDENTITY [...] -> GeneratedAsIdentity
    /// 2. GENERATED ALWAYS AS (expr) [STORED|VIRTUAL] -> ComputedColumn
    /// 3. GENERATED ALWAYS AS ROW START|END [HIDDEN] -> GeneratedAsRow
    fn parse_generated_column_constraint(&mut self, col_def: &mut ColumnDef) -> Result<()> {
        let always;
        let mut on_null = false;

        // BY DEFAULT [ON NULL] | ALWAYS
        if self.match_token(TokenType::By) {
            self.expect(TokenType::Default)?;
            on_null = self.match_keywords(&[TokenType::On, TokenType::Null]);
            always = false;
        } else {
            self.expect(TokenType::Always)?;
            always = true;
        }

        // Expect AS
        self.expect(TokenType::As)?;

        // Check what follows AS
        if self.check(TokenType::Row) {
            // GENERATED ALWAYS AS ROW START|END [HIDDEN]
            self.advance(); // consume ROW
            let start = if self.match_token(TokenType::Start) {
                true
            } else {
                self.expect(TokenType::End)?;
                false
            };
            let hidden = self.match_identifier("HIDDEN");
            col_def
                .constraints
                .push(ColumnConstraint::GeneratedAsRow(GeneratedAsRow {
                    start,
                    hidden,
                }));
            col_def
                .constraint_order
                .push(ConstraintType::GeneratedAsRow);
        } else if self.check(TokenType::Identity) {
            // GENERATED [BY DEFAULT | ALWAYS] AS IDENTITY [(...)]
            self.advance(); // consume IDENTITY

            let mut start = None;
            let mut increment = None;
            let mut minvalue = None;
            let mut maxvalue = None;
            let mut cycle = None;

            // Optional sequence options in parentheses
            if self.match_token(TokenType::LParen) {
                loop {
                    if self.match_token(TokenType::Start) {
                        self.match_token(TokenType::With);
                        start = Some(Box::new(self.parse_unary()?));
                    } else if self.match_token(TokenType::Increment) {
                        self.match_token(TokenType::By);
                        increment = Some(Box::new(self.parse_unary()?));
                    } else if self.match_token(TokenType::Minvalue) {
                        minvalue = Some(Box::new(self.parse_unary()?));
                    } else if self.match_token(TokenType::Maxvalue) {
                        maxvalue = Some(Box::new(self.parse_unary()?));
                    } else if self.match_token(TokenType::Cycle) {
                        cycle = Some(true);
                    } else if self.match_keywords(&[TokenType::No, TokenType::Cycle]) {
                        cycle = Some(false);
                    } else if self.check(TokenType::RParen) {
                        break;
                    } else {
                        self.advance();
                    }
                }
                self.expect(TokenType::RParen)?;
            }

            col_def
                .constraints
                .push(ColumnConstraint::GeneratedAsIdentity(GeneratedAsIdentity {
                    always,
                    on_null,
                    start,
                    increment,
                    minvalue,
                    maxvalue,
                    cycle,
                }));
            col_def
                .constraint_order
                .push(ConstraintType::GeneratedAsIdentity);
        } else if self.check(TokenType::LParen) {
            // GENERATED ALWAYS AS (expr) [STORED|VIRTUAL]
            self.advance(); // consume LParen
            let expr = self.parse_expression()?;
            self.expect(TokenType::RParen)?;

            // Check for STORED or VIRTUAL
            let (persisted, persistence_kind) = if self.match_identifier("STORED") {
                (true, Some("STORED".to_string()))
            } else if self.match_identifier("VIRTUAL") {
                (false, Some("VIRTUAL".to_string()))
            } else {
                (false, None)
            };

            col_def
                .constraints
                .push(ColumnConstraint::ComputedColumn(ComputedColumn {
                    expression: Box::new(expr),
                    persisted,
                    not_null: false,
                    persistence_kind,
                    data_type: None,
                }));
            col_def
                .constraint_order
                .push(ConstraintType::ComputedColumn);
        } else {
            // Fallback: treat as GENERATED AS IDENTITY without explicit IDENTITY keyword
            col_def
                .constraints
                .push(ColumnConstraint::GeneratedAsIdentity(GeneratedAsIdentity {
                    always,
                    on_null,
                    start: None,
                    increment: None,
                    minvalue: None,
                    maxvalue: None,
                    cycle: None,
                }));
            col_def
                .constraint_order
                .push(ConstraintType::GeneratedAsIdentity);
        }
        Ok(())
    }

    /// Parse AS (expr) [STORED|VIRTUAL|PERSISTED] [TYPE] [NOT NULL] for computed columns.
    /// Called after AS token has been consumed and we've confirmed LParen follows.
    /// SingleStore: AS (expr) PERSISTED TYPE NOT NULL
    fn parse_as_computed_column(&mut self, col_def: &mut ColumnDef) -> Result<()> {
        self.expect(TokenType::LParen)?;
        let expr = self.parse_expression()?;
        self.expect(TokenType::RParen)?;

        // Check for STORED, VIRTUAL, or PERSISTED
        let (persisted, persistence_kind) = if self.match_identifier("STORED") {
            (true, Some("STORED".to_string()))
        } else if self.match_identifier("VIRTUAL") {
            (false, Some("VIRTUAL".to_string()))
        } else if self.match_identifier("PERSISTED") {
            (true, Some("PERSISTED".to_string()))
        } else {
            (false, None)
        };

        // For PERSISTED columns, check for optional data type (SingleStore: PERSISTED TYPE NOT NULL)
        // Also check for AUTO keyword for SingleStore: PERSISTED AUTO NOT NULL
        let data_type = if persistence_kind.as_deref() == Some("PERSISTED") {
            // Check if next token looks like a data type (not NOT, not end of input, not comma/rparen)
            if !self.is_at_end()
                && !self.check(TokenType::Not)
                && !self.check(TokenType::Comma)
                && !self.check(TokenType::RParen)
                && !self.check(TokenType::Semicolon)
            {
                let tok = self.peek();
                // Check for AUTO keyword (SingleStore: PERSISTED AUTO)
                if tok.text.to_uppercase() == "AUTO" {
                    self.advance(); // consume AUTO
                    None // AUTO is not a data type, just a modifier
                } else if tok.token_type.is_keyword()
                    || tok.token_type == TokenType::Identifier
                    || tok.token_type == TokenType::Var
                {
                    Some(self.parse_data_type()?)
                } else {
                    None
                }
            } else {
                None
            }
        } else {
            None
        };

        // For PERSISTED columns, check for NOT NULL
        let not_null = if persistence_kind.as_deref() == Some("PERSISTED") {
            self.match_keywords(&[TokenType::Not, TokenType::Null])
        } else {
            false
        };

        col_def
            .constraints
            .push(ColumnConstraint::ComputedColumn(ComputedColumn {
                expression: Box::new(expr),
                persisted,
                not_null,
                persistence_kind,
                data_type,
            }));
        col_def
            .constraint_order
            .push(ConstraintType::ComputedColumn);
        Ok(())
    }

    /// Parse PERIOD FOR SYSTEM_TIME (start_col, end_col) as a table constraint.
    /// Returns None if this is not actually PERIOD FOR SYSTEM_TIME (e.g., just a column named PERIOD).
    fn parse_period_for_system_time_table_constraint(&mut self) -> Result<Option<TableConstraint>> {
        // Save position for possible retreat
        let saved = self.current;

        if self.match_identifier("PERIOD") {
            // Check if followed by FOR SYSTEM_TIME
            if self.match_token(TokenType::For) {
                if self.match_identifier("SYSTEM_TIME") {
                    // Parse (start_col, end_col)
                    self.expect(TokenType::LParen)?;
                    let start_name = self.expect_identifier_or_safe_keyword_with_quoted()?;
                    self.expect(TokenType::Comma)?;
                    let end_name = self.expect_identifier_or_safe_keyword_with_quoted()?;
                    self.expect(TokenType::RParen)?;
                    return Ok(Some(TableConstraint::PeriodForSystemTime {
                        start_col: start_name,
                        end_col: end_name,
                    }));
                }
            }
        }

        // Not PERIOD FOR SYSTEM_TIME, retreat
        self.current = saved;
        Ok(None)
    }

    /// Parse MySQL table options that appear after the closing paren of column definitions.
    /// Handles ENGINE=val, AUTO_INCREMENT=val, DEFAULT CHARSET=val, ROW_FORMAT=val,
    /// COMMENT='val', COLLATE=val, etc.
    fn parse_mysql_table_options(&mut self) -> Vec<(String, String)> {
        let mut options = Vec::new();
        loop {
            // Skip optional commas between options
            self.match_token(TokenType::Comma);

            // DEFAULT CHARSET=val or DEFAULT CHARACTER SET=val
            if self.check(TokenType::Default) {
                let saved = self.current;
                self.advance(); // consume DEFAULT
                if self.check_identifier("CHARSET") || self.check_identifier("CHARACTER") {
                    let is_character = self.check_identifier("CHARACTER");
                    let key_part = self.advance().text.to_uppercase();
                    if is_character {
                        // CHARACTER SET
                        self.match_token(TokenType::Set);
                    }
                    if self.match_token(TokenType::Eq) {
                        let value = if self.check(TokenType::String) {
                            let v = format!("'{}'", self.peek().text);
                            self.advance();
                            v
                        } else if self.is_identifier_token()
                            || self.is_safe_keyword_as_identifier()
                            || self.check(TokenType::Number)
                        {
                            self.advance().text
                        } else {
                            self.current = saved;
                            break;
                        };
                        // Normalize CHARSET -> CHARACTER SET
                        let key = if is_character || key_part == "CHARSET" {
                            "DEFAULT CHARACTER SET".to_string()
                        } else {
                            format!("DEFAULT {}", key_part)
                        };
                        options.push((key, value));
                        continue;
                    }
                }
                self.current = saved;
                break;
            }

            // ENGINE=val, AUTO_INCREMENT=val, ROW_FORMAT=val, COLLATE=val, KEY_BLOCK_SIZE=val
            let is_known_option = self.check_identifier("ENGINE")
                || self.check(TokenType::AutoIncrement)
                || self.check_identifier("ROW_FORMAT")
                || self.check(TokenType::Collate)
                || self.check_identifier("KEY_BLOCK_SIZE")
                || self.check_identifier("PACK_KEYS")
                || self.check_identifier("STATS_AUTO_RECALC")
                || self.check_identifier("STATS_PERSISTENT")
                || self.check_identifier("STATS_SAMPLE_PAGES")
                || self.check_identifier("MAX_ROWS")
                || self.check_identifier("MIN_ROWS")
                || self.check_identifier("CHECKSUM")
                || self.check_identifier("DELAY_KEY_WRITE")
                || self.check_identifier("COMPRESSION")
                || self.check_identifier("CONNECTION")
                || self.check_identifier("TABLESPACE")
                || self.check_identifier("ENCRYPTION");

            if is_known_option {
                let key = self.advance().text.to_uppercase();
                if self.match_token(TokenType::Eq) {
                    let value = if self.check(TokenType::String) {
                        let v = format!("'{}'", self.peek().text);
                        self.advance();
                        v
                    } else if self.check(TokenType::Number) {
                        self.advance().text
                    } else if self.is_identifier_token() || self.is_safe_keyword_as_identifier() {
                        self.advance().text
                    } else {
                        break;
                    };
                    options.push((key, value));
                    continue;
                }
                break;
            }

            // COMMENT='val' (Comment is a keyword token type)
            if self.check(TokenType::Comment) {
                let saved = self.current;
                self.advance(); // consume COMMENT
                if self.match_token(TokenType::Eq) {
                    if self.check(TokenType::String) {
                        let v = format!("'{}'", self.peek().text);
                        self.advance();
                        options.push(("COMMENT".to_string(), v));
                        continue;
                    }
                } else if self.check(TokenType::String) {
                    let v = format!("'{}'", self.peek().text);
                    self.advance();
                    options.push(("COMMENT".to_string(), v));
                    continue;
                }
                self.current = saved;
                break;
            }

            // CHARACTER SET=val or CHARSET=val (without DEFAULT prefix)
            if self.check_identifier("CHARACTER") || self.check_identifier("CHARSET") {
                let saved = self.current;
                let is_character = self.check_identifier("CHARACTER");
                self.advance(); // consume CHARACTER or CHARSET
                if is_character {
                    // CHARACTER SET
                    if !self.match_token(TokenType::Set) {
                        self.current = saved;
                        break;
                    }
                }
                if self.match_token(TokenType::Eq) {
                    let value = if self.check(TokenType::String) {
                        let v = format!("'{}'", self.peek().text);
                        self.advance();
                        v
                    } else if self.is_identifier_token()
                        || self.is_safe_keyword_as_identifier()
                        || self.check(TokenType::Number)
                    {
                        self.advance().text
                    } else {
                        self.current = saved;
                        break;
                    };
                    options.push(("CHARACTER SET".to_string(), value));
                    continue;
                }
                self.current = saved;
                break;
            }

            break;
        }
        options
    }

    /// Parse Hive-specific table properties that appear after column definitions.
    /// Handles: ROW FORMAT (SERDE/DELIMITED), STORED AS/BY, LOCATION, TBLPROPERTIES
    fn parse_hive_table_properties(&mut self) -> Result<Vec<Expression>> {
        let mut properties = Vec::new();

        loop {
            // ROW FORMAT SERDE 'class' [WITH SERDEPROPERTIES (...)]
            // ROW FORMAT DELIMITED [FIELDS TERMINATED BY ...] [...]
            if self.match_token(TokenType::Row) {
                if let Some(row_format) = self.parse_row()? {
                    properties.push(row_format);
                    continue;
                }
            }

            // STORED AS INPUTFORMAT 'input' OUTPUTFORMAT 'output'
            // STORED AS format_name
            // STORED BY 'storage_handler_class'
            if self.match_identifier("STORED") {
                if self.match_token(TokenType::By) {
                    // STORED BY 'storage_handler_class'
                    let handler = self.parse_string()?.unwrap_or(Expression::Null(Null));
                    properties.push(Expression::StorageHandlerProperty(Box::new(
                        StorageHandlerProperty {
                            this: Box::new(handler),
                        },
                    )));
                    continue;
                } else if self.match_token(TokenType::As) {
                    // STORED AS INPUTFORMAT 'x' OUTPUTFORMAT 'y' or STORED AS format
                    if self.match_token(TokenType::InputFormat) {
                        let input_format = self.parse_string()?;
                        let output_format = if self.match_identifier("OUTPUTFORMAT") {
                            self.parse_string()?
                        } else {
                            None
                        };
                        // Use InputOutputFormat inside FileFormatProperty.this
                        let io_format =
                            Expression::InputOutputFormat(Box::new(InputOutputFormat {
                                input_format: input_format.map(Box::new),
                                output_format: output_format.map(Box::new),
                            }));
                        properties.push(Expression::FileFormatProperty(Box::new(
                            FileFormatProperty {
                                this: Some(Box::new(io_format)),
                                expressions: vec![],
                                hive_format: Some(Box::new(Expression::Boolean(BooleanLiteral {
                                    value: true,
                                }))),
                            },
                        )));
                        continue;
                    } else {
                        // STORED AS format_name (e.g., STORED AS TEXTFILE, STORED AS ORC)
                        let format = if self.check(TokenType::String) {
                            Expression::Literal(Literal::String(self.advance().text.clone()))
                        } else if self.is_identifier_token() || self.is_safe_keyword_as_identifier()
                        {
                            Expression::Identifier(Identifier::new(self.advance().text.clone()))
                        } else {
                            break;
                        };
                        properties.push(Expression::FileFormatProperty(Box::new(
                            FileFormatProperty {
                                this: Some(Box::new(format)),
                                expressions: vec![],
                                hive_format: Some(Box::new(Expression::Boolean(BooleanLiteral {
                                    value: true,
                                }))),
                            },
                        )));
                        continue;
                    }
                }
            }

            // USING format_name (Databricks/Spark) e.g., USING DELTA, USING PARQUET
            // This is similar to STORED AS but uses different syntax
            if self.match_token(TokenType::Using) {
                // Parse the format name (e.g., DELTA, PARQUET, ICEBERG, etc.)
                let format = if self.check(TokenType::String) {
                    Expression::Literal(Literal::String(self.advance().text.clone()))
                } else if self.is_identifier_token() || self.is_safe_keyword_as_identifier() {
                    Expression::Identifier(Identifier::new(self.advance().text.clone()))
                } else {
                    break;
                };
                // Create FileFormatProperty WITHOUT hive_format to signal USING syntax
                properties.push(Expression::FileFormatProperty(Box::new(
                    FileFormatProperty {
                        this: Some(Box::new(format)),
                        expressions: vec![],
                        hive_format: None, // None indicates USING syntax (not STORED AS)
                    },
                )));
                continue;
            }

            // LOCATION 'path'
            if self.match_identifier("LOCATION") {
                let path = self.parse_string()?.unwrap_or(Expression::Null(Null));
                properties.push(Expression::LocationProperty(Box::new(LocationProperty {
                    this: Box::new(path),
                })));
                continue;
            }

            // TBLPROPERTIES ('key'='value', ...)
            if self.match_identifier("TBLPROPERTIES") {
                // Parse the property list manually since parse_property doesn't handle key=value
                self.expect(TokenType::LParen)?;
                let mut prop_exprs = Vec::new();
                loop {
                    if self.check(TokenType::RParen) {
                        break;
                    }
                    // Parse 'key'='value' or key=value
                    let key = self.parse_primary()?;
                    if self.match_token(TokenType::Eq) {
                        let value = self.parse_primary()?;
                        prop_exprs.push(Expression::Eq(Box::new(BinaryOp::new(key, value))));
                    } else {
                        prop_exprs.push(key);
                    }
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
                self.expect(TokenType::RParen)?;
                properties.push(Expression::Properties(Box::new(Properties {
                    expressions: prop_exprs,
                })));
                continue;
            }

            // DISTRIBUTED BY HASH (col1, col2) [BUCKETS n] (StarRocks/Doris)
            if self.match_identifier("DISTRIBUTED") {
                if let Some(dist_prop) = self.parse_distributed_property()? {
                    properties.push(dist_prop);
                    continue;
                }
            }

            // CLUSTERED BY (col, col, ...) [SORTED BY (col, col, ...)] INTO n BUCKETS (Hive/Athena)
            if self.match_identifier("CLUSTERED") {
                self.expect(TokenType::By)?;
                self.expect(TokenType::LParen)?;
                let expressions = self.parse_expression_list()?;
                self.expect(TokenType::RParen)?;

                // Optional SORTED BY (col, col, ...)
                let sorted_by = if self.match_identifier("SORTED") {
                    self.expect(TokenType::By)?;
                    self.expect(TokenType::LParen)?;
                    let sorted_exprs = self.parse_expression_list()?;
                    self.expect(TokenType::RParen)?;
                    Some(Box::new(Expression::Tuple(Box::new(Tuple {
                        expressions: sorted_exprs,
                    }))))
                } else {
                    None
                };

                // INTO n BUCKETS
                let buckets = if self.match_token(TokenType::Into) {
                    let num = self.parse_expression()?;
                    if !self.match_identifier("BUCKETS") {
                        return Err(self.parse_error("Expected BUCKETS after INTO <n>"));
                    }
                    Some(Box::new(num))
                } else {
                    None
                };

                properties.push(Expression::ClusteredByProperty(Box::new(
                    ClusteredByProperty {
                        expressions,
                        sorted_by,
                        buckets,
                    },
                )));
                continue;
            }

            // PARTITIONED BY (col, col, ...) or PARTITIONED BY (col, BUCKET(n, col), ...) (Hive/Athena/Iceberg)
            if self.match_identifier("PARTITIONED") {
                self.expect(TokenType::By)?;
                self.expect(TokenType::LParen)?;

                let mut partition_exprs = Vec::new();
                loop {
                    if self.check(TokenType::RParen) {
                        break;
                    }

                    // Check for transform functions like BUCKET(n, col), TRUNCATE(n, col), etc.
                    if self.check_identifier("BUCKET") || self.check_identifier("TRUNCATE") {
                        let func_name = self.advance().text.clone();
                        self.expect(TokenType::LParen)?;
                        let args = self.parse_expression_list()?;
                        self.expect(TokenType::RParen)?;

                        // Create a Function expression for BUCKET/TRUNCATE
                        partition_exprs.push(Expression::Function(Box::new(Function {
                            name: func_name,
                            args,
                            distinct: false,
                            trailing_comments: Vec::new(),
                            use_bracket_syntax: false,
                            no_parens: false,
                            quoted: false,
                            span: None,
                            inferred_type: None,
                        })));
                    } else {
                        // Try to parse as column definition (name data_type) for Hive-style partitioned by
                        // e.g., PARTITIONED BY (y INT, z STRING)
                        let saved_pos = self.current;
                        let mut parsed_as_column = false;
                        // Allow type keywords (like DATE, TIMESTAMP) as column names in PARTITIONED BY
                        if self.check(TokenType::Var)
                            || self.check(TokenType::Identifier)
                            || self.check(TokenType::Date)
                            || self.check(TokenType::Timestamp)
                            || self.check(TokenType::Int)
                            || self.check(TokenType::BigInt)
                            || self.check(TokenType::SmallInt)
                            || self.check(TokenType::TinyInt)
                            || self.check(TokenType::Float)
                            || self.check(TokenType::Double)
                            || self.check(TokenType::Boolean)
                        {
                            let col_name = self.advance().text.clone();
                            // Check if next token looks like a data type
                            if self.check(TokenType::Var)
                                || self.check(TokenType::Identifier)
                                || self.check(TokenType::Int)
                                || self.check(TokenType::BigInt)
                                || self.check(TokenType::SmallInt)
                                || self.check(TokenType::TinyInt)
                                || self.check(TokenType::Float)
                                || self.check(TokenType::Double)
                                || self.check(TokenType::Boolean)
                                || self.check(TokenType::Date)
                                || self.check(TokenType::Timestamp)
                            {
                                let type_text = self.peek().text.to_uppercase();
                                let is_type = matches!(
                                    type_text.as_str(),
                                    "INT"
                                        | "INTEGER"
                                        | "BIGINT"
                                        | "SMALLINT"
                                        | "TINYINT"
                                        | "FLOAT"
                                        | "DOUBLE"
                                        | "DECIMAL"
                                        | "NUMERIC"
                                        | "STRING"
                                        | "VARCHAR"
                                        | "CHAR"
                                        | "BINARY"
                                        | "BOOLEAN"
                                        | "DATE"
                                        | "TIMESTAMP"
                                        | "DATETIME"
                                        | "ARRAY"
                                        | "MAP"
                                        | "STRUCT"
                                );
                                if is_type {
                                    // Parse as column definition
                                    let data_type = self.parse_data_type()?;
                                    // Store as ColumnDef expression
                                    partition_exprs.push(Expression::ColumnDef(Box::new(
                                        crate::expressions::ColumnDef::new(col_name, data_type),
                                    )));
                                    parsed_as_column = true;
                                }
                            }
                        }
                        if !parsed_as_column {
                            // Backtrack and parse as regular expression
                            self.current = saved_pos;
                            partition_exprs.push(self.parse_expression()?);
                        }
                    }

                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
                self.expect(TokenType::RParen)?;

                properties.push(Expression::PartitionedByProperty(Box::new(
                    PartitionedByProperty {
                        this: Box::new(Expression::Tuple(Box::new(Tuple {
                            expressions: partition_exprs,
                        }))),
                    },
                )));
                continue;
            }

            // No more Hive properties
            break;
        }

        Ok(properties)
    }

    /// Parse table-level properties that appear after the closing paren of column definitions.
    /// Currently handles TSQL WITH(SYSTEM_VERSIONING=ON(...)).
    fn parse_post_table_properties(&mut self) -> Result<Vec<Expression>> {
        let mut properties = Vec::new();

        // Doris/StarRocks: UNIQUE KEY (cols) or DUPLICATE KEY (cols) after column definitions
        // These are table key properties that define the distribution/sort key
        let is_doris_starrocks = matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::Doris)
                | Some(crate::dialects::DialectType::StarRocks)
        );
        if is_doris_starrocks {
            // UNIQUE KEY (c1, c2, ...) - defines unique key columns
            if self.match_text_seq(&["UNIQUE", "KEY"]) {
                let exprs = self.parse_composite_key_expressions()?;
                properties.push(Expression::UniqueKeyProperty(Box::new(
                    crate::expressions::UniqueKeyProperty { expressions: exprs },
                )));
            }
            // DUPLICATE KEY (c1, c2, ...) - defines duplicate key columns
            else if self.match_text_seq(&["DUPLICATE", "KEY"]) {
                let exprs = self.parse_composite_key_expressions()?;
                properties.push(Expression::DuplicateKeyProperty(Box::new(
                    crate::expressions::DuplicateKeyProperty { expressions: exprs },
                )));
            }

            // DISTRIBUTED BY HASH (col1, col2) [BUCKETS n] - comes after UNIQUE KEY / DUPLICATE KEY
            if self.match_identifier("DISTRIBUTED") {
                if let Some(dist_prop) = self.parse_distributed_property()? {
                    properties.push(dist_prop);
                }
            }

            // PROPERTIES ('key'='value', ...) - comes after DISTRIBUTED BY
            if self.match_identifier("PROPERTIES") {
                let props = self.parse_options_list()?;
                if !props.is_empty() {
                    properties.push(Expression::Properties(Box::new(Properties {
                        expressions: props,
                    })));
                }
            }
        }

        // Check for WITH( that might contain SYSTEM_VERSIONING
        // We need to be careful not to consume a WITH that is meant for WITH properties
        // or other purposes. We only handle WITH(SYSTEM_VERSIONING=...) here.
        if self.check(TokenType::With) {
            // Look ahead: WITH followed by ( followed by SYSTEM_VERSIONING
            let saved = self.current;
            if self.match_token(TokenType::With) {
                if self.match_token(TokenType::LParen) {
                    if self.check_identifier("SYSTEM_VERSIONING") {
                        self.advance(); // consume SYSTEM_VERSIONING
                        self.expect(TokenType::Eq)?;

                        let on = if self.match_token(TokenType::On) {
                            true
                        } else if self.match_identifier("OFF") {
                            false
                        } else {
                            return Err(
                                self.parse_error("Expected ON or OFF after SYSTEM_VERSIONING=")
                            );
                        };

                        let mut history_table = None;
                        let mut data_consistency = None;

                        // Optional parameters: ON(HISTORY_TABLE=..., DATA_CONSISTENCY_CHECK=...)
                        if on && self.match_token(TokenType::LParen) {
                            loop {
                                if self.check(TokenType::RParen) {
                                    break;
                                }
                                if self.match_identifier("HISTORY_TABLE") {
                                    self.expect(TokenType::Eq)?;
                                    // Parse table reference (could be [dbo].[table])
                                    let table_ref = self.parse_table_ref()?;
                                    history_table = Some(Expression::Table(table_ref));
                                } else if self.match_identifier("DATA_CONSISTENCY_CHECK") {
                                    self.expect(TokenType::Eq)?;
                                    let val = self.expect_identifier_or_keyword()?;
                                    data_consistency = Some(Expression::Identifier(
                                        crate::expressions::Identifier::new(val),
                                    ));
                                } else if self.check(TokenType::RParen) {
                                    break;
                                } else {
                                    self.advance();
                                }
                                self.match_token(TokenType::Comma);
                            }
                            self.expect(TokenType::RParen)?;
                        }

                        self.expect(TokenType::RParen)?; // close WITH(...)

                        properties.push(Expression::WithSystemVersioningProperty(Box::new(
                            WithSystemVersioningProperty {
                                on: if on {
                                    Some(Box::new(Expression::Boolean(
                                        crate::expressions::BooleanLiteral { value: true },
                                    )))
                                } else {
                                    None
                                },
                                this: history_table.map(Box::new),
                                data_consistency: data_consistency.map(Box::new),
                                retention_period: None,
                                with_: Some(Box::new(Expression::Boolean(
                                    crate::expressions::BooleanLiteral { value: true },
                                ))),
                            },
                        )));
                    } else {
                        // Not SYSTEM_VERSIONING, retreat
                        self.current = saved;
                    }
                } else {
                    // Not WITH(...), retreat
                    self.current = saved;
                }
            }
        }

        Ok(properties)
    }

    /// Parse composite key expressions for UNIQUE KEY (cols) or DUPLICATE KEY (cols)
    /// Returns a vector of column identifiers
    fn parse_composite_key_expressions(&mut self) -> Result<Vec<Expression>> {
        self.expect(TokenType::LParen)?;
        let mut expressions = Vec::new();
        loop {
            if let Some(id) = self.parse_id_var()? {
                expressions.push(id);
            } else {
                break;
            }
            if !self.match_token(TokenType::Comma) {
                break;
            }
        }
        self.expect(TokenType::RParen)?;
        Ok(expressions)
    }

    /// Parse a table-level constraint
    fn parse_table_constraint(&mut self) -> Result<TableConstraint> {
        // Optional constraint name
        let name = if self.match_token(TokenType::Constraint) {
            // Use safe keyword version to accept keywords as constraint names (e.g., CONSTRAINT identity CHECK ...)
            Some(self.expect_identifier_or_safe_keyword_with_quoted()?)
        } else {
            None
        };

        self.parse_constraint_definition(name)
    }

    /// Parse constraint definition (after optional CONSTRAINT name)
    fn parse_constraint_definition(&mut self, name: Option<Identifier>) -> Result<TableConstraint> {
        if self.match_keywords(&[TokenType::PrimaryKey, TokenType::Key]) {
            // PRIMARY KEY [CLUSTERED|NONCLUSTERED] [name] (col1, col2) [INCLUDE (col3, col4)]
            // MySQL allows: PRIMARY KEY pk_name (col1, col2)
            // TSQL allows: PRIMARY KEY CLUSTERED (col1, col2)

            // Check for TSQL CLUSTERED/NONCLUSTERED modifier
            let clustered = if self.check_identifier("CLUSTERED") {
                self.advance();
                Some("CLUSTERED".to_string())
            } else if self.check_identifier("NONCLUSTERED") {
                self.advance();
                Some("NONCLUSTERED".to_string())
            } else {
                None
            };

            let actual_name = if name.is_none() && !self.check(TokenType::LParen) {
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) {
                    // ClickHouse: PRIMARY KEY col (without parentheses)
                    None
                } else if self.is_identifier_token() || self.check(TokenType::QuotedIdentifier) {
                    Some(self.expect_identifier_with_quoted()?)
                } else if self.check(TokenType::String)
                    && matches!(
                        self.config.dialect,
                        Some(crate::dialects::DialectType::MySQL)
                    )
                {
                    // MySQL: double-quoted strings can be used as constraint names
                    // e.g., PRIMARY KEY "pk_name" (id) -> PRIMARY KEY `pk_name` (id)
                    let s = self.advance().text.clone();
                    Some(Identifier {
                        name: s,
                        quoted: true,
                        trailing_comments: Vec::new(),
                        span: None,
                    })
                } else {
                    None
                }
            } else {
                name.clone()
            };
            // ClickHouse: PRIMARY KEY col without parens — parse single column
            let columns = if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && !self.check(TokenType::LParen)
                && (self.is_identifier_token() || self.is_safe_keyword_as_identifier())
            {
                let col_name = self.expect_identifier_or_keyword_with_quoted()?;
                vec![col_name]
            } else {
                self.expect(TokenType::LParen)?;
                // ClickHouse: allow empty PRIMARY KEY ()
                let cols = if self.check(TokenType::RParen) {
                    Vec::new()
                } else if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) {
                    // ClickHouse: PRIMARY KEY(v1, gcd(v1, v2)) - expressions allowed
                    let mut exprs = Vec::new();
                    loop {
                        let expr = self.parse_expression()?;
                        let name = self.expression_to_sql(&expr);
                        exprs.push(Identifier::new(name));
                        if !self.match_token(TokenType::Comma) {
                            break;
                        }
                    }
                    exprs
                } else {
                    self.parse_index_identifier_list()?
                };
                self.expect(TokenType::RParen)?;
                cols
            };
            // Parse optional INCLUDE (columns)
            let include_columns = if self.match_identifier("INCLUDE") {
                self.expect(TokenType::LParen)?;
                let cols = self.parse_identifier_list()?;
                self.expect(TokenType::RParen)?;
                cols
            } else {
                Vec::new()
            };
            // Parse optional constraint modifiers (ENFORCED, DEFERRABLE, etc.)
            let mut modifiers = self.parse_constraint_modifiers();
            modifiers.clustered = clustered;
            let has_constraint_keyword = name.is_some();
            Ok(TableConstraint::PrimaryKey {
                name: actual_name.or(name),
                columns,
                include_columns,
                modifiers,
                has_constraint_keyword,
            })
        } else if self.match_token(TokenType::Unique) {
            // UNIQUE [CLUSTERED|NONCLUSTERED] [KEY|INDEX] [NULLS NOT DISTINCT] [name] (col1, col2) or UNIQUE column_name
            // MySQL allows: UNIQUE KEY name (cols), UNIQUE INDEX name (cols), UNIQUE (cols)
            // TSQL allows: UNIQUE CLUSTERED (cols)
            // PostgreSQL 15+: UNIQUE NULLS NOT DISTINCT (cols)

            // Check for TSQL CLUSTERED/NONCLUSTERED modifier
            let clustered = if self.check_identifier("CLUSTERED") {
                self.advance();
                Some("CLUSTERED".to_string())
            } else if self.check_identifier("NONCLUSTERED") {
                self.advance();
                Some("NONCLUSTERED".to_string())
            } else {
                None
            };

            let use_key_keyword =
                self.match_token(TokenType::Key) || self.match_token(TokenType::Index);

            // Check for NULLS NOT DISTINCT (PostgreSQL 15+ feature)
            let nulls_not_distinct = self.match_text_seq(&["NULLS", "NOT", "DISTINCT"]);

            // Check for optional constraint name (before columns)
            let actual_name = if name.is_none()
                && self.is_identifier_token()
                && !self.check_next(TokenType::Comma)
            {
                // Name might be here: UNIQUE KEY idx_name (cols)
                if self.check_next(TokenType::LParen) {
                    Some(self.expect_identifier_with_quoted()?)
                } else {
                    None
                }
            } else {
                name.clone()
            };

            if self.match_token(TokenType::LParen) {
                let columns = self.parse_index_identifier_list()?;
                self.expect(TokenType::RParen)?;
                let mut modifiers = self.parse_constraint_modifiers();
                modifiers.clustered = clustered;
                if use_key_keyword {
                    // UNIQUE KEY/INDEX - use Index constraint type with UNIQUE kind
                    Ok(TableConstraint::Index {
                        name: actual_name.or(name),
                        columns,
                        kind: Some("UNIQUE".to_string()),
                        modifiers,
                        use_key_keyword,
                        expression: None,
                        index_type: None,
                        granularity: None,
                    })
                } else {
                    let has_constraint_keyword = name.is_some();
                    Ok(TableConstraint::Unique {
                        name: actual_name.or(name),
                        columns,
                        columns_parenthesized: true,
                        modifiers,
                        has_constraint_keyword,
                        nulls_not_distinct,
                    })
                }
            } else {
                // Single column unique (for ALTER TABLE ADD CONSTRAINT name UNIQUE colname)
                let col_name = self.expect_identifier()?;
                let mut modifiers = self.parse_constraint_modifiers();
                modifiers.clustered = clustered;
                let has_constraint_keyword = name.is_some();
                Ok(TableConstraint::Unique {
                    name: actual_name.or(name),
                    columns: vec![Identifier::new(col_name)],
                    columns_parenthesized: false,
                    modifiers,
                    has_constraint_keyword,
                    nulls_not_distinct,
                })
            }
        } else if self.match_keywords(&[TokenType::ForeignKey, TokenType::Key]) {
            // FOREIGN KEY (col1) [REFERENCES other_table(col2)] [ON DELETE ...] [ON UPDATE ...]
            self.expect(TokenType::LParen)?;
            let columns = self.parse_identifier_list()?;
            self.expect(TokenType::RParen)?;
            if self.match_token(TokenType::References) {
                let references = self.parse_foreign_key_ref()?;
                let modifiers = self.parse_constraint_modifiers();
                Ok(TableConstraint::ForeignKey {
                    name,
                    columns,
                    references: Some(references),
                    on_delete: None,
                    on_update: None,
                    modifiers,
                })
            } else {
                // No REFERENCES - parse optional ON DELETE/ON UPDATE directly
                let mut on_delete = None;
                let mut on_update = None;
                loop {
                    if self.check(TokenType::On) {
                        let saved = self.current;
                        self.advance(); // consume ON
                        if self.match_token(TokenType::Delete) {
                            on_delete = Some(self.parse_referential_action()?);
                        } else if self.match_token(TokenType::Update) {
                            on_update = Some(self.parse_referential_action()?);
                        } else {
                            self.current = saved;
                            break;
                        }
                    } else {
                        break;
                    }
                }
                let modifiers = self.parse_constraint_modifiers();
                Ok(TableConstraint::ForeignKey {
                    name,
                    columns,
                    references: None,
                    on_delete,
                    on_update,
                    modifiers,
                })
            }
        } else if self.match_token(TokenType::Check) {
            // CHECK (expression) or CHECK (SELECT ...) or ClickHouse: CHECK expression (without parens)
            let expression = if self.match_token(TokenType::LParen) {
                let expr = if self.check(TokenType::Select) || self.check(TokenType::With) {
                    // Subquery in CHECK constraint
                    let stmt = self.parse_statement()?;
                    Expression::Subquery(Box::new(Subquery {
                        this: stmt,
                        alias: None,
                        column_aliases: Vec::new(),
                        order_by: None,
                        limit: None,
                        offset: None,
                        distribute_by: None,
                        sort_by: None,
                        cluster_by: None,
                        lateral: false,
                        modifiers_inside: false,
                        trailing_comments: Vec::new(),
                        inferred_type: None,
                    }))
                } else {
                    self.parse_expression()?
                };
                self.expect(TokenType::RParen)?;
                expr
            } else if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) {
                self.parse_or()?
            } else {
                self.expect(TokenType::LParen)?;
                unreachable!()
            };
            let modifiers = self.parse_constraint_modifiers();
            Ok(TableConstraint::Check {
                name,
                expression,
                modifiers,
            })
        } else if self.match_token(TokenType::Exclude) {
            // PostgreSQL EXCLUDE constraint
            // EXCLUDE [USING method] (element WITH operator, ...) [INCLUDE (cols)] [WHERE (expr)] [WITH (params)]
            let using = if self.match_token(TokenType::Using) {
                Some(self.expect_identifier()?)
            } else {
                None
            };

            self.expect(TokenType::LParen)?;
            let mut elements = Vec::new();
            loop {
                // Parse element expression: may be a function call like INT4RANGE(vid, nid)
                // or column name possibly with operator class, ASC/DESC, NULLS FIRST/LAST
                let mut expr_parts = Vec::new();
                let mut paren_depth = 0;
                while !self.is_at_end() {
                    if self.check(TokenType::LParen) {
                        paren_depth += 1;
                        expr_parts.push(self.advance().text);
                    } else if self.check(TokenType::RParen) {
                        if paren_depth == 0 {
                            break;
                        }
                        paren_depth -= 1;
                        expr_parts.push(self.advance().text);
                    } else if paren_depth == 0 && self.check(TokenType::With) {
                        break;
                    } else if self.check(TokenType::String) {
                        // Preserve string literal quotes
                        let token = self.advance();
                        expr_parts.push(format!("'{}'", token.text));
                    } else {
                        expr_parts.push(self.advance().text);
                    }
                }
                let expression = expr_parts
                    .join(" ")
                    .replace(" (", "(")
                    .replace(" )", ")")
                    .replace("( ", "(")
                    .replace(" ,", ",");

                // Parse WITH operator
                self.expect(TokenType::With)?;
                let operator = self.advance().text.clone();

                elements.push(ExcludeElement {
                    expression,
                    operator,
                });

                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            self.expect(TokenType::RParen)?;

            // Parse optional INCLUDE (columns)
            let include_columns = if self.match_identifier("INCLUDE") {
                self.expect(TokenType::LParen)?;
                let cols = self.parse_identifier_list()?;
                self.expect(TokenType::RParen)?;
                cols
            } else {
                Vec::new()
            };

            // Parse optional WITH (storage_parameters)
            let with_params = if self.match_token(TokenType::With) {
                self.expect(TokenType::LParen)?;
                let mut params = Vec::new();
                loop {
                    let key = self.expect_identifier()?;
                    self.expect(TokenType::Eq)?;
                    let val = self.advance().text.clone();
                    params.push((key, val));
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
                self.expect(TokenType::RParen)?;
                params
            } else {
                Vec::new()
            };

            // Parse optional USING INDEX TABLESPACE tablespace_name
            let using_index_tablespace =
                if self.check(TokenType::Using) && self.check_next(TokenType::Index) {
                    self.advance(); // consume USING
                    self.advance(); // consume INDEX
                    if self.match_identifier("TABLESPACE") {
                        Some(self.expect_identifier()?)
                    } else {
                        None
                    }
                } else {
                    None
                };

            // Parse optional WHERE clause
            let where_clause = if self.match_token(TokenType::Where) {
                self.expect(TokenType::LParen)?;
                let expr = self.parse_expression()?;
                self.expect(TokenType::RParen)?;
                Some(Box::new(expr))
            } else {
                None
            };

            let modifiers = self.parse_constraint_modifiers();
            Ok(TableConstraint::Exclude {
                name,
                using,
                elements,
                include_columns,
                where_clause,
                with_params,
                using_index_tablespace,
                modifiers,
            })
        } else if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) && self.check_identifier("ASSUME")
        {
            // ClickHouse: CONSTRAINT name ASSUME expression
            // Used for query optimization assumptions — store as CHECK constraint
            self.advance(); // consume ASSUME
            let expr = self.parse_expression()?;
            Ok(TableConstraint::Check {
                name,
                expression: expr,
                modifiers: Default::default(),
            })
        } else {
            Err(self.parse_error("Expected PRIMARY KEY, UNIQUE, FOREIGN KEY, CHECK, or EXCLUDE"))
        }
    }

    /// Parse INDEX/KEY table constraint for MySQL
    /// Syntax: [FULLTEXT|SPATIAL] {INDEX|KEY} [name] [USING {BTREE|HASH}] (columns)
    ///     or: [FULLTEXT|SPATIAL] {INDEX|KEY} [USING {BTREE|HASH}] (columns)  -- no name
    fn parse_index_table_constraint(&mut self) -> Result<TableConstraint> {
        // Check for FULLTEXT or SPATIAL prefix
        let kind = if self.match_identifier("FULLTEXT") {
            Some("FULLTEXT".to_string())
        } else if self.match_identifier("SPATIAL") {
            Some("SPATIAL".to_string())
        } else {
            None
        };

        // Consume INDEX or KEY keyword, track which was used
        let use_key_keyword = if self.match_token(TokenType::Key) {
            true
        } else {
            self.match_token(TokenType::Index);
            false
        };

        // Check for USING before index name (MySQL allows: INDEX USING BTREE (col))
        let early_using = if self.check(TokenType::Using) {
            self.match_token(TokenType::Using);
            if self.match_identifier("BTREE") {
                Some("BTREE".to_string())
            } else if self.match_identifier("HASH") {
                Some("HASH".to_string())
            } else {
                None
            }
        } else {
            None
        };

        // Optional index name (only if next token is not LParen or Using)
        let name = if !self.check(TokenType::LParen)
            && !self.check(TokenType::Using)
            && self.is_identifier_token()
        {
            Some(Identifier::new(self.advance().text))
        } else {
            None
        };

        // Check for USING after index name (if not already parsed)
        let late_using = if early_using.is_none() && self.match_token(TokenType::Using) {
            if self.match_identifier("BTREE") {
                Some("BTREE".to_string())
            } else if self.match_identifier("HASH") {
                Some("HASH".to_string())
            } else {
                None
            }
        } else {
            None
        };

        // Parse columns (with optional prefix length and DESC)
        self.expect(TokenType::LParen)?;
        let columns = self.parse_index_identifier_list()?;
        self.expect(TokenType::RParen)?;

        // Parse optional constraint modifiers (USING after columns, COMMENT, etc.)
        let mut modifiers = self.parse_constraint_modifiers();

        // Set the using value from wherever we found it
        // Both early_using (before name) and late_using (after name, before columns) mean USING is before columns
        if early_using.is_some() {
            modifiers.using = early_using;
            modifiers.using_before_columns = true;
        } else if late_using.is_some() {
            modifiers.using = late_using;
            modifiers.using_before_columns = true; // USING was after name but before columns
        }
        // If using was found in parse_constraint_modifiers (after columns), using_before_columns stays false

        Ok(TableConstraint::Index {
            name,
            columns,
            kind,
            modifiers,
            use_key_keyword,
            expression: None,
            index_type: None,
            granularity: None,
        })
    }

    /// Parse constraint modifiers like ENFORCED, DEFERRABLE, NORELY, USING, etc.
    fn parse_constraint_modifiers(&mut self) -> ConstraintModifiers {
        let mut modifiers = ConstraintModifiers::default();
        loop {
            if self.match_token(TokenType::Not) {
                // NOT ENFORCED, NOT DEFERRABLE, NOT VALID
                if self.match_identifier("ENFORCED") {
                    modifiers.enforced = Some(false);
                } else if self.match_identifier("DEFERRABLE") {
                    modifiers.deferrable = Some(false);
                } else if self.match_identifier("VALID") {
                    modifiers.not_valid = true;
                }
            } else if self.match_identifier("ENFORCED") {
                modifiers.enforced = Some(true);
            } else if self.match_identifier("DEFERRABLE") {
                modifiers.deferrable = Some(true);
            } else if self.match_identifier("INITIALLY") {
                // INITIALLY DEFERRED or INITIALLY IMMEDIATE
                if self.match_identifier("DEFERRED") {
                    modifiers.initially_deferred = Some(true);
                } else if self.match_identifier("IMMEDIATE") {
                    modifiers.initially_deferred = Some(false);
                }
            } else if self.match_identifier("NORELY") {
                modifiers.norely = true;
            } else if self.match_identifier("RELY") {
                modifiers.rely = true;
            } else if self.match_token(TokenType::Using) {
                // USING BTREE or USING HASH (MySQL)
                if self.match_identifier("BTREE") {
                    modifiers.using = Some("BTREE".to_string());
                } else if self.match_identifier("HASH") {
                    modifiers.using = Some("HASH".to_string());
                }
            } else if self.match_token(TokenType::Comment) {
                // MySQL index COMMENT 'text'
                if self.check(TokenType::String) {
                    modifiers.comment = Some(self.advance().text);
                }
            } else if self.match_identifier("VISIBLE") {
                modifiers.visible = Some(true);
            } else if self.match_identifier("INVISIBLE") {
                modifiers.visible = Some(false);
            } else if self.match_identifier("ENGINE_ATTRIBUTE") {
                // MySQL ENGINE_ATTRIBUTE = 'value'
                self.match_token(TokenType::Eq);
                if self.check(TokenType::String) {
                    modifiers.engine_attribute = Some(self.advance().text);
                }
            } else if self.check(TokenType::With) {
                let saved_with = self.current;
                self.advance(); // consume WITH
                if self.match_identifier("PARSER") {
                    // MySQL WITH PARSER name
                    if self.is_identifier_token() || self.is_safe_keyword_as_identifier() {
                        modifiers.with_parser = Some(self.advance().text);
                    }
                } else if self.check(TokenType::LParen) {
                    // TSQL: WITH (PAD_INDEX=ON, STATISTICS_NORECOMPUTE=OFF, ...)
                    // Parse and store the options
                    self.advance(); // consume (
                    loop {
                        if self.check(TokenType::RParen) || self.is_at_end() {
                            break;
                        }
                        // Parse KEY=VALUE pair
                        let key = self.advance().text.clone();
                        if self.match_token(TokenType::Eq) {
                            let value = self.advance().text.clone();
                            modifiers.with_options.push((key, value));
                        }
                        if !self.match_token(TokenType::Comma) {
                            break;
                        }
                    }
                    let _ = self.match_token(TokenType::RParen);
                } else {
                    // Not WITH PARSER or WITH (...), backtrack
                    self.current = saved_with;
                    break;
                }
            } else if self.check(TokenType::On) {
                let saved_on = self.current;
                self.advance(); // consume ON
                if self.match_identifier("CONFLICT") {
                    // SQLite ON CONFLICT action: ROLLBACK, ABORT, FAIL, IGNORE, REPLACE
                    if self.match_token(TokenType::Rollback) {
                        modifiers.on_conflict = Some("ROLLBACK".to_string());
                    } else if self.match_identifier("ABORT") {
                        modifiers.on_conflict = Some("ABORT".to_string());
                    } else if self.match_identifier("FAIL") {
                        modifiers.on_conflict = Some("FAIL".to_string());
                    } else if self.match_token(TokenType::Ignore) {
                        modifiers.on_conflict = Some("IGNORE".to_string());
                    } else if self.match_token(TokenType::Replace) {
                        modifiers.on_conflict = Some("REPLACE".to_string());
                    }
                } else if self.is_identifier_token() || self.check(TokenType::QuotedIdentifier) {
                    // TSQL: ON [filegroup] - parse and store
                    let quoted = self.check(TokenType::QuotedIdentifier);
                    let name = self.advance().text.clone();
                    modifiers.on_filegroup = Some(Identifier {
                        name,
                        quoted,
                        trailing_comments: Vec::new(),
                        span: None,
                    });
                } else {
                    // Unknown ON clause, backtrack
                    self.current = saved_on;
                    break;
                }
            } else {
                break;
            }
        }
        modifiers
    }

    /// Parse foreign key reference
    fn parse_foreign_key_ref(&mut self) -> Result<ForeignKeyRef> {
        let table = self.parse_table_ref()?;

        let columns = if self.match_token(TokenType::LParen) {
            let cols = self.parse_identifier_list()?;
            self.expect(TokenType::RParen)?;
            cols
        } else {
            Vec::new()
        };

        // Handle optional MATCH clause (MATCH FULL, MATCH PARTIAL, MATCH SIMPLE)
        // MATCH clause comes BEFORE ON DELETE/ON UPDATE in PostgreSQL
        let match_type = if self.match_token(TokenType::Match) {
            if self.check(TokenType::Full) {
                self.advance();
                Some(MatchType::Full)
            } else if self.check(TokenType::Identifier) || self.check(TokenType::Var) {
                let text = self.advance().text.to_uppercase();
                match text.as_str() {
                    "PARTIAL" => Some(MatchType::Partial),
                    "SIMPLE" => Some(MatchType::Simple),
                    _ => None,
                }
            } else {
                None
            }
        } else {
            None
        };

        // ON DELETE and ON UPDATE can appear in either order
        let mut on_delete = None;
        let mut on_update = None;
        let mut on_update_first = false;
        let mut first_clause = true;

        // Try parsing up to 2 ON clauses
        for _ in 0..2 {
            if on_delete.is_none() && self.match_keywords(&[TokenType::On, TokenType::Delete]) {
                on_delete = Some(self.parse_referential_action()?);
            } else if on_update.is_none()
                && self.match_keywords(&[TokenType::On, TokenType::Update])
            {
                if first_clause {
                    on_update_first = true;
                }
                on_update = Some(self.parse_referential_action()?);
            } else {
                break;
            }
            first_clause = false;
        }

        // MATCH clause can also appear after ON DELETE/ON UPDATE
        let mut match_after_actions = false;
        let match_type = if match_type.is_none() && self.match_token(TokenType::Match) {
            match_after_actions = on_delete.is_some() || on_update.is_some();
            if self.check(TokenType::Full) {
                self.advance();
                Some(MatchType::Full)
            } else if self.check(TokenType::Identifier) || self.check(TokenType::Var) {
                let text = self.advance().text.to_uppercase();
                match text.as_str() {
                    "PARTIAL" => Some(MatchType::Partial),
                    "SIMPLE" => Some(MatchType::Simple),
                    _ => None,
                }
            } else {
                None
            }
        } else {
            match_type
        };

        // Handle optional DEFERRABLE / NOT DEFERRABLE
        let deferrable = if self.match_identifier("DEFERRABLE") {
            Some(true)
        } else if self.match_token(TokenType::Not) && self.match_identifier("DEFERRABLE") {
            Some(false)
        } else {
            None
        };

        Ok(ForeignKeyRef {
            table,
            columns,
            on_delete,
            on_update,
            on_update_first,
            match_type,
            match_after_actions,
            constraint_name: None, // Will be set by caller if CONSTRAINT was used
            deferrable,
            has_foreign_key_keywords: false, // Will be set by caller if FOREIGN KEY preceded REFERENCES
        })
    }

    /// Parse referential action (CASCADE, SET NULL, etc.)
    fn parse_referential_action(&mut self) -> Result<ReferentialAction> {
        if self.match_token(TokenType::Cascade) {
            Ok(ReferentialAction::Cascade)
        } else if self.match_keywords(&[TokenType::Set, TokenType::Null]) {
            Ok(ReferentialAction::SetNull)
        } else if self.match_keywords(&[TokenType::Set, TokenType::Default]) {
            Ok(ReferentialAction::SetDefault)
        } else if self.match_token(TokenType::Restrict) {
            Ok(ReferentialAction::Restrict)
        } else if self.match_token(TokenType::No) {
            // NO ACTION - NO is a token, ACTION is an identifier
            if self.check(TokenType::Var) && self.peek().text.to_uppercase() == "ACTION" {
                self.advance();
            }
            Ok(ReferentialAction::NoAction)
        } else {
            Err(self.parse_error("Expected CASCADE, SET NULL, SET DEFAULT, RESTRICT, or NO ACTION"))
        }
    }

    /// Parse Snowflake TAG clause: TAG (key='value', key2='value2')
    fn parse_tags(&mut self) -> Result<Tags> {
        self.expect(TokenType::LParen)?;
        let mut expressions = Vec::new();

        loop {
            // Parse key = 'value' as a Property expression
            let key = self.expect_identifier_or_keyword()?;
            self.expect(TokenType::Eq)?;
            let value = self.parse_primary()?;

            // Create a Property expression: key = value
            expressions.push(Expression::Property(Box::new(Property {
                this: Box::new(Expression::Identifier(Identifier::new(key))),
                value: Some(Box::new(value)),
            })));

            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        self.expect(TokenType::RParen)?;

        Ok(Tags { expressions })
    }

    /// Parse CREATE VIEW
    fn parse_create_view(
        &mut self,
        or_replace: bool,
        materialized: bool,
        temporary: bool,
        algorithm: Option<String>,
        definer: Option<String>,
        security: Option<FunctionSecurity>,
        secure: bool,
    ) -> Result<Expression> {
        self.expect(TokenType::View)?;

        // Handle IF NOT EXISTS
        let if_not_exists =
            self.match_keywords(&[TokenType::If, TokenType::Not, TokenType::Exists]);

        let name = self.parse_table_ref()?;

        // ClickHouse: UUID 'xxx' clause after view name
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) && self.check_identifier("UUID")
        {
            self.advance(); // consume UUID
            let _ = self.advance(); // consume UUID string value
        }

        // ClickHouse: ON CLUSTER clause (after view name)
        let on_cluster = self.parse_on_cluster_clause()?;

        // ClickHouse: TO destination_table clause
        let to_table = if self.match_token(TokenType::To) {
            Some(self.parse_table_ref()?)
        } else {
            None
        };

        // Snowflake: COPY GRANTS (before column list)
        let copy_grants = self.match_text_seq(&["COPY", "GRANTS"]);

        // For materialized views, column definitions can include data types: (c1 INT, c2 INT)
        // This applies to Doris, ClickHouse, and potentially other dialects
        // We need to parse this as a schema instead of simple column names
        // Track if we parsed a schema (with types) vs simple columns
        let mut schema: Option<Schema> = None;
        let mut unique_key: Option<UniqueKeyProperty> = None;

        // Optional column list with optional COMMENT and OPTIONS per column
        let columns = if self.check(TokenType::LParen) {
            // For materialized views or ClickHouse views, try to parse as schema with typed columns
            if materialized
                || matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                )
            {
                // Save position to backtrack if needed
                let saved_pos = self.current;

                // Try to parse as schema (with typed columns)
                if let Some(Expression::Schema(parsed_schema)) = self.parse_schema()? {
                    schema = Some(*parsed_schema);

                    // Doris: KEY (columns) after schema
                    if self.match_text_seq(&["KEY"]) {
                        let exprs = self.parse_composite_key_expressions()?;
                        unique_key = Some(UniqueKeyProperty { expressions: exprs });
                    }

                    Vec::new() // Use schema instead of columns
                } else {
                    // Backtrack and parse as simple columns
                    self.current = saved_pos;
                    self.parse_view_columns()?
                }
            } else {
                self.parse_view_columns()?
            }
        } else {
            Vec::new()
        };

        // Snowflake: COPY GRANTS can also appear after column list
        let copy_grants = copy_grants || self.match_text_seq(&["COPY", "GRANTS"]);

        // Presto/Trino/StarRocks: SECURITY DEFINER/INVOKER/NONE (after view name, before AS)
        // This differs from MySQL's SQL SECURITY which comes before VIEW keyword
        let (security, security_sql_style) = if security.is_some() {
            // MySQL-style SQL SECURITY was parsed before VIEW keyword
            (security, true)
        } else if self.match_identifier("SECURITY") {
            // Presto-style SECURITY after view name
            let sec = if self.match_identifier("DEFINER") {
                Some(FunctionSecurity::Definer)
            } else if self.match_identifier("INVOKER") {
                Some(FunctionSecurity::Invoker)
            } else if self.match_identifier("NONE") {
                Some(FunctionSecurity::None)
            } else {
                None
            };
            (sec, false)
        } else {
            (None, true)
        };

        // Snowflake: COMMENT = 'text'
        let view_comment = if self.match_token(TokenType::Comment) {
            // Match = or skip if not present (some dialects use COMMENT='text')
            let _ = self.match_token(TokenType::Eq);
            Some(self.expect_string()?)
        } else {
            None
        };

        // Snowflake: TAG (name='value', ...)
        let tags = if self.match_identifier("TAG") {
            let mut tag_list = Vec::new();
            if self.match_token(TokenType::LParen) {
                loop {
                    let tag_name = self.expect_identifier()?;
                    let tag_value = if self.match_token(TokenType::Eq) {
                        self.expect_string()?
                    } else {
                        String::new()
                    };
                    tag_list.push((tag_name, tag_value));
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
                self.expect(TokenType::RParen)?;
            }
            tag_list
        } else {
            Vec::new()
        };

        // BigQuery: OPTIONS (key=value, ...)
        let options = if self.match_identifier("OPTIONS") {
            self.parse_options_list()?
        } else {
            Vec::new()
        };

        // Doris: BUILD IMMEDIATE/DEFERRED for materialized views
        let build = if self.match_identifier("BUILD") {
            if self.match_identifier("IMMEDIATE") {
                Some("IMMEDIATE".to_string())
            } else if self.match_identifier("DEFERRED") {
                Some("DEFERRED".to_string())
            } else {
                // Unexpected token after BUILD - try to consume it
                let value = self.expect_identifier_or_keyword()?;
                Some(value.to_uppercase())
            }
        } else {
            None
        };

        // Doris: REFRESH COMPLETE/AUTO ON MANUAL/COMMIT/SCHEDULE [EVERY n UNIT] [STARTS 'datetime']
        // ClickHouse: REFRESH AFTER interval / REFRESH EVERY interval [OFFSET interval] [RANDOMIZE FOR interval] [APPEND]
        let refresh = if self.match_token(TokenType::Refresh) {
            if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) {
                // ClickHouse REFRESH syntax: consume tokens until AS/POPULATE/TO/ENGINE or end
                while !self.is_at_end()
                    && !self.check(TokenType::As)
                    && !self.check_identifier("POPULATE")
                    && !self.check_identifier("TO")
                    && !self.check_identifier("APPEND")
                    && !self.check_identifier("ENGINE")
                    && !self.check(TokenType::Semicolon)
                {
                    self.advance();
                }
                // Consume APPEND if present (REFRESH ... APPEND TO target)
                let _ = self.match_identifier("APPEND");
                None
            } else {
                Some(Box::new(self.parse_refresh_trigger_property()?))
            }
        } else {
            None
        };

        // ClickHouse: TO destination_table after REFRESH ... APPEND
        // e.g., CREATE MATERIALIZED VIEW v REFRESH AFTER 1 SECOND APPEND TO tab (cols) EMPTY AS ...
        let to_table = if to_table.is_none() && self.match_token(TokenType::To) {
            Some(self.parse_table_ref()?)
        } else {
            to_table
        };

        // ClickHouse: column definitions after REFRESH ... APPEND TO tab (cols)
        if schema.is_none()
            && self.check(TokenType::LParen)
            && matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            )
        {
            let saved_pos = self.current;
            if let Some(Expression::Schema(parsed_schema)) = self.parse_schema()? {
                schema = Some(*parsed_schema);
            } else {
                self.current = saved_pos;
            }
        }

        // Redshift: AUTO REFRESH YES|NO for materialized views
        let auto_refresh = if self.match_text_seq(&["AUTO", "REFRESH"]) {
            if self.match_identifier("YES") {
                Some(true)
            } else if self.match_identifier("NO") {
                Some(false)
            } else {
                None
            }
        } else {
            None
        };

        // ClickHouse: Parse table properties (ENGINE, ORDER BY, SAMPLE, SETTINGS, TTL, etc.)
        // These appear after column definitions but before AS clause for materialized views
        let mut table_properties = Vec::new();
        if materialized
            && matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            )
        {
            self.parse_clickhouse_table_properties(&mut table_properties)?;
        }

        // ClickHouse: POPULATE / EMPTY keywords before AS in materialized views
        if materialized
            && matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            )
        {
            let _ = self.match_identifier("POPULATE");
            let _ = self.match_identifier("EMPTY");
        }

        // AS is optional - some dialects (e.g., Presto) allow SELECT without AS
        let has_as = self.match_token(TokenType::As);
        if !has_as && !self.check(TokenType::Select) && !self.check(TokenType::With) {
            // No AS and no SELECT/WITH means no query - return empty view (for partial statements)
            return Ok(Expression::CreateView(Box::new(CreateView {
                name,
                columns,
                query: Expression::Null(Null), // Placeholder for incomplete VIEW
                or_replace,
                if_not_exists,
                materialized,
                temporary,
                secure,
                algorithm,
                definer,
                security,
                security_sql_style,
                query_parenthesized: false,
                locking_mode: None,
                locking_access: None,
                copy_grants,
                comment: view_comment,
                tags,
                options,
                build,
                refresh,
                schema: schema.map(Box::new),
                unique_key: unique_key.map(Box::new),
                no_schema_binding: false,
                auto_refresh,
                on_cluster,
                to_table,
                table_properties,
            })));
        }

        // Parse Teradata LOCKING clause: LOCKING ROW|TABLE|DATABASE FOR ACCESS|READ|WRITE
        let mut locking_mode: Option<String> = None;
        let mut locking_access: Option<String> = None;
        if self.match_token(TokenType::Lock) || self.match_identifier("LOCKING") {
            // Capture: ROW, TABLE, DATABASE, etc.
            if self.match_token(TokenType::Row) {
                locking_mode = Some("ROW".to_string());
            } else if self.match_token(TokenType::Table) {
                locking_mode = Some("TABLE".to_string());
            } else if self.match_token(TokenType::Database) || self.match_identifier("DATABASE") {
                locking_mode = Some("DATABASE".to_string());
            }
            // Capture FOR ACCESS|READ|WRITE
            if self.match_token(TokenType::For) {
                if self.match_identifier("ACCESS") {
                    locking_access = Some("ACCESS".to_string());
                } else if self.match_identifier("READ") {
                    locking_access = Some("READ".to_string());
                } else if self.match_identifier("WRITE") {
                    locking_access = Some("WRITE".to_string());
                }
            }
        }

        // Use parse_statement to handle SELECT, WITH...SELECT, or (SELECT...)
        let query_parenthesized = self.check(TokenType::LParen);
        let query = if self.check(TokenType::With) {
            self.parse_statement()?
        } else if query_parenthesized {
            // Handle (SELECT ...) or (WITH ... SELECT ...) - parenthesized query
            self.advance(); // consume (
            let inner = if self.check(TokenType::With) {
                self.parse_statement()?
            } else {
                self.parse_select()?
            };
            self.expect(TokenType::RParen)?;
            inner
        } else {
            self.parse_select()?
        };

        // Redshift: WITH NO SCHEMA BINDING (after the query)
        let no_schema_binding = self.match_text_seq(&["WITH", "NO", "SCHEMA", "BINDING"]);

        Ok(Expression::CreateView(Box::new(CreateView {
            name,
            columns,
            query,
            or_replace,
            if_not_exists,
            materialized,
            temporary,
            secure,
            algorithm,
            definer,
            security,
            security_sql_style,
            query_parenthesized,
            locking_mode,
            locking_access,
            copy_grants,
            comment: view_comment,
            tags,
            options,
            build,
            refresh,
            schema: schema.map(Box::new),
            unique_key: unique_key.map(Box::new),
            no_schema_binding,
            auto_refresh,
            on_cluster,
            to_table,
            table_properties,
        })))
    }

    /// Parse view column list: (col1, col2 OPTIONS(...) COMMENT 'text', ...)
    /// For simple view definitions without data types
    fn parse_view_columns(&mut self) -> Result<Vec<ViewColumn>> {
        self.expect(TokenType::LParen)?;
        let mut cols = Vec::new();
        loop {
            let col_name = self.expect_identifier()?;
            // BigQuery: OPTIONS (key=value, ...) on view column
            let options = if self.match_identifier("OPTIONS") {
                self.parse_options_list()?
            } else {
                Vec::new()
            };
            // Optional COMMENT 'text'
            let comment = if self.match_token(TokenType::Comment) {
                Some(self.expect_string()?)
            } else {
                None
            };
            cols.push(ViewColumn {
                name: Identifier::new(col_name),
                comment,
                options,
            });
            if !self.match_token(TokenType::Comma) {
                break;
            }
        }
        self.expect(TokenType::RParen)?;
        Ok(cols)
    }

    /// Parse CREATE [CLUSTERED|NONCLUSTERED] INDEX
    fn parse_create_index_with_clustered(
        &mut self,
        unique: bool,
        clustered: Option<String>,
    ) -> Result<Expression> {
        self.expect(TokenType::Index)?;

        // PostgreSQL: CREATE INDEX CONCURRENTLY idx ON t(c)
        let concurrently = self.match_identifier("CONCURRENTLY");

        // Handle IF NOT EXISTS
        let if_not_exists =
            self.match_keywords(&[TokenType::If, TokenType::Not, TokenType::Exists]);

        // Index name is optional when IF NOT EXISTS is specified (PostgreSQL)
        let name = if if_not_exists && self.check(TokenType::On) {
            Identifier::new("") // Empty name when omitted
        } else {
            self.expect_identifier_with_quoted()?
        };
        self.expect(TokenType::On)?;
        let table = self.parse_table_ref()?;

        // Optional USING clause
        let using = if self.match_token(TokenType::Using) {
            Some(self.expect_identifier()?)
        } else {
            None
        };

        // Parse index columns (optional for COLUMNSTORE indexes)
        let columns = if self.match_token(TokenType::LParen) {
            let cols = self.parse_index_columns()?;
            self.expect(TokenType::RParen)?;
            cols
        } else if clustered
            .as_ref()
            .is_some_and(|c| c.contains("COLUMNSTORE"))
        {
            // COLUMNSTORE indexes don't require a column list
            Vec::new()
        } else if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) {
            // ClickHouse: CREATE INDEX idx ON table expr TYPE minmax GRANULARITY 1
            // No parentheses around the expression — consume to semicolon as Command
            let mut parts = vec![
                "CREATE".to_string(),
                if unique {
                    "UNIQUE INDEX".to_string()
                } else {
                    "INDEX".to_string()
                },
                name.name.clone(),
                "ON".to_string(),
            ];
            // Rebuild table name
            if let Some(ref s) = table.schema {
                parts.push(format!("{}.{}", s.name, table.name.name));
            } else {
                parts.push(table.name.name.clone());
            }
            while !self.is_at_end() && !self.check(TokenType::Semicolon) {
                let token = self.advance();
                if token.token_type == TokenType::String {
                    parts.push(format!("'{}'", token.text));
                } else if token.token_type == TokenType::QuotedIdentifier {
                    parts.push(format!("\"{}\"", token.text));
                } else {
                    parts.push(token.text.clone());
                }
            }
            return Ok(Expression::Command(Box::new(crate::expressions::Command {
                this: parts.join(" "),
            })));
        } else {
            self.expect(TokenType::LParen)?;
            let cols = self.parse_index_columns()?;
            self.expect(TokenType::RParen)?;
            cols
        };

        // PostgreSQL: INCLUDE (col1, col2) clause
        let include_columns = if self.match_identifier("INCLUDE") {
            self.expect(TokenType::LParen)?;
            let mut cols = Vec::new();
            loop {
                cols.push(self.expect_identifier_with_quoted()?);
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            self.expect(TokenType::RParen)?;
            cols
        } else {
            Vec::new()
        };

        // TSQL: WITH (option=value, ...) clause for index options
        let with_options = if self.check(TokenType::With) {
            // parse_with_properties expects the WITH keyword to NOT be consumed
            // but we need to check if we have WITH followed by LParen
            if self
                .peek_nth(1)
                .is_some_and(|t| t.token_type == TokenType::LParen)
            {
                self.advance(); // consume WITH
                self.parse_with_properties()?
            } else {
                Vec::new()
            }
        } else {
            Vec::new()
        };

        // PostgreSQL: WHERE clause for partial indexes
        let where_clause = if self.match_token(TokenType::Where) {
            Some(Box::new(self.parse_expression()?))
        } else {
            None
        };

        // TSQL: ON filegroup or partition scheme clause
        // e.g., ON PRIMARY, ON X([y])
        let on_filegroup = if self.match_token(TokenType::On) {
            // Get the filegroup/partition scheme name
            let token = self.advance();
            let mut filegroup = token.text.clone();
            // Check for partition scheme with column: ON partition_scheme(column)
            if self.match_token(TokenType::LParen) {
                filegroup.push('(');
                // Parse the partition column(s)
                loop {
                    let col_token = self.advance();
                    // For TSQL, use bracket quoting for quoted identifiers
                    if col_token.token_type == TokenType::QuotedIdentifier {
                        filegroup.push('[');
                        filegroup.push_str(&col_token.text);
                        filegroup.push(']');
                    } else {
                        filegroup.push_str(&col_token.text);
                    }
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                    filegroup.push_str(", ");
                }
                self.expect(TokenType::RParen)?;
                filegroup.push(')');
            }
            Some(filegroup)
        } else {
            None
        };

        Ok(Expression::CreateIndex(Box::new(CreateIndex {
            name,
            table,
            columns,
            unique,
            if_not_exists,
            using,
            clustered,
            concurrently,
            where_clause,
            include_columns,
            with_options,
            on_filegroup,
        })))
    }

    /// Parse index columns - can be identifiers or expressions (like function calls)
    fn parse_index_columns(&mut self) -> Result<Vec<IndexColumn>> {
        let mut columns = Vec::new();
        loop {
            // Parse as expression to handle function calls like BOX(location, location)
            let expr = self.parse_expression()?;

            // Extract column name from expression
            let column = match &expr {
                Expression::Identifier(ident) => ident.clone(),
                Expression::Column(col) => {
                    // For column expressions (e.g., simple identifier like [Col]),
                    // extract the identifier directly to preserve quoting
                    col.name.clone()
                }
                Expression::Function(_func) => {
                    // For function expressions, create an identifier from the function call
                    Identifier::new(self.expression_to_sql(&expr))
                }
                _ => Identifier::new(self.expression_to_sql(&expr)),
            };

            // Parse optional PostgreSQL operator class (e.g., varchar_pattern_ops, public.gin_trgm_ops)
            // An opclass is an identifier that appears before ASC/DESC/NULLS and is not a keyword
            let opclass = if self.is_identifier_token()
                && !self.check(TokenType::Asc)
                && !self.check(TokenType::Desc)
                && !self.check(TokenType::Nulls)
            {
                let mut opclass_name = self.advance().text;
                // Handle qualified opclass names like public.gin_trgm_ops
                while self.match_token(TokenType::Dot) {
                    opclass_name.push('.');
                    if self.is_identifier_token() || self.is_safe_keyword_as_identifier() {
                        opclass_name.push_str(&self.advance().text);
                    }
                }
                Some(opclass_name)
            } else {
                None
            };

            let desc = self.match_token(TokenType::Desc);
            let asc = if !desc {
                self.match_token(TokenType::Asc)
            } else {
                false
            };
            let nulls_first = if self.match_token(TokenType::Nulls) {
                if self.match_token(TokenType::First) {
                    Some(true)
                } else if self.match_token(TokenType::Last) {
                    Some(false)
                } else {
                    None
                }
            } else {
                None
            };
            columns.push(IndexColumn {
                column,
                desc,
                asc,
                nulls_first,
                opclass,
            });
            if !self.match_token(TokenType::Comma) {
                break;
            }
        }
        Ok(columns)
    }

    /// Convert an expression to its SQL string representation (simple version for index expressions)
    fn expression_to_sql(&self, expr: &Expression) -> String {
        match expr {
            Expression::Identifier(ident) => ident.name.clone(),
            Expression::Function(func) => {
                let args = func
                    .args
                    .iter()
                    .map(|a| self.expression_to_sql(a))
                    .collect::<Vec<_>>()
                    .join(", ");
                format!("{}({})", func.name, args)
            }
            Expression::Column(col) => {
                if let Some(ref table) = col.table {
                    format!("{}.{}", table, col.name)
                } else {
                    col.name.to_string()
                }
            }
            Expression::Literal(lit) => match lit {
                Literal::String(s) => format!("'{}'", s),
                Literal::Number(n) => n.clone(),
                _ => "?".to_string(),
            },
            Expression::Null(_) => "NULL".to_string(),
            Expression::Boolean(b) => {
                if b.value {
                    "TRUE".to_string()
                } else {
                    "FALSE".to_string()
                }
            }
            _ => "?".to_string(),
        }
    }

    /// Parse DROP statement
    fn parse_drop(&mut self) -> Result<Expression> {
        // Capture leading comments from the DROP token (e.g., "-- comment\nDROP TABLE ...")
        let leading_comments = self.current_leading_comments();
        self.expect(TokenType::Drop)?;

        // ClickHouse: DROP TEMPORARY TABLE / DROP TEMPORARY VIEW
        if self.check(TokenType::Temporary)
            && matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            )
        {
            self.advance(); // consume TEMPORARY
            if self.check(TokenType::View) {
                return self.parse_drop_view(false);
            }
            return self.parse_drop_table(leading_comments.clone());
        }

        match self.peek().token_type {
            TokenType::Table => self.parse_drop_table(leading_comments),
            TokenType::View => self.parse_drop_view(false),
            TokenType::Materialized => {
                self.advance(); // consume MATERIALIZED
                self.parse_drop_view(true)
            }
            TokenType::Index => self.parse_drop_index(),
            TokenType::Schema => self.parse_drop_schema(),
            TokenType::Database => self.parse_drop_database(),
            TokenType::Function => self.parse_drop_function(),
            TokenType::Procedure => self.parse_drop_procedure(),
            TokenType::Sequence => self.parse_drop_sequence(),
            TokenType::Trigger => self.parse_drop_trigger(),
            TokenType::Type => self.parse_drop_type(),
            TokenType::Domain => {
                // DROP DOMAIN is similar to DROP TYPE
                self.advance();
                let if_exists = self.match_keywords(&[TokenType::If, TokenType::Exists]);
                let name = self.parse_table_ref()?;
                let cascade = self.match_token(TokenType::Cascade);
                if !cascade {
                    self.match_token(TokenType::Restrict);
                }
                Ok(Expression::DropType(Box::new(DropType {
                    name,
                    if_exists,
                    cascade,
                })))
            }
            TokenType::Namespace => {
                // DROP NAMESPACE is similar to DROP SCHEMA (Spark/Databricks)
                self.advance();
                let if_exists = self.match_keywords(&[TokenType::If, TokenType::Exists]);
                // Parse potentially qualified namespace name (a.b.c)
                let mut name_parts = vec![self.expect_identifier()?];
                while self.match_token(TokenType::Dot) {
                    name_parts.push(self.expect_identifier()?);
                }
                let name = Identifier::new(name_parts.join("."));
                let cascade = self.match_token(TokenType::Cascade);
                if !cascade {
                    self.match_token(TokenType::Restrict);
                }
                Ok(Expression::DropNamespace(Box::new(DropNamespace {
                    name,
                    if_exists,
                    cascade,
                })))
            }
            _ => {
                // ClickHouse: DROP DICTIONARY, DROP USER, DROP QUOTA, DROP ROLE,
                // DROP ROW POLICY, DROP SETTINGS PROFILE, DROP NAMED COLLECTION
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) {
                    let text_upper = self.peek().text.to_uppercase();
                    if matches!(
                        text_upper.as_str(),
                        "DICTIONARY"
                            | "USER"
                            | "QUOTA"
                            | "ROLE"
                            | "ROW"
                            | "POLICY"
                            | "NAMED"
                            | "WORKLOAD"
                            | "RESOURCE"
                            | "PROFILE"
                    ) || self.check(TokenType::Settings)
                        || self.check(TokenType::Partition)
                    {
                        self.advance(); // consume keyword, previous() is now set
                        let mut tokens: Vec<(String, TokenType)> = vec![
                            ("DROP".to_string(), TokenType::Var),
                            (
                                self.previous().text.to_uppercase(),
                                self.previous().token_type,
                            ),
                        ];
                        while !self.is_at_end() && !self.check(TokenType::Semicolon) {
                            let token = self.advance();
                            let text = if token.token_type == TokenType::QuotedIdentifier {
                                format!("\"{}\"", token.text)
                            } else if token.token_type == TokenType::String {
                                format!("'{}'", token.text)
                            } else {
                                token.text.clone()
                            };
                            tokens.push((text, token.token_type));
                        }
                        return Ok(Expression::Command(Box::new(Command {
                            this: self.join_command_tokens(tokens),
                        })));
                    }
                }
                Err(self.parse_error(format!(
                    "Expected TABLE, VIEW, INDEX, SCHEMA, DATABASE, FUNCTION, PROCEDURE, SEQUENCE, TRIGGER, TYPE, or NAMESPACE after DROP, got {:?}",
                    self.peek().token_type
                )))
            }
        }
    }

    /// Parse DROP TABLE
    fn parse_drop_table(&mut self, leading_comments: Vec<String>) -> Result<Expression> {
        self.expect(TokenType::Table)?;

        let if_exists = self.match_keywords(&[TokenType::If, TokenType::Exists]);

        // ClickHouse: IF EMPTY
        if !if_exists
            && matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            )
        {
            if self.check(TokenType::If)
                && self.current + 1 < self.tokens.len()
                && self.tokens[self.current + 1]
                    .text
                    .eq_ignore_ascii_case("EMPTY")
            {
                self.advance(); // consume IF
                self.advance(); // consume EMPTY
            }
        }

        // Parse table names (can be multiple)
        let mut names = Vec::new();
        loop {
            names.push(self.parse_table_ref()?);
            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        // Handle CASCADE [CONSTRAINTS] or RESTRICT
        let mut cascade = false;
        let mut cascade_constraints = false;
        if self.match_token(TokenType::Cascade) {
            if self.match_identifier("CONSTRAINTS") {
                cascade_constraints = true;
            } else {
                cascade = true;
            }
        } else {
            self.match_token(TokenType::Restrict); // consume optional RESTRICT
        }

        // Handle PURGE (Oracle)
        let purge = self.match_identifier("PURGE");

        // ClickHouse: ON CLUSTER clause
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) {
            let _ = self.parse_on_cluster_clause()?;
        }

        // ClickHouse: SYNC keyword
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) {
            self.match_identifier("SYNC");
            self.match_identifier("NO");
            self.match_identifier("DELAY");
        }

        Ok(Expression::DropTable(Box::new(DropTable {
            names,
            if_exists,
            cascade,
            cascade_constraints,
            purge,
            leading_comments,
            object_id_args: None,
        })))
    }

    /// Parse DROP VIEW
    fn parse_drop_view(&mut self, materialized: bool) -> Result<Expression> {
        self.expect(TokenType::View)?;

        let if_exists = self.match_keywords(&[TokenType::If, TokenType::Exists]);
        let name = self.parse_table_ref()?;

        // ClickHouse: ON CLUSTER clause
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) {
            let _ = self.parse_on_cluster_clause()?;
            self.match_identifier("SYNC");
        }

        Ok(Expression::DropView(Box::new(DropView {
            name,
            if_exists,
            materialized,
        })))
    }

    /// Parse DROP INDEX
    fn parse_drop_index(&mut self) -> Result<Expression> {
        self.expect(TokenType::Index)?;

        // PostgreSQL CONCURRENTLY modifier
        let concurrently = self.match_identifier("CONCURRENTLY");

        let if_exists = self.match_keywords(&[TokenType::If, TokenType::Exists]);

        // Parse potentially qualified index name (a.b.c)
        let mut name_parts = vec![self.expect_identifier()?];
        while self.match_token(TokenType::Dot) {
            name_parts.push(self.expect_identifier()?);
        }
        let name = Identifier::new(name_parts.join("."));

        // Optional ON table
        let table = if self.match_token(TokenType::On) {
            Some(self.parse_table_ref()?)
        } else {
            None
        };

        Ok(Expression::DropIndex(Box::new(DropIndex {
            name,
            table,
            if_exists,
            concurrently,
        })))
    }

    /// Parse ALTER statement
    fn parse_alter(&mut self) -> Result<Expression> {
        self.expect(TokenType::Alter)?;

        match self.peek().token_type {
            TokenType::Table => {
                self.advance();
                // Handle IF EXISTS after ALTER TABLE
                let if_exists = self.match_keywords(&[TokenType::If, TokenType::Exists]);
                // Handle PostgreSQL ONLY modifier: ALTER TABLE ONLY "Album" ...
                let has_only = self.match_token(TokenType::Only);
                let mut name = self.parse_table_ref()?;
                if has_only {
                    name.only = true;
                }

                // ClickHouse: ON CLUSTER clause
                let on_cluster = self.parse_on_cluster_clause()?;

                // Hive: PARTITION(key=value, ...) clause before actions
                let partition = if self.match_token(TokenType::Partition) {
                    self.expect(TokenType::LParen)?;
                    let mut parts = Vec::new();
                    loop {
                        let key = self.expect_identifier()?;
                        self.expect(TokenType::Eq)?;
                        let value = self.parse_expression()?;
                        parts.push((Identifier::new(key), value));
                        if !self.match_token(TokenType::Comma) {
                            break;
                        }
                    }
                    self.expect(TokenType::RParen)?;
                    Some(parts)
                } else {
                    None
                };

                let mut actions = Vec::new();
                let mut last_was_add_column = false;
                let mut with_check_modifier: Option<String> = None;

                loop {
                    // Check for MySQL trailing options (ALGORITHM=val, LOCK=val)
                    // before trying to parse as a column def or action.
                    // The comma before ALGORITHM was consumed at the bottom of the previous iteration.
                    if self.check_identifier("ALGORITHM") || self.check_identifier("LOCK") {
                        break;
                    }

                    // TSQL: WITH CHECK / WITH NOCHECK before ADD CONSTRAINT
                    if self.check(TokenType::With) {
                        let saved = self.current;
                        self.advance(); // consume WITH
                        if self.check(TokenType::Check) {
                            self.advance(); // consume CHECK
                            with_check_modifier = Some("WITH CHECK".to_string());
                            // Continue to parse the actual action (ADD CONSTRAINT, etc.)
                        } else if self.check_identifier("NOCHECK") {
                            self.advance(); // consume NOCHECK
                            with_check_modifier = Some("WITH NOCHECK".to_string());
                            // Continue to parse the actual action (ADD CONSTRAINT, etc.)
                        } else {
                            // Not WITH CHECK/NOCHECK, restore position
                            self.current = saved;
                        }
                    }

                    // If last action was ADD COLUMN and we just saw a comma,
                    // check if this is another column definition (not a new action keyword)
                    if last_was_add_column
                        && !self.check(TokenType::Add)
                        && !self.check(TokenType::Drop)
                        && !self.check(TokenType::Alter)
                        && !self.check(TokenType::Rename)
                        && !self.check(TokenType::Set)
                        && !self.check_identifier("MODIFY")
                        && !self.check(TokenType::Delete)
                        && !self.check(TokenType::Update)
                        && !self.check_identifier("DETACH")
                        && !self.check_identifier("ATTACH")
                        && !self.check_identifier("FREEZE")
                        && !self.check_identifier("CLEAR")
                        && !self.check_identifier("MATERIALIZE")
                        && !self.check(TokenType::Comment)
                        && !self.check(TokenType::Replace)
                        && !self.check_identifier("MOVE")
                        && !self.check_identifier("REMOVE")
                        && !self.check_identifier("APPLY")
                    {
                        // Parse additional column definition
                        self.match_token(TokenType::Column); // optional COLUMN keyword
                        let if_not_exists = self.match_keywords(&[
                            TokenType::If,
                            TokenType::Not,
                            TokenType::Exists,
                        ]);
                        let col_def = self.parse_column_def()?;
                        let position = if self.match_token(TokenType::First) {
                            Some(ColumnPosition::First)
                        } else if self.match_token(TokenType::After) {
                            let after_col = self.expect_identifier()?;
                            // ClickHouse: AFTER n.a (dotted nested column name)
                            let after_name = if self.match_token(TokenType::Dot) {
                                let field = self.expect_identifier()?;
                                format!("{}.{}", after_col, field)
                            } else {
                                after_col
                            };
                            Some(ColumnPosition::After(Identifier::new(after_name)))
                        } else {
                            None
                        };
                        actions.push(AlterTableAction::AddColumn {
                            column: col_def,
                            if_not_exists,
                            position,
                        });
                        // last_was_add_column remains true
                    } else {
                        // Check for MySQL trailing options (ALGORITHM=val, LOCK=val)
                        // before trying to parse as an action
                        if self.check_identifier("ALGORITHM") || self.check_identifier("LOCK") {
                            // Retreat one to re-process the comma in the trailing options loop
                            self.current -= 1; // back up past the comma consumed in loop
                            break;
                        }
                        let action = self.parse_alter_action()?;
                        last_was_add_column = matches!(action, AlterTableAction::AddColumn { .. });
                        actions.push(action);
                    }
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }

                // Parse trailing MySQL ALTER TABLE options: ALGORITHM=val, LOCK=val
                // These can appear after actions separated by commas (comma already consumed)
                // or directly if no actions were parsed
                let mut algorithm = None;
                let mut lock = None;
                loop {
                    // First check without consuming comma (comma may have been consumed by action loop)
                    if self.check_identifier("ALGORITHM") {
                        self.advance();
                        self.expect(TokenType::Eq)?;
                        algorithm = Some(self.expect_identifier_or_keyword()?.to_uppercase());
                        self.match_token(TokenType::Comma); // optional trailing comma
                    } else if self.check_identifier("LOCK") {
                        self.advance();
                        self.expect(TokenType::Eq)?;
                        lock = Some(self.expect_identifier_or_keyword()?.to_uppercase());
                        self.match_token(TokenType::Comma); // optional trailing comma
                    } else if self.match_token(TokenType::Comma) {
                        // Try after comma
                        if self.check_identifier("ALGORITHM") {
                            self.advance();
                            self.expect(TokenType::Eq)?;
                            algorithm = Some(self.expect_identifier_or_keyword()?.to_uppercase());
                        } else if self.check_identifier("LOCK") {
                            self.advance();
                            self.expect(TokenType::Eq)?;
                            lock = Some(self.expect_identifier_or_keyword()?.to_uppercase());
                        } else {
                            self.current -= 1;
                            break;
                        }
                    } else {
                        break;
                    }
                }

                // ClickHouse: consume optional trailing SETTINGS clause
                // e.g., ALTER TABLE t ADD COLUMN c Int64 SETTINGS mutations_sync=2, alter_sync=2
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) && self.check(TokenType::Settings)
                {
                    self.advance(); // consume SETTINGS
                    let _ = self.parse_settings_property()?;
                }

                Ok(Expression::AlterTable(Box::new(AlterTable {
                    name,
                    actions,
                    if_exists,
                    algorithm,
                    lock,
                    with_check: with_check_modifier,
                    partition,
                    on_cluster,
                })))
            }
            TokenType::View => self.parse_alter_view_with_modifiers(None, None, None),
            TokenType::Index => self.parse_alter_index(),
            TokenType::Sequence => self.parse_alter_sequence(),
            _ if self.check_identifier("SESSION") => {
                // ALTER SESSION SET/UNSET (Snowflake)
                self.advance(); // consume SESSION
                match self.parse_alter_session()? {
                    Some(expr) => Ok(expr),
                    None => {
                        // Fall back to command
                        Ok(Expression::Command(Box::new(Command {
                            this: "ALTER SESSION".to_string(),
                        })))
                    }
                }
            }
            _ => {
                // MySQL: ALTER ALGORITHM = val VIEW, ALTER DEFINER = val VIEW,
                // ALTER SQL SECURITY = val VIEW
                let mut view_algorithm = None;
                let mut view_definer = None;
                let mut view_sql_security = None;

                loop {
                    if self.check_identifier("ALGORITHM") {
                        self.advance();
                        self.expect(TokenType::Eq)?;
                        view_algorithm = Some(self.expect_identifier_or_keyword()?.to_uppercase());
                    } else if self.check_identifier("DEFINER") {
                        self.advance();
                        self.expect(TokenType::Eq)?;
                        // Parse user@host format: 'admin'@'localhost'
                        let mut definer_str = String::new();
                        if self.check(TokenType::String) {
                            definer_str.push_str(&format!("'{}'", self.advance().text));
                        } else {
                            definer_str.push_str(&self.expect_identifier_or_keyword()?);
                        }
                        // Check for @ separator
                        if !self.is_at_end() && self.peek().text == "@" {
                            definer_str.push_str(&self.advance().text);
                            if self.check(TokenType::String) {
                                definer_str.push_str(&format!("'{}'", self.advance().text));
                            } else if !self.is_at_end() {
                                definer_str.push_str(&self.advance().text);
                            }
                        }
                        view_definer = Some(definer_str);
                    } else if self.check_identifier("SQL") {
                        self.advance();
                        if self.match_identifier("SECURITY") {
                            self.match_token(TokenType::Eq);
                            view_sql_security =
                                Some(self.expect_identifier_or_keyword()?.to_uppercase());
                        }
                    } else {
                        break;
                    }
                }

                if self.check(TokenType::View) {
                    self.parse_alter_view_with_modifiers(
                        view_algorithm,
                        view_definer,
                        view_sql_security,
                    )
                } else {
                    // Fall back to Raw for unrecognized ALTER targets
                    let start = self.current;
                    while !self.is_at_end() && !self.check(TokenType::Semicolon) {
                        self.advance();
                    }
                    let sql = self.tokens_to_sql(start, self.current);
                    Ok(Expression::Raw(Raw {
                        sql: format!("ALTER {}", sql),
                    }))
                }
            }
        }
    }

    /// Parse ALTER TABLE action
    fn parse_alter_action(&mut self) -> Result<AlterTableAction> {
        if self.match_token(TokenType::Add) {
            // ClickHouse: ADD INDEX idx expr TYPE minmax GRANULARITY 1
            // ClickHouse: ADD PROJECTION name (SELECT ...)
            // ClickHouse: ADD STATISTICS col1, col2 TYPE tdigest, uniq
            // These have different syntax from MySQL ADD INDEX, so consume as Raw
            if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && (self.check(TokenType::Index)
                || self.check_identifier("PROJECTION")
                || self.check_identifier("STATISTICS"))
            {
                let is_statistics = self.check_identifier("STATISTICS");
                let mut tokens: Vec<(String, TokenType)> =
                    vec![("ADD".to_string(), TokenType::Add)];
                let mut paren_depth = 0i32;
                while !self.is_at_end() && !self.check(TokenType::Semicolon) {
                    // STATISTICS uses commas internally (col1, col2 TYPE t1, t2), don't break at comma
                    if self.check(TokenType::Comma) && paren_depth == 0 && !is_statistics {
                        break;
                    }
                    let token = self.advance();
                    if token.token_type == TokenType::LParen {
                        paren_depth += 1;
                    }
                    if token.token_type == TokenType::RParen {
                        paren_depth -= 1;
                    }
                    let text = if token.token_type == TokenType::QuotedIdentifier {
                        format!("\"{}\"", token.text)
                    } else if token.token_type == TokenType::String {
                        format!("'{}'", token.text)
                    } else {
                        token.text.clone()
                    };
                    tokens.push((text, token.token_type));
                }
                return Ok(AlterTableAction::Raw {
                    sql: self.join_command_tokens(tokens),
                });
            }
            // ADD CONSTRAINT or ADD COLUMN or ADD INDEX
            if self.match_token(TokenType::Constraint) {
                // ADD CONSTRAINT name ...
                let name = Some(self.expect_identifier_with_quoted()?);
                let constraint = self.parse_constraint_definition(name)?;
                Ok(AlterTableAction::AddConstraint(constraint))
            } else if self.check(TokenType::PrimaryKey)
                || self.check(TokenType::ForeignKey)
                || self.check(TokenType::Check)
            {
                // ADD PRIMARY KEY / FOREIGN KEY / CHECK (without CONSTRAINT keyword)
                let constraint = self.parse_table_constraint()?;
                Ok(AlterTableAction::AddConstraint(constraint))
            } else if self.check(TokenType::Index)
                || self.check(TokenType::Key)
                || self.check(TokenType::Unique)
                || self.check_identifier("FULLTEXT")
                || self.check_identifier("SPATIAL")
            {
                // ADD [UNIQUE|FULLTEXT|SPATIAL] [{INDEX|KEY}] [name] (columns) [USING {BTREE|HASH}]
                let kind = if self.match_token(TokenType::Unique) {
                    Some("UNIQUE".to_string())
                } else if self.match_identifier("FULLTEXT") {
                    Some("FULLTEXT".to_string())
                } else if self.match_identifier("SPATIAL") {
                    Some("SPATIAL".to_string())
                } else {
                    None
                };
                // Consume optional INDEX or KEY keyword, track which was used
                let use_key_keyword = if self.match_token(TokenType::Key) {
                    true
                } else {
                    self.match_token(TokenType::Index);
                    false
                };

                // Optional index name (before the columns)
                let name = if !self.check(TokenType::LParen) && !self.check(TokenType::Using) {
                    Some(self.expect_identifier_with_quoted()?)
                } else {
                    None
                };

                // Parse columns (with optional prefix length and DESC)
                self.expect(TokenType::LParen)?;
                let columns = self.parse_index_identifier_list()?;
                self.expect(TokenType::RParen)?;

                // Parse optional USING BTREE|HASH
                let modifiers = self.parse_constraint_modifiers();

                Ok(AlterTableAction::AddConstraint(TableConstraint::Index {
                    name,
                    columns,
                    kind,
                    modifiers,
                    use_key_keyword,
                    expression: None,
                    index_type: None,
                    granularity: None,
                }))
            } else if self.match_identifier("COLUMNS") {
                // ADD COLUMNS (col1 TYPE, col2 TYPE, ...) [CASCADE] - Hive/Spark syntax
                self.expect(TokenType::LParen)?;
                let mut columns = Vec::new();
                loop {
                    let col_def = self.parse_column_def()?;
                    columns.push(col_def);
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
                self.expect(TokenType::RParen)?;
                let cascade = self.match_token(TokenType::Cascade);
                Ok(AlterTableAction::AddColumns { columns, cascade })
            } else if self.match_keywords(&[TokenType::If, TokenType::Not, TokenType::Exists]) {
                // ADD IF NOT EXISTS PARTITION(key = value) - Hive/Spark syntax
                // ADD IF NOT EXISTS col1 INT, col2 INT - Snowflake syntax
                if self.match_token(TokenType::Partition) {
                    self.expect(TokenType::LParen)?;
                    let mut partition_exprs = Vec::new();
                    loop {
                        if let Some(expr) = self.parse_conjunction()? {
                            partition_exprs.push(expr);
                        }
                        if !self.match_token(TokenType::Comma) {
                            break;
                        }
                    }
                    self.expect(TokenType::RParen)?;
                    let partition =
                        Expression::Partition(Box::new(crate::expressions::Partition {
                            expressions: partition_exprs,
                            subpartition: false,
                        }));
                    let location = if self.match_text_seq(&["LOCATION"]) {
                        self.parse_property()?
                    } else {
                        None
                    };
                    return Ok(AlterTableAction::AddPartition {
                        partition,
                        if_not_exists: true,
                        location,
                    });
                } else {
                    // Snowflake: ADD IF NOT EXISTS col1 INT, [IF NOT EXISTS] col2 INT
                    // Parse just the first column; the caller's comma loop handles the rest
                    let col_def = self.parse_column_def()?;
                    return Ok(AlterTableAction::AddColumn {
                        column: col_def,
                        if_not_exists: true,
                        position: None,
                    });
                }
            } else if self.check(TokenType::Partition) {
                // ADD PARTITION(key = value) - Hive/Spark syntax
                self.advance(); // consume PARTITION
                self.expect(TokenType::LParen)?;
                let mut partition_exprs = Vec::new();
                loop {
                    if let Some(expr) = self.parse_conjunction()? {
                        partition_exprs.push(expr);
                    }
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
                self.expect(TokenType::RParen)?;
                let partition = Expression::Partition(Box::new(crate::expressions::Partition {
                    expressions: partition_exprs,
                    subpartition: false,
                }));
                let location = if self.match_text_seq(&["LOCATION"]) {
                    // Parse the LOCATION value (typically a string literal like 'path')
                    Some(self.parse_primary()?)
                } else {
                    None
                };
                Ok(AlterTableAction::AddPartition {
                    partition,
                    if_not_exists: false,
                    location,
                })
            } else {
                // ADD COLUMN or ADD (col1 TYPE, col2 TYPE) for Oracle
                let has_column_keyword = self.match_token(TokenType::Column); // optional COLUMN keyword

                // Check for Oracle-style ADD (col1 TYPE, col2 TYPE, ...) without COLUMN keyword
                if !has_column_keyword && self.check(TokenType::LParen) {
                    // Oracle multi-column ADD syntax: ADD (col1 TYPE, col2 TYPE, ...)
                    self.advance(); // consume '('
                    let mut columns = Vec::new();
                    loop {
                        let col_def = self.parse_column_def()?;
                        columns.push(col_def);
                        if !self.match_token(TokenType::Comma) {
                            break;
                        }
                    }
                    self.expect(TokenType::RParen)?;
                    // Use AddColumns with cascade=false for Oracle syntax
                    Ok(AlterTableAction::AddColumns {
                        columns,
                        cascade: false,
                    })
                } else {
                    // Handle IF NOT EXISTS for ADD COLUMN
                    let if_not_exists =
                        self.match_keywords(&[TokenType::If, TokenType::Not, TokenType::Exists]);
                    let col_def = self.parse_column_def()?;
                    // Check for FIRST or AFTER position modifiers (MySQL/MariaDB)
                    let position = if self.match_token(TokenType::First) {
                        Some(ColumnPosition::First)
                    } else if self.match_token(TokenType::After) {
                        let after_col = self.expect_identifier()?;
                        // ClickHouse: AFTER n.a (dotted nested column name)
                        let after_name = if self.match_token(TokenType::Dot) {
                            let field = self.expect_identifier()?;
                            format!("{}.{}", after_col, field)
                        } else {
                            after_col
                        };
                        Some(ColumnPosition::After(Identifier::new(after_name)))
                    } else {
                        None
                    };
                    Ok(AlterTableAction::AddColumn {
                        column: col_def,
                        if_not_exists,
                        position,
                    })
                }
            }
        } else if self.match_token(TokenType::Drop) {
            // ClickHouse: DROP INDEX idx, DROP PROJECTION name, DROP STATISTICS, etc.
            // These have different syntax from MySQL, so consume as Raw
            if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && (self.check(TokenType::Index)
                || self.check_identifier("PROJECTION")
                || self.check_identifier("STATISTICS")
                || self.check_identifier("DETACHED")
                || self.check_identifier("PART"))
            {
                let is_statistics = self.check_identifier("STATISTICS");
                let mut tokens: Vec<(String, TokenType)> =
                    vec![("DROP".to_string(), TokenType::Drop)];
                let mut paren_depth = 0i32;
                while !self.is_at_end() && !self.check(TokenType::Semicolon) {
                    if self.check(TokenType::Comma) && paren_depth == 0 && !is_statistics {
                        break;
                    }
                    let token = self.advance();
                    if token.token_type == TokenType::LParen {
                        paren_depth += 1;
                    }
                    if token.token_type == TokenType::RParen {
                        paren_depth -= 1;
                    }
                    let text = if token.token_type == TokenType::QuotedIdentifier {
                        format!("\"{}\"", token.text)
                    } else if token.token_type == TokenType::String {
                        format!("'{}'", token.text)
                    } else {
                        token.text.clone()
                    };
                    tokens.push((text, token.token_type));
                }
                return Ok(AlterTableAction::Raw {
                    sql: self.join_command_tokens(tokens),
                });
            }
            // Handle IF EXISTS before determining what to drop
            let if_exists = self.match_keywords(&[TokenType::If, TokenType::Exists]);

            if self.match_token(TokenType::Partition) {
                // DROP [IF EXISTS] PARTITION expr [, PARTITION expr ...]
                // ClickHouse supports: PARTITION 201901, PARTITION ALL,
                // PARTITION tuple(...), PARTITION ID '...'
                let mut partitions = Vec::new();
                loop {
                    if self.check(TokenType::LParen) {
                        // ClickHouse: PARTITION (expr) or PARTITION (expr, expr, ...)
                        // Standard SQL: PARTITION (key=value, ...)
                        // Peek ahead: if LParen is followed by String/Number (not identifier=),
                        // parse as expression
                        let is_ch_expr = matches!(
                            self.config.dialect,
                            Some(crate::dialects::DialectType::ClickHouse)
                        ) && self.current + 1 < self.tokens.len()
                            && (self.tokens[self.current + 1].token_type == TokenType::String
                                || self.tokens[self.current + 1].token_type == TokenType::Number
                                || self.tokens[self.current + 1].token_type == TokenType::LParen
                                || (self.current + 2 < self.tokens.len()
                                    && self.tokens[self.current + 2].token_type != TokenType::Eq));
                        if is_ch_expr {
                            // Parse as tuple expression
                            let expr = self.parse_expression()?;
                            partitions.push(vec![(Identifier::new("__expr__".to_string()), expr)]);
                        } else {
                            self.advance(); // consume (
                            let mut parts = Vec::new();
                            loop {
                                let key = self.expect_identifier()?;
                                self.expect(TokenType::Eq)?;
                                let value = self.parse_expression()?;
                                parts.push((Identifier::new(key), value));
                                if !self.match_token(TokenType::Comma) {
                                    break;
                                }
                            }
                            self.expect(TokenType::RParen)?;
                            partitions.push(parts);
                        }
                    } else if self.match_text_seq(&["ALL"]) {
                        // ClickHouse: PARTITION ALL
                        partitions.push(vec![(
                            Identifier::new("ALL".to_string()),
                            Expression::Boolean(BooleanLiteral { value: true }),
                        )]);
                    } else if self.match_text_seq(&["ID"]) {
                        // ClickHouse: PARTITION ID 'string'
                        let id_val = self.parse_expression()?;
                        partitions.push(vec![(Identifier::new("ID".to_string()), id_val)]);
                    } else {
                        // ClickHouse: PARTITION <expression> (number, tuple(...), etc.)
                        let expr = self.parse_expression()?;
                        partitions.push(vec![(Identifier::new("__expr__".to_string()), expr)]);
                    }
                    // Check for ", PARTITION" for multiple partitions
                    if self.match_token(TokenType::Comma) {
                        if !self.match_token(TokenType::Partition) {
                            break;
                        }
                    } else {
                        break;
                    }
                }
                Ok(AlterTableAction::DropPartition {
                    partitions,
                    if_exists,
                })
            } else if self.match_token(TokenType::Column) {
                // DROP [IF EXISTS] COLUMN [IF EXISTS] name [CASCADE]
                // Check for IF EXISTS after COLUMN as well
                let if_exists =
                    if_exists || self.match_keywords(&[TokenType::If, TokenType::Exists]);
                let mut name = self.expect_identifier_with_quoted()?;
                // ClickHouse: nested column names like n.ui8
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) && self.match_token(TokenType::Dot)
                {
                    let sub = self.expect_identifier_with_quoted()?;
                    name.name = format!("{}.{}", name.name, sub.name);
                }
                let cascade = self.match_token(TokenType::Cascade);
                Ok(AlterTableAction::DropColumn {
                    name,
                    if_exists,
                    cascade,
                })
            } else if self.match_token(TokenType::Constraint) {
                // DROP [IF EXISTS] CONSTRAINT name
                let name = self.expect_identifier_with_quoted()?;
                Ok(AlterTableAction::DropConstraint { name, if_exists })
            } else if self.match_keywords(&[TokenType::ForeignKey, TokenType::Key]) {
                // DROP FOREIGN KEY name (Oracle/MySQL)
                let name = self.expect_identifier_with_quoted()?;
                Ok(AlterTableAction::DropForeignKey { name })
            } else if self.check_identifier("COLUMNS") && self.check_next(TokenType::LParen) {
                // DROP COLUMNS (col1, col2, ...) - Spark/Databricks syntax
                self.advance(); // consume COLUMNS
                self.expect(TokenType::LParen)?;
                let mut names = Vec::new();
                loop {
                    let name = self.expect_identifier_with_quoted()?;
                    names.push(name);
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
                self.expect(TokenType::RParen)?;
                Ok(AlterTableAction::DropColumns { names })
            } else {
                // DROP [IF EXISTS] name (implicit column) [CASCADE]
                let mut name = self.expect_identifier_with_quoted()?;
                // ClickHouse: nested column names like n.ui8
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) && self.match_token(TokenType::Dot)
                {
                    let sub = self.expect_identifier_with_quoted()?;
                    name.name = format!("{}.{}", name.name, sub.name);
                }
                let cascade = self.match_token(TokenType::Cascade);
                Ok(AlterTableAction::DropColumn {
                    name,
                    if_exists,
                    cascade,
                })
            }
        } else if self.match_token(TokenType::Rename) {
            if self.match_token(TokenType::Column) {
                // RENAME COLUMN [IF EXISTS] old TO new
                let if_exists = self.match_keywords(&[TokenType::If, TokenType::Exists]);
                let mut old_name = self.expect_identifier_or_safe_keyword_with_quoted()?;
                // ClickHouse: nested column names like n.x
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) && self.match_token(TokenType::Dot)
                {
                    let field = self.expect_identifier_with_quoted()?;
                    old_name = Identifier {
                        name: format!("{}.{}", old_name.name, field.name),
                        quoted: false,
                        trailing_comments: Vec::new(),
                        span: None,
                    };
                }
                self.expect(TokenType::To)?;
                let mut new_name = self.expect_identifier_or_safe_keyword_with_quoted()?;
                // ClickHouse: nested column names like n.y
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) && self.match_token(TokenType::Dot)
                {
                    let field = self.expect_identifier_or_safe_keyword_with_quoted()?;
                    new_name = Identifier {
                        name: format!("{}.{}", new_name.name, field.name),
                        quoted: false,
                        trailing_comments: Vec::new(),
                        span: None,
                    };
                }
                Ok(AlterTableAction::RenameColumn {
                    old_name,
                    new_name,
                    if_exists,
                })
            } else if self.match_token(TokenType::To) {
                // RENAME TO new_table
                let new_name = self.parse_table_ref()?;
                Ok(AlterTableAction::RenameTable(new_name))
            } else if self.is_identifier_token() || self.is_safe_keyword_as_identifier() {
                // StarRocks/Doris: RENAME new_name (without TO)
                // SQLite: RENAME old_name TO new_name (without COLUMN keyword)
                let first_name = self.expect_identifier_with_quoted()?;
                if self.match_token(TokenType::To) {
                    let new_name = self.expect_identifier_with_quoted()?;
                    Ok(AlterTableAction::RenameColumn {
                        old_name: first_name,
                        new_name,
                        if_exists: false,
                    })
                } else {
                    // No TO keyword: treat as RENAME TABLE (StarRocks/Doris)
                    Ok(AlterTableAction::RenameTable(TableRef::new(
                        first_name.name,
                    )))
                }
            } else {
                Err(self.parse_error("Expected COLUMN or TO after RENAME"))
            }
        } else if self.match_token(TokenType::Alter) {
            // Check for ALTER INDEX (MySQL: ALTER TABLE t ALTER INDEX i VISIBLE/INVISIBLE)
            if self.match_token(TokenType::Index) {
                let name = self.expect_identifier_with_quoted()?;
                let visible = if self.match_identifier("VISIBLE") {
                    true
                } else if self.match_identifier("INVISIBLE") {
                    false
                } else {
                    return Err(
                        self.parse_error("Expected VISIBLE or INVISIBLE after ALTER INDEX name")
                    );
                };
                Ok(AlterTableAction::AlterIndex { name, visible })
            } else if self.check_identifier("SORTKEY") {
                // Redshift: ALTER TABLE t ALTER SORTKEY AUTO|NONE|(col1, col2)
                self.advance(); // consume SORTKEY
                if self.match_texts(&["AUTO", "NONE"]) {
                    let style = self.previous().text.to_uppercase();
                    Ok(AlterTableAction::AlterSortKey {
                        this: Some(style),
                        expressions: Vec::new(),
                        compound: false,
                    })
                } else if self.check(TokenType::LParen) {
                    // (col1, col2) syntax
                    let wrapped = self.parse_wrapped_id_vars()?;
                    let expressions = if let Some(Expression::Tuple(t)) = wrapped {
                        t.expressions
                    } else {
                        Vec::new()
                    };
                    Ok(AlterTableAction::AlterSortKey {
                        this: None,
                        expressions,
                        compound: false,
                    })
                } else {
                    Err(self.parse_error("Expected AUTO, NONE, or (columns) after SORTKEY"))
                }
            } else if self.check_identifier("COMPOUND") {
                // Redshift: ALTER TABLE t ALTER COMPOUND SORTKEY (col1, col2)
                self.advance(); // consume COMPOUND
                if !self.match_identifier("SORTKEY") {
                    return Err(self.parse_error("Expected SORTKEY after COMPOUND"));
                }
                if self.check(TokenType::LParen) {
                    let wrapped = self.parse_wrapped_id_vars()?;
                    let expressions = if let Some(Expression::Tuple(t)) = wrapped {
                        t.expressions
                    } else {
                        Vec::new()
                    };
                    Ok(AlterTableAction::AlterSortKey {
                        this: None,
                        expressions,
                        compound: true,
                    })
                } else {
                    Err(self.parse_error("Expected (columns) after COMPOUND SORTKEY"))
                }
            } else if self.check_identifier("DISTSTYLE") {
                // Redshift: ALTER TABLE t ALTER DISTSTYLE ALL|EVEN|AUTO|KEY [DISTKEY col]
                self.advance(); // consume DISTSTYLE
                if self.match_texts(&["ALL", "EVEN", "AUTO"]) {
                    let style = self.previous().text.to_uppercase();
                    Ok(AlterTableAction::AlterDistStyle {
                        style,
                        distkey: None,
                    })
                } else if self.match_token(TokenType::Key) || self.match_identifier("KEY") {
                    // DISTSTYLE KEY DISTKEY col
                    if !self.match_identifier("DISTKEY") {
                        return Err(self.parse_error("Expected DISTKEY after DISTSTYLE KEY"));
                    }
                    let col = self.expect_identifier_with_quoted()?;
                    Ok(AlterTableAction::AlterDistStyle {
                        style: "KEY".to_string(),
                        distkey: Some(col),
                    })
                } else {
                    Err(self.parse_error("Expected ALL, EVEN, AUTO, or KEY after DISTSTYLE"))
                }
            } else if self.check_identifier("DISTKEY") {
                // Redshift: ALTER TABLE t ALTER DISTKEY col (shorthand for DISTSTYLE KEY DISTKEY col)
                self.advance(); // consume DISTKEY
                let col = self.expect_identifier_with_quoted()?;
                Ok(AlterTableAction::AlterDistStyle {
                    style: "KEY".to_string(),
                    distkey: Some(col),
                })
            } else {
                // ALTER COLUMN
                self.match_token(TokenType::Column); // optional COLUMN keyword
                let name = self.expect_identifier_with_quoted()?;
                let action = self.parse_alter_column_action()?;
                Ok(AlterTableAction::AlterColumn {
                    name,
                    action,
                    use_modify_keyword: false,
                })
            }
        } else if self.match_identifier("MODIFY") {
            // ClickHouse: MODIFY ORDER BY, MODIFY SETTING, MODIFY TTL, MODIFY QUERY,
            // MODIFY COLUMN name type [DEFAULT|MATERIALIZED|ALIAS] [CODEC] [TTL] [COMMENT], etc.
            // These are ClickHouse-specific and have richer syntax than MySQL MODIFY COLUMN.
            // Consume all ClickHouse MODIFY actions as Raw.
            if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) {
                // MODIFY SETTING uses commas between settings (not action separators)
                let is_setting =
                    self.check(TokenType::Settings) || self.check_identifier("SETTING");
                let mut tokens: Vec<(String, TokenType)> =
                    vec![("MODIFY".to_string(), TokenType::Var)];
                let mut paren_depth = 0i32;
                while !self.is_at_end() && !self.check(TokenType::Semicolon) {
                    if self.check(TokenType::Comma) && paren_depth == 0 && !is_setting {
                        break;
                    }
                    let token = self.advance();
                    if token.token_type == TokenType::LParen {
                        paren_depth += 1;
                    }
                    if token.token_type == TokenType::RParen {
                        paren_depth -= 1;
                    }
                    let text = if token.token_type == TokenType::QuotedIdentifier {
                        format!("\"{}\"", token.text)
                    } else if token.token_type == TokenType::String {
                        format!("'{}'", token.text)
                    } else {
                        token.text.clone()
                    };
                    tokens.push((text, token.token_type));
                }
                return Ok(AlterTableAction::Raw {
                    sql: self.join_command_tokens(tokens),
                });
            }
            // MODIFY COLUMN (MySQL syntax for altering column type)
            self.match_token(TokenType::Column); // optional COLUMN keyword
            let name = Identifier::new(self.expect_identifier()?);
            // Parse the data type directly (MySQL MODIFY COLUMN col TYPE)
            let data_type = self.parse_data_type()?;
            // Parse optional COLLATE clause
            let collate = if self.match_token(TokenType::Collate) {
                if self.check(TokenType::String) {
                    Some(self.advance().text)
                } else if self.check(TokenType::Identifier) || self.check(TokenType::Var) {
                    Some(self.advance().text)
                } else {
                    None
                }
            } else {
                None
            };
            Ok(AlterTableAction::AlterColumn {
                name,
                action: AlterColumnAction::SetDataType {
                    data_type,
                    using: None,
                    collate,
                },
                use_modify_keyword: true,
            })
        } else if self.match_identifier("CHANGE") {
            // CHANGE [COLUMN] old_name new_name [data_type] [COMMENT 'comment'] - Hive/MySQL/SingleStore syntax
            // In SingleStore, data_type can be omitted for simple renames
            self.match_token(TokenType::Column); // optional COLUMN keyword
            let old_name = Identifier::new(self.expect_identifier()?);
            let new_name = Identifier::new(self.expect_identifier()?);
            // Try to parse data type - it's optional in SingleStore
            let data_type = if !self.is_at_end()
                && !self.check(TokenType::Comment)
                && !self.check(TokenType::Comma)
                && !self.check(TokenType::Semicolon)
            {
                // Check if next token could start a data type
                let tok = self.peek();
                if tok.token_type.is_keyword()
                    || tok.token_type == TokenType::Identifier
                    || tok.token_type == TokenType::Var
                {
                    Some(self.parse_data_type()?)
                } else {
                    None
                }
            } else {
                None
            };
            let comment = if self.match_token(TokenType::Comment) {
                Some(self.expect_string()?)
            } else {
                None
            };
            let cascade = self.match_text_seq(&["CASCADE"]);
            // Also check for RESTRICT (the opposite, just consume it)
            if !cascade {
                self.match_text_seq(&["RESTRICT"]);
            }
            Ok(AlterTableAction::ChangeColumn {
                old_name,
                new_name,
                data_type,
                comment,
                cascade,
            })
        } else if self.match_token(TokenType::Constraint) {
            // CONSTRAINT name ... (implicit ADD, CONSTRAINT already consumed)
            // Parse the constraint name and then the constraint definition
            let name = Some(self.expect_identifier_with_quoted()?);
            let constraint = self.parse_constraint_definition(name)?;
            Ok(AlterTableAction::AddConstraint(constraint))
        } else if self.check(TokenType::PrimaryKey)
            || self.check(TokenType::ForeignKey)
            || self.check(TokenType::Unique)
        {
            // ADD CONSTRAINT (implicit ADD, no CONSTRAINT keyword)
            let constraint = self.parse_table_constraint()?;
            Ok(AlterTableAction::AddConstraint(constraint))
        } else if self.match_token(TokenType::Delete) {
            // ALTER TABLE t DELETE WHERE x = 1 (BigQuery syntax)
            self.expect(TokenType::Where)?;
            let where_clause = self.parse_expression()?;
            Ok(AlterTableAction::Delete { where_clause })
        } else if self.match_keyword("SWAP") {
            // Snowflake: ALTER TABLE a SWAP WITH b
            self.expect(TokenType::With)?;
            let target = self.parse_table_ref()?;
            Ok(AlterTableAction::SwapWith(target))
        } else if self.match_token(TokenType::Set) {
            // TSQL: ALTER TABLE t SET (SYSTEM_VERSIONING=ON, DATA_DELETION=ON, ...)
            if self.check(TokenType::LParen) {
                self.advance(); // consume (
                let mut expressions = Vec::new();
                loop {
                    if self.check(TokenType::RParen) {
                        break;
                    }
                    if self.check_identifier("SYSTEM_VERSIONING") {
                        let expr = self.parse_system_versioning_option()?;
                        expressions.push(expr);
                    } else if self.check_identifier("DATA_DELETION") {
                        let expr = self.parse_data_deletion_option()?;
                        expressions.push(expr);
                    } else {
                        // Generic key=value (e.g., FILESTREAM_ON = 'test')
                        let expr = self.parse_expression()?;
                        expressions.push(expr);
                    }
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
                self.expect(TokenType::RParen)?;
                Ok(AlterTableAction::SetOptions { expressions })
            } else if self.match_keyword("TAG") {
                // Snowflake: SET TAG key='value', ... (key can be qualified like schema.tagname)
                let mut tags = Vec::new();
                loop {
                    // Parse qualified tag name (e.g., foo.bar or just bar)
                    let mut key = self.expect_identifier_or_keyword()?;
                    while self.match_token(TokenType::Dot) {
                        let next = self.expect_identifier_or_keyword()?;
                        key = format!("{}.{}", key, next);
                    }
                    self.expect(TokenType::Eq)?;
                    let value = self.parse_primary()?;
                    tags.push((key, value));
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
                Ok(AlterTableAction::SetTag { expressions: tags })
            } else if self.check_identifier("LOGGED") {
                // PostgreSQL: ALTER TABLE t SET LOGGED
                self.advance();
                Ok(AlterTableAction::SetAttribute {
                    attribute: "LOGGED".to_string(),
                })
            } else if self.check_identifier("UNLOGGED") {
                // PostgreSQL: ALTER TABLE t SET UNLOGGED
                self.advance();
                Ok(AlterTableAction::SetAttribute {
                    attribute: "UNLOGGED".to_string(),
                })
            } else if self.match_identifier("WITHOUT") {
                // PostgreSQL: ALTER TABLE t SET WITHOUT CLUSTER/OIDS
                let what = self.expect_identifier_or_keyword()?;
                Ok(AlterTableAction::SetAttribute {
                    attribute: format!("WITHOUT {}", what),
                })
            } else if self.check_identifier("ACCESS") {
                // PostgreSQL: ALTER TABLE t SET ACCESS METHOD method
                self.advance();
                // Consume "METHOD"
                if !self.match_identifier("METHOD") {
                    return Err(self.parse_error("Expected METHOD after ACCESS"));
                }
                let method = self.expect_identifier_or_keyword()?;
                Ok(AlterTableAction::SetAttribute {
                    attribute: format!("ACCESS METHOD {}", method),
                })
            } else if self.check_identifier("TABLESPACE") {
                // PostgreSQL: ALTER TABLE t SET TABLESPACE tablespace
                self.advance();
                let name = self.expect_identifier_or_keyword()?;
                Ok(AlterTableAction::SetAttribute {
                    attribute: format!("TABLESPACE {}", name),
                })
            } else if self.check_identifier("STAGE_FILE_FORMAT") {
                // Snowflake: ALTER TABLE t SET STAGE_FILE_FORMAT = (options)
                self.advance();
                let options = self.parse_wrapped_options()?;
                Ok(AlterTableAction::SetStageFileFormat { options })
            } else if self.check_identifier("STAGE_COPY_OPTIONS") {
                // Snowflake: ALTER TABLE t SET STAGE_COPY_OPTIONS = (options)
                self.advance();
                let options = self.parse_wrapped_options()?;
                Ok(AlterTableAction::SetStageCopyOptions { options })
            } else if self.match_token(TokenType::Authorization) {
                // Trino: ALTER TABLE t SET AUTHORIZATION [ROLE] user
                let mut auth_text = String::new();
                if self.match_texts(&["ROLE"]) {
                    auth_text.push_str("ROLE ");
                }
                let user = self.expect_identifier_or_keyword()?;
                auth_text.push_str(&user);
                Ok(AlterTableAction::SetAttribute {
                    attribute: format!("AUTHORIZATION {}", auth_text),
                })
            } else if self.match_identifier("PROPERTIES") {
                // Trino: ALTER TABLE t SET PROPERTIES x = 'y', ...
                let mut properties = Vec::new();
                loop {
                    // Parse property name (could be identifier or string literal)
                    let key = if self.check(TokenType::String) {
                        self.expect_string()?
                    } else {
                        self.expect_identifier_or_keyword()?
                    };
                    self.expect(TokenType::Eq)?;
                    // Parse value (could be DEFAULT or an expression)
                    let value = if self.match_token(TokenType::Default) {
                        // Use Var instead of Identifier so it won't be quoted
                        Expression::Var(Box::new(crate::expressions::Var {
                            this: "DEFAULT".to_string(),
                        }))
                    } else {
                        self.parse_expression()?
                    };
                    properties.push((key, value));
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
                Ok(AlterTableAction::SetProperty { properties })
            } else if self.match_text_seq(&["TABLE", "PROPERTIES"]) {
                // Redshift: ALTER TABLE t SET TABLE PROPERTIES ('a' = '5', 'b' = 'c')
                self.expect(TokenType::LParen)?;
                let mut properties = Vec::new();
                loop {
                    if self.check(TokenType::RParen) {
                        break;
                    }
                    // Parse key (string literal)
                    let key = self.parse_primary()?;
                    self.expect(TokenType::Eq)?;
                    // Parse value (string literal)
                    let value = self.parse_primary()?;
                    properties.push((key, value));
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
                self.expect(TokenType::RParen)?;
                Ok(AlterTableAction::SetTableProperties { properties })
            } else if self.match_text_seq(&["LOCATION"]) {
                // Redshift: ALTER TABLE t SET LOCATION 's3://bucket/folder/'
                let location = self.expect_string()?;
                Ok(AlterTableAction::SetLocation { location })
            } else if self.match_text_seq(&["FILE", "FORMAT"]) {
                // Redshift: ALTER TABLE t SET FILE FORMAT AVRO
                let format = self.expect_identifier_or_keyword()?;
                Ok(AlterTableAction::SetFileFormat { format })
            } else {
                // Snowflake: SET property=value, ...
                let mut properties = Vec::new();
                loop {
                    let key = self.expect_identifier_or_keyword()?;
                    self.expect(TokenType::Eq)?;
                    let value = self.parse_expression()?;
                    properties.push((key, value));
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
                Ok(AlterTableAction::SetProperty { properties })
            }
        } else if self.match_keyword("UNSET") {
            // Snowflake: ALTER TABLE t UNSET property or UNSET TAG key
            if self.match_keyword("TAG") {
                // UNSET TAG key1, key2 (keys can be qualified like schema.tagname)
                let mut names = Vec::new();
                loop {
                    let mut name = self.expect_identifier_or_keyword()?;
                    while self.match_token(TokenType::Dot) {
                        let next = self.expect_identifier_or_keyword()?;
                        name = format!("{}.{}", name, next);
                    }
                    names.push(name);
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
                Ok(AlterTableAction::UnsetTag { names })
            } else {
                // UNSET property1, property2
                let mut properties = Vec::new();
                loop {
                    let name = self.expect_identifier_or_keyword()?;
                    properties.push(name);
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
                Ok(AlterTableAction::UnsetProperty { properties })
            }
        } else if self.match_keyword("CLUSTER") {
            // Snowflake: ALTER TABLE t CLUSTER BY (col1, col2 DESC)
            self.expect(TokenType::By)?;
            self.expect(TokenType::LParen)?;
            // Parse ordered expressions (can have ASC/DESC modifiers)
            let ordered = self.parse_order_by_list()?;
            // Convert Ordered to Expression (wrapping in Ordered if it has ordering)
            let expressions: Vec<Expression> = ordered
                .into_iter()
                .map(|o| Expression::Ordered(Box::new(o)))
                .collect();
            self.expect(TokenType::RParen)?;
            Ok(AlterTableAction::ClusterBy { expressions })
        } else if self.match_token(TokenType::Replace) {
            // ClickHouse: REPLACE PARTITION expr FROM table
            if self.match_token(TokenType::Partition) {
                let partition_expr = if self.match_text_seq(&["ALL"]) {
                    Expression::Identifier(Identifier::new("ALL".to_string()))
                } else if self.match_text_seq(&["ID"]) {
                    let id_val = self.parse_expression()?;
                    // Store as Raw to preserve "ID <value>" format
                    let id_str = match &id_val {
                        Expression::Literal(Literal::String(s)) => format!("ID '{}'", s),
                        _ => format!("ID {}", "?"),
                    };
                    Expression::Raw(Raw { sql: id_str })
                } else {
                    self.parse_expression()?
                };
                let source = if self.match_token(TokenType::From) {
                    let tref = self.parse_table_ref()?;
                    Some(Box::new(Expression::Table(tref)))
                } else {
                    None
                };
                Ok(AlterTableAction::ReplacePartition {
                    partition: partition_expr,
                    source,
                })
            } else {
                Err(self.parse_error("Expected PARTITION after REPLACE in ALTER TABLE"))
            }
        } else if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) {
            // ClickHouse-specific ALTER TABLE mutations: UPDATE, DELETE, DETACH, ATTACH,
            // FREEZE, UNFREEZE, MATERIALIZE, CLEAR, COMMENT COLUMN, MODIFY ORDER BY,
            // MOVE PARTITION, FETCH PARTITION, ADD INDEX, DROP INDEX, CLEAR INDEX
            // For ClickHouse, consume any unrecognized ALTER TABLE action as Raw
            // (covers UPDATE, DELETE, DETACH, ATTACH, FREEZE, MOVE, FETCH, etc.)
            {
                let keyword = self.advance().text.clone();
                let mut tokens: Vec<(String, TokenType)> = vec![(keyword, TokenType::Var)];
                let mut paren_depth = 0i32;
                while !self.is_at_end() && !self.check(TokenType::Semicolon) {
                    // Stop at comma only when at top-level (not inside parens) — it separates ALTER actions
                    if self.check(TokenType::Comma) && paren_depth == 0 {
                        break;
                    }
                    let token = self.advance();
                    if token.token_type == TokenType::LParen {
                        paren_depth += 1;
                    }
                    if token.token_type == TokenType::RParen {
                        paren_depth -= 1;
                    }
                    let text = if token.token_type == TokenType::QuotedIdentifier {
                        format!("\"{}\"", token.text)
                    } else if token.token_type == TokenType::String {
                        format!("'{}'", token.text)
                    } else {
                        token.text.clone()
                    };
                    tokens.push((text, token.token_type));
                }
                Ok(AlterTableAction::Raw {
                    sql: self.join_command_tokens(tokens),
                })
            }
        } else {
            Err(self.parse_error(format!(
                "Expected ADD, DROP, RENAME, ALTER, SET, UNSET, SWAP, CLUSTER, or REPLACE in ALTER TABLE, got {:?}",
                self.peek().token_type
            )))
        }
    }

    /// Parse TSQL SYSTEM_VERSIONING option in ALTER TABLE SET (...)
    /// Handles: SYSTEM_VERSIONING=OFF, SYSTEM_VERSIONING=ON, SYSTEM_VERSIONING=ON(HISTORY_TABLE=..., ...)
    fn parse_system_versioning_option(&mut self) -> Result<Expression> {
        self.advance(); // consume SYSTEM_VERSIONING
        self.expect(TokenType::Eq)?;

        let mut prop = WithSystemVersioningProperty {
            on: None,
            this: None,
            data_consistency: None,
            retention_period: None,
            with_: None,
        };

        if self.match_identifier("OFF") {
            // SYSTEM_VERSIONING=OFF
            // on is None => generates OFF
            return Ok(Expression::WithSystemVersioningProperty(Box::new(prop)));
        }

        // SYSTEM_VERSIONING=ON or SYSTEM_VERSIONING=ON(...)
        if self.match_token(TokenType::On) || self.match_identifier("ON") {
            prop.on = Some(Box::new(Expression::Boolean(BooleanLiteral {
                value: true,
            })));
        }

        if self.match_token(TokenType::LParen) {
            // Parse options inside ON(...)
            loop {
                if self.check(TokenType::RParen) {
                    break;
                }
                if self.match_identifier("HISTORY_TABLE") {
                    self.expect(TokenType::Eq)?;
                    let table = self.parse_table_ref()?;
                    prop.this = Some(Box::new(Expression::Table(table)));
                } else if self.match_identifier("DATA_CONSISTENCY_CHECK") {
                    self.expect(TokenType::Eq)?;
                    let val = self.expect_identifier_or_keyword()?;
                    prop.data_consistency = Some(Box::new(Expression::Identifier(
                        Identifier::new(val.to_uppercase()),
                    )));
                } else if self.match_identifier("HISTORY_RETENTION_PERIOD") {
                    self.expect(TokenType::Eq)?;
                    if let Some(rp) = self.parse_retention_period()? {
                        prop.retention_period = Some(Box::new(rp));
                    }
                } else {
                    // Skip unknown options
                    self.advance();
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            self.expect(TokenType::RParen)?;
        }

        Ok(Expression::WithSystemVersioningProperty(Box::new(prop)))
    }

    /// Parse TSQL DATA_DELETION option in ALTER TABLE SET (...)
    /// Handles: DATA_DELETION=ON, DATA_DELETION=OFF, DATA_DELETION=ON(FILTER_COLUMN=..., RETENTION_PERIOD=...)
    fn parse_data_deletion_option(&mut self) -> Result<Expression> {
        self.advance(); // consume DATA_DELETION
        self.expect(TokenType::Eq)?;

        let on = if self.match_identifier("ON") || self.match_token(TokenType::On) {
            true
        } else if self.match_identifier("OFF") {
            false
        } else {
            false
        };

        let on_expr = Box::new(Expression::Boolean(BooleanLiteral { value: on }));
        let mut filter_column = None;
        let mut retention_period = None;

        if self.match_token(TokenType::LParen) {
            loop {
                if self.check(TokenType::RParen) {
                    break;
                }
                if self.match_identifier("FILTER_COLUMN") {
                    self.expect(TokenType::Eq)?;
                    let col = self.expect_identifier_or_keyword()?;
                    filter_column = Some(Box::new(Expression::Column(Column {
                        name: Identifier::new(col),
                        table: None,
                        join_mark: false,
                        trailing_comments: Vec::new(),
                        span: None,
                        inferred_type: None,
                    })));
                } else if self.match_identifier("RETENTION_PERIOD") {
                    self.expect(TokenType::Eq)?;
                    if let Some(rp) = self.parse_retention_period()? {
                        retention_period = Some(Box::new(rp));
                    }
                } else {
                    self.advance();
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            self.expect(TokenType::RParen)?;
        }

        Ok(Expression::DataDeletionProperty(Box::new(
            DataDeletionProperty {
                on: on_expr,
                filter_column,
                retention_period,
            },
        )))
    }

    /// Parse ALTER COLUMN action
    fn parse_alter_column_action(&mut self) -> Result<AlterColumnAction> {
        if self.match_token(TokenType::Set) {
            if self.match_keywords(&[TokenType::Not, TokenType::Null]) {
                Ok(AlterColumnAction::SetNotNull)
            } else if self.match_token(TokenType::Default) {
                let expr = self.parse_primary()?;
                Ok(AlterColumnAction::SetDefault(expr))
            } else if self.match_identifier("DATA") {
                // SET DATA TYPE
                // TYPE can be a keyword token or identifier
                let _ = self.match_token(TokenType::Type) || self.match_identifier("TYPE");
                let data_type = self.parse_data_type()?;
                // Optional COLLATE
                let collate = if self.match_token(TokenType::Collate) {
                    Some(self.expect_identifier_or_keyword()?)
                } else {
                    None
                };
                // Optional USING expression
                let using = if self.match_token(TokenType::Using) {
                    Some(self.parse_expression()?)
                } else {
                    None
                };
                Ok(AlterColumnAction::SetDataType {
                    data_type,
                    using,
                    collate,
                })
            } else if self.match_identifier("VISIBLE") {
                Ok(AlterColumnAction::SetVisible)
            } else if self.match_identifier("INVISIBLE") {
                Ok(AlterColumnAction::SetInvisible)
            } else {
                Err(self.parse_error("Expected NOT NULL, DEFAULT, VISIBLE, or INVISIBLE after SET"))
            }
        } else if self.match_token(TokenType::Drop) {
            if self.match_keywords(&[TokenType::Not, TokenType::Null]) {
                Ok(AlterColumnAction::DropNotNull)
            } else if self.match_token(TokenType::Default) {
                Ok(AlterColumnAction::DropDefault)
            } else {
                Err(self.parse_error("Expected NOT NULL or DEFAULT after DROP"))
            }
        } else if self.match_token(TokenType::Comment) {
            // ALTER COLUMN col COMMENT 'comment'
            let comment = self.expect_string()?;
            Ok(AlterColumnAction::Comment(comment))
        } else if self.match_token(TokenType::Type)
            || self.match_identifier("TYPE")
            || self.is_identifier_token()
        {
            // TYPE data_type or just data_type (PostgreSQL/Redshift: ALTER COLUMN col TYPE datatype)
            let data_type = self.parse_data_type()?;
            // Optional COLLATE
            let collate = if self.match_token(TokenType::Collate) {
                Some(self.expect_identifier_or_keyword()?)
            } else {
                None
            };
            // Optional USING expression
            let using = if self.match_token(TokenType::Using) {
                Some(self.parse_expression()?)
            } else {
                None
            };
            Ok(AlterColumnAction::SetDataType {
                data_type,
                using,
                collate,
            })
        } else {
            Err(self.parse_error("Expected SET, DROP, or TYPE in ALTER COLUMN"))
        }
    }

    /// Parse TRUNCATE statement
    fn parse_truncate(&mut self) -> Result<Expression> {
        self.expect(TokenType::Truncate)?;

        // ClickHouse: TRUNCATE ALL TABLES FROM [IF EXISTS] db
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) && self.check_identifier("ALL")
            && self.current + 1 < self.tokens.len()
            && self.tokens[self.current + 1]
                .text
                .eq_ignore_ascii_case("TABLES")
        {
            // Consume remaining tokens as Command
            let mut parts = vec!["TRUNCATE".to_string()];
            while !self.is_at_end() && !self.check(TokenType::Semicolon) {
                let token = self.advance();
                if token.token_type == TokenType::String {
                    parts.push(format!("'{}'", token.text));
                } else {
                    parts.push(token.text.clone());
                }
            }
            return Ok(Expression::Command(Box::new(crate::expressions::Command {
                this: parts.join(" "),
            })));
        }

        let target = if self.match_token(TokenType::Database) {
            TruncateTarget::Database
        } else {
            // ClickHouse: TRUNCATE TEMPORARY TABLE t
            self.match_token(TokenType::Temporary);
            self.match_token(TokenType::Table); // optional TABLE keyword
            TruncateTarget::Table
        };

        // Parse optional IF EXISTS
        let if_exists = self.match_keywords(&[TokenType::If, TokenType::Exists]);

        // Parse first table with optional ONLY modifier
        let has_only = self.match_token(TokenType::Only);
        let mut table = self.parse_table_ref()?;
        if has_only {
            table.only = true;
        }

        // Check for * suffix on table name (PostgreSQL: inherit children)
        let first_star = self.match_token(TokenType::Star);

        // TSQL: WITH (PARTITIONS(1, 2 TO 5, 10 TO 20, 84))
        if self.check(TokenType::With) && self.check_next(TokenType::LParen) {
            if let Some(hint_expr) = self.parse_truncate_table_hints()? {
                match hint_expr {
                    Expression::Tuple(tuple) => {
                        table.hints = tuple.expressions;
                    }
                    other => {
                        table.hints = vec![other];
                    }
                }
            }
        }

        // ClickHouse: ON CLUSTER clause
        let on_cluster = self.parse_on_cluster_clause()?;

        // Parse additional tables for multi-table TRUNCATE
        let mut extra_tables = Vec::new();
        if first_star {
            // The first table has a * suffix, so create an entry for it
            extra_tables.push(TruncateTableEntry {
                table: table.clone(),
                star: true,
            });
        }
        while self.match_token(TokenType::Comma) {
            let extra_only = self.match_token(TokenType::Only);
            let mut extra_table = self.parse_table_ref()?;
            if extra_only {
                extra_table.only = true;
            }
            let extra_star = self.match_token(TokenType::Star);
            extra_tables.push(TruncateTableEntry {
                table: extra_table,
                star: extra_star,
            });
        }

        // Parse RESTART IDENTITY / CONTINUE IDENTITY
        // RESTART is TokenType::Restart keyword, IDENTITY is TokenType::Identity keyword
        let identity = if self.match_token(TokenType::Restart) {
            self.match_token(TokenType::Identity);
            Some(TruncateIdentity::Restart)
        } else if self.match_identifier("CONTINUE") {
            self.match_token(TokenType::Identity);
            Some(TruncateIdentity::Continue)
        } else {
            None
        };

        // Parse CASCADE or RESTRICT
        // CASCADE is TokenType::Cascade keyword, RESTRICT is TokenType::Restrict keyword
        let cascade = self.match_token(TokenType::Cascade);
        let restrict = if !cascade {
            self.match_token(TokenType::Restrict)
        } else {
            false
        };

        // Parse Hive PARTITION clause: PARTITION(key = value, ...)
        // parse_partition consumes the PARTITION keyword itself
        let partition = self.parse_partition()?;

        // ClickHouse: TRUNCATE TABLE t SETTINGS key=value, ...
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) && self.match_token(TokenType::Settings)
        {
            // Consume settings expressions (they're not stored in the AST for TRUNCATE)
            loop {
                let _ = self.parse_expression()?;
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
        }

        Ok(Expression::Truncate(Box::new(Truncate {
            target,
            if_exists,
            table,
            on_cluster,
            cascade,
            extra_tables,
            identity,
            restrict,
            partition: partition.map(Box::new),
        })))
    }

    /// Parse VALUES table constructor: VALUES (1, 'a'), (2, 'b')
    fn parse_values(&mut self) -> Result<Expression> {
        self.expect(TokenType::Values)?;

        let mut expressions = Vec::new();

        // Handle bare VALUES without parentheses: VALUES 1, 2, 3 -> VALUES (1), (2), (3)
        if !self.check(TokenType::LParen) {
            loop {
                let val = self.parse_expression()?;
                expressions.push(Tuple {
                    expressions: vec![val],
                });
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
        } else {
            loop {
                self.expect(TokenType::LParen)?;
                // Parse VALUES tuple elements with optional AS aliases (Hive syntax)
                let row_values = self.parse_values_expression_list()?;
                self.expect(TokenType::RParen)?;

                expressions.push(Tuple {
                    expressions: row_values,
                });

                if !self.match_token(TokenType::Comma) {
                    break;
                }
                // ClickHouse: allow trailing comma after last tuple
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) && !self.check(TokenType::LParen)
                {
                    break;
                }
            }
        }

        // Check for alias: VALUES (1, 2) AS new_data or VALUES (1, 2) new_data
        let (alias, column_aliases) = if self.match_token(TokenType::As) {
            let alias_name = self.expect_identifier()?;
            let alias = Some(Identifier::new(alias_name));

            // Check for column aliases: AS new_data(a, b)
            let col_aliases = if self.match_token(TokenType::LParen) {
                let aliases = self.parse_identifier_list()?;
                self.expect(TokenType::RParen)?;
                aliases
            } else {
                Vec::new()
            };
            (alias, col_aliases)
        } else if self.check(TokenType::Var) && !self.check_keyword() {
            // Implicit alias: VALUES (0) foo(bar)
            let alias_name = self.advance().text.clone();
            let alias = Some(Identifier::new(alias_name));
            let col_aliases = if self.match_token(TokenType::LParen) {
                let aliases = self.parse_identifier_list()?;
                self.expect(TokenType::RParen)?;
                aliases
            } else {
                Vec::new()
            };
            (alias, col_aliases)
        } else {
            (None, Vec::new())
        };

        // VALUES can be followed by set operations (UNION, etc.)
        let values_expr = Expression::Values(Box::new(Values {
            expressions,
            alias,
            column_aliases,
        }));

        // Check for set operations after VALUES
        self.parse_set_operation(values_expr)
    }

    /// Parse USE statement: USE db, USE DATABASE x, USE SCHEMA x.y, USE ROLE x, etc.
    fn parse_use(&mut self) -> Result<Expression> {
        self.expect(TokenType::Use)?;

        // Check for Snowflake: USE SECONDARY ROLES ALL|NONE|role1, role2, ...
        if self.check(TokenType::Var) && self.peek().text.to_uppercase() == "SECONDARY" {
            self.advance(); // consume SECONDARY
                            // Check for ROLES
            if self.check(TokenType::Var) && self.peek().text.to_uppercase() == "ROLES" {
                self.advance(); // consume ROLES
                                // Parse ALL, NONE, or comma-separated role list
                let mut roles = Vec::new();
                loop {
                    if self.check(TokenType::Var)
                        || self.check(TokenType::All)
                        || self.check(TokenType::Identifier)
                    {
                        let role = self.advance().text.clone();
                        roles.push(role);
                        if !self.match_token(TokenType::Comma) {
                            break;
                        }
                    } else {
                        break;
                    }
                }
                let name = if roles.is_empty() {
                    "ALL".to_string()
                } else {
                    roles.join(", ")
                };
                return Ok(Expression::Use(Box::new(Use {
                    kind: Some(UseKind::SecondaryRoles),
                    this: Identifier::new(name),
                })));
            }
        }

        // Check for kind: DATABASE, SCHEMA, ROLE, WAREHOUSE, CATALOG
        // Note: ROLE and CATALOG are not keywords, so we check the text
        let kind = if self.match_token(TokenType::Database) {
            Some(UseKind::Database)
        } else if self.match_token(TokenType::Schema) {
            Some(UseKind::Schema)
        } else if self.match_token(TokenType::Warehouse) {
            Some(UseKind::Warehouse)
        } else if self.check(TokenType::Var) && self.peek().text.to_uppercase() == "ROLE" {
            self.advance();
            Some(UseKind::Role)
        } else if self.check(TokenType::Var) && self.peek().text.to_uppercase() == "CATALOG" {
            self.advance();
            Some(UseKind::Catalog)
        } else {
            None
        };

        // Parse the name (can be qualified like x.y)
        // Use expect_identifier_or_keyword_with_quoted because names like "default", "system" are valid
        let mut ident = self.expect_identifier_or_keyword_with_quoted()?;

        // Handle qualified names like schema.table for USE SCHEMA x.y
        if self.match_token(TokenType::Dot) {
            let second_part = self.expect_identifier_or_keyword_with_quoted()?;
            ident.name = format!("{}.{}", ident.name, second_part.name);
        }

        Ok(Expression::Use(Box::new(Use { kind, this: ident })))
    }

    /// Parse EXPORT DATA statement (BigQuery)
    /// EXPORT DATA [WITH CONNECTION connection] OPTIONS (...) AS SELECT ...
    fn parse_export_data(&mut self) -> Result<Expression> {
        self.advance(); // consume EXPORT

        // Expect DATA
        if !self.match_identifier("DATA") {
            return Err(self.parse_error("Expected DATA after EXPORT"));
        }

        // Optional: WITH CONNECTION connection
        let connection = if self.match_text_seq(&["WITH", "CONNECTION"]) {
            // Parse connection identifier (can be qualified: project.location.connection)
            let first = self.expect_identifier()?;
            let connection_name = if self.match_token(TokenType::Dot) {
                let second = self.expect_identifier()?;
                if self.match_token(TokenType::Dot) {
                    let third = self.expect_identifier()?;
                    format!("{}.{}.{}", first, second, third)
                } else {
                    format!("{}.{}", first, second)
                }
            } else {
                first
            };
            Some(Box::new(Expression::Identifier(Identifier::new(
                connection_name,
            ))))
        } else {
            None
        };

        // Expect OPTIONS (...)
        let options = if self.match_identifier("OPTIONS") {
            self.parse_options_list()?
        } else {
            Vec::new()
        };

        // Expect AS
        self.expect(TokenType::As)?;

        // Parse the SELECT query
        let query = self.parse_statement()?;

        Ok(Expression::Export(Box::new(Export {
            this: Box::new(query),
            connection,
            options,
        })))
    }

    /// Parse CACHE TABLE statement (Spark)
    /// CACHE [LAZY] TABLE name [OPTIONS(...)] [AS query]
    fn parse_cache(&mut self) -> Result<Expression> {
        self.expect(TokenType::Cache)?;

        // Check for LAZY keyword
        let lazy = self.check(TokenType::Var) && self.peek().text.to_uppercase() == "LAZY";
        if lazy {
            self.advance();
        }

        self.expect(TokenType::Table)?;
        let table = Identifier::new(self.expect_identifier()?);

        // Check for OPTIONS clause
        let options = if self.check(TokenType::Var) && self.peek().text.to_uppercase() == "OPTIONS"
        {
            self.advance();
            self.expect(TokenType::LParen)?;
            let mut opts = Vec::new();
            loop {
                // Parse key = value pairs (key can be string literal or identifier)
                let key = if self.check(TokenType::NationalString) {
                    let token = self.advance();
                    Expression::Literal(Literal::NationalString(token.text))
                } else if self.check(TokenType::String) {
                    let token = self.advance();
                    Expression::Literal(Literal::String(token.text))
                } else {
                    Expression::Identifier(Identifier::new(self.expect_identifier()?))
                };
                // Eq is optional - Spark allows space-separated key value pairs
                // e.g., OPTIONS ('storageLevel' 'DISK_ONLY') or OPTIONS ('key' = 'value')
                let _ = self.match_token(TokenType::Eq);
                let value = self.parse_expression()?;
                opts.push((key, value));
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            self.expect(TokenType::RParen)?;
            opts
        } else {
            Vec::new()
        };

        // Check for AS clause or implicit query (SELECT without AS in Spark)
        let query = if self.match_token(TokenType::As) {
            Some(self.parse_statement()?)
        } else if self.check(TokenType::Select) || self.check(TokenType::With) {
            // Spark allows SELECT without AS keyword after CACHE TABLE
            Some(self.parse_statement()?)
        } else {
            None
        };

        Ok(Expression::Cache(Box::new(Cache {
            table,
            lazy,
            options,
            query,
        })))
    }

    /// Parse UNCACHE TABLE statement (Spark)
    /// UNCACHE TABLE [IF EXISTS] name
    fn parse_uncache(&mut self) -> Result<Expression> {
        self.expect(TokenType::Uncache)?;
        self.expect(TokenType::Table)?;

        let if_exists = self.match_keywords(&[TokenType::If, TokenType::Exists]);
        let table = Identifier::new(self.expect_identifier()?);

        Ok(Expression::Uncache(Box::new(Uncache { table, if_exists })))
    }

    /// Parse LOAD DATA statement (Hive)
    /// LOAD DATA [LOCAL] INPATH 'path' [OVERWRITE] INTO TABLE table_name
    /// [PARTITION (col=val, ...)] [INPUTFORMAT 'format'] [SERDE 'serde']
    fn parse_load_data(&mut self) -> Result<Expression> {
        self.expect(TokenType::Load)?;

        // Expect DATA keyword
        let data_token = self.advance();
        if data_token.text.to_uppercase() != "DATA" {
            return Err(self.parse_error("Expected DATA after LOAD"));
        }

        // Check for LOCAL keyword
        let local = self.match_token(TokenType::Local);

        // Expect INPATH
        self.expect(TokenType::Inpath)?;

        // Parse the path (string literal)
        let inpath = if self.check(TokenType::String) {
            self.advance().text
        } else {
            return Err(self.parse_error("Expected string literal after INPATH"));
        };

        // Check for OVERWRITE keyword
        let overwrite = self.match_token(TokenType::Overwrite);

        // Expect INTO TABLE
        self.expect(TokenType::Into)?;
        self.expect(TokenType::Table)?;

        // Parse table name (can be qualified)
        let table = Expression::Table(self.parse_table_ref()?);

        // Check for PARTITION clause
        let partition = if self.match_token(TokenType::Partition) {
            self.expect(TokenType::LParen)?;
            let mut partitions = Vec::new();
            loop {
                let col = Identifier::new(self.expect_identifier_or_keyword()?);
                self.expect(TokenType::Eq)?;
                let val = self.parse_expression()?;
                partitions.push((col, val));
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            self.expect(TokenType::RParen)?;
            partitions
        } else {
            Vec::new()
        };

        // Check for INPUTFORMAT clause
        let input_format = if self.match_token(TokenType::InputFormat) {
            if self.check(TokenType::String) {
                Some(self.advance().text)
            } else {
                return Err(self.parse_error("Expected string literal after INPUTFORMAT"));
            }
        } else {
            None
        };

        // Check for SERDE clause
        let serde = if self.match_token(TokenType::Serde) {
            if self.check(TokenType::String) {
                Some(self.advance().text)
            } else {
                return Err(self.parse_error("Expected string literal after SERDE"));
            }
        } else {
            None
        };

        Ok(Expression::LoadData(Box::new(LoadData {
            local,
            inpath,
            overwrite,
            table,
            partition,
            input_format,
            serde,
        })))
    }

    /// Parse PRAGMA statement (SQLite)
    /// PRAGMA [schema.]name [= value | (args...)]
    fn parse_pragma(&mut self) -> Result<Expression> {
        self.expect(TokenType::Pragma)?;

        // Parse schema.name or just name
        let first_name = self.expect_identifier_or_keyword()?;

        let (schema, name) = if self.match_token(TokenType::Dot) {
            // First name was schema
            let pragma_name = self.expect_identifier_or_keyword()?;
            (
                Some(Identifier::new(first_name)),
                Identifier::new(pragma_name),
            )
        } else {
            (None, Identifier::new(first_name))
        };

        // Check for assignment or function call
        let (value, args) = if self.match_token(TokenType::Eq) {
            // PRAGMA name = value
            let val = self.parse_expression()?;
            (Some(val), Vec::new())
        } else if self.match_token(TokenType::LParen) {
            // PRAGMA name(args...)
            let mut arguments = Vec::new();
            if !self.check(TokenType::RParen) {
                loop {
                    arguments.push(self.parse_expression()?);
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
            }
            self.expect(TokenType::RParen)?;
            (None, arguments)
        } else {
            (None, Vec::new())
        };

        Ok(Expression::Pragma(Box::new(Pragma {
            schema,
            name,
            value,
            args,
        })))
    }

    /// Parse ROLLBACK statement
    /// ROLLBACK [TO [SAVEPOINT] <name>]
    fn parse_rollback(&mut self) -> Result<Expression> {
        self.expect(TokenType::Rollback)?;

        // Check for optional TRANSACTION, TRAN, or WORK keyword
        let has_transaction = self.match_token(TokenType::Transaction)
            || self.match_identifier("TRAN")
            || self.match_identifier("WORK");

        // Check for TO SAVEPOINT (standard SQL) or transaction name (TSQL)
        let (savepoint, this) = if self.match_token(TokenType::To) {
            // Optional SAVEPOINT keyword
            self.match_token(TokenType::Savepoint);
            // Savepoint name
            if self.is_identifier_token() || self.is_safe_keyword_as_identifier() {
                let name = self.advance().text;
                (
                    Some(Box::new(Expression::Identifier(Identifier::new(name)))),
                    None,
                )
            } else {
                (None, None)
            }
        } else if has_transaction
            && (self.is_identifier_token() || self.is_safe_keyword_as_identifier())
        {
            // TSQL: ROLLBACK TRANSACTION transaction_name
            let name = self.advance().text;
            (
                None,
                Some(Box::new(Expression::Identifier(Identifier::new(name)))),
            )
        } else if has_transaction {
            // Just ROLLBACK TRANSACTION - store marker
            (
                None,
                Some(Box::new(Expression::Identifier(Identifier::new(
                    "TRANSACTION".to_string(),
                )))),
            )
        } else {
            (None, None)
        };

        Ok(Expression::Rollback(Box::new(Rollback { savepoint, this })))
    }

    /// Parse COMMIT statement
    /// COMMIT [TRANSACTION|TRAN|WORK] [transaction_name] [WITH (DELAYED_DURABILITY = ON|OFF)] [AND [NO] CHAIN]
    fn parse_commit(&mut self) -> Result<Expression> {
        self.expect(TokenType::Commit)?;

        // Check for optional TRANSACTION, TRAN, or WORK keyword
        let has_transaction = self.match_token(TokenType::Transaction)
            || self.match_identifier("TRAN")
            || self.match_identifier("WORK");

        // Parse optional transaction name (TSQL)
        let this = if has_transaction
            && (self.is_identifier_token() || self.is_safe_keyword_as_identifier())
            && !self.check(TokenType::With)
            && !self.check(TokenType::And)
        {
            let name = self.advance().text;
            Some(Box::new(Expression::Identifier(Identifier::new(name))))
        } else if has_transaction {
            // Store marker that TRANSACTION keyword was present
            Some(Box::new(Expression::Identifier(Identifier::new(
                "TRANSACTION".to_string(),
            ))))
        } else {
            None
        };

        // Parse WITH (DELAYED_DURABILITY = ON|OFF) for TSQL
        let durability = if self.match_token(TokenType::With) && self.match_token(TokenType::LParen)
        {
            // Check for DELAYED_DURABILITY
            if self.match_identifier("DELAYED_DURABILITY") && self.match_token(TokenType::Eq) {
                // ON is a keyword (TokenType::On), OFF is an identifier
                let on = self.match_token(TokenType::On) || self.match_identifier("ON");
                if !on {
                    self.match_identifier("OFF");
                }
                self.expect(TokenType::RParen)?;
                Some(Box::new(Expression::Boolean(BooleanLiteral { value: on })))
            } else {
                // Skip to RParen
                while !self.check(TokenType::RParen) && !self.is_at_end() {
                    self.advance();
                }
                self.match_token(TokenType::RParen);
                None
            }
        } else {
            None
        };

        // Parse AND [NO] CHAIN
        let chain = if self.match_token(TokenType::And) {
            let no_chain = self.match_token(TokenType::No);
            self.match_identifier("CHAIN");
            if no_chain {
                // AND NO CHAIN - explicit false
                Some(Box::new(Expression::Boolean(BooleanLiteral {
                    value: false,
                })))
            } else {
                // AND CHAIN - explicit true
                Some(Box::new(Expression::Boolean(BooleanLiteral {
                    value: true,
                })))
            }
        } else {
            None
        };

        Ok(Expression::Commit(Box::new(Commit {
            chain,
            this,
            durability,
        })))
    }

    /// Parse END statement (PostgreSQL alias for COMMIT)
    /// END [WORK|TRANSACTION] [AND [NO] CHAIN]
    fn parse_end_transaction(&mut self) -> Result<Expression> {
        self.expect(TokenType::End)?;

        // Check for optional WORK or TRANSACTION keyword
        let _has_work = self.match_identifier("WORK") || self.match_token(TokenType::Transaction);

        // Parse AND [NO] CHAIN
        let chain = if self.match_token(TokenType::And) {
            let no_chain = self.match_token(TokenType::No);
            self.match_identifier("CHAIN");
            if no_chain {
                // AND NO CHAIN - explicit false
                Some(Box::new(Expression::Boolean(BooleanLiteral {
                    value: false,
                })))
            } else {
                // AND CHAIN - explicit true
                Some(Box::new(Expression::Boolean(BooleanLiteral {
                    value: true,
                })))
            }
        } else {
            None
        };

        // Return as COMMIT since END is an alias
        Ok(Expression::Commit(Box::new(Commit {
            chain,
            this: None,
            durability: None,
        })))
    }

    /// Parse BEGIN/START TRANSACTION statement
    /// BEGIN [DEFERRED|IMMEDIATE|EXCLUSIVE] [TRANSACTION|TRAN|WORK] [transaction_name] [WITH MARK 'description']
    /// Also handles procedural BEGIN blocks (BigQuery, etc.): BEGIN statement_list END
    fn parse_transaction(&mut self) -> Result<Expression> {
        self.expect(TokenType::Begin)?;

        // Check if this is a procedural BEGIN block rather than a transaction
        // If next token is not a transaction keyword and we have more tokens, it's a procedural block
        let is_transaction = self.is_at_end()
            || self.check(TokenType::Semicolon)
            || self.check(TokenType::Transaction)
            || self.check_identifier("TRAN")
            || self.check_identifier("WORK")
            || self.check_identifier("DEFERRED")
            || self.check_identifier("IMMEDIATE")
            || self.check_identifier("EXCLUSIVE");

        if !is_transaction {
            // This is a procedural BEGIN block - parse as Command
            // Collect remaining tokens until end of statement
            return self
                .parse_command()?
                .ok_or_else(|| self.parse_error("Failed to parse BEGIN block"));
        }

        // Check for transaction kind: DEFERRED, IMMEDIATE, EXCLUSIVE (SQLite)
        let kind = if self.match_identifier("DEFERRED")
            || self.match_identifier("IMMEDIATE")
            || self.match_identifier("EXCLUSIVE")
        {
            Some(self.previous().text.clone())
        } else {
            None
        };

        // Check for TRANSACTION, TRAN, or WORK keyword
        let has_transaction_keyword = self.match_token(TokenType::Transaction)
            || self.match_identifier("TRAN")
            || self.match_identifier("WORK");

        // Parse optional transaction name (TSQL style: BEGIN TRANSACTION trans_name)
        let trans_name = if has_transaction_keyword
            && (self.is_identifier_token() || self.is_safe_keyword_as_identifier())
            && !self.check(TokenType::With)
        {
            // Could be a transaction name or @variable
            let name = self.advance().text;
            Some(name)
        } else {
            None
        };

        // Combine kind and trans_name into `this`
        let this = if let Some(name) = trans_name {
            Some(Box::new(Expression::Identifier(Identifier::new(name))))
        } else if let Some(k) = kind {
            Some(Box::new(Expression::Identifier(Identifier::new(k))))
        } else {
            None
        };

        // Parse WITH MARK 'description' (TSQL)
        let mark = if self.match_token(TokenType::With) && self.match_identifier("MARK") {
            if self.check(TokenType::String) {
                let desc = self.advance().text;
                Some(Box::new(Expression::Literal(Literal::String(desc))))
            } else {
                Some(Box::new(Expression::Literal(Literal::String(
                    "".to_string(),
                ))))
            }
        } else if has_transaction_keyword {
            // Store "TRANSACTION" marker to preserve round-trip
            Some(Box::new(Expression::Identifier(Identifier::new(
                "TRANSACTION".to_string(),
            ))))
        } else {
            None
        };

        // Parse any additional transaction modes (isolation levels, etc.)
        let mut mode_parts: Vec<String> = Vec::new();
        while self.is_identifier_token() || self.is_safe_keyword_as_identifier() {
            let mut mode_tokens: Vec<String> = Vec::new();
            while (self.is_identifier_token() || self.is_safe_keyword_as_identifier())
                && !self.check(TokenType::Comma)
            {
                mode_tokens.push(self.advance().text);
            }
            if !mode_tokens.is_empty() {
                mode_parts.push(mode_tokens.join(" "));
            }
            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        let modes = if !mode_parts.is_empty() {
            Some(Box::new(Expression::Identifier(Identifier::new(
                mode_parts.join(", "),
            ))))
        } else {
            None
        };

        Ok(Expression::Transaction(Box::new(Transaction {
            this,
            modes,
            mark,
        })))
    }

    /// Parse START TRANSACTION statement
    /// START TRANSACTION [READ ONLY | READ WRITE] [, ISOLATION LEVEL ...]
    fn parse_start_transaction(&mut self) -> Result<Expression> {
        self.expect(TokenType::Start)?;

        // Expect TRANSACTION keyword
        self.expect(TokenType::Transaction)?;

        // Parse any transaction modes (READ ONLY, READ WRITE, ISOLATION LEVEL, etc.)
        let mut mode_parts: Vec<String> = Vec::new();
        while self.is_identifier_token()
            || self.is_safe_keyword_as_identifier()
            || self.match_identifier("READ")
        {
            // If we matched READ, add it to tokens
            let read_matched = if self.previous().text.eq_ignore_ascii_case("READ") {
                true
            } else {
                false
            };
            let mut mode_tokens: Vec<String> = Vec::new();
            if read_matched {
                mode_tokens.push("READ".to_string());
            }
            while (self.is_identifier_token() || self.is_safe_keyword_as_identifier())
                && !self.check(TokenType::Comma)
            {
                mode_tokens.push(self.advance().text);
            }
            if !mode_tokens.is_empty() {
                mode_parts.push(mode_tokens.join(" "));
            }
            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        let modes = if !mode_parts.is_empty() {
            Some(Box::new(Expression::Identifier(Identifier::new(
                mode_parts.join(", "),
            ))))
        } else {
            None
        };

        Ok(Expression::Transaction(Box::new(Transaction {
            this: None, // START TRANSACTION doesn't have a kind like DEFERRED/IMMEDIATE
            modes,
            // Mark as START to differentiate from BEGIN
            mark: Some(Box::new(Expression::Identifier(Identifier::new(
                "START".to_string(),
            )))),
        })))
    }

    /// Parse DESCRIBE statement
    /// DESCRIBE [EXTENDED|FORMATTED|ANALYZE] <table_or_query>
    /// Also handles EXPLAIN (parsed as Describe)
    fn parse_describe(&mut self) -> Result<Expression> {
        // Accept DESCRIBE, DESC, and EXPLAIN (Var token)
        // Capture leading comments from the first token
        let leading_comments = if self.check(TokenType::Describe) {
            let token = self.advance();
            token.comments
        } else if self.check(TokenType::Desc) {
            let token = self.advance();
            token.comments
        } else if self.check(TokenType::Var) && self.peek().text.eq_ignore_ascii_case("EXPLAIN") {
            let token = self.advance(); // consume EXPLAIN
            token.comments
        } else {
            return Err(self.parse_error("Expected DESCRIBE, DESC, or EXPLAIN"));
        };

        // Check for EXTENDED or FORMATTED keywords
        let extended = self.match_identifier("EXTENDED");
        let formatted = if !extended {
            self.match_identifier("FORMATTED")
        } else {
            false
        };

        // Check for style keywords like ANALYZE, HISTORY
        // ClickHouse: EXPLAIN SYNTAX/AST/PLAN/PIPELINE/ESTIMATE/TABLE OVERRIDE/CURRENT TRANSACTION
        // For HISTORY, we need to look ahead to ensure it's not part of a schema-qualified
        // table name like "history.tbl". If the next token is a Dot, "history" is a schema name.
        let style = if !extended && !formatted && self.match_identifier("ANALYZE") {
            Some("ANALYZE".to_string())
        } else if !extended
            && !formatted
            && matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            )
        {
            // ClickHouse EXPLAIN styles
            let text_upper = if !self.is_at_end() {
                self.peek().text.to_uppercase()
            } else {
                String::new()
            };
            match text_upper.as_str() {
                "SYNTAX" | "AST" | "PLAN" | "PIPELINE" | "ESTIMATE" | "QUERY" | "CURRENT" => {
                    self.advance();
                    let mut style_str = text_upper;
                    // Handle multi-word: TABLE OVERRIDE, CURRENT TRANSACTION, QUERY TREE
                    if style_str == "CURRENT" && self.check_identifier("TRANSACTION") {
                        style_str.push_str(" TRANSACTION");
                        self.advance();
                    }
                    if style_str == "QUERY" && self.check_identifier("TREE") {
                        style_str.push_str(" TREE");
                        self.advance();
                    }
                    Some(style_str)
                }
                _ if self.check(TokenType::Table) => {
                    // EXPLAIN TABLE OVERRIDE
                    self.advance(); // consume TABLE
                    if self.check_identifier("OVERRIDE") {
                        self.advance();
                        Some("TABLE OVERRIDE".to_string())
                    } else {
                        // Not TABLE OVERRIDE, backtrack
                        self.current -= 1;
                        None
                    }
                }
                _ => None,
            }
        } else if !extended
            && !formatted
            && (self.check(TokenType::Identifier)
                || self.check(TokenType::Var)
                || self.check(TokenType::QuotedIdentifier))
            && self.peek().text.to_uppercase() == "HISTORY"
            && self.peek_nth(1).map(|t| t.token_type) != Some(TokenType::Dot)
        {
            self.advance(); // consume HISTORY
            Some("HISTORY".to_string())
        } else {
            None
        };

        // Check for object kind like SEMANTIC VIEW, TABLE, INPUT, OUTPUT, etc.
        let kind = if self.match_identifier("SEMANTIC") {
            if self.match_token(TokenType::View) {
                Some("SEMANTIC VIEW".to_string())
            } else {
                Some("SEMANTIC".to_string())
            }
        } else if self.match_token(TokenType::Table) {
            Some("TABLE".to_string())
        } else if self.match_token(TokenType::View) {
            Some("VIEW".to_string())
        } else if self.match_identifier("DATABASE") {
            Some("DATABASE".to_string())
        } else if self.match_identifier("SCHEMA") {
            Some("SCHEMA".to_string())
        } else if self.match_token(TokenType::Input) {
            Some("INPUT".to_string())
        } else if self.match_token(TokenType::Output) {
            Some("OUTPUT".to_string())
        } else {
            None
        };

        // ClickHouse: parse EXPLAIN settings before the target statement
        // e.g., EXPLAIN actions=1, description=0 SELECT ...
        // e.g., EXPLAIN PLAN actions=1 SELECT ...
        let mut properties = Vec::new();
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) {
            while !self.is_at_end() && !self.check(TokenType::Semicolon) {
                // Look for key=value pairs before a statement keyword
                if (self.is_identifier_token()
                    || self.is_safe_keyword_as_identifier()
                    || self.check(TokenType::Type))
                    && self.current + 1 < self.tokens.len()
                    && self.tokens[self.current + 1].token_type == TokenType::Eq
                {
                    let name = self.advance().text.to_lowercase();
                    self.advance(); // consume =
                    let value = self.advance().text.clone();
                    properties.push((name, value));
                    self.match_token(TokenType::Comma); // optional comma between settings
                } else {
                    break;
                }
            }
        }

        // Parse target - could be a table name or a SELECT/INSERT/other statement
        // ClickHouse: EXPLAIN/DESC can precede any statement or subquery
        let target = if self.check(TokenType::Select) || self.check(TokenType::With) {
            self.parse_statement()?
        } else if self.check(TokenType::LParen) && {
            // Look through nested parens for SELECT/WITH
            let mut depth = 0usize;
            let mut found_select = false;
            for i in 0..100 {
                match self.peek_nth(i).map(|t| t.token_type) {
                    Some(TokenType::LParen) => depth += 1,
                    Some(TokenType::Select) | Some(TokenType::With) if depth > 0 => {
                        found_select = true;
                        break;
                    }
                    _ => break,
                }
            }
            found_select
        } {
            // DESC (((SELECT ...))) — deeply nested parenthesized subquery
            self.parse_statement()?
        } else if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) && (self.check(TokenType::Insert)
            || self.check(TokenType::Create)
            || self.check(TokenType::Alter)
            || self.check(TokenType::Drop)
            || self.check(TokenType::Set)
            || self.check(TokenType::System))
        {
            self.parse_statement()?
        } else if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) && (self.is_identifier_token() || self.is_safe_keyword_as_identifier())
            && self.peek_nth(1).map(|t| t.token_type) == Some(TokenType::LParen)
        {
            // ClickHouse: DESC format(Values, '(123)') — function call as target
            self.parse_expression()?
        } else {
            // Parse as table reference
            let table = self.parse_table_ref()?;
            Expression::Table(table)
        };

        // Parse optional PARTITION clause (Spark/Hive)
        let partition = if self.match_token(TokenType::Partition) {
            // PARTITION(key = value, ...)
            self.expect(TokenType::LParen)?;
            // Parse partition expressions (e.g., ds = '2024-01-01')
            let mut partition_exprs = Vec::new();
            loop {
                if let Some(expr) = self.parse_conjunction()? {
                    partition_exprs.push(expr);
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            self.expect(TokenType::RParen)?;
            let partition = Expression::Partition(Box::new(crate::expressions::Partition {
                expressions: partition_exprs,
                subpartition: false,
            }));
            Some(Box::new(partition))
        } else {
            None
        };

        // ClickHouse: consume optional SETTINGS clause after target
        // e.g., DESC format(CSV, '...') SETTINGS key='val', key2='val2'
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) && self.check(TokenType::Settings)
        {
            self.advance(); // consume SETTINGS
            let _ = self.parse_settings_property()?;
        }

        // Databricks: DESCRIBE ... AS JSON
        let as_json = if self.check(TokenType::As)
            && self
                .peek_nth(1)
                .map(|t| t.text.eq_ignore_ascii_case("JSON"))
                == Some(true)
        {
            self.advance(); // consume AS
            self.advance(); // consume JSON
            true
        } else {
            false
        };

        // Parse optional post-target properties like type=stage (non-ClickHouse)
        if properties.is_empty() {
            while !self.is_at_end() && !self.check(TokenType::Semicolon) {
                // Check for identifier or keyword that could be a property name
                if self.check(TokenType::Var) || self.check(TokenType::Type) || self.check_keyword()
                {
                    let name = self.advance().text.to_lowercase();
                    if self.match_token(TokenType::Eq) {
                        let value = self.advance().text.clone();
                        properties.push((name, value));
                    } else {
                        // Not a property, put it back (can't easily undo, so break)
                        break;
                    }
                } else {
                    break;
                }
            }
        }

        Ok(Expression::Describe(Box::new(Describe {
            target,
            extended,
            formatted,
            kind,
            properties,
            style,
            partition,
            leading_comments,
            as_json,
        })))
    }

    /// Parse SHOW statement
    /// SHOW [TERSE] <object_type> [HISTORY] [LIKE pattern] [IN <scope>] [STARTS WITH pattern] [LIMIT n] [FROM object]
    fn parse_show(&mut self) -> Result<Expression> {
        self.expect(TokenType::Show)?;

        // Check for TERSE
        let terse = self.match_identifier("TERSE");

        // Parse the thing to show (DATABASES, TABLES, SCHEMAS, etc.)
        // This can be multiple words like "PRIMARY KEYS" or "IMPORTED KEYS"
        let mut this_parts = Vec::new();
        let mut target: Option<Expression> = None;
        let mut mutex: Option<bool> = None;

        // Consume identifier tokens until we hit a keyword like LIKE, IN, FROM, LIMIT, HISTORY
        // Special handling for SingleStore SHOW variations
        while !self.is_at_end() {
            let current = self.peek();
            // Stop at keywords that start clauses
            if matches!(
                current.token_type,
                TokenType::Like
                    | TokenType::In
                    | TokenType::From
                    | TokenType::Limit
                    | TokenType::Semicolon
                    | TokenType::Eof
                    | TokenType::Where
                    | TokenType::For
                    | TokenType::Offset
                    | TokenType::Settings
            ) {
                // ClickHouse: SHOW CREATE SETTINGS PROFILE - don't stop at SETTINGS
                if current.token_type == TokenType::Settings
                    && matches!(
                        self.config.dialect,
                        Some(crate::dialects::DialectType::ClickHouse)
                    )
                    && this_parts.join(" ") == "CREATE"
                {
                    // Fall through to process SETTINGS as part of the type name
                } else {
                    break;
                }
            }
            // Handle comma-separated profile types (e.g., SHOW PROFILE BLOCK IO, PAGE FAULTS)
            // Append comma to the last part to preserve spacing
            if current.token_type == TokenType::Comma {
                if !this_parts.is_empty() {
                    let last = this_parts.pop().unwrap();
                    this_parts.push(format!("{},", last));
                }
                self.advance();
                continue;
            }
            // Stop at HISTORY keyword (but not as the first word)
            if !this_parts.is_empty() && current.text.to_uppercase() == "HISTORY" {
                break;
            }
            // Stop at STARTS keyword
            if current.text.to_uppercase() == "STARTS" {
                break;
            }
            // SingleStore: SHOW PLAN <id> - handle number directly (before Var/keyword check)
            // This is needed because numbers don't pass the Var/keyword check
            let joined_check = this_parts.join(" ");
            if joined_check == "PLAN" && current.token_type == TokenType::Number {
                let id = self.advance().text;
                target = Some(Expression::Literal(Literal::Number(id)));
                break;
            }
            // Accept identifiers and keywords as part of the object type
            if current.token_type == TokenType::Var || current.token_type.is_keyword() {
                let joined = this_parts.join(" ");

                // SingleStore: SHOW CREATE <type> <name> - preserve case for name
                // Types: AGGREGATE, PIPELINE, PROJECTION
                if matches!(
                    joined.as_str(),
                    "CREATE AGGREGATE" | "CREATE PIPELINE" | "CREATE PROJECTION"
                ) {
                    let name = self.advance().text;
                    target = Some(Expression::Identifier(Identifier::new(name)));
                    break;
                }

                // SingleStore: SHOW <type> ON <name> - preserve case for name after ON
                // Check if current token is "ON" (but not at start)
                if current.text.to_uppercase() == "ON" && !this_parts.is_empty() {
                    this_parts.push("ON".to_string());
                    self.advance();
                    // Parse the name after ON, preserving case
                    if !self.is_at_end() {
                        let next = self.peek();
                        // Handle "ON TABLE name" pattern
                        if next.text.to_uppercase() == "TABLE" {
                            this_parts.push("TABLE".to_string());
                            self.advance();
                        }
                        // Parse the actual name
                        if !self.is_at_end() {
                            let name_tok = self.peek();
                            if name_tok.token_type == TokenType::Var
                                || name_tok.token_type.is_keyword()
                            {
                                let name = self.advance().text;
                                target = Some(Expression::Identifier(Identifier::new(name)));
                            }
                        }
                    }
                    break;
                }

                // SingleStore: SHOW REPRODUCTION INTO OUTFILE 'filename'
                if current.text.to_uppercase() == "INTO" && joined == "REPRODUCTION" {
                    this_parts.push("INTO".to_string());
                    self.advance();
                    if !self.is_at_end() && self.peek().text.to_uppercase() == "OUTFILE" {
                        this_parts.push("OUTFILE".to_string());
                        self.advance();
                        // Parse the filename
                        if !self.is_at_end() && self.check(TokenType::String) {
                            let filename = self.advance().text;
                            target = Some(Expression::Literal(Literal::String(filename)));
                        }
                    }
                    break;
                }

                // SingleStore: SHOW PLAN [JSON] <id> - capture the numeric ID
                if joined == "PLAN" {
                    // Check if current is "JSON" - if so, push it and check for number
                    if current.text.to_uppercase() == "JSON" {
                        this_parts.push("JSON".to_string());
                        self.advance();
                        // Now check for number
                        if !self.is_at_end() && self.check(TokenType::Number) {
                            let id = self.advance().text;
                            target = Some(Expression::Literal(Literal::Number(id)));
                        }
                        break;
                    }
                    // Check if current is a number (plan ID)
                    if current.token_type == TokenType::Number {
                        let id = self.advance().text;
                        target = Some(Expression::Literal(Literal::Number(id)));
                        break;
                    }
                }

                this_parts.push(current.text.to_uppercase());
                self.advance();

                // ClickHouse: SHOW CREATE TABLE/VIEW/DICTIONARY <qualified_name>
                // After detecting CREATE TABLE/VIEW/DICTIONARY, parse the next as a table ref
                let joined = this_parts.join(" ");
                if matches!(
                    joined.as_str(),
                    "CREATE TABLE"
                        | "CREATE VIEW"
                        | "CREATE DICTIONARY"
                        | "CREATE DATABASE"
                        | "CREATE MATERIALIZED VIEW"
                        | "CREATE LIVE VIEW"
                ) {
                    if !self.is_at_end()
                        && (self.check(TokenType::Var)
                            || self.check(TokenType::QuotedIdentifier)
                            || self.is_safe_keyword_as_identifier())
                    {
                        let table = self.parse_table_ref()?;
                        target = Some(Expression::Table(table));
                    }
                    break;
                }

                // ClickHouse: SHOW CREATE ROLE/PROFILE/QUOTA/ROW POLICY/POLICY with multi-name or ON clause
                // These have complex syntax (comma-separated names, ON db.table) - consume as raw text
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) && (matches!(
                    joined.as_str(),
                    "CREATE ROLE"
                        | "CREATE QUOTA"
                        | "CREATE SETTINGS PROFILE"
                        | "CREATE PROFILE"
                        | "CREATE ROW POLICY"
                        | "CREATE POLICY"
                        | "CREATE USER"
                ) || matches!(
                    joined.as_str(),
                    "SHOW CREATE ROLE"
                        | "SHOW CREATE QUOTA"
                        | "SHOW CREATE SETTINGS PROFILE"
                        | "SHOW CREATE PROFILE"
                        | "SHOW CREATE ROW POLICY"
                        | "SHOW CREATE POLICY"
                        | "SHOW CREATE USER"
                )) {
                    let mut parts = Vec::new();
                    while !self.is_at_end() && self.peek().token_type != TokenType::Semicolon {
                        parts.push(self.advance().text.clone());
                    }
                    target = Some(Expression::Identifier(Identifier::new(parts.join(" "))));
                    break;
                }

                // ClickHouse: SHOW CREATE <qualified_name> (without TABLE/VIEW keyword)
                // e.g., SHOW CREATE INFORMATION_SCHEMA.COLUMNS
                if joined == "CREATE"
                    && matches!(
                        self.config.dialect,
                        Some(crate::dialects::DialectType::ClickHouse)
                    )
                    && !self.is_at_end()
                    && (self.check(TokenType::Var) || self.check(TokenType::QuotedIdentifier))
                    && !matches!(
                        self.peek().text.to_uppercase().as_str(),
                        "TABLE"
                            | "VIEW"
                            | "DICTIONARY"
                            | "DATABASE"
                            | "MATERIALIZED"
                            | "LIVE"
                            | "TEMPORARY"
                            | "ROLE"
                            | "QUOTA"
                            | "POLICY"
                            | "PROFILE"
                            | "USER"
                            | "ROW"
                            | "SETTINGS"
                    )
                {
                    let table = self.parse_table_ref()?;
                    target = Some(Expression::Table(table));
                    break;
                }

                // Special handling for ENGINE: the next token is the engine name (case-preserved)
                // followed by STATUS or MUTEX
                if joined == "ENGINE" {
                    // Parse engine name (case-preserved)
                    if !self.is_at_end() {
                        let engine_tok = self.peek();
                        if engine_tok.token_type == TokenType::Var
                            || engine_tok.token_type.is_keyword()
                        {
                            let engine_name = self.advance().text;
                            target = Some(Expression::Identifier(Identifier::new(engine_name)));
                            // Parse STATUS or MUTEX
                            if !self.is_at_end() {
                                let next = self.peek();
                                let next_upper = next.text.to_uppercase();
                                if next_upper == "STATUS" {
                                    self.advance();
                                    mutex = Some(false);
                                } else if next_upper == "MUTEX" {
                                    self.advance();
                                    mutex = Some(true);
                                }
                            }
                        }
                    }
                    break;
                }
            } else {
                break;
            }
        }

        let this = this_parts.join(" ");

        // Check for HISTORY
        let history = self.match_identifier("HISTORY");

        // Check for FOR target (MySQL: SHOW GRANTS FOR foo, SHOW PROFILE ... FOR QUERY 5)
        // SingleStore: SHOW GROUPS FOR ROLE 'role_name', SHOW GROUPS FOR USER 'username'
        let for_target = if self.match_token(TokenType::For) {
            // Parse the target (can be multi-word like QUERY 5, or ROLE 'name')
            let mut parts = Vec::new();
            while !self.is_at_end() {
                let tok = self.peek();
                if matches!(
                    tok.token_type,
                    TokenType::Like
                        | TokenType::In
                        | TokenType::From
                        | TokenType::Limit
                        | TokenType::Semicolon
                        | TokenType::Eof
                        | TokenType::Where
                ) {
                    break;
                }
                if tok.token_type == TokenType::Var
                    || tok.token_type.is_keyword()
                    || tok.token_type == TokenType::Number
                {
                    parts.push(self.advance().text);
                } else if tok.token_type == TokenType::String {
                    // Handle string literals (e.g., SHOW GROUPS FOR ROLE 'role_name')
                    let text = self.advance().text;
                    parts.push(format!("'{}'", text));
                } else {
                    break;
                }
            }
            if parts.is_empty() {
                None
            } else {
                Some(Expression::Identifier(Identifier::new(parts.join(" "))))
            }
        } else {
            None
        };

        // Check for LIKE pattern
        let like = if self.match_token(TokenType::Like) {
            Some(self.parse_primary()?)
        } else {
            None
        };

        // Check for IN scope
        let (scope_kind, scope) = if self.match_token(TokenType::In) {
            // Parse scope kind and optionally scope object
            // Check for keywords: ACCOUNT, DATABASE, SCHEMA, TABLE, CLASS, APPLICATION
            let (kind, scope_obj) = if self.match_keyword("ACCOUNT") {
                (Some("ACCOUNT".to_string()), None)
            } else if self.match_token(TokenType::Database) {
                // IN DATABASE [name]
                let scope_obj = if !self.is_at_end()
                    && !self.check(TokenType::Like)
                    && !self.check(TokenType::Limit)
                    && !self.check(TokenType::Semicolon)
                    && !self.check_keyword_text("STARTS")
                {
                    let table = self.parse_table_ref()?;
                    Some(Expression::Table(table))
                } else {
                    None
                };
                (Some("DATABASE".to_string()), scope_obj)
            } else if self.match_token(TokenType::Schema) {
                // IN SCHEMA [name]
                let scope_obj = if !self.is_at_end()
                    && !self.check(TokenType::Like)
                    && !self.check(TokenType::Limit)
                    && !self.check(TokenType::Semicolon)
                    && !self.check_keyword_text("STARTS")
                {
                    let table = self.parse_table_ref()?;
                    Some(Expression::Table(table))
                } else {
                    None
                };
                (Some("SCHEMA".to_string()), scope_obj)
            } else if self.match_token(TokenType::Table) {
                // IN TABLE [name]
                let scope_obj = if !self.is_at_end()
                    && !self.check(TokenType::Like)
                    && !self.check(TokenType::Limit)
                    && !self.check(TokenType::Semicolon)
                    && !self.check_keyword_text("STARTS")
                {
                    let table = self.parse_table_ref()?;
                    Some(Expression::Table(table))
                } else {
                    None
                };
                (Some("TABLE".to_string()), scope_obj)
            } else if self.match_token(TokenType::View) {
                // IN VIEW [name]
                let scope_obj = if !self.is_at_end()
                    && !self.check(TokenType::Like)
                    && !self.check(TokenType::Limit)
                    && !self.check(TokenType::Semicolon)
                    && !self.check_keyword_text("STARTS")
                {
                    let table = self.parse_table_ref()?;
                    Some(Expression::Table(table))
                } else {
                    None
                };
                (Some("VIEW".to_string()), scope_obj)
            } else if self.match_keyword("CLASS") {
                // IN CLASS name
                let scope_obj = if !self.is_at_end() {
                    let table = self.parse_table_ref()?;
                    Some(Expression::Table(table))
                } else {
                    None
                };
                (Some("CLASS".to_string()), scope_obj)
            } else if self.match_keyword("APPLICATION") {
                // IN APPLICATION [PACKAGE] name
                let kind = if self.match_keyword("PACKAGE") {
                    "APPLICATION PACKAGE".to_string()
                } else {
                    "APPLICATION".to_string()
                };
                let scope_obj = if !self.is_at_end() {
                    let table = self.parse_table_ref()?;
                    Some(Expression::Table(table))
                } else {
                    None
                };
                (Some(kind), scope_obj)
            } else {
                // Default - infer scope_kind based on what we're showing
                // Python SQLGlot: SCHEMA_KINDS = {"OBJECTS", "TABLES", "VIEWS", "SEQUENCES", "UNIQUE KEYS", "IMPORTED KEYS"}
                let table = self.parse_table_ref()?;
                let inferred_kind = match this.as_str() {
                    "OBJECTS" | "TABLES" | "VIEWS" | "SEQUENCES" | "UNIQUE KEYS"
                    | "IMPORTED KEYS" => "SCHEMA",
                    "PRIMARY KEYS" => "TABLE",
                    _ => "SCHEMA", // Default to SCHEMA for unknown types
                };
                (
                    Some(inferred_kind.to_string()),
                    Some(Expression::Table(table)),
                )
            };
            (kind, scope_obj)
        } else {
            (None, None)
        };

        // Check for STARTS WITH
        let starts_with = if self.match_keyword("STARTS") {
            self.match_token(TokenType::With); // WITH is a keyword token
            Some(self.parse_primary()?)
        } else {
            None
        };

        // Check for LIMIT
        let limit = if self.match_token(TokenType::Limit) {
            Some(Box::new(Limit {
                this: self.parse_expression()?,
                percent: false,
                comments: Vec::new(),
            }))
        } else {
            None
        };

        // Check for FROM (can be a string literal or identifier)
        // For MySQL SHOW COLUMNS/INDEX, the first FROM is the target table,
        // and the second FROM is the database
        let mut from = if self.match_token(TokenType::From) {
            Some(self.parse_primary()?)
        } else {
            None
        };

        // Check for second FROM clause (MySQL: SHOW COLUMNS FROM tbl FROM db, SHOW INDEX FROM foo FROM bar)
        let mut db = if from.is_some() && self.match_token(TokenType::From) {
            Some(self.parse_primary()?)
        } else {
            None
        };

        // Normalize MySQL SHOW INDEX/COLUMNS FROM db.tbl -> FROM tbl FROM db.
        if matches!(this.as_str(), "INDEX" | "COLUMNS") && db.is_none() {
            if let Some(from_expr) = from.take() {
                match from_expr {
                    Expression::Table(mut t) => {
                        if let Some(db_ident) = t.schema.take().or(t.catalog.take()) {
                            db = Some(Expression::Identifier(db_ident));
                            from = Some(Expression::Identifier(t.name));
                        } else {
                            from = Some(Expression::Table(t));
                        }
                    }
                    Expression::Column(c) => {
                        if let Some(table_ident) = c.table {
                            db = Some(Expression::Identifier(table_ident));
                            from = Some(Expression::Identifier(c.name));
                        } else {
                            from = Some(Expression::Column(c));
                        }
                    }
                    Expression::Identifier(id) => {
                        if let Some((db_name, table_name)) = id.name.split_once('.') {
                            db = Some(Expression::Identifier(Identifier::new(db_name)));
                            from = Some(Expression::Identifier(Identifier {
                                name: table_name.to_string(),
                                quoted: id.quoted,
                                trailing_comments: id.trailing_comments,
                                span: None,
                            }));
                        } else {
                            from = Some(Expression::Identifier(id));
                        }
                    }
                    other => {
                        from = Some(other);
                    }
                }
            }
        }

        // MySQL: SHOW TABLES FROM db LIKE 'pattern' (LIKE can come after FROM)
        let like = if like.is_none() && self.match_token(TokenType::Like) {
            Some(self.parse_primary()?)
        } else {
            like
        };

        // ClickHouse: SHOW ... NOT LIKE 'pattern' / NOT ILIKE 'pattern'
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) && self.check(TokenType::Not)
        {
            if self.current + 1 < self.tokens.len()
                && matches!(
                    self.tokens[self.current + 1].token_type,
                    TokenType::Like | TokenType::ILike
                )
            {
                self.advance(); // consume NOT
                self.advance(); // consume LIKE/ILIKE
                let _ = self.parse_primary()?; // consume pattern
            }
        }

        // ClickHouse: SHOW ... ILIKE 'pattern'
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) && self.match_token(TokenType::ILike)
        {
            let _ = self.parse_primary()?; // consume pattern
        }

        // Check for WHERE clause (MySQL: SHOW STATUS WHERE condition)
        let where_clause = if self.match_token(TokenType::Where) {
            Some(self.parse_expression()?)
        } else {
            None
        };

        // Check for WITH PRIVILEGES clause (Snowflake: SHOW ... WITH PRIVILEGES USAGE, MODIFY)
        let privileges = if self.match_token(TokenType::With) && self.match_keyword("PRIVILEGES") {
            // Parse comma-separated list of privilege names (no parentheses)
            let mut privs = Vec::new();
            loop {
                if self.is_at_end() || self.check(TokenType::Semicolon) {
                    break;
                }
                let tok = self.peek();
                if tok.token_type == TokenType::Var || tok.token_type.is_keyword() {
                    privs.push(self.advance().text.to_uppercase());
                    // Check for comma to continue
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                } else {
                    break;
                }
            }
            privs
        } else {
            Vec::new()
        };

        // ClickHouse: SHOW ... SETTINGS key=val, key=val
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) {
            self.parse_clickhouse_settings_clause()?;
        }

        Ok(Expression::Show(Box::new(Show {
            this,
            terse,
            history,
            like,
            scope_kind,
            scope,
            starts_with,
            limit,
            from,
            where_clause,
            for_target,
            db,
            target,
            mutex,
            privileges,
        })))
    }

    /// Parse COPY statement (Snowflake, PostgreSQL)
    /// COPY INTO <table> FROM <source> [(<parameters>)]
    /// COPY INTO <location> FROM <table> [(<parameters>)]
    fn parse_copy(&mut self) -> Result<Expression> {
        self.expect(TokenType::Copy)?;

        // Check for INTO (Snowflake/TSQL style: COPY INTO)
        let is_into = self.match_token(TokenType::Into);

        // Parse target table or location (possibly with column list)
        let this = if self.check(TokenType::LParen) {
            // Subquery: COPY (SELECT ...) TO ...
            self.parse_primary()?
        } else if self.check(TokenType::DAt)
            || self.check(TokenType::String)
            || self.is_stage_reference()
        {
            // Stage or file destination (for exports): COPY INTO @stage or COPY INTO 's3://...'
            self.parse_file_location()?
        } else {
            // Table reference, possibly with column list: COPY table (col1, col2)
            let table = self.parse_table_ref()?;
            // Check for column list
            if self.check(TokenType::LParen) {
                // Peek ahead to see if this is a column list or a subquery
                // Column list won't start with SELECT
                let has_column_list = {
                    let start = self.current;
                    self.advance(); // consume (
                    let is_select = self.check(TokenType::Select);
                    self.current = start; // backtrack
                    !is_select
                };
                if has_column_list {
                    self.advance(); // consume (
                    let mut columns = Vec::new();
                    loop {
                        let col_name = self.expect_identifier_or_keyword()?;
                        columns.push(col_name);
                        if !self.match_token(TokenType::Comma) {
                            break;
                        }
                    }
                    self.expect(TokenType::RParen)?;
                    // Create a schema expression with the table and columns
                    Expression::Schema(Box::new(Schema {
                        this: Some(Box::new(Expression::Table(table))),
                        expressions: columns
                            .into_iter()
                            .map(|c| {
                                Expression::Column(Column {
                                    name: Identifier::new(c),
                                    table: None,
                                    join_mark: false,
                                    trailing_comments: Vec::new(),
                                    span: None,
                                    inferred_type: None,
                                })
                            })
                            .collect(),
                    }))
                } else {
                    Expression::Table(table)
                }
            } else {
                Expression::Table(table)
            }
        };

        // Determine direction: FROM means loading into table, TO means exporting
        let kind = self.match_token(TokenType::From);
        let has_to = if !kind {
            // Try TO keyword for export (TO is a keyword token, not an identifier)
            self.match_token(TokenType::To)
        } else {
            false
        };

        // Parse source/destination files or stage only if FROM/TO was found
        // and we're not at a parameter (which would start with identifier = ...)
        let mut files = Vec::new();
        if kind
            || has_to
            || self.check(TokenType::String)
            || self.is_stage_reference()
            || self.check(TokenType::LParen)
        {
            // Check for subquery: FROM (SELECT ...)
            if self.check(TokenType::LParen) {
                // Peek ahead to see if this is a subquery
                let start = self.current;
                self.advance(); // consume (
                let is_select = self.check(TokenType::Select);
                self.current = start; // backtrack
                if is_select {
                    // Parse the subquery
                    let subquery = self.parse_primary()?;
                    files.push(subquery);
                }
            }
            // Parse file location(s) until we hit a parameter or end
            while !self.is_at_end() && !self.check(TokenType::Semicolon) && files.is_empty()
                || (self.check(TokenType::Comma) && !files.is_empty())
            {
                // Consume comma if present (for multiple files)
                if !files.is_empty() && !self.match_token(TokenType::Comma) {
                    break;
                }
                // Check if this looks like a parameter (identifier followed by =)
                // But stage references (@stage) are not parameters
                if (self.check(TokenType::Var) || self.check_keyword())
                    && !self.is_stage_reference()
                {
                    let lookahead = self.current + 1;
                    if lookahead < self.tokens.len()
                        && self.tokens[lookahead].token_type == TokenType::Eq
                    {
                        break; // This is a parameter, stop parsing files
                    }
                }
                // Check for WITH keyword - stop parsing files
                if self.check(TokenType::With) {
                    break;
                }
                // Stop if we don't see a file location start
                // Include QuotedIdentifier for Databricks backtick-quoted paths like `s3://link`
                if !self.check(TokenType::String)
                    && !self.is_stage_reference()
                    && !self.check(TokenType::Var)
                    && !self.check_keyword()
                    && !self.check(TokenType::QuotedIdentifier)
                {
                    break;
                }
                // For COPY INTO ... FROM table_name, handle dotted table references
                // If the next token is a Var/Identifier and the one after is a Dot, parse as table reference
                if (self.check(TokenType::Var) || self.is_identifier_token())
                    && !self.is_stage_reference()
                {
                    let lookahead = self.current + 1;
                    let has_dot = lookahead < self.tokens.len()
                        && self.tokens[lookahead].token_type == TokenType::Dot;
                    if has_dot {
                        let table = self.parse_table_ref()?;
                        files.push(Expression::Table(table));
                        continue;
                    }
                }
                let location = self.parse_file_location()?;
                files.push(location);
            }
        }

        // Parse credentials and parameters
        let mut params = Vec::new();
        let mut credentials = None;
        let mut with_wrapped = false;

        // Parse Snowflake-style parameters: KEY = VALUE or KEY = (nested values)
        // or DuckDB/PostgreSQL WITH (KEY VALUE, ...) format
        while !self.is_at_end() && !self.check(TokenType::Semicolon) {
            // Match WITH keyword if present (some dialects use WITH before params)
            let had_with = self.match_token(TokenType::With);

            // Check for wrapped parameters in parentheses
            if self.match_token(TokenType::LParen) {
                if had_with {
                    with_wrapped = true;
                }
                while !self.check(TokenType::RParen) && !self.is_at_end() {
                    let param = self.parse_copy_parameter()?;
                    params.push(param);
                    // Consume optional comma between params
                    self.match_token(TokenType::Comma);
                }
                self.expect(TokenType::RParen)?;
                break;
            }

            // Parse individual parameter: NAME = value
            if self.check(TokenType::Var) || self.check_keyword() {
                let param = self.parse_copy_parameter()?;

                // Handle special CREDENTIALS parameter (case-insensitive)
                if param.name.eq_ignore_ascii_case("CREDENTIALS") {
                    // For Redshift-style CREDENTIALS 'string' (single string value)
                    // vs Snowflake-style CREDENTIALS = (KEY='value', KEY2='value')
                    if let Some(Expression::Literal(Literal::String(s))) = &param.value {
                        // Redshift style: store as a simple credentials string
                        let creds = Credentials {
                            credentials: vec![("".to_string(), s.clone())],
                            storage: None,
                            encryption: None,
                        };
                        credentials = Some(Box::new(creds));
                    } else {
                        // Snowflake style: key=value pairs
                        let creds = Credentials {
                            credentials: param
                                .values
                                .iter()
                                .filter_map(|v| {
                                    if let Expression::Eq(eq) = v {
                                        let key = if let Expression::Column(c) = &eq.left {
                                            c.name.name.clone()
                                        } else {
                                            return None;
                                        };
                                        let val = if let Expression::Literal(Literal::String(s)) =
                                            &eq.right
                                        {
                                            s.clone()
                                        } else {
                                            return None;
                                        };
                                        Some((key, val))
                                    } else {
                                        None
                                    }
                                })
                                .collect(),
                            storage: None,
                            encryption: None,
                        };
                        credentials = Some(Box::new(creds));
                    }
                } else if param.name.eq_ignore_ascii_case("STORAGE_INTEGRATION") {
                    // Store STORAGE_INTEGRATION as a regular parameter only
                    // Don't use the credentials.storage field for this
                    params.push(param);
                } else {
                    params.push(param);
                }
            } else {
                break;
            }
        }

        Ok(Expression::Copy(Box::new(CopyStmt {
            this,
            kind,
            files,
            params,
            credentials,
            is_into,
            with_wrapped,
        })))
    }

    /// Parse a single COPY parameter: NAME = value, NAME = (nested values), or NAME value (no =)
    fn parse_copy_parameter(&mut self) -> Result<CopyParameter> {
        // Preserve original case for parameter name (important for Redshift COPY options)
        let name = self.expect_identifier_or_keyword()?;

        let mut value = None;
        let mut values = Vec::new();

        let has_eq = self.match_token(TokenType::Eq);

        if has_eq {
            if self.match_token(TokenType::LParen) {
                // Nested parameter list: KEY = (nested_key=value, ...) or KEY = (value1, value2)
                // Check if this is a list of simple values (like strings) or key=value pairs
                // If the first token is a string/number, it's a list of values
                if self.check(TokenType::String) || self.check(TokenType::Number) {
                    // Simple value list: FILES = ('test1.csv', 'test2.csv')
                    while !self.check(TokenType::RParen) && !self.is_at_end() {
                        values.push(self.parse_primary()?);
                        if !self.match_token(TokenType::Comma) {
                            break;
                        }
                    }
                } else {
                    // Key=value pairs: CREDENTIALS = (AWS_KEY_ID='id' AWS_SECRET_KEY='key')
                    while !self.check(TokenType::RParen) && !self.is_at_end() {
                        // Parse nested key=value pairs
                        let nested_key = self.expect_identifier_or_keyword()?.to_uppercase();
                        if self.match_token(TokenType::Eq) {
                            let nested_value = self.parse_copy_param_value()?;
                            // Create an Eq expression for the nested key=value
                            values.push(Expression::Eq(Box::new(BinaryOp {
                                left: Expression::Column(Column {
                                    name: Identifier::new(nested_key),
                                    table: None,
                                    join_mark: false,
                                    trailing_comments: Vec::new(),
                                    span: None,
                                    inferred_type: None,
                                }),
                                right: nested_value,
                                left_comments: Vec::new(),
                                operator_comments: Vec::new(),
                                trailing_comments: Vec::new(),
                                inferred_type: None,
                            })));
                        } else {
                            // Just a keyword/value without =
                            values.push(Expression::Column(Column {
                                name: Identifier::new(nested_key),
                                table: None,
                                join_mark: false,
                                trailing_comments: Vec::new(),
                                span: None,
                                inferred_type: None,
                            }));
                        }
                        // Consume optional comma between nested values
                        self.match_token(TokenType::Comma);
                    }
                }
                self.expect(TokenType::RParen)?;
            } else {
                // Simple value: KEY = value
                value = Some(self.parse_copy_param_value()?);
            }
        } else {
            // No = sign: DuckDB/PostgreSQL format (KEY value or KEY (col1, col2))
            // Check if followed by a value: string, number, boolean, identifier, or tuple
            if self.check(TokenType::LParen) {
                // Check if this is a COPY_INTO_VARLEN_OPTIONS parameter
                // These are Databricks/Snowflake options that contain key='value' pairs without = before (
                let is_varlen_option = matches!(
                    name.as_str(),
                    "FORMAT_OPTIONS" | "COPY_OPTIONS" | "FILE_FORMAT" | "CREDENTIAL"
                );

                self.advance(); // consume (

                if is_varlen_option {
                    // Parse as key='value' pairs: FORMAT_OPTIONS ('opt1'='true', 'opt2'='test')
                    while !self.check(TokenType::RParen) && !self.is_at_end() {
                        if self.check(TokenType::String) {
                            // Parse 'key'='value' pair
                            let key_token = self.advance();
                            let key = key_token.text.clone();
                            if self.match_token(TokenType::Eq) {
                                let val = self.parse_copy_param_value()?;
                                values.push(Expression::Eq(Box::new(BinaryOp {
                                    left: Expression::Literal(Literal::String(key)),
                                    right: val,
                                    left_comments: Vec::new(),
                                    operator_comments: Vec::new(),
                                    trailing_comments: Vec::new(),
                                    inferred_type: None,
                                })));
                            } else {
                                // Just a string without =
                                values.push(Expression::Literal(Literal::String(key)));
                            }
                        } else if self.check(TokenType::Var)
                            || self.check_keyword()
                            || self.is_identifier_token()
                        {
                            // Parse identifier='value' pair (unquoted key)
                            let key = self.advance().text.clone();
                            if self.match_token(TokenType::Eq) {
                                let val = self.parse_copy_param_value()?;
                                values.push(Expression::Eq(Box::new(BinaryOp {
                                    left: Expression::Column(Column {
                                        name: Identifier::new(key),
                                        table: None,
                                        join_mark: false,
                                        trailing_comments: Vec::new(),
                                        span: None,
                                        inferred_type: None,
                                    }),
                                    right: val,
                                    left_comments: Vec::new(),
                                    operator_comments: Vec::new(),
                                    trailing_comments: Vec::new(),
                                    inferred_type: None,
                                })));
                            } else {
                                // Just an identifier without =
                                values.push(Expression::Column(Column {
                                    name: Identifier::new(key),
                                    table: None,
                                    join_mark: false,
                                    trailing_comments: Vec::new(),
                                    span: None,
                                    inferred_type: None,
                                }));
                            }
                        } else {
                            break;
                        }
                        self.match_token(TokenType::Comma);
                    }
                } else {
                    // Tuple value: FORCE_NOT_NULL (col1, col2)
                    let mut items = Vec::new();
                    while !self.check(TokenType::RParen) && !self.is_at_end() {
                        items.push(self.parse_primary()?);
                        if !self.match_token(TokenType::Comma) {
                            break;
                        }
                    }
                    value = Some(Expression::Tuple(Box::new(Tuple { expressions: items })));
                }
                self.expect(TokenType::RParen)?;
            } else if self.check(TokenType::LBrace) {
                // Map literal: KV_METADATA {'key': 'value', ...}
                value = Some(self.parse_primary()?);
            } else if self.check(TokenType::String) || self.check(TokenType::Number) {
                // String or number value
                value = Some(self.parse_copy_param_value()?);
            } else if self.check(TokenType::True) || self.check(TokenType::False) {
                // Boolean value (TRUE/FALSE are keyword tokens)
                value = Some(self.parse_copy_param_value()?);
            } else if !self.check(TokenType::Comma)
                && !self.check(TokenType::RParen)
                && !self.is_at_end()
                && !self.check(TokenType::Semicolon)
            {
                // Identifier value: FORMAT JSON, HEADER MATCH, etc.
                // But skip if this is a known flag-only parameter (Redshift COPY options that take no value)
                let name_upper = name.to_uppercase();
                let is_flag_param = matches!(
                    name_upper.as_str(),
                    "EMPTYASNULL"
                        | "BLANKSASNULL"
                        | "ACCEPTINVCHARS"
                        | "COMPUPDATE"
                        | "STATUPDATE"
                        | "NOLOAD"
                        | "ESCAPE"
                        | "REMOVEQUOTES"
                        | "EXPLICIT_IDS"
                        | "FILLRECORD"
                        | "TRIMBLANKS"
                        | "TRUNCATECOLUMNS"
                        | "ROUNDEC"
                        | "IGNOREHEADER"
                        | "IGNOREBLANKLINES"
                        | "ACCEPTANYDATE"
                );
                if !is_flag_param && (self.check(TokenType::Var) || self.check_keyword()) {
                    value = Some(self.parse_copy_param_value()?);
                }
            }
            // If nothing matched, it's a bare flag parameter with no value (allowed)
        }

        Ok(CopyParameter {
            name,
            value,
            values,
            eq: has_eq,
        })
    }

    /// Parse a value for COPY parameters (handles strings, identifiers, numbers, lists)
    fn parse_copy_param_value(&mut self) -> Result<Expression> {
        // Handle lists like ('file1', 'file2')
        if self.match_token(TokenType::LParen) {
            let mut items = Vec::new();
            while !self.check(TokenType::RParen) && !self.is_at_end() {
                items.push(self.parse_primary()?);
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            self.expect(TokenType::RParen)?;
            return Ok(Expression::Tuple(Box::new(Tuple { expressions: items })));
        }

        // Handle string, number, boolean, identifier
        if self.check(TokenType::String) {
            let token = self.advance();
            return Ok(Expression::Literal(Literal::String(token.text.clone())));
        }
        // Handle quoted identifier (e.g., STORAGE_INTEGRATION = "storage")
        if self.check(TokenType::QuotedIdentifier) {
            let token = self.advance();
            return Ok(Expression::Column(Column {
                name: Identifier::quoted(token.text.clone()),
                table: None,
                join_mark: false,
                trailing_comments: Vec::new(),
                span: None,
                inferred_type: None,
            }));
        }
        if self.check(TokenType::Number) {
            let token = self.advance();
            return Ok(Expression::Literal(Literal::Number(token.text.clone())));
        }
        if self.match_token(TokenType::True) {
            return Ok(Expression::Boolean(BooleanLiteral { value: true }));
        }
        if self.match_token(TokenType::False) {
            return Ok(Expression::Boolean(BooleanLiteral { value: false }));
        }
        // Identifier (e.g., FORMAT_NAME=my_format)
        if self.check(TokenType::Var) || self.check_keyword() {
            // Could be a qualified name like MY_DATABASE.MY_SCHEMA.MY_FORMAT
            let first = self.advance().text.clone();
            if self.match_token(TokenType::Dot) {
                let second = self.expect_identifier_or_keyword()?;
                if self.match_token(TokenType::Dot) {
                    let third = self.expect_identifier_or_keyword()?;
                    return Ok(Expression::Column(Column {
                        name: Identifier::new(format!("{}.{}.{}", first, second, third)),
                        table: None,
                        join_mark: false,
                        trailing_comments: Vec::new(),
                        span: None,
                        inferred_type: None,
                    }));
                }
                return Ok(Expression::Column(Column {
                    name: Identifier::new(format!("{}.{}", first, second)),
                    table: None,
                    join_mark: false,
                    trailing_comments: Vec::new(),
                    span: None,
                    inferred_type: None,
                }));
            }
            return Ok(Expression::Column(Column {
                name: Identifier::new(first),
                table: None,
                join_mark: false,
                trailing_comments: Vec::new(),
                span: None,
                inferred_type: None,
            }));
        }

        Err(self.parse_error("Expected value for COPY parameter"))
    }

    /// Parse Snowflake stage reference when tokenized as String (e.g., '@mystage', '@external/location')
    /// Handles: '@mystage', '@external/location'
    fn parse_stage_reference_from_string(&mut self) -> Result<Expression> {
        use crate::expressions::StageReference;

        // The String token contains @ and the entire path
        let string_token = self.advance();
        let full_path = string_token.text.clone();

        // Split on / to get stage name and path
        let parts: Vec<&str> = full_path.splitn(2, '/').collect();
        let name = parts[0].to_string();
        let path = if parts.len() > 1 {
            Some(format!("/{}", parts[1]))
        } else {
            None
        };

        // Handle optional parameters: (FILE_FORMAT => 'fmt', PATTERN => '*.csv')
        let (file_format, pattern) = if self.match_token(TokenType::LParen) {
            let mut ff = None;
            let mut pat = None;

            loop {
                if self.match_identifier("FILE_FORMAT") {
                    self.expect(TokenType::FArrow)?; // =>
                    ff = Some(self.parse_primary()?);
                } else if self.match_identifier("PATTERN") || self.match_token(TokenType::Pattern) {
                    // PATTERN can be tokenized as keyword or identifier
                    self.expect(TokenType::FArrow)?; // =>
                    if let Expression::Literal(Literal::String(s)) = self.parse_primary()? {
                        pat = Some(s);
                    }
                } else {
                    break;
                }

                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }

            self.expect(TokenType::RParen)?;
            (ff, pat)
        } else {
            (None, None)
        };

        Ok(Expression::StageReference(Box::new(StageReference {
            name,
            path,
            file_format,
            pattern,
            quoted: true, // Stage reference came from a quoted string
        })))
    }

    /// Parse Snowflake stage reference when tokenized as Var (e.g., @mystage becomes Var token)
    /// Handles: @mystage, @mystage/path/to/file.csv
    fn parse_stage_reference_from_var(&mut self) -> Result<Expression> {
        use crate::expressions::StageReference;

        // The Var token already contains @ and the stage name
        let var_token = self.advance();
        let mut name = var_token.text.clone();

        // Handle qualified names: @namespace.stage
        while self.match_token(TokenType::Dot) {
            name.push('.');
            if self.check(TokenType::Identifier) || self.check(TokenType::Var) {
                name.push_str(&self.advance().text);
            } else if self.check(TokenType::Percent) {
                // Handle table stage in qualified path: @namespace.%table_name
                self.advance();
                name.push('%');
                if self.check(TokenType::Identifier) || self.check(TokenType::Var) {
                    name.push_str(&self.advance().text);
                }
            } else {
                break;
            }
        }

        // Handle path after stage: @stage/path/to/file.csv
        let path = if self.match_token(TokenType::Slash) {
            let mut path_str = String::from("/");
            // Consume path components until we hit whitespace/paren/etc.
            while !self.is_at_end() {
                if self.check(TokenType::Identifier)
                    || self.check(TokenType::Var)
                    || self.check(TokenType::Number)
                    || self.check(TokenType::Dot)
                    || self.check(TokenType::Dash)
                    || self.check(TokenType::Star)
                    || self.check(TokenType::To)
                    || self.is_safe_keyword_as_identifier()
                {
                    path_str.push_str(&self.advance().text);
                } else if self.match_token(TokenType::Slash) {
                    path_str.push('/');
                } else {
                    break;
                }
            }
            Some(path_str)
        } else {
            None
        };

        // Handle optional parameters: (FILE_FORMAT => 'fmt', PATTERN => '*.csv')
        let (file_format, pattern) = if self.match_token(TokenType::LParen) {
            let mut ff = None;
            let mut pat = None;

            loop {
                if self.match_identifier("FILE_FORMAT") {
                    self.expect(TokenType::FArrow)?; // =>
                    ff = Some(self.parse_primary()?);
                } else if self.match_identifier("PATTERN") || self.match_token(TokenType::Pattern) {
                    // PATTERN can be tokenized as keyword or identifier
                    self.expect(TokenType::FArrow)?; // =>
                    if let Expression::Literal(Literal::String(s)) = self.parse_primary()? {
                        pat = Some(s);
                    }
                } else {
                    break;
                }

                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }

            self.expect(TokenType::RParen)?;
            (ff, pat)
        } else {
            (None, None)
        };

        Ok(Expression::StageReference(Box::new(StageReference {
            name,
            path,
            file_format,
            pattern,
            quoted: false,
        })))
    }

    /// Parse Snowflake stage reference in FROM clause
    /// Handles: @stage, @"stage", @namespace.stage, @stage/path/file.csv, @~, @%table
    fn parse_stage_reference(&mut self) -> Result<Expression> {
        use crate::expressions::StageReference;

        self.expect(TokenType::DAt)?; // consume @

        // Build the stage name - can include dots, slashes, etc.
        let mut name = String::from("@");

        // Handle special stage types:
        // @~ = user stage
        // @% = table stage (followed by table name)
        if self.check(TokenType::Tilde) {
            self.advance();
            name.push('~');
        } else if self.check(TokenType::Percent) {
            self.advance();
            name.push('%');
            // Table name follows (can be qualified: schema.table)
            loop {
                if self.check(TokenType::Identifier) || self.check(TokenType::Var) {
                    name.push_str(&self.advance().text);
                } else {
                    break;
                }
                // Handle qualified table names: %db.schema.table
                if self.match_token(TokenType::Dot) {
                    name.push('.');
                } else {
                    break;
                }
            }
        } else {
            // Handle quoted or unquoted stage names
            loop {
                if self.check(TokenType::QuotedIdentifier) {
                    // Preserve quotes for quoted identifiers
                    let text = self.advance().text;
                    name.push('"');
                    name.push_str(&text);
                    name.push('"');
                } else if self.check(TokenType::Percent) {
                    // Handle table stage in qualified path: @namespace.%table_name
                    self.advance();
                    name.push('%');
                    if self.check(TokenType::Identifier) || self.check(TokenType::Var) {
                        name.push_str(&self.advance().text);
                    }
                } else if self.check(TokenType::Identifier)
                    || self.check(TokenType::Var)
                    || self.is_safe_keyword_as_identifier()
                {
                    name.push_str(&self.advance().text);
                } else {
                    break;
                }

                // Handle dots for qualified names: @namespace.stage or @"schema"."stage"
                if self.match_token(TokenType::Dot) {
                    name.push('.');
                } else {
                    break;
                }
            }
        }

        // Handle path after stage: @stage/path/to/file.csv
        let path = if self.match_token(TokenType::Slash) {
            let mut path_str = String::from("/");
            // Consume path components until we hit whitespace/paren/etc.
            // Note: path can include keywords like 'to', 'data', etc.
            while !self.is_at_end() {
                if self.check(TokenType::Identifier)
                    || self.check(TokenType::Var)
                    || self.check(TokenType::Number)
                    || self.check(TokenType::Dot)
                    || self.check(TokenType::Dash)
                    || self.check(TokenType::Star)
                    || self.check(TokenType::To)
                    || self.is_safe_keyword_as_identifier()
                {
                    path_str.push_str(&self.advance().text);
                } else if self.match_token(TokenType::Slash) {
                    path_str.push('/');
                } else {
                    break;
                }
            }
            Some(path_str)
        } else {
            None
        };

        // Handle optional parameters: (FILE_FORMAT => 'fmt', PATTERN => '*.csv')
        let (file_format, pattern) = if self.match_token(TokenType::LParen) {
            let mut ff = None;
            let mut pat = None;

            loop {
                if self.match_identifier("FILE_FORMAT") {
                    self.expect(TokenType::FArrow)?; // =>
                    ff = Some(self.parse_primary()?);
                } else if self.match_identifier("PATTERN") || self.match_token(TokenType::Pattern) {
                    // PATTERN can be tokenized as keyword or identifier
                    self.expect(TokenType::FArrow)?; // =>
                    if let Expression::Literal(Literal::String(s)) = self.parse_primary()? {
                        pat = Some(s);
                    }
                } else {
                    break;
                }

                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }

            self.expect(TokenType::RParen)?;
            (ff, pat)
        } else {
            (None, None)
        };

        Ok(Expression::StageReference(Box::new(StageReference {
            name,
            path,
            file_format,
            pattern,
            quoted: false,
        })))
    }

    /// Parse file location for COPY/PUT statements
    /// Handles: @stage, @db.schema.stage, @stage/path, 's3://bucket/path', file:///path
    fn parse_file_location(&mut self) -> Result<Expression> {
        // Stage reference starting with @ (tokenized as DAt or as a Var starting with @)
        if self.check(TokenType::DAt) {
            self.advance(); // consume @
            let mut stage_path = String::from("@");

            // Handle table stage prefix: @%table
            if self.check(TokenType::Percent) || self.check(TokenType::Mod) {
                stage_path.push('%');
                self.advance(); // consume %
            }
            // Handle user stage: @~
            else if self.check(TokenType::Tilde) {
                stage_path.push('~');
                self.advance(); // consume ~
            }

            // Get stage name
            if self.check(TokenType::Var) || self.check_keyword() || self.is_identifier_token() {
                stage_path.push_str(&self.advance().text);
            }
            // Parse qualified name parts: .schema.stage
            while self.check(TokenType::Dot) {
                self.advance(); // consume .
                stage_path.push('.');
                if self.check(TokenType::Var) || self.check_keyword() || self.is_identifier_token()
                {
                    stage_path.push_str(&self.advance().text);
                }
            }
            // Parse path segments: /path/to/file (slash is tokenized separately)
            while self.check(TokenType::Slash) {
                self.advance(); // consume /
                stage_path.push('/');
                // Get path segment (identifier, keyword, or special chars)
                // But don't consume if followed by = (that's a parameter, not path)
                if (self.check(TokenType::Var)
                    || self.check_keyword()
                    || self.is_identifier_token())
                    && !self.check_next(TokenType::Eq)
                {
                    stage_path.push_str(&self.advance().text);
                }
            }
            return Ok(Expression::Literal(Literal::String(stage_path)));
        }

        // Stage reference tokenized as a Var starting with @ (e.g., @random_stage)
        // This happens when the tokenizer combines @ with the following identifier
        if self.check(TokenType::Var) && self.peek().text.starts_with('@') {
            let mut stage_path = self.advance().text.clone();
            // Parse qualified name parts: .schema.stage
            while self.check(TokenType::Dot) {
                self.advance(); // consume .
                stage_path.push('.');
                if self.check(TokenType::Var) || self.check_keyword() || self.is_identifier_token()
                {
                    stage_path.push_str(&self.advance().text);
                }
            }
            // Parse path segments: /path/to/file
            while self.check(TokenType::Slash) {
                self.advance(); // consume /
                stage_path.push('/');
                // Get path segment (identifier, keyword, or special chars)
                // But don't consume if followed by = (that's a parameter, not path)
                if (self.check(TokenType::Var)
                    || self.check_keyword()
                    || self.is_identifier_token())
                    && !self.check_next(TokenType::Eq)
                {
                    stage_path.push_str(&self.advance().text);
                }
            }
            return Ok(Expression::Literal(Literal::String(stage_path)));
        }

        // String literal (file path or URL)
        if self.check(TokenType::String) {
            let token = self.advance();
            return Ok(Expression::Literal(Literal::String(token.text.clone())));
        }

        // Backtick-quoted identifier (Databricks style: `s3://link`)
        if self.check(TokenType::QuotedIdentifier) {
            let token = self.advance();
            return Ok(Expression::Identifier(Identifier::quoted(
                token.text.clone(),
            )));
        }

        // Identifier (could be a stage name without @)
        if self.check(TokenType::Var) || self.check_keyword() {
            let ident = self.advance().text.clone();
            return Ok(Expression::Column(Column {
                name: Identifier::new(ident),
                table: None,
                join_mark: false,
                trailing_comments: Vec::new(),
                span: None,
                inferred_type: None,
            }));
        }

        Err(self.parse_error("Expected file location"))
    }

    /// Parse Snowflake stage reference as a string for PUT/GET/COPY statements
    /// Handles: @stage, @%table, @~, @db.schema.stage, @"quoted"."stage", @stage/path
    /// Returns a Literal::String containing the stage path
    fn parse_stage_reference_as_string(&mut self) -> Result<Expression> {
        // Stage reference starting with @ (tokenized as DAt)
        if self.check(TokenType::DAt) {
            self.advance(); // consume @
            let mut stage_path = String::from("@");

            // Handle table stage prefix: @%table
            if self.check(TokenType::Percent) || self.check(TokenType::Mod) {
                stage_path.push('%');
                self.advance(); // consume %
            }
            // Handle user stage: @~
            else if self.check(TokenType::Tilde) {
                stage_path.push('~');
                self.advance(); // consume ~
                                // After @~, parse any path segments
                while self.check(TokenType::Slash) {
                    self.advance(); // consume /
                    stage_path.push('/');
                    if (self.check(TokenType::Var)
                        || self.check_keyword()
                        || self.is_identifier_token())
                        && !self.check_next(TokenType::Eq)
                    {
                        stage_path.push_str(&self.advance().text);
                    }
                }
                return Ok(Expression::Literal(Literal::String(stage_path)));
            }

            // Get stage name (could be quoted identifier)
            if self.check(TokenType::QuotedIdentifier) {
                // Preserve quoted identifier with quotes
                let text = &self.peek().text;
                stage_path.push('"');
                stage_path.push_str(text);
                stage_path.push('"');
                self.advance();
            } else if self.check(TokenType::Var)
                || self.check_keyword()
                || self.check(TokenType::Identifier)
            {
                stage_path.push_str(&self.advance().text);
            }

            // Parse qualified name parts: .schema.stage (may include quoted identifiers)
            while self.check(TokenType::Dot) {
                self.advance(); // consume .
                stage_path.push('.');
                if self.check(TokenType::QuotedIdentifier) {
                    // Preserve quoted identifier with quotes
                    let text = &self.peek().text;
                    stage_path.push('"');
                    stage_path.push_str(text);
                    stage_path.push('"');
                    self.advance();
                } else if self.check(TokenType::Var)
                    || self.check_keyword()
                    || self.check(TokenType::Identifier)
                {
                    stage_path.push_str(&self.advance().text);
                }
            }

            // Parse path segments: /path/to/file
            while self.check(TokenType::Slash) {
                self.advance(); // consume /
                stage_path.push('/');
                // Get path segment but don't consume if followed by = (that's a parameter)
                if (self.check(TokenType::Var)
                    || self.check_keyword()
                    || self.is_identifier_token())
                    && !self.check_next(TokenType::Eq)
                {
                    stage_path.push_str(&self.advance().text);
                }
            }
            return Ok(Expression::Literal(Literal::String(stage_path)));
        }

        // Stage reference tokenized as a Var starting with @ (e.g., @s1)
        if self.check(TokenType::Var) && self.peek().text.starts_with('@') {
            let mut stage_path = self.advance().text.clone();

            // Parse qualified name parts: .schema.stage (may include quoted identifiers)
            while self.check(TokenType::Dot) {
                self.advance(); // consume .
                stage_path.push('.');
                if self.check(TokenType::QuotedIdentifier) {
                    let text = &self.peek().text;
                    stage_path.push('"');
                    stage_path.push_str(text);
                    stage_path.push('"');
                    self.advance();
                } else if self.check(TokenType::Var)
                    || self.check_keyword()
                    || self.check(TokenType::Identifier)
                {
                    stage_path.push_str(&self.advance().text);
                }
            }

            // Parse path segments: /path/to/file
            while self.check(TokenType::Slash) {
                self.advance(); // consume /
                stage_path.push('/');
                if (self.check(TokenType::Var)
                    || self.check_keyword()
                    || self.is_identifier_token())
                    && !self.check_next(TokenType::Eq)
                {
                    stage_path.push_str(&self.advance().text);
                }
            }
            return Ok(Expression::Literal(Literal::String(stage_path)));
        }

        Err(self.parse_error("Expected stage reference starting with @"))
    }

    /// Parse PUT statement (Snowflake)
    /// PUT file://<path> @<stage> [AUTO_COMPRESS = TRUE|FALSE] ...
    fn parse_put(&mut self) -> Result<Expression> {
        self.expect(TokenType::Put)?;

        // Parse source file path (usually file:///path/to/file)
        let (source, source_quoted) = if self.check(TokenType::String) {
            (self.advance().text.clone(), true)
        } else {
            // Handle file://path syntax (parsed as identifier + colon + etc.)
            // Stop when we see @ (start of stage reference)
            let mut source_parts = Vec::new();
            while !self.is_at_end() {
                // Stop if we see @ (DAt token or Var starting with @)
                if self.check(TokenType::DAt) {
                    break;
                }
                if self.check(TokenType::Var) && self.peek().text.starts_with('@') {
                    break;
                }
                let token = self.advance();
                source_parts.push(token.text.clone());
            }
            (source_parts.join(""), false)
        };

        // Parse target stage (@stage_name)
        let target = self.parse_stage_reference_as_string()?;

        // Parse optional parameters
        // Note: Some parameter names like OVERWRITE are keywords, so we check for those explicitly
        // Preserve original casing for identity tests
        let mut params = Vec::new();
        while !self.is_at_end() && !self.check(TokenType::Semicolon) {
            let is_param_name = self.check(TokenType::Var)
                || self.check_keyword()
                || self.check(TokenType::Overwrite);
            if is_param_name {
                let name = self.advance().text.clone();
                let value = if self.match_token(TokenType::Eq) {
                    Some(self.parse_primary()?)
                } else {
                    None
                };
                params.push(CopyParameter {
                    name,
                    value,
                    values: Vec::new(),
                    eq: true,
                });
            } else {
                break;
            }
        }

        Ok(Expression::Put(Box::new(PutStmt {
            source,
            source_quoted,
            target,
            params,
        })))
    }

    /// Helper to join command tokens with smart spacing
    /// Preserves the structure of file paths, stage references, etc.
    fn join_command_tokens(&self, tokens: Vec<(String, TokenType)>) -> String {
        let mut result = String::new();
        let mut prev_token_type: Option<TokenType> = None;
        let mut prev_prev_token_type: Option<TokenType> = None;

        for (i, (text, token_type)) in tokens.iter().enumerate() {
            let needs_space = if result.is_empty() {
                false
            } else {
                match (prev_token_type, *token_type) {
                    // No space after @ (stage references: @stage, @%, @~)
                    (Some(TokenType::DAt), _) => false,
                    // No space around dots (identifiers: a.b.c)
                    (Some(TokenType::Dot), _) => false,
                    (_, TokenType::Dot) => false,
                    // No space around parentheses
                    (Some(TokenType::LParen), _) => false,
                    (_, TokenType::LParen) => false,
                    (_, TokenType::RParen) => false,
                    // No space around square brackets (array access: arr[i])
                    (Some(TokenType::LBracket), _) => false,
                    (_, TokenType::LBracket) => false,
                    (_, TokenType::RBracket) => false,
                    // No space before ,
                    (_, TokenType::Comma) => false,
                    // No space around / (paths: @s1/test)
                    (Some(TokenType::Slash), _) => false,
                    (_, TokenType::Slash) => false,
                    // No space around : (file://path)
                    (Some(TokenType::Colon), _) => false,
                    (_, TokenType::Colon) => false,
                    // No space around % (table stage: @%table)
                    (Some(TokenType::Mod), _) => false,
                    (_, TokenType::Mod) => false,
                    (Some(TokenType::Percent), _) => false,
                    (_, TokenType::Percent) => false,
                    // Handle = contextually:
                    // - No space around = in simple KEY=VALUE patterns where value is terminal
                    //   (PARALLEL=1, ENABLED=TRUE, FILE_FORMAT='csv')
                    // - Keep space for expressions like SET x = x + 1
                    (Some(TokenType::Var), TokenType::Eq) => {
                        // If the var starts with @ (parameter like @id = 123), always use spaces
                        if i >= 1 && tokens[i - 1].0.starts_with('@') {
                            true
                        } else if i + 1 < tokens.len() {
                            // Check what follows: Var=Number where number is terminal (end or followed by Var)
                            let next_type = tokens[i + 1].1;
                            // Is the value terminal (end of tokens, or followed by another Var=... pattern)?
                            let is_terminal_value =
                                i + 2 >= tokens.len() || tokens[i + 2].1 == TokenType::Var;
                            match next_type {
                                // No space for terminal numbers/bools: PARALLEL=1, ENABLED=TRUE
                                // Return false (no space) when terminal
                                TokenType::Number | TokenType::True | TokenType::False => {
                                    !is_terminal_value
                                }
                                // No space for terminal strings: FILE_FORMAT='csv'
                                TokenType::String => !is_terminal_value,
                                // Always space if followed by Var (SET x = y ...)
                                _ => true,
                            }
                        } else {
                            true
                        }
                    }
                    // No space after = in terminal KEY=VALUE patterns
                    (Some(TokenType::Eq), TokenType::Number)
                    | (Some(TokenType::Eq), TokenType::True)
                    | (Some(TokenType::Eq), TokenType::False)
                    | (Some(TokenType::Eq), TokenType::String) => {
                        // Is this a terminal value (end or followed by another Var=...)?
                        let is_terminal =
                            i + 1 >= tokens.len() || tokens[i + 1].1 == TokenType::Var;
                        match prev_prev_token_type {
                            // No space (return false) when terminal, space otherwise
                            // But always space if the var before = was preceded by @ (parameter)
                            Some(TokenType::Var) => {
                                // Always space if the var before = starts with @ (parameter)
                                if i >= 2 && tokens[i - 2].0.starts_with('@') {
                                    true
                                } else {
                                    !is_terminal
                                }
                            }
                            _ => true, // Space for other cases
                        }
                    }
                    // Always space after = when followed by Var (SET x = y, could be expression)
                    (Some(TokenType::Eq), TokenType::Var) => true,
                    // No space around :: (cast)
                    (Some(TokenType::DColon), _) => false,
                    (_, TokenType::DColon) => false,
                    // Default: add space
                    _ => true,
                }
            };

            if needs_space {
                result.push(' ');
            }
            result.push_str(text);
            prev_prev_token_type = prev_token_type;
            prev_token_type = Some(*token_type);
        }
        result
    }

    /// Join Teradata table option tokens with Teradata-specific spacing
    /// - No spaces around '='
    /// - No spaces around dots or parentheses
    /// - Space-separated words otherwise
    fn join_teradata_option_tokens(&self, tokens: Vec<(String, TokenType)>) -> String {
        let mut result = String::new();
        let mut prev_token_type: Option<TokenType> = None;

        for (text, token_type) in tokens {
            let needs_space = if result.is_empty() {
                false
            } else {
                match (prev_token_type, token_type) {
                    (Some(TokenType::Dot), _) => false,
                    (_, TokenType::Dot) => false,
                    (Some(TokenType::LParen), _) => false,
                    (_, TokenType::LParen) => false,
                    (_, TokenType::RParen) => false,
                    (_, TokenType::Comma) => false,
                    (Some(TokenType::Eq), _) => false,
                    (_, TokenType::Eq) => false,
                    _ => true,
                }
            };

            if needs_space {
                result.push(' ');
            }
            result.push_str(&text);
            prev_token_type = Some(token_type);
        }

        result
    }

    /// Parse RM or REMOVE command (Snowflake)
    /// RM @stage_name / REMOVE @stage_name
    fn parse_rm_command(&mut self) -> Result<Expression> {
        let command_token = self.advance(); // RM or REMOVE
        let command_name = command_token.text.to_uppercase();

        // Collect remaining tokens with their types
        let mut tokens = vec![(command_name, command_token.token_type)];
        while !self.is_at_end() && !self.check(TokenType::Semicolon) {
            let token = self.advance();
            tokens.push((token.text.clone(), token.token_type));
        }

        Ok(Expression::Command(Box::new(Command {
            this: self.join_command_tokens(tokens),
        })))
    }

    /// Parse GET command (Snowflake)
    /// GET @stage_name 'file:///path'
    fn parse_get_command(&mut self) -> Result<Expression> {
        let get_token = self.advance(); // consume GET (it's already matched)

        // Collect remaining tokens with their types, preserving quotes
        let mut tokens = vec![("GET".to_string(), get_token.token_type)];
        while !self.is_at_end() && !self.check(TokenType::Semicolon) {
            let token = self.advance();
            // Re-add quotes around string and quoted identifier tokens
            let text = match token.token_type {
                TokenType::String => format!("'{}'", token.text),
                TokenType::QuotedIdentifier => format!("\"{}\"", token.text),
                _ => token.text.clone(),
            };
            tokens.push((text, token.token_type));
        }

        Ok(Expression::Command(Box::new(Command {
            this: self.join_command_tokens(tokens),
        })))
    }

    /// Parse CALL statement (stored procedure call)
    /// CALL procedure_name(args, ...)
    fn parse_call(&mut self) -> Result<Expression> {
        let call_token = self.advance(); // consume CALL

        // Collect remaining tokens with their types
        let mut tokens = vec![("CALL".to_string(), call_token.token_type)];
        while !self.is_at_end() && !self.check(TokenType::Semicolon) {
            let token = self.advance();
            tokens.push((token.text.clone(), token.token_type));
        }

        Ok(Expression::Command(Box::new(Command {
            this: self.join_command_tokens(tokens),
        })))
    }

    /// Parse KILL statement (MySQL/MariaDB)
    /// KILL [CONNECTION | QUERY] <id>
    fn parse_kill(&mut self) -> Result<Expression> {
        self.expect(TokenType::Kill)?;

        // Check for optional kind: CONNECTION or QUERY
        let kind = if self.match_identifier("CONNECTION") {
            Some("CONNECTION".to_string())
        } else if self.match_identifier("QUERY") {
            Some("QUERY".to_string())
        } else {
            None
        };

        // Parse the target (process ID - usually a number or string)
        let this = self.parse_primary()?;

        Ok(Expression::Kill(Box::new(Kill { this, kind })))
    }

    /// Parse EXEC/EXECUTE statement (TSQL stored procedure call)
    /// EXEC [schema.]procedure_name [@param=value, ...]
    fn parse_execute(&mut self) -> Result<Expression> {
        self.expect(TokenType::Execute)?;

        // Parse procedure name (can be qualified: schema.proc_name)
        let proc_name = self.parse_table_ref()?;
        let this = Expression::Table(proc_name);

        // Parse optional parameters: @param=value, ...
        let mut parameters = Vec::new();

        // Check if there are parameters (starts with @ or identifier)
        while self.check(TokenType::Var) || self.check(TokenType::Parameter) {
            // Get the parameter name (starts with @)
            let token = self.advance();
            let param_name = if token.text.starts_with('@') {
                token.text.clone()
            } else {
                format!("@{}", token.text)
            };

            // Check for = (named parameter) or positional parameter
            if self.match_token(TokenType::Eq) {
                // Named parameter: @param = value
                let value = self.parse_primary()?;
                parameters.push(ExecuteParameter {
                    name: param_name,
                    value,
                    positional: false,
                });
            } else {
                // Positional parameter: @var (no = sign)
                // Positional parameter: @var (no = sign)
                parameters.push(ExecuteParameter {
                    name: param_name.clone(),
                    value: Expression::Column(Column {
                        name: Identifier::new(&param_name),
                        table: None,
                        join_mark: false,
                        trailing_comments: Vec::new(),
                        span: None,
                        inferred_type: None,
                    }),
                    positional: true,
                });
            }

            // Check for comma to continue
            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        Ok(Expression::Execute(Box::new(ExecuteStatement {
            this,
            parameters,
        })))
    }

    /// Parse GRANT statement
    /// GRANT <privileges> ON [<kind>] <object> TO <principals> [WITH GRANT OPTION]
    fn parse_grant(&mut self) -> Result<Expression> {
        self.expect(TokenType::Grant)?;

        // ClickHouse: GRANT can grant roles (no ON clause), grant privileges (has ON clause),
        // or use complex syntax. If we see TO before ON, treat as command.
        // Also: multi-privilege grants (multiple ON), wildcard grants (test*.*),
        // WITH REPLACE OPTION all parse as commands.
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) {
            // Save position after GRANT keyword
            let saved_pos = self.current;
            // Scan ahead to check grant structure
            let mut depth = 0i32;
            let mut on_count = 0;
            let mut found_to = false;
            let mut has_star_in_name = false;
            let mut has_replace_option = false;
            let mut i = self.current;
            while i < self.tokens.len() && self.tokens[i].token_type != TokenType::Semicolon {
                match self.tokens[i].token_type {
                    TokenType::LParen => depth += 1,
                    TokenType::RParen => depth -= 1,
                    TokenType::On if depth == 0 => on_count += 1,
                    TokenType::To if depth == 0 => {
                        found_to = true;
                    }
                    TokenType::Star if depth == 0 && on_count > 0 && !found_to => {
                        // Check if star is part of a wildcard name (e.g., test*.*)
                        if i > 0
                            && self.tokens[i - 1].token_type != TokenType::Dot
                            && self.tokens[i - 1].token_type != TokenType::On
                        {
                            has_star_in_name = true;
                        }
                    }
                    TokenType::Replace if depth == 0 && found_to => {
                        has_replace_option = true;
                    }
                    _ => {}
                }
                i += 1;
            }
            if (found_to && on_count == 0) || on_count > 1 || has_star_in_name || has_replace_option
            {
                // Role grant, multi-privilege grant, wildcard grant, or REPLACE OPTION — parse as command
                self.current = saved_pos;
                return self
                    .parse_command()?
                    .ok_or_else(|| self.parse_error("Failed to parse GRANT statement"));
            }
            self.current = saved_pos;
        }

        // Parse privileges (e.g., SELECT, INSERT, UPDATE)
        let privileges = self.parse_privileges()?;

        // Expect ON
        self.expect(TokenType::On)?;

        // Parse optional kind (TABLE, SCHEMA, FUNCTION, etc.)
        let kind = self.parse_object_kind()?;

        // Parse securable (the object) - may be dot-separated qualified name
        let securable = self.parse_securable_name()?;

        // Parse optional function parameter types: func(type1, type2, ...)
        let function_params = if self.check(TokenType::LParen) {
            self.parse_function_param_types()?
        } else {
            Vec::new()
        };

        // Expect TO
        self.expect(TokenType::To)?;

        // Parse principals
        let principals = self.parse_principals()?;

        // Check for WITH GRANT OPTION
        let grant_option = self.match_token(TokenType::With)
            && self.check(TokenType::Grant)
            && {
                self.advance();
                self.check(TokenType::Var) && self.peek().text.to_uppercase() == "OPTION"
            }
            && {
                self.advance();
                true
            };

        // Check for TSQL AS principal clause
        let as_principal = if self.match_token(TokenType::As) {
            let name = self.expect_identifier_or_keyword()?;
            Some(Identifier::new(name))
        } else {
            None
        };

        Ok(Expression::Grant(Box::new(Grant {
            privileges,
            kind,
            securable,
            function_params,
            principals,
            grant_option,
            as_principal,
        })))
    }

    /// Parse REVOKE statement
    /// REVOKE [GRANT OPTION FOR] <privileges> ON [<kind>] <object> FROM <principals> [CASCADE]
    fn parse_revoke(&mut self) -> Result<Expression> {
        self.expect(TokenType::Revoke)?;

        // ClickHouse: REVOKE role FROM user (no ON clause), multi-privilege, or wildcard — parse as command
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) {
            let saved_pos = self.current;
            let mut depth = 0i32;
            let mut on_count = 0;
            let mut found_from = false;
            let mut has_star_in_name = false;
            let mut i = self.current;
            while i < self.tokens.len() && self.tokens[i].token_type != TokenType::Semicolon {
                match self.tokens[i].token_type {
                    TokenType::LParen => depth += 1,
                    TokenType::RParen => depth -= 1,
                    TokenType::On if depth == 0 => on_count += 1,
                    TokenType::From if depth == 0 => {
                        found_from = true;
                    }
                    TokenType::Star if depth == 0 && on_count > 0 && !found_from => {
                        if i > 0
                            && self.tokens[i - 1].token_type != TokenType::Dot
                            && self.tokens[i - 1].token_type != TokenType::On
                        {
                            has_star_in_name = true;
                        }
                    }
                    _ => {}
                }
                i += 1;
            }
            if (found_from && on_count == 0) || on_count > 1 || has_star_in_name {
                self.current = saved_pos;
                return self
                    .parse_command()?
                    .ok_or_else(|| self.parse_error("Failed to parse REVOKE statement"));
            }
            self.current = saved_pos;
        }

        // Check for GRANT OPTION FOR
        let grant_option = if self.check(TokenType::Grant) {
            self.advance();
            if self.check(TokenType::Var) && self.peek().text.to_uppercase() == "OPTION" {
                self.advance();
                self.expect(TokenType::For)?;
                true
            } else {
                return Err(self.parse_error("Expected OPTION after GRANT in REVOKE"));
            }
        } else {
            false
        };

        // Parse privileges
        let privileges = self.parse_privileges()?;

        // Expect ON
        self.expect(TokenType::On)?;

        // Parse optional kind
        let kind = self.parse_object_kind()?;

        // Parse securable - may be dot-separated qualified name
        let securable = self.parse_securable_name()?;

        // Parse optional function parameter types: func(type1, type2, ...)
        let function_params = if self.check(TokenType::LParen) {
            self.parse_function_param_types()?
        } else {
            Vec::new()
        };

        // Expect FROM
        self.expect(TokenType::From)?;

        // Parse principals
        let principals = self.parse_principals()?;

        // Check for CASCADE or RESTRICT
        let cascade = self.match_token(TokenType::Cascade);
        let restrict = if !cascade {
            self.match_token(TokenType::Restrict)
        } else {
            false
        };

        Ok(Expression::Revoke(Box::new(Revoke {
            privileges,
            kind,
            securable,
            function_params,
            principals,
            grant_option,
            cascade,
            restrict,
        })))
    }

    /// Parse privilege list for GRANT/REVOKE
    /// Handles multi-word privileges like "ALL PRIVILEGES" and column-level privileges like "SELECT(col1, col2)"
    fn parse_privileges(&mut self) -> Result<Vec<Privilege>> {
        let mut privileges = Vec::new();
        loop {
            let mut priv_parts = Vec::new();
            // Collect privilege words until we hit ON, comma, LParen, or similar terminator
            while !self.is_at_end() {
                if self.check(TokenType::On)
                    || self.check(TokenType::Comma)
                    || self.check(TokenType::LParen)
                {
                    break;
                }
                if self.is_identifier_or_keyword_token() {
                    priv_parts.push(self.advance().text.to_uppercase());
                } else {
                    break;
                }
            }
            if priv_parts.is_empty() {
                break;
            }
            let priv_name = priv_parts.join(" ");

            // Check for column list in parentheses: SELECT(col1, col2)
            let columns = if self.match_token(TokenType::LParen) {
                let mut cols = Vec::new();
                loop {
                    // Parse column name (identifier)
                    if self.is_identifier_or_keyword_token() {
                        cols.push(self.advance().text.to_string());
                    } else if self.check(TokenType::RParen) {
                        break;
                    } else {
                        break;
                    }
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
                self.expect(TokenType::RParen)?;
                cols
            } else {
                Vec::new()
            };

            privileges.push(Privilege {
                name: priv_name,
                columns,
            });
            if !self.match_token(TokenType::Comma) {
                break;
            }
        }
        Ok(privileges)
    }

    /// Parse object kind (TABLE, SCHEMA, FUNCTION, PROCEDURE, SEQUENCE, etc.)
    fn parse_object_kind(&mut self) -> Result<Option<String>> {
        if self.check(TokenType::Table) {
            self.advance();
            Ok(Some("TABLE".to_string()))
        } else if self.check(TokenType::Schema) {
            self.advance();
            Ok(Some("SCHEMA".to_string()))
        } else if self.check(TokenType::Database) {
            self.advance();
            Ok(Some("DATABASE".to_string()))
        } else if self.check(TokenType::Function) {
            self.advance();
            Ok(Some("FUNCTION".to_string()))
        } else if self.check(TokenType::View) {
            self.advance();
            Ok(Some("VIEW".to_string()))
        } else if self.check(TokenType::Procedure) {
            self.advance();
            Ok(Some("PROCEDURE".to_string()))
        } else if self.check(TokenType::Sequence) {
            self.advance();
            Ok(Some("SEQUENCE".to_string()))
        } else {
            Ok(None)
        }
    }

    /// Parse principal list for GRANT/REVOKE
    fn parse_principals(&mut self) -> Result<Vec<GrantPrincipal>> {
        let mut principals = Vec::new();
        loop {
            // Check for ROLE keyword (TokenType::Var with text "ROLE")
            let is_role = if self.check(TokenType::Var) && self.peek().text.to_uppercase() == "ROLE"
            {
                self.advance();
                true
            } else {
                false
            };
            // Check for GROUP keyword (Redshift) - TokenType::Group
            let is_group = if !is_role && self.check(TokenType::Group) {
                self.advance();
                true
            } else {
                false
            };
            // Parse principal name (with quoted flag preserved for backtick-quoted identifiers)
            let name = self.expect_identifier_or_keyword_with_quoted()?;
            principals.push(GrantPrincipal {
                name,
                is_role,
                is_group,
            });
            if !self.match_token(TokenType::Comma) {
                break;
            }
        }
        Ok(principals)
    }

    /// Parse a securable name (potentially dot-separated qualified name)
    /// e.g., "mydb.myschema.ADD5" -> Identifier("mydb.myschema.ADD5")
    fn parse_securable_name(&mut self) -> Result<Identifier> {
        // Accept * as a name part (e.g., GRANT ON *.* or GRANT ON db.*)
        let first = if self.match_token(TokenType::Star) {
            "*".to_string()
        } else {
            self.expect_identifier_or_keyword()?
        };
        let mut parts = vec![first];

        while self.match_token(TokenType::Dot) {
            let next = if self.match_token(TokenType::Star) {
                "*".to_string()
            } else {
                self.expect_identifier_or_keyword()?
            };
            parts.push(next);
        }

        Ok(Identifier::new(parts.join(".")))
    }

    /// Parse function parameter types for GRANT/REVOKE ON FUNCTION
    /// e.g., "(number, varchar)" -> vec!["number", "varchar"]
    fn parse_function_param_types(&mut self) -> Result<Vec<String>> {
        self.expect(TokenType::LParen)?;

        let mut params = Vec::new();
        if !self.check(TokenType::RParen) {
            loop {
                // Parse parameter type - can be a keyword (INT, VARCHAR) or identifier
                let param_type = self.expect_identifier_or_keyword()?;
                params.push(param_type);
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
        }

        self.expect(TokenType::RParen)?;
        Ok(params)
    }

    /// Parse COMMENT ON statement
    fn parse_comment(&mut self) -> Result<Expression> {
        self.expect(TokenType::Comment)?;

        // Check for IF EXISTS
        let exists = self.match_keywords(&[TokenType::If, TokenType::Exists]);

        // Expect ON
        self.expect(TokenType::On)?;

        // Check for MATERIALIZED (can be TokenType::Materialized or TokenType::Var)
        let materialized = if self.match_token(TokenType::Materialized) {
            true
        } else if self.check(TokenType::Var) && self.peek().text.to_uppercase() == "MATERIALIZED" {
            self.advance();
            true
        } else {
            false
        };

        // Parse the object kind (COLUMN, TABLE, DATABASE, PROCEDURE, etc.)
        let kind = self.expect_identifier_or_keyword()?.to_uppercase();

        // Parse the object name (can be qualified like schema.table.column)
        // For PROCEDURE/FUNCTION, we need to handle the parameter list like my_proc(integer, integer)
        let this = if kind == "PROCEDURE" || kind == "FUNCTION" {
            // Parse name possibly with parameter types, preserving original case
            let name_token = self.advance();
            let mut name_str = name_token.text.clone();

            // Parse additional qualified parts
            while self.match_token(TokenType::Dot) {
                let next = self.advance();
                name_str.push('.');
                name_str.push_str(&next.text);
            }

            // Check for parameter types in parentheses
            if self.match_token(TokenType::LParen) {
                name_str.push('(');
                let mut first = true;
                while !self.check(TokenType::RParen) && !self.is_at_end() {
                    if !first {
                        name_str.push_str(", ");
                    }
                    first = false;
                    let param_token = self.advance();
                    name_str.push_str(&param_token.text);
                    self.match_token(TokenType::Comma);
                }
                self.expect(TokenType::RParen)?;
                name_str.push(')');
            }

            Expression::Identifier(Identifier::new(name_str))
        } else {
            self.parse_qualified_name()?
        };

        // Expect IS
        if self.check(TokenType::Is) {
            self.advance();
        } else {
            return Err(self.parse_error("Expected IS in COMMENT ON statement"));
        }

        // Parse the comment expression (usually a string literal)
        let expression = self.parse_primary()?;

        Ok(Expression::Comment(Box::new(Comment {
            this,
            kind,
            expression,
            exists,
            materialized,
        })))
    }

    /// Parse SET statement
    fn parse_set(&mut self) -> Result<Expression> {
        self.expect(TokenType::Set)?;

        let mut items = Vec::new();

        // ClickHouse: SET DEFAULT ROLE ... TO user - parse as command
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) && self.check(TokenType::Default)
        {
            let mut parts = vec!["SET".to_string()];
            while !self.is_at_end() && self.peek().token_type != TokenType::Semicolon {
                parts.push(self.advance().text.clone());
            }
            return Ok(Expression::Command(Box::new(crate::expressions::Command {
                this: parts.join(" "),
            })));
        }

        // Teradata: SET QUERY_BAND = ... [UPDATE] [FOR scope]
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::Teradata)
        ) && self.match_identifier("QUERY_BAND")
        {
            return self.parse_query_band();
        }

        // Handle MySQL SET CHARACTER SET / SET NAMES
        if self.match_identifier("CHARACTER") {
            // SET CHARACTER SET <charset> | SET CHARACTER SET DEFAULT
            self.expect(TokenType::Set)?;
            let value = if self.match_token(TokenType::Default) {
                Expression::Identifier(Identifier::new("DEFAULT".to_string()))
            } else {
                self.parse_primary()?
            };
            items.push(SetItem {
                name: Expression::Identifier(Identifier::new("CHARACTER SET".to_string())),
                value,
                kind: None,
                no_equals: false,
            });
            return Ok(Expression::SetStatement(Box::new(SetStatement { items })));
        }

        if self.match_identifier("NAMES") {
            // SET NAMES <charset> [COLLATE <collation>] | SET NAMES DEFAULT
            let value = if self.match_token(TokenType::Default) {
                Expression::Identifier(Identifier::new("DEFAULT".to_string()))
            } else {
                self.parse_primary()?
            };
            // Check for optional COLLATE clause
            let collation = if self.match_identifier("COLLATE") {
                Some(self.parse_primary()?)
            } else {
                None
            };
            items.push(SetItem {
                name: Expression::Identifier(Identifier::new("NAMES".to_string())),
                value,
                kind: None,
                no_equals: false,
            });
            if let Some(coll) = collation {
                items.push(SetItem {
                    name: Expression::Identifier(Identifier::new("COLLATE".to_string())),
                    value: coll,
                    kind: None,
                    no_equals: false,
                });
            }
            return Ok(Expression::SetStatement(Box::new(SetStatement { items })));
        }

        loop {
            // Check for GLOBAL, LOCAL, SESSION, PERSIST, PERSIST_ONLY modifiers
            // LOCAL is a token type, others are identifiers
            let kind = if self.match_identifier("GLOBAL") {
                Some("GLOBAL".to_string())
            } else if self.match_token(TokenType::Local) {
                Some("LOCAL".to_string())
            } else if self.match_identifier("SESSION") {
                Some("SESSION".to_string())
            } else if self.match_identifier("PERSIST") {
                Some("PERSIST".to_string())
            } else if self.match_identifier("PERSIST_ONLY") {
                Some("PERSIST_ONLY".to_string())
            } else {
                None
            };

            // Check for SET [GLOBAL|SESSION] TRANSACTION (MySQL)
            if self.match_token(TokenType::Transaction) {
                // Parse transaction characteristics (ISOLATION LEVEL, READ ONLY, READ WRITE)
                let mut characteristics = Vec::new();
                loop {
                    let mut char_tokens = Vec::new();
                    // Parse ISOLATION LEVEL ... or READ ONLY/WRITE
                    // Must handle keywords like ONLY, REPEATABLE, SERIALIZABLE, etc.
                    while !self.is_at_end()
                        && !self.check(TokenType::Comma)
                        && !self.check(TokenType::Semicolon)
                    {
                        // Allow identifiers and common transaction-related keywords
                        if self.is_identifier_token()
                            || self.is_safe_keyword_as_identifier()
                            || self.check(TokenType::Only)
                            || self.check(TokenType::Repeatable)
                        {
                            char_tokens.push(self.advance().text);
                        } else {
                            break;
                        }
                    }
                    if !char_tokens.is_empty() {
                        characteristics.push(char_tokens.join(" "));
                    }
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }

                let name = Expression::Identifier(Identifier::new("TRANSACTION".to_string()));
                let value = if characteristics.is_empty() {
                    Expression::Identifier(Identifier::new("".to_string()))
                } else {
                    Expression::Identifier(Identifier::new(characteristics.join(", ")))
                };

                items.push(SetItem {
                    name,
                    value,
                    kind,
                    no_equals: false,
                });
                break;
            }

            // Handle DuckDB: SET VARIABLE var = value
            // Only match if "VARIABLE" is followed by another identifier (not by = or TO)
            let is_variable = if self.check(TokenType::Var)
                && self.peek().text.eq_ignore_ascii_case("VARIABLE")
            {
                // Look ahead: VARIABLE should be followed by another name, not by = or TO
                if let Some(next) = self.tokens.get(self.current + 1) {
                    if next.token_type != TokenType::Eq
                        && next.token_type != TokenType::To
                        && next.token_type != TokenType::ColonEq
                    {
                        self.advance(); // consume VARIABLE
                        true
                    } else {
                        false
                    }
                } else {
                    false
                }
            } else {
                false
            };

            // Parse variable name - use a simple approach to avoid expression parsing issues
            // Variable names can be dotted identifiers or keywords used as names
            let name = {
                if self.check(TokenType::AtAt) {
                    // @@SCOPE.variable or @@variable syntax (MySQL system variables)
                    self.advance(); // consume @@
                    let mut name_str = "@@".to_string();
                    let first = self.advance().text.clone();
                    name_str.push_str(&first);
                    // Handle @@scope.variable (e.g., @@GLOBAL.max_connections)
                    while self.match_token(TokenType::Dot) {
                        let next = self.advance().text.clone();
                        name_str.push('.');
                        name_str.push_str(&next);
                    }
                    Expression::Identifier(Identifier::new(name_str))
                } else if self.check(TokenType::DAt) {
                    // @variable syntax (MySQL user variables)
                    self.advance(); // consume @
                    let mut name_str = "@".to_string();
                    let first = self.advance().text.clone();
                    name_str.push_str(&first);
                    Expression::Identifier(Identifier::new(name_str))
                } else {
                    let first = self.advance().text.clone();
                    let mut name_str = first;
                    // Handle dotted identifiers (e.g., schema.variable)
                    while self.match_token(TokenType::Dot) {
                        let next = self.advance().text.clone();
                        name_str.push('.');
                        name_str.push_str(&next);
                    }
                    // Handle Hive-style colon-separated names (e.g., hiveconf:some_var)
                    // But not := which is assignment
                    while self.check(TokenType::Colon) && !self.check_next(TokenType::Eq) {
                        self.advance(); // consume :
                        let next = self.advance().text.clone();
                        name_str.push(':');
                        name_str.push_str(&next);
                    }
                    Expression::Identifier(Identifier::new(name_str))
                }
            };

            // Wrap name with VARIABLE marker if SET VARIABLE was used
            let name = if is_variable {
                // Store as "VARIABLE name" identifier
                let name_str = match &name {
                    Expression::Column(col) => col.name.name.clone(),
                    Expression::Identifier(id) => id.name.clone(),
                    _ => format!("{:?}", name),
                };
                Expression::Identifier(Identifier::new(format!("VARIABLE {}", name_str)))
            } else {
                name
            };

            // Expect = or := or TO
            if self.match_token(TokenType::Eq) || self.match_token(TokenType::ColonEq) {
                // ok - standard assignment
            } else if self.match_token(TokenType::To) {
                // PostgreSQL uses SET var TO value
            } else if self.is_at_end()
                || self.check(TokenType::Semicolon)
                || self.check(TokenType::Comma)
            {
                // SET x ON/OFF without = (TSQL: SET XACT_ABORT ON)
                // The ON/OFF was already parsed as part of the name expression
                // Handle as a name-only set (value is empty)
                items.push(SetItem {
                    name,
                    value: Expression::Identifier(Identifier::new("".to_string())),
                    kind,
                    no_equals: false,
                });
                if !self.match_token(TokenType::Comma) {
                    break;
                }
                continue;
            } else {
                // Check if the next token looks like a value (ON/OFF without =)
                // TSQL: SET XACT_ABORT ON, SET NOCOUNT ON
                if self.check(TokenType::On) || self.check_keyword_text("OFF") {
                    let val = self.advance().text;
                    // Include ON/OFF in the name so generator doesn't add "="
                    let name_with_val = match &name {
                        Expression::Column(col) => format!("{} {}", col.name.name, val),
                        Expression::Identifier(id) => format!("{} {}", id.name, val),
                        _ => val.clone(),
                    };
                    items.push(SetItem {
                        name: Expression::Identifier(Identifier::new(name_with_val)),
                        value: Expression::Identifier(Identifier::new("".to_string())),
                        kind,
                        no_equals: false,
                    });
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                    continue;
                }
                // TSQL/Generic: SET key value (without = or TO)
                // Parse the next token as the value
                if !self.is_at_end() && !self.check(TokenType::Semicolon) {
                    let value = self.parse_expression()?;
                    items.push(SetItem {
                        name,
                        value,
                        kind,
                        no_equals: true,
                    });
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                    continue;
                }
                return Err(self.parse_error("Expected '=' or 'TO' in SET statement"));
            }

            // Parse value - handle ON/OFF keywords as identifiers (MySQL: SET autocommit = ON)
            let value = if self.check(TokenType::On) || self.check_keyword_text("OFF") {
                Expression::Identifier(Identifier::new(self.advance().text.clone()))
            } else if self.match_token(TokenType::Default) {
                Expression::Identifier(Identifier::new("DEFAULT".to_string()))
            } else {
                self.parse_expression()?
            };

            items.push(SetItem {
                name,
                value,
                kind,
                no_equals: false,
            });

            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        Ok(Expression::SetStatement(Box::new(SetStatement { items })))
    }

    /// Parse Teradata SET QUERY_BAND statement
    fn parse_query_band(&mut self) -> Result<Expression> {
        self.expect(TokenType::Eq)?;

        let value = if self.match_identifier("NONE") {
            Expression::Var(Box::new(Var {
                this: "NONE".to_string(),
            }))
        } else if self.check(TokenType::String) {
            Expression::Literal(Literal::String(self.expect_string()?))
        } else {
            self.parse_primary()?
        };

        let update = if self.match_token(TokenType::Update) || self.match_identifier("UPDATE") {
            Some(Box::new(Expression::Boolean(BooleanLiteral {
                value: true,
            })))
        } else {
            None
        };

        let _ = self.match_token(TokenType::For);

        let scope = if self.match_token(TokenType::Session) || self.match_identifier("SESSION") {
            if self.match_identifier("VOLATILE") {
                Some("SESSION VOLATILE".to_string())
            } else {
                Some("SESSION".to_string())
            }
        } else if self.match_token(TokenType::Transaction) || self.match_identifier("TRANSACTION") {
            Some("TRANSACTION".to_string())
        } else if self.match_identifier("VOLATILE") {
            Some("VOLATILE".to_string())
        } else {
            None
        };

        Ok(Expression::QueryBand(Box::new(QueryBand {
            this: Box::new(value),
            scope: scope.map(|s| Box::new(Expression::Var(Box::new(Var { this: s })))),
            update,
        })))
    }

    /// Parse FETCH FIRST/NEXT clause
    fn parse_fetch(&mut self) -> Result<Fetch> {
        // FETCH [FIRST|NEXT] [count] [PERCENT] [ROW|ROWS] [ONLY|WITH TIES]

        // FIRST or NEXT
        let direction = if self.match_token(TokenType::First) {
            "FIRST".to_string()
        } else if self.match_token(TokenType::Next) {
            "NEXT".to_string()
        } else {
            "FIRST".to_string() // Default
        };

        // Optional count - but check if next token is ROW/ROWS/PERCENT/ONLY (no count)
        let count = if !self.check(TokenType::Row)
            && !self.check(TokenType::Rows)
            && !self.check(TokenType::Percent)
            && !self.check(TokenType::Only)
        {
            // Accept number, parenthesized expression, or TSQL @variable (Var token)
            if self.check(TokenType::Number)
                || self.check(TokenType::LParen)
                || self.check(TokenType::DAt)
                || self.check(TokenType::Var)
            {
                Some(self.parse_primary()?)
            } else {
                None
            }
        } else {
            None
        };

        // PERCENT modifier
        let percent = self.match_token(TokenType::Percent);

        // ROW or ROWS
        let rows = self.match_token(TokenType::Row) || self.match_token(TokenType::Rows);

        // ONLY or WITH TIES
        self.match_token(TokenType::Only);
        let with_ties = self.match_keywords(&[TokenType::With, TokenType::Ties]);

        Ok(Fetch {
            direction,
            count,
            percent,
            rows,
            with_ties,
        })
    }

    /// Parse a qualified name (schema.table.column or just table)
    fn parse_qualified_name(&mut self) -> Result<Expression> {
        let first = self.expect_identifier_or_keyword()?;
        let mut parts = vec![first];

        while self.match_token(TokenType::Dot) {
            let next = self.expect_identifier_or_keyword()?;
            parts.push(next);
        }

        if parts.len() == 1 {
            Ok(Expression::Identifier(Identifier::new(parts.remove(0))))
        } else if parts.len() == 2 {
            Ok(Expression::Column(Column {
                table: Some(Identifier::new(parts[0].clone())),
                name: Identifier::new(parts[1].clone()),
                join_mark: false,
                trailing_comments: Vec::new(),
                span: None,
                inferred_type: None,
            }))
        } else {
            // For 3+ parts, create a Column with concatenated table parts
            let column_name = parts.pop().unwrap();
            let table_name = parts.join(".");
            Ok(Expression::Column(Column {
                table: Some(Identifier::new(table_name)),
                name: Identifier::new(column_name),
                join_mark: false,
                trailing_comments: Vec::new(),
                span: None,
                inferred_type: None,
            }))
        }
    }

    // ==================== Phase 4: Additional DDL Parsing ====================

    /// Parse CREATE SCHEMA statement
    fn parse_create_schema(&mut self, leading_comments: Vec<String>) -> Result<Expression> {
        self.expect(TokenType::Schema)?;

        let if_not_exists =
            self.match_keywords(&[TokenType::If, TokenType::Not, TokenType::Exists]);
        let name = self.expect_identifier_with_quoted()?;

        // Parse CLONE clause (Snowflake)
        let clone_from = if self.match_identifier("CLONE") {
            Some(self.expect_identifier_with_quoted()?)
        } else {
            None
        };

        // Parse AT/BEFORE clause for time travel (Snowflake)
        // Note: BEFORE is a keyword token, AT is an identifier
        let at_clause = if self.match_identifier("AT") || self.match_token(TokenType::Before) {
            let keyword = self.previous().text.to_uppercase();
            self.expect(TokenType::LParen)?;
            // Parse the content: OFFSET => value or TIMESTAMP => value
            let mut result = format!("{} (", keyword);
            let mut prev_token_type: Option<TokenType> = None;
            let mut paren_depth = 1; // Track nested parens
            while !self.is_at_end() && paren_depth > 0 {
                let token = self.advance();
                if token.token_type == TokenType::LParen {
                    paren_depth += 1;
                } else if token.token_type == TokenType::RParen {
                    paren_depth -= 1;
                    if paren_depth == 0 {
                        break; // Don't include the closing paren in result yet
                    }
                }
                // Smart spacing: no space after ( or => or - and no space before (
                let needs_space = !result.ends_with('(')
                    && prev_token_type != Some(TokenType::Arrow)
                    && prev_token_type != Some(TokenType::Dash)
                    && prev_token_type != Some(TokenType::LParen)
                    && token.token_type != TokenType::LParen; // no space before (
                if needs_space
                    && token.token_type != TokenType::RParen
                    && token.token_type != TokenType::Comma
                {
                    result.push(' ');
                }
                // Properly quote string literals
                if token.token_type == TokenType::String {
                    result.push('\'');
                    result.push_str(&token.text.replace('\'', "''"));
                    result.push('\'');
                } else {
                    result.push_str(&token.text);
                }
                if token.token_type == TokenType::Arrow || token.token_type == TokenType::Comma {
                    result.push(' ');
                }
                prev_token_type = Some(token.token_type);
            }
            result.push(')');
            Some(Expression::Raw(Raw { sql: result }))
        } else {
            None
        };

        let authorization = if self.match_token(TokenType::Authorization) {
            Some(Identifier::new(self.expect_identifier()?))
        } else {
            None
        };

        // Parse schema properties like DEFAULT COLLATE or WITH (properties)
        let mut properties = Vec::new();

        // Parse WITH (prop1=val1, prop2=val2, ...) (Trino/Presto)
        if self.match_token(TokenType::With) {
            self.expect(TokenType::LParen)?;
            loop {
                // Parse property name (identifier or string)
                let prop_name = if self.check(TokenType::String) {
                    Expression::Literal(Literal::String(self.expect_string()?))
                } else {
                    Expression::Identifier(Identifier::new(self.expect_identifier_or_keyword()?))
                };
                self.expect(TokenType::Eq)?;
                // Parse property value
                let prop_value = self.parse_expression()?;
                // Create Property expression: key=value
                properties.push(Expression::Property(Box::new(Property {
                    this: Box::new(prop_name),
                    value: Some(Box::new(prop_value)),
                })));
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            self.expect(TokenType::RParen)?;
        }

        // Parse DEFAULT COLLATE 'value' (BigQuery)
        if self.match_token(TokenType::Default) && self.match_token(TokenType::Collate) {
            // Parse the collation value (could be string literal or identifier)
            let collation = self.parse_primary()?;
            properties.push(Expression::CollateProperty(Box::new(CollateProperty {
                this: Box::new(collation),
                default: Some(Box::new(Expression::Boolean(BooleanLiteral {
                    value: true,
                }))),
            })));
        }

        Ok(Expression::CreateSchema(Box::new(CreateSchema {
            name,
            if_not_exists,
            authorization,
            clone_from,
            at_clause,
            properties,
            leading_comments,
        })))
    }

    /// Parse DROP SCHEMA statement
    fn parse_drop_schema(&mut self) -> Result<Expression> {
        self.expect(TokenType::Schema)?;

        let if_exists = self.match_keywords(&[TokenType::If, TokenType::Exists]);
        let name = Identifier::new(self.expect_identifier()?);

        let cascade = self.match_token(TokenType::Cascade);
        if !cascade {
            self.match_token(TokenType::Restrict);
        }

        Ok(Expression::DropSchema(Box::new(DropSchema {
            name,
            if_exists,
            cascade,
        })))
    }

    /// Parse CREATE DATABASE statement
    fn parse_create_database(&mut self) -> Result<Expression> {
        self.expect(TokenType::Database)?;

        let if_not_exists =
            self.match_keywords(&[TokenType::If, TokenType::Not, TokenType::Exists]);
        let name = Identifier::new(self.expect_identifier()?);

        // Check for Snowflake CLONE clause
        let clone_from = if self.match_identifier("CLONE") {
            Some(Identifier::new(self.expect_identifier()?))
        } else {
            None
        };

        // Parse AT/BEFORE clause for time travel (Snowflake)
        // Note: BEFORE is a keyword token, AT is an identifier
        let at_clause = if self.match_identifier("AT") || self.match_token(TokenType::Before) {
            let keyword = self.previous().text.to_uppercase();
            self.expect(TokenType::LParen)?;
            // Parse the content: OFFSET => value or TIMESTAMP => value
            let mut result = format!("{} (", keyword);
            let mut prev_token_type: Option<TokenType> = None;
            let mut paren_depth = 1; // Track nested parens
            while !self.is_at_end() && paren_depth > 0 {
                let token = self.advance();
                if token.token_type == TokenType::LParen {
                    paren_depth += 1;
                } else if token.token_type == TokenType::RParen {
                    paren_depth -= 1;
                    if paren_depth == 0 {
                        break; // Don't include the closing paren in result yet
                    }
                }
                // Smart spacing: no space after ( or => or - and no space before (
                let needs_space = !result.ends_with('(')
                    && prev_token_type != Some(TokenType::Arrow)
                    && prev_token_type != Some(TokenType::Dash)
                    && prev_token_type != Some(TokenType::LParen)
                    && token.token_type != TokenType::LParen; // no space before (
                if needs_space
                    && token.token_type != TokenType::RParen
                    && token.token_type != TokenType::Comma
                {
                    result.push(' ');
                }
                // Properly quote string literals
                if token.token_type == TokenType::String {
                    result.push('\'');
                    result.push_str(&token.text.replace('\'', "''"));
                    result.push('\'');
                } else {
                    result.push_str(&token.text);
                }
                if token.token_type == TokenType::Arrow || token.token_type == TokenType::Comma {
                    result.push(' ');
                }
                prev_token_type = Some(token.token_type);
            }
            result.push(')');
            Some(Expression::Raw(Raw { sql: result }))
        } else {
            None
        };

        // ClickHouse: ON CLUSTER clause
        let _on_cluster = self.parse_on_cluster_clause()?;

        let mut options = Vec::new();

        // Parse database options
        while !self.is_at_end() && !self.check(TokenType::Semicolon) {
            if self.match_identifier("OWNER") || self.match_token(TokenType::Eq) {
                self.match_token(TokenType::Eq);
                options.push(DatabaseOption::Owner(Identifier::new(
                    self.expect_identifier()?,
                )));
            } else if self.match_identifier("TEMPLATE") {
                self.match_token(TokenType::Eq);
                options.push(DatabaseOption::Template(Identifier::new(
                    self.expect_identifier()?,
                )));
            } else if self.match_identifier("ENCODING") {
                self.match_token(TokenType::Eq);
                let encoding = if self.check(TokenType::String) {
                    let tok = self.advance();
                    tok.text.trim_matches('\'').to_string()
                } else {
                    self.expect_identifier()?
                };
                options.push(DatabaseOption::Encoding(encoding));
            } else if self.match_identifier("CHARACTER") {
                self.match_token(TokenType::Set);
                self.match_token(TokenType::Eq);
                let charset = if self.check(TokenType::String) {
                    let tok = self.advance();
                    tok.text.trim_matches('\'').to_string()
                } else {
                    self.expect_identifier()?
                };
                options.push(DatabaseOption::CharacterSet(charset));
            } else if self.match_identifier("COLLATE") {
                self.match_token(TokenType::Eq);
                let collate = if self.check(TokenType::String) {
                    let tok = self.advance();
                    tok.text.trim_matches('\'').to_string()
                } else {
                    self.expect_identifier()?
                };
                options.push(DatabaseOption::Collate(collate));
            } else if self.match_identifier("LOCATION") {
                self.match_token(TokenType::Eq);
                let loc = if self.check(TokenType::String) {
                    let tok = self.advance();
                    tok.text.trim_matches('\'').to_string()
                } else {
                    self.expect_identifier()?
                };
                options.push(DatabaseOption::Location(loc));
            } else {
                break;
            }
        }

        Ok(Expression::CreateDatabase(Box::new(CreateDatabase {
            name,
            if_not_exists,
            options,
            clone_from,
            at_clause,
        })))
    }

    /// Parse DROP DATABASE statement
    fn parse_drop_database(&mut self) -> Result<Expression> {
        self.expect(TokenType::Database)?;

        let if_exists = self.match_keywords(&[TokenType::If, TokenType::Exists]);

        // ClickHouse: IF EMPTY
        if !if_exists
            && matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            )
        {
            if self.check(TokenType::If)
                && self.current + 1 < self.tokens.len()
                && self.tokens[self.current + 1]
                    .text
                    .eq_ignore_ascii_case("EMPTY")
            {
                self.advance(); // consume IF
                self.advance(); // consume EMPTY
            }
        }
        let name = Identifier::new(self.expect_identifier()?);

        // ClickHouse: ON CLUSTER clause
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) {
            let _ = self.parse_on_cluster_clause()?;
            self.match_identifier("SYNC");
        }

        Ok(Expression::DropDatabase(Box::new(DropDatabase {
            name,
            if_exists,
        })))
    }

    /// Parse CREATE FUNCTION statement
    fn parse_create_function(
        &mut self,
        or_replace: bool,
        temporary: bool,
        is_table_function: bool,
    ) -> Result<Expression> {
        self.expect(TokenType::Function)?;

        let if_not_exists =
            self.match_keywords(&[TokenType::If, TokenType::Not, TokenType::Exists]);
        let name = self.parse_table_ref()?;

        // Parse parameters (optional - some dialects allow CREATE FUNCTION f AS 'body')
        let (parameters, has_parens) = if self.match_token(TokenType::LParen) {
            let params = self.parse_function_parameters()?;
            self.expect(TokenType::RParen)?;
            (params, true)
        } else {
            (Vec::new(), false)
        };

        // Track if LANGUAGE appears before RETURNS
        let mut language_first = false;
        let mut return_type = None;
        let mut language = None;
        let mut sql_data_access = None;

        // Check for LANGUAGE before RETURNS
        if self.match_token(TokenType::Language) {
            language = Some(self.expect_identifier_or_keyword()?);
            language_first = true;
        }

        // Parse RETURNS clause (may come before or after LANGUAGE)
        let mut returns_table_body: Option<String> = None;
        if self.match_token(TokenType::Returns) {
            if self.check(TokenType::Var) && self.peek().text.starts_with('@') {
                // TSQL: RETURNS @var TABLE (col_defs)
                let var_name = self.advance().text.clone();
                if self.check(TokenType::Table) {
                    self.advance(); // consume TABLE
                    return_type = Some(DataType::Custom {
                        name: "TABLE".to_string(),
                    });
                    // Parse column definitions
                    if self.match_token(TokenType::LParen) {
                        let start = self.current;
                        let mut depth = 1;
                        while depth > 0 && !self.is_at_end() {
                            if self.check(TokenType::LParen) {
                                depth += 1;
                            }
                            if self.check(TokenType::RParen) {
                                depth -= 1;
                                if depth == 0 {
                                    break;
                                }
                            }
                            self.advance();
                        }
                        // Reconstruct the column definitions with proper spacing
                        let mut col_defs_str = String::new();
                        for (i, tok) in self.tokens[start..self.current].iter().enumerate() {
                            // Don't add space before comma, LParen, RParen
                            // Don't add space after LParen
                            let prev_tok = if i > 0 {
                                Some(&self.tokens[start + i - 1])
                            } else {
                                None
                            };
                            let needs_space = i > 0
                                && tok.token_type != TokenType::Comma
                                && tok.token_type != TokenType::RParen
                                && tok.token_type != TokenType::LParen
                                && prev_tok
                                    .map(|p| p.token_type != TokenType::LParen)
                                    .unwrap_or(true);
                            if needs_space {
                                col_defs_str.push(' ');
                            }
                            col_defs_str.push_str(&tok.text);
                        }
                        returns_table_body = Some(format!("{} TABLE ({})", var_name, col_defs_str));
                        self.expect(TokenType::RParen)?;
                    } else {
                        returns_table_body = Some(format!("{} TABLE", var_name));
                    }
                } else {
                    // Parse data type after var name
                    return_type = Some(self.parse_data_type()?);
                }
            } else if self.check(TokenType::Table) {
                // Could be:
                // - TSQL: RETURNS TABLE AS RETURN ...
                // - BigQuery: RETURNS TABLE <col1 TYPE, col2 TYPE>
                // - Snowflake: RETURNS TABLE(col1 TYPE, col2 TYPE)
                self.advance(); // consume TABLE
                if self.check(TokenType::Lt) {
                    // BigQuery: RETURNS TABLE <col1 TYPE, col2 TYPE>
                    self.advance(); // consume <
                    let mut cols = Vec::new();
                    loop {
                        let col_name = self.expect_identifier()?;
                        let col_type = self.parse_data_type()?;
                        cols.push(format!(
                            "{} {}",
                            col_name,
                            self.data_type_to_string(&col_type)
                        ));
                        if !self.match_token(TokenType::Comma) {
                            break;
                        }
                    }
                    if !self.match_token(TokenType::Gt) {
                        return Err(self.parse_error("Expected > after TABLE column definitions"));
                    }
                    returns_table_body = Some(format!("TABLE <{}>", cols.join(", ")));
                } else if self.check(TokenType::LParen) {
                    // Snowflake: RETURNS TABLE(col1 TYPE, col2 TYPE)
                    self.advance(); // consume (
                    let mut cols = Vec::new();
                    loop {
                        let col_name = self.expect_identifier()?;
                        let col_type = self.parse_data_type()?;
                        cols.push(format!(
                            "{} {}",
                            col_name,
                            self.data_type_to_string(&col_type)
                        ));
                        if !self.match_token(TokenType::Comma) {
                            break;
                        }
                    }
                    self.expect(TokenType::RParen)?;
                    returns_table_body = Some(format!("TABLE ({})", cols.join(", ")));
                } else {
                    // TSQL: RETURNS TABLE AS RETURN ...
                    return_type = Some(DataType::Custom {
                        name: "TABLE".to_string(),
                    });
                }
            } else {
                // Use parse_function_return_type to preserve original type names like 'integer'
                return_type = Some(self.parse_function_return_type()?);
            }
        }

        let mut deterministic = None;
        let mut returns_null_on_null_input = None;
        let mut strict = false;
        let mut security = None;
        let mut body = None;
        let mut set_options: Vec<FunctionSetOption> = Vec::new();
        let mut property_order: Vec<FunctionPropertyKind> = Vec::new();
        let mut options: Vec<Expression> = Vec::new();
        let mut environment: Vec<Expression> = Vec::new();

        // Parse function options
        while !self.is_at_end() && !self.check(TokenType::Semicolon) {
            if self.check(TokenType::Returns)
                && self.current + 1 < self.tokens.len()
                && self.tokens[self.current + 1].token_type == TokenType::Null
            {
                // RETURNS NULL ON NULL INPUT
                self.advance(); // consume RETURNS
                self.advance(); // consume NULL
                self.match_token(TokenType::On);
                self.match_token(TokenType::Null);
                self.match_token(TokenType::Input);
                returns_null_on_null_input = Some(true);
                if !property_order.contains(&FunctionPropertyKind::NullInput) {
                    property_order.push(FunctionPropertyKind::NullInput);
                }
            } else if self.match_token(TokenType::Returns) {
                // RETURNS can come after LANGUAGE
                return_type = Some(self.parse_data_type()?);
            } else if self.match_token(TokenType::Language) {
                // Language can be SQL, PLPGSQL, PYTHON, etc.
                language = Some(self.expect_identifier_or_keyword()?);
                if !property_order.contains(&FunctionPropertyKind::Language) {
                    property_order.push(FunctionPropertyKind::Language);
                }
            } else if self.match_token(TokenType::Not) && self.match_identifier("DETERMINISTIC") {
                deterministic = Some(false);
                if !property_order.contains(&FunctionPropertyKind::Determinism) {
                    property_order.push(FunctionPropertyKind::Determinism);
                }
            } else if self.match_identifier("DETERMINISTIC") {
                deterministic = Some(true);
                if !property_order.contains(&FunctionPropertyKind::Determinism) {
                    property_order.push(FunctionPropertyKind::Determinism);
                }
            } else if self.match_identifier("IMMUTABLE") {
                deterministic = Some(true);
                if !property_order.contains(&FunctionPropertyKind::Determinism) {
                    property_order.push(FunctionPropertyKind::Determinism);
                }
            } else if self.match_identifier("STABLE") || self.match_identifier("VOLATILE") {
                deterministic = Some(false);
                if !property_order.contains(&FunctionPropertyKind::Determinism) {
                    property_order.push(FunctionPropertyKind::Determinism);
                }
            } else if self.match_identifier("STRICT") {
                returns_null_on_null_input = Some(true);
                strict = true;
                if !property_order.contains(&FunctionPropertyKind::NullInput) {
                    property_order.push(FunctionPropertyKind::NullInput);
                }
            } else if self.match_identifier("CALLED") {
                self.match_token(TokenType::On);
                self.match_token(TokenType::Null);
                self.match_token(TokenType::Input);
                returns_null_on_null_input = Some(false);
                if !property_order.contains(&FunctionPropertyKind::NullInput) {
                    property_order.push(FunctionPropertyKind::NullInput);
                }
            } else if self.match_identifier("SECURITY") {
                if self.match_identifier("DEFINER") {
                    security = Some(FunctionSecurity::Definer);
                } else if self.match_identifier("INVOKER") {
                    security = Some(FunctionSecurity::Invoker);
                }
                if !property_order.contains(&FunctionPropertyKind::Security) {
                    property_order.push(FunctionPropertyKind::Security);
                }
            } else if self.match_identifier("CONTAINS") {
                // CONTAINS SQL
                self.match_identifier("SQL");
                sql_data_access = Some(SqlDataAccess::ContainsSql);
                if !property_order.contains(&FunctionPropertyKind::SqlDataAccess) {
                    property_order.push(FunctionPropertyKind::SqlDataAccess);
                }
            } else if self.match_identifier("READS") {
                // READS SQL DATA
                self.match_identifier("SQL");
                self.match_identifier("DATA");
                sql_data_access = Some(SqlDataAccess::ReadsSqlData);
                if !property_order.contains(&FunctionPropertyKind::SqlDataAccess) {
                    property_order.push(FunctionPropertyKind::SqlDataAccess);
                }
            } else if self.match_identifier("MODIFIES") {
                // MODIFIES SQL DATA
                self.match_identifier("SQL");
                self.match_identifier("DATA");
                sql_data_access = Some(SqlDataAccess::ModifiesSqlData);
                if !property_order.contains(&FunctionPropertyKind::SqlDataAccess) {
                    property_order.push(FunctionPropertyKind::SqlDataAccess);
                }
            } else if self.match_token(TokenType::No) && self.match_identifier("SQL") {
                // NO SQL
                sql_data_access = Some(SqlDataAccess::NoSql);
                if !property_order.contains(&FunctionPropertyKind::SqlDataAccess) {
                    property_order.push(FunctionPropertyKind::SqlDataAccess);
                }
            } else if self.match_token(TokenType::Set) {
                // PostgreSQL: SET key = value / SET key TO value / SET key FROM CURRENT
                let opt_name = self.expect_identifier_or_keyword()?;
                let value = if self.match_token(TokenType::From) {
                    // SET key FROM CURRENT
                    if !self.match_token(TokenType::Current) {
                        return Err(self.parse_error("Expected CURRENT after FROM in SET option"));
                    }
                    FunctionSetValue::FromCurrent
                } else {
                    // SET key = value or SET key TO value
                    let use_to = self.match_token(TokenType::To);
                    if !use_to && !self.match_token(TokenType::Eq) {
                        return Err(self.parse_error("Expected = or TO after SET key"));
                    }
                    // Value can be a string literal or identifier
                    let val = if self.check(TokenType::String) {
                        let tok = self.advance();
                        format!("'{}'", tok.text)
                    } else {
                        self.expect_identifier_or_keyword()?
                    };
                    FunctionSetValue::Value { value: val, use_to }
                };
                set_options.push(FunctionSetOption {
                    name: opt_name,
                    value,
                });
                if !property_order.contains(&FunctionPropertyKind::Set) {
                    property_order.push(FunctionPropertyKind::Set);
                }
            } else if self.match_token(TokenType::As) {
                // Parse function body: AS RETURN x, AS $$ ... $$, AS BEGIN ... END, AS 'body'
                if !property_order.contains(&FunctionPropertyKind::As) {
                    property_order.push(FunctionPropertyKind::As);
                }
                if self.match_identifier("RETURN") {
                    // AS RETURN expression (or SELECT statement for TSQL TVFs)
                    let expr = if self.check(TokenType::Select) || self.check(TokenType::With) {
                        // TSQL: AS RETURN SELECT ... for table-valued functions
                        self.parse_statement()?
                    } else {
                        self.parse_expression()?
                    };
                    body = Some(FunctionBody::Return(expr));
                } else if self.check(TokenType::Select) || self.check(TokenType::With) {
                    // TSQL: AS SELECT ... for table-valued functions (without RETURN keyword)
                    let stmt = self.parse_statement()?;
                    body = Some(FunctionBody::Expression(stmt));
                } else if self.check(TokenType::DollarString) {
                    let tok = self.advance();
                    // Parse the dollar string token to extract tag and content
                    let (tag, content) = crate::tokens::parse_dollar_string_token(&tok.text);
                    body = Some(FunctionBody::DollarQuoted { content, tag });
                } else if self.check(TokenType::String) {
                    let tok = self.advance();
                    body = Some(FunctionBody::StringLiteral(tok.text.clone()));
                } else if self.match_token(TokenType::Begin) {
                    // Parse BEGIN...END block
                    let mut block_content = String::new();
                    let mut depth = 1;
                    while depth > 0 && !self.is_at_end() {
                        let tok = self.advance();
                        if tok.token_type == TokenType::Begin {
                            depth += 1;
                        } else if tok.token_type == TokenType::End {
                            depth -= 1;
                            if depth == 0 {
                                break;
                            }
                        }
                        block_content.push_str(&tok.text);
                        block_content.push(' ');
                    }
                    body = Some(FunctionBody::Block(block_content.trim().to_string()));
                } else {
                    // Expression-based body
                    let expr = self.parse_expression()?;
                    body = Some(FunctionBody::Expression(expr));
                }
            } else if self.match_identifier("RETURN") {
                // RETURN expression (or SELECT statement for TSQL TVFs)
                let expr = if self.check(TokenType::Select) || self.check(TokenType::With) {
                    self.parse_statement()?
                } else {
                    self.parse_expression()?
                };
                body = Some(FunctionBody::Return(expr));
            } else if self.match_identifier("EXTERNAL") {
                self.match_identifier("NAME");
                let ext_name = if self.check(TokenType::String) {
                    let tok = self.advance();
                    tok.text.trim_matches('\'').to_string()
                } else {
                    self.expect_identifier()?
                };
                body = Some(FunctionBody::External(ext_name));
            } else if self.match_identifier("OPTIONS") {
                // BigQuery: OPTIONS (key=value, ...) - track in property_order
                let parsed_options = self.parse_options_list()?;
                options.extend(parsed_options);
                if !property_order.contains(&FunctionPropertyKind::Options) {
                    property_order.push(FunctionPropertyKind::Options);
                }
            } else if self.match_identifier("ENVIRONMENT") {
                // Databricks: ENVIRONMENT (dependencies = '...', environment_version = '...')
                let parsed_env = self.parse_environment_list()?;
                environment.extend(parsed_env);
                if !property_order.contains(&FunctionPropertyKind::Environment) {
                    property_order.push(FunctionPropertyKind::Environment);
                }
            } else {
                break;
            }
        }

        // BigQuery: OPTIONS (key=value, ...) can also appear after AS body (legacy position)
        if options.is_empty() && self.match_identifier("OPTIONS") {
            let parsed_options = self.parse_options_list()?;
            options.extend(parsed_options);
            if !property_order.contains(&FunctionPropertyKind::Options) {
                property_order.push(FunctionPropertyKind::Options);
            }
        }

        Ok(Expression::CreateFunction(Box::new(CreateFunction {
            name,
            parameters,
            return_type,
            body,
            or_replace,
            if_not_exists,
            temporary,
            language,
            deterministic,
            returns_null_on_null_input,
            security,
            has_parens,
            sql_data_access,
            returns_table_body,
            language_first,
            set_options,
            strict,
            options,
            is_table_function,
            property_order,
            environment,
        })))
    }

    /// Parse function parameters
    fn parse_function_parameters(&mut self) -> Result<Vec<FunctionParameter>> {
        let mut params = Vec::new();

        if self.check(TokenType::RParen) {
            return Ok(params);
        }

        loop {
            let mut mode = None;
            let mut mode_text: Option<String> = None;

            // Check for parameter mode (IN, OUT, INOUT, VARIADIC)
            // Note: OUT, INOUT, VARIADIC are tokenized as Var, not as dedicated keywords
            if self.match_token(TokenType::In) {
                // IN or IN OUT
                if self.check(TokenType::Var) && self.peek().text.eq_ignore_ascii_case("OUT") {
                    let out_text = self.advance().text.clone(); // consume OUT
                    mode_text = Some(format!("IN {}", out_text));
                    mode = Some(ParameterMode::InOut);
                } else {
                    mode_text = Some("IN".to_string());
                    mode = Some(ParameterMode::In);
                }
            } else if self.check(TokenType::Var) && self.peek().text.eq_ignore_ascii_case("OUT") {
                let text = self.advance().text.clone();
                mode_text = Some(text);
                mode = Some(ParameterMode::Out);
            } else if self.check(TokenType::Var) && self.peek().text.eq_ignore_ascii_case("INOUT") {
                let text = self.advance().text.clone();
                mode_text = Some(text);
                mode = Some(ParameterMode::InOut);
            } else if self.check(TokenType::Var)
                && self.peek().text.eq_ignore_ascii_case("VARIADIC")
            {
                let text = self.advance().text.clone();
                mode_text = Some(text);
                mode = Some(ParameterMode::Variadic);
            }

            // Try to parse name and type
            // After a mode keyword (VARIADIC, OUT, etc.), the next thing could be:
            //   - a type directly (e.g., VARIADIC INT[], OUT INT)
            //   - a name then a type (e.g., VARIADIC a INT[], OUT result INT)
            //
            // Strategy: use backtracking. Save position, try parsing as data type.
            // If the result is followed by , or ) or DEFAULT, it was a type-only param.
            // Otherwise, restore position and parse as name + type.
            let (name, data_type) = if mode.is_some() {
                let saved = self.current;
                // Try parsing as a data type directly
                let type_result = self.parse_data_type();
                if let Ok(dt) = type_result {
                    if self.check(TokenType::Comma)
                        || self.check(TokenType::RParen)
                        || self.check(TokenType::Default)
                        || self.check(TokenType::Eq)
                    {
                        // Successfully parsed as a type-only parameter
                        (None, dt)
                    } else {
                        // Not followed by comma/rparen — restore and parse as name + type
                        self.current = saved;
                        let first_ident =
                            if self.check(TokenType::Input) || self.check(TokenType::Output) {
                                let token = self.advance();
                                Identifier {
                                    name: token.text,
                                    quoted: false,
                                    trailing_comments: Vec::new(),
                                    span: None,
                                }
                            } else {
                                self.expect_identifier_with_quoted()?
                            };
                        self.match_token(TokenType::As);
                        let dt = self.parse_data_type()?;
                        (Some(first_ident), dt)
                    }
                } else {
                    // Type parse failed — restore and try as name + type
                    self.current = saved;
                    let first_ident =
                        if self.check(TokenType::Input) || self.check(TokenType::Output) {
                            let token = self.advance();
                            Identifier {
                                name: token.text,
                                quoted: false,
                                trailing_comments: Vec::new(),
                                span: None,
                            }
                        } else {
                            self.expect_identifier_with_quoted()?
                        };
                    if self.check(TokenType::Comma)
                        || self.check(TokenType::RParen)
                        || self.check(TokenType::Default)
                    {
                        (None, self.identifier_to_datatype(&first_ident.name)?)
                    } else {
                        self.match_token(TokenType::As);
                        let dt = self.parse_data_type()?;
                        (Some(first_ident), dt)
                    }
                }
            } else {
                // No mode keyword — original logic
                // Handle keywords like INPUT that may be used as parameter names
                let first_ident = if self.check(TokenType::Input) || self.check(TokenType::Output) {
                    let token = self.advance();
                    Identifier {
                        name: token.text,
                        quoted: false,
                        trailing_comments: Vec::new(),
                        span: None,
                    }
                } else {
                    self.expect_identifier_with_quoted()?
                };

                // Check if next token is a type or if this was the type
                if self.check(TokenType::Comma)
                    || self.check(TokenType::RParen)
                    || self.check(TokenType::Default)
                {
                    // This was the type, no name
                    (None, self.identifier_to_datatype(&first_ident.name)?)
                } else {
                    // This was the name, next is type
                    // TSQL allows: @param AS type (optional AS keyword)
                    self.match_token(TokenType::As);
                    let dt = self.parse_data_type()?;
                    (Some(first_ident), dt)
                }
            };

            let default = if self.match_token(TokenType::Default) || self.match_token(TokenType::Eq)
            {
                Some(self.parse_expression()?)
            } else {
                None
            };

            params.push(FunctionParameter {
                name,
                data_type,
                mode,
                default,
                mode_text: mode_text.clone(),
            });

            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        Ok(params)
    }

    /// Parse TSQL-style unparenthesized procedure parameters
    /// Format: @param1 TYPE, @param2 TYPE, ... AS
    fn parse_tsql_procedure_params(&mut self) -> Result<Vec<FunctionParameter>> {
        let mut params = Vec::new();
        loop {
            if !self.check(TokenType::Var) {
                break;
            }
            let name = self.advance().text.clone();
            // Skip optional AS keyword between name and type
            self.match_token(TokenType::As);
            let data_type = self.parse_data_type()?;
            let default = if self.match_token(TokenType::Default) || self.match_token(TokenType::Eq)
            {
                Some(self.parse_expression()?)
            } else {
                None
            };
            params.push(FunctionParameter {
                name: Some(Identifier::new(name)),
                data_type,
                mode: None,
                default,
                mode_text: None,
            });
            if !self.match_token(TokenType::Comma) {
                break;
            }
        }
        Ok(params)
    }

    /// Convert identifier to DataType for function parameters.
    /// Preserves the original identifier name to maintain exact type name as written.
    /// This matches Python sqlglot's behavior where function parameter types like 'integer'
    /// are stored as Identifiers rather than normalized DataTypes.
    fn identifier_to_datatype(&self, ident: &str) -> Result<DataType> {
        // Always use DataType::Custom to preserve the exact type name as written.
        // This is important for identity tests where e.g. 'integer' should not be normalized to 'INT'.
        Ok(DataType::Custom {
            name: ident.to_string(),
        })
    }

    /// Parse a data type for function RETURNS clause, preserving original type names.
    /// For simple type names like 'integer', preserves the original name rather than
    /// normalizing to INT. This matches Python sqlglot's behavior.
    fn parse_function_return_type(&mut self) -> Result<DataType> {
        // Check if it's a simple identifier that could be a type name
        if (self.check(TokenType::Identifier) || self.check(TokenType::Var))
            && !self.check_next(TokenType::LParen)  // Not a parameterized type like VARCHAR(10)
            && !self.check_next(TokenType::LBracket)
        // Not an array type
        {
            let type_name = self.advance().text.clone();
            // Check if the next token indicates we should use parse_data_type instead
            // For complex types, fall through to parse_data_type
            return Ok(DataType::Custom { name: type_name });
        }

        // For complex types, use standard parsing
        self.parse_data_type()
    }

    /// Parse DROP FUNCTION statement
    fn parse_drop_function(&mut self) -> Result<Expression> {
        self.expect(TokenType::Function)?;

        let if_exists = self.match_keywords(&[TokenType::If, TokenType::Exists]);
        let name = self.parse_table_ref()?;

        // Optional parameter types for overloaded functions
        let parameters = if self.match_token(TokenType::LParen) {
            let mut types = Vec::new();
            if !self.check(TokenType::RParen) {
                loop {
                    types.push(self.parse_data_type()?);
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
            }
            self.expect(TokenType::RParen)?;
            Some(types)
        } else {
            None
        };

        let cascade = self.match_token(TokenType::Cascade);
        if !cascade {
            self.match_token(TokenType::Restrict);
        }

        Ok(Expression::DropFunction(Box::new(DropFunction {
            name,
            parameters,
            if_exists,
            cascade,
        })))
    }

    /// Parse CREATE PROCEDURE statement
    fn parse_create_procedure(&mut self, or_replace: bool) -> Result<Expression> {
        // Check if PROC shorthand was used before consuming the token
        let use_proc_keyword = self.peek().text.to_uppercase() == "PROC";
        self.expect(TokenType::Procedure)?;

        let if_not_exists =
            self.match_keywords(&[TokenType::If, TokenType::Not, TokenType::Exists]);
        let name = self.parse_table_ref()?;

        // Parse parameters (optional parentheses for TSQL)
        let (parameters, has_parens) = if self.match_token(TokenType::LParen) {
            let params = self.parse_function_parameters()?;
            self.expect(TokenType::RParen)?;
            (params, true)
        } else if self.check(TokenType::Var) && !self.check(TokenType::As) {
            // TSQL: CREATE PROCEDURE foo @a INTEGER, @b INTEGER AS ...
            // Parameters without parentheses
            let params = self.parse_tsql_procedure_params()?;
            (params, false)
        } else {
            (Vec::new(), false)
        };

        let mut language = None;
        let mut security = None;
        let mut body = None;
        let mut return_type = None;
        let mut execute_as = None;
        let mut with_options: Vec<String> = Vec::new();

        // Parse procedure options
        while !self.is_at_end() && !self.check(TokenType::Semicolon) {
            if self.match_token(TokenType::Returns) {
                // RETURNS type (Snowflake)
                return_type = Some(self.parse_data_type()?);
            } else if self.match_identifier("EXECUTE") || self.match_token(TokenType::Execute) {
                // EXECUTE AS CALLER/OWNER (Snowflake)
                if self.match_token(TokenType::As) {
                    if self.match_identifier("CALLER") {
                        execute_as = Some("CALLER".to_string());
                    } else if self.match_identifier("OWNER") {
                        execute_as = Some("OWNER".to_string());
                    } else if self.match_identifier("SELF") {
                        execute_as = Some("SELF".to_string());
                    }
                }
            } else if self.match_token(TokenType::Language) {
                // Language can be SQL, PLPGSQL, PYTHON, etc.
                language = Some(self.expect_identifier_or_keyword()?);
            } else if self.match_identifier("SECURITY") {
                if self.match_identifier("DEFINER") {
                    security = Some(FunctionSecurity::Definer);
                } else if self.match_identifier("INVOKER") {
                    security = Some(FunctionSecurity::Invoker);
                }
            } else if self.match_token(TokenType::With) {
                // TSQL: WITH option1, option2, ... AS body
                // Options: ENCRYPTION, RECOMPILE, SCHEMABINDING, NATIVE_COMPILATION,
                //          EXECUTE AS {OWNER|SELF|CALLER|'username'}
                loop {
                    if self.match_identifier("EXECUTE") || self.match_token(TokenType::Execute) {
                        // EXECUTE AS {OWNER|SELF|CALLER|'username'}
                        self.expect(TokenType::As)?;
                        if self.check(TokenType::String) {
                            let tok = self.advance();
                            with_options.push(format!("EXECUTE AS '{}'", tok.text));
                        } else {
                            let ident = self.expect_identifier_or_keyword()?;
                            with_options.push(format!("EXECUTE AS {}", ident.to_uppercase()));
                        }
                    } else {
                        let opt = self.expect_identifier_or_keyword()?;
                        with_options.push(opt.to_uppercase());
                    }
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
            } else if self.match_token(TokenType::As) {
                // Parse procedure body
                if self.check(TokenType::String) {
                    // TokenType::String means single-quoted - tokenizer strips quotes
                    let tok = self.advance();
                    body = Some(FunctionBody::StringLiteral(tok.text.clone()));
                } else if self.match_token(TokenType::Begin) {
                    // Parse BEGIN ... END block as a list of statements
                    let mut statements = Vec::new();
                    while !self.check(TokenType::End) && !self.is_at_end() {
                        // Skip optional semicolons between statements
                        while self.match_token(TokenType::Semicolon) {}
                        if self.check(TokenType::End) {
                            break;
                        }
                        statements.push(self.parse_statement()?);
                        // Skip optional semicolon after statement
                        self.match_token(TokenType::Semicolon);
                    }
                    self.expect(TokenType::End)?;
                    body = Some(FunctionBody::Statements(statements));
                } else {
                    // TSQL: AS <statement> (e.g., AS SELECT 1)
                    let stmt = self.parse_statement()?;
                    body = Some(FunctionBody::Expression(stmt));
                }
            } else {
                break;
            }
        }

        Ok(Expression::CreateProcedure(Box::new(CreateProcedure {
            name,
            parameters,
            body,
            or_replace,
            if_not_exists,
            language,
            security,
            return_type,
            execute_as,
            with_options,
            has_parens,
            use_proc_keyword,
        })))
    }

    /// Parse DROP PROCEDURE statement
    fn parse_drop_procedure(&mut self) -> Result<Expression> {
        self.expect(TokenType::Procedure)?;

        let if_exists = self.match_keywords(&[TokenType::If, TokenType::Exists]);
        let name = self.parse_table_ref()?;

        let parameters = if self.match_token(TokenType::LParen) {
            let mut types = Vec::new();
            if !self.check(TokenType::RParen) {
                loop {
                    types.push(self.parse_data_type()?);
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
            }
            self.expect(TokenType::RParen)?;
            Some(types)
        } else {
            None
        };

        let cascade = self.match_token(TokenType::Cascade);
        if !cascade {
            self.match_token(TokenType::Restrict);
        }

        Ok(Expression::DropProcedure(Box::new(DropProcedure {
            name,
            parameters,
            if_exists,
            cascade,
        })))
    }

    /// Parse CREATE SEQUENCE statement
    fn parse_create_sequence(&mut self, temporary: bool, or_replace: bool) -> Result<Expression> {
        self.expect(TokenType::Sequence)?;

        let if_not_exists =
            self.match_keywords(&[TokenType::If, TokenType::Not, TokenType::Exists]);
        let name = self.parse_table_ref()?;

        let mut seq = CreateSequence {
            name,
            if_not_exists,
            temporary,
            or_replace,
            as_type: None,
            increment: None,
            minvalue: None,
            maxvalue: None,
            start: None,
            cache: None,
            cycle: false,
            owned_by: None,
            owned_by_none: false,
            order: None,
            comment: None,
            sharing: None,
            scale_modifier: None,
            shard_modifier: None,
            property_order: Vec::new(),
        };

        // Parse optional AS <type> clause (e.g., AS SMALLINT, AS BIGINT)
        if self.match_token(TokenType::As) {
            seq.as_type = Some(self.parse_data_type()?);
        }

        // Parse sequence options
        // Handle optional WITH keyword before options (Snowflake: WITH START = n INCREMENT = n)
        self.match_token(TokenType::With);

        loop {
            // Skip optional commas between options (Snowflake uses comma-separated options)
            self.match_token(TokenType::Comma);

            if self.is_at_end() || self.check(TokenType::Semicolon) {
                break;
            }

            if self.match_token(TokenType::Increment) || self.match_identifier("INCREMENT") {
                self.match_token(TokenType::By);
                self.match_token(TokenType::Eq); // Snowflake uses = instead of BY
                seq.increment = Some(self.parse_signed_integer()?);
                seq.property_order.push(SeqPropKind::Increment);
            } else if self.match_token(TokenType::Minvalue) {
                seq.minvalue = Some(SequenceBound::Value(self.parse_signed_integer()?));
                seq.property_order.push(SeqPropKind::Minvalue);
            } else if self.match_keywords(&[TokenType::No, TokenType::Minvalue]) {
                seq.minvalue = Some(SequenceBound::None);
                seq.property_order.push(SeqPropKind::Minvalue);
            } else if self.match_identifier("NOMINVALUE") {
                seq.minvalue = Some(SequenceBound::None);
                seq.property_order.push(SeqPropKind::NoMinvalueWord);
            } else if self.match_token(TokenType::Maxvalue) {
                seq.maxvalue = Some(SequenceBound::Value(self.parse_signed_integer()?));
                seq.property_order.push(SeqPropKind::Maxvalue);
            } else if self.match_keywords(&[TokenType::No, TokenType::Maxvalue]) {
                seq.maxvalue = Some(SequenceBound::None);
                seq.property_order.push(SeqPropKind::Maxvalue);
            } else if self.match_identifier("NOMAXVALUE") {
                seq.maxvalue = Some(SequenceBound::None);
                seq.property_order.push(SeqPropKind::NoMaxvalueWord);
            } else if self.match_token(TokenType::Start) {
                self.match_token(TokenType::With);
                self.match_token(TokenType::Eq); // Snowflake uses = instead of WITH
                seq.start = Some(self.parse_signed_integer()?);
                seq.property_order.push(SeqPropKind::Start);
            } else if self.match_token(TokenType::Cache) {
                seq.cache = Some(self.parse_signed_integer()?);
                seq.property_order.push(SeqPropKind::Cache);
            } else if self.match_identifier("NOCACHE") {
                // Oracle: NOCACHE (single word)
                seq.property_order.push(SeqPropKind::NoCacheWord);
            } else if self.match_token(TokenType::Cycle) {
                seq.cycle = true;
                seq.property_order.push(SeqPropKind::Cycle);
            } else if self.match_token(TokenType::NoCycle) {
                // NOCYCLE keyword token - preserve as single word
                seq.cycle = false;
                seq.property_order.push(SeqPropKind::NoCycleWord);
            } else if self.match_token(TokenType::No) {
                // Two-word NO forms
                if self.match_token(TokenType::Cycle) {
                    seq.cycle = false;
                    seq.property_order.push(SeqPropKind::NoCycle);
                } else if self.match_token(TokenType::Cache) || self.match_identifier("CACHE") {
                    seq.property_order.push(SeqPropKind::NoCache);
                } else if self.match_token(TokenType::Minvalue) {
                    seq.minvalue = Some(SequenceBound::None);
                    seq.property_order.push(SeqPropKind::Minvalue);
                } else if self.match_token(TokenType::Maxvalue) {
                    seq.maxvalue = Some(SequenceBound::None);
                    seq.property_order.push(SeqPropKind::Maxvalue);
                } else {
                    // Unexpected token after NO
                    break;
                }
            } else if self.match_token(TokenType::Owned) {
                self.expect(TokenType::By)?;
                if self.match_identifier("NONE") {
                    seq.owned_by = None;
                    seq.owned_by_none = true;
                } else {
                    seq.owned_by = Some(self.parse_table_ref()?);
                }
                seq.property_order.push(SeqPropKind::OwnedBy);
            } else if self.match_token(TokenType::Order) {
                // Snowflake/Oracle: ORDER option
                seq.order = Some(true);
                seq.property_order.push(SeqPropKind::Order);
            } else if self.match_identifier("NOORDER") {
                // Snowflake/Oracle: NOORDER option
                seq.order = Some(false);
                seq.property_order.push(SeqPropKind::NoOrder);
            } else if self.match_token(TokenType::Comment) || self.match_identifier("COMMENT") {
                // Snowflake: COMMENT = 'value'
                self.expect(TokenType::Eq)?;
                let comment_val = self.expect(TokenType::String)?;
                seq.comment = Some(comment_val.text.clone());
                seq.property_order.push(SeqPropKind::Comment);
            } else if self.match_identifier("SHARING") {
                // Oracle: SHARING=value
                self.expect(TokenType::Eq)?;
                let val = self.expect_identifier_or_keyword()?;
                seq.sharing = Some(val);
                seq.property_order.push(SeqPropKind::Sharing);
            } else if self.match_identifier("NOKEEP") {
                seq.property_order.push(SeqPropKind::NoKeep);
            } else if self.match_token(TokenType::Keep) || self.match_identifier("KEEP") {
                seq.property_order.push(SeqPropKind::Keep);
            } else if self.match_identifier("SCALE") {
                let modifier = if self.match_identifier("EXTEND") {
                    "EXTEND".to_string()
                } else if self.match_identifier("NOEXTEND") {
                    "NOEXTEND".to_string()
                } else {
                    String::new()
                };
                seq.scale_modifier = Some(modifier);
                seq.property_order.push(SeqPropKind::Scale);
            } else if self.match_identifier("NOSCALE") {
                seq.property_order.push(SeqPropKind::NoScale);
            } else if self.match_identifier("SHARD") {
                let modifier = if self.match_identifier("EXTEND") {
                    "EXTEND".to_string()
                } else if self.match_identifier("NOEXTEND") {
                    "NOEXTEND".to_string()
                } else {
                    String::new()
                };
                seq.shard_modifier = Some(modifier);
                seq.property_order.push(SeqPropKind::Shard);
            } else if self.match_identifier("NOSHARD") {
                seq.property_order.push(SeqPropKind::NoShard);
            } else if self.match_identifier("SESSION") {
                seq.property_order.push(SeqPropKind::Session);
            } else if self.match_identifier("GLOBAL") {
                seq.property_order.push(SeqPropKind::Global);
            } else {
                break;
            }
        }

        Ok(Expression::CreateSequence(Box::new(seq)))
    }

    /// Parse a signed integer (positive or negative)
    fn parse_signed_integer(&mut self) -> Result<i64> {
        let negative = self.match_token(TokenType::Dash);
        let tok = self.expect(TokenType::Number)?;
        let value: i64 = tok
            .text
            .parse()
            .map_err(|_| self.parse_error(format!("Invalid integer: {}", tok.text)))?;
        Ok(if negative { -value } else { value })
    }

    /// Parse DROP SEQUENCE statement
    fn parse_drop_sequence(&mut self) -> Result<Expression> {
        self.expect(TokenType::Sequence)?;

        let if_exists = self.match_keywords(&[TokenType::If, TokenType::Exists]);
        let name = self.parse_table_ref()?;

        let cascade = self.match_token(TokenType::Cascade);
        if !cascade {
            self.match_token(TokenType::Restrict);
        }

        Ok(Expression::DropSequence(Box::new(DropSequence {
            name,
            if_exists,
            cascade,
        })))
    }

    /// Parse ALTER SEQUENCE statement
    fn parse_alter_sequence(&mut self) -> Result<Expression> {
        self.expect(TokenType::Sequence)?;

        let if_exists = self.match_keywords(&[TokenType::If, TokenType::Exists]);
        let name = self.parse_table_ref()?;

        let mut seq = AlterSequence {
            name,
            if_exists,
            increment: None,
            minvalue: None,
            maxvalue: None,
            start: None,
            restart: None,
            cache: None,
            cycle: None,
            owned_by: None,
        };

        // Parse sequence options
        while !self.is_at_end() && !self.check(TokenType::Semicolon) {
            if self.match_token(TokenType::Increment) || self.match_identifier("INCREMENT") {
                self.match_token(TokenType::By);
                seq.increment = Some(self.parse_signed_integer()?);
            } else if self.match_token(TokenType::Minvalue) {
                seq.minvalue = Some(SequenceBound::Value(self.parse_signed_integer()?));
            } else if self.match_keywords(&[TokenType::No, TokenType::Minvalue]) {
                seq.minvalue = Some(SequenceBound::None);
            } else if self.match_token(TokenType::Maxvalue) {
                seq.maxvalue = Some(SequenceBound::Value(self.parse_signed_integer()?));
            } else if self.match_keywords(&[TokenType::No, TokenType::Maxvalue]) {
                seq.maxvalue = Some(SequenceBound::None);
            } else if self.match_token(TokenType::Start) {
                self.match_token(TokenType::With);
                seq.start = Some(self.parse_signed_integer()?);
            } else if self.match_token(TokenType::Restart) {
                if self.match_token(TokenType::With)
                    || self.check(TokenType::Number)
                    || self.check(TokenType::Dash)
                {
                    seq.restart = Some(Some(self.parse_signed_integer()?));
                } else {
                    seq.restart = Some(None);
                }
            } else if self.match_token(TokenType::Cache) {
                seq.cache = Some(self.parse_signed_integer()?);
            } else if self.match_token(TokenType::Cycle) {
                seq.cycle = Some(true);
            } else if self.match_token(TokenType::NoCycle) {
                seq.cycle = Some(false);
            } else if self.match_token(TokenType::Owned) {
                self.expect(TokenType::By)?;
                if self.match_identifier("NONE") {
                    seq.owned_by = Some(None);
                } else {
                    seq.owned_by = Some(Some(self.parse_table_ref()?));
                }
            } else {
                break;
            }
        }

        Ok(Expression::AlterSequence(Box::new(seq)))
    }

    /// Parse CREATE TRIGGER statement
    fn parse_create_trigger(
        &mut self,
        or_replace: bool,
        constraint: bool,
        create_pos: usize,
    ) -> Result<Expression> {
        self.expect(TokenType::Trigger)?;

        let name = self.expect_identifier_with_quoted()?;

        // TSQL triggers: CREATE TRIGGER name ON table AFTER INSERT AS BEGIN...END
        // These have ON before timing, unlike standard triggers.
        // Fall back to Command for these (matches Python sqlglot behavior).
        if self.check(TokenType::On) && !constraint {
            self.current = create_pos;
            return self.fallback_to_command(create_pos);
        }

        // Parse timing (BEFORE, AFTER, INSTEAD OF)
        let timing = if self.match_token(TokenType::Before) {
            TriggerTiming::Before
        } else if self.match_token(TokenType::After) {
            TriggerTiming::After
        } else if self.match_token(TokenType::Instead) {
            self.expect(TokenType::Of)?;
            TriggerTiming::InsteadOf
        } else {
            // Fall back to Command for unknown trigger syntax
            self.current = create_pos;
            return self.fallback_to_command(create_pos);
        };

        // Parse events
        let mut events = Vec::new();
        loop {
            if self.match_token(TokenType::Insert) {
                events.push(TriggerEvent::Insert);
            } else if self.match_token(TokenType::Update) {
                if self.match_token(TokenType::Of) {
                    let mut cols = Vec::new();
                    loop {
                        cols.push(Identifier::new(self.expect_identifier()?));
                        if !self.match_token(TokenType::Comma) {
                            break;
                        }
                    }
                    events.push(TriggerEvent::Update(Some(cols)));
                } else {
                    events.push(TriggerEvent::Update(None));
                }
            } else if self.match_token(TokenType::Delete) {
                events.push(TriggerEvent::Delete);
            } else if self.match_token(TokenType::Truncate) {
                events.push(TriggerEvent::Truncate);
            } else {
                break;
            }

            if !self.match_token(TokenType::Or) {
                break;
            }
        }

        self.expect(TokenType::On)?;
        let table = self.parse_table_ref()?;

        // Parse optional REFERENCING clause (for non-constraint triggers)
        let referencing = if !constraint && self.match_token(TokenType::Referencing) {
            let mut ref_clause = TriggerReferencing {
                old_table: None,
                new_table: None,
                old_row: None,
                new_row: None,
            };
            while self.match_token(TokenType::Old) || self.match_token(TokenType::New) {
                let is_old = self.previous().token_type == TokenType::Old;
                let is_table = self.match_token(TokenType::Table);
                let _is_row = !is_table && self.match_token(TokenType::Row);
                self.match_token(TokenType::As);
                let alias = Identifier::new(self.expect_identifier()?);

                if is_old {
                    if is_table {
                        ref_clause.old_table = Some(alias);
                    } else {
                        ref_clause.old_row = Some(alias);
                    }
                } else {
                    if is_table {
                        ref_clause.new_table = Some(alias);
                    } else {
                        ref_clause.new_row = Some(alias);
                    }
                }
            }
            Some(ref_clause)
        } else {
            None
        };

        // Parse deferrable options for constraint triggers (comes before FOR EACH ROW in PostgreSQL)
        let mut deferrable = None;
        let mut initially_deferred = None;
        if constraint {
            if self.match_identifier("DEFERRABLE") {
                deferrable = Some(true);
            } else if self.match_keywords(&[TokenType::Not, TokenType::Identifier]) {
                // NOT DEFERRABLE
                deferrable = Some(false);
            }
            if self.match_identifier("INITIALLY") {
                if self.match_identifier("DEFERRED") {
                    initially_deferred = Some(true);
                } else if self.match_identifier("IMMEDIATE") {
                    initially_deferred = Some(false);
                }
            }
        }

        // Parse FOR EACH ROW/STATEMENT (optional)
        let for_each = if self.match_token(TokenType::For) {
            self.match_token(TokenType::Each);
            if self.match_token(TokenType::Row) {
                Some(TriggerForEach::Row)
            } else if self.match_token(TokenType::Statement) {
                Some(TriggerForEach::Statement)
            } else {
                Some(TriggerForEach::Row)
            }
        } else {
            None
        };

        // Parse optional WHEN clause (parentheses are optional, e.g. SQLite)
        let (when, when_paren) = if self.match_token(TokenType::When) {
            let has_paren = self.match_token(TokenType::LParen);
            let expr = self.parse_expression()?;
            if has_paren {
                self.expect(TokenType::RParen)?;
            }
            (Some(expr), has_paren)
        } else {
            (None, false)
        };

        // Parse trigger body
        let body = if self.match_token(TokenType::Execute) {
            self.match_token(TokenType::Function);
            self.match_token(TokenType::Procedure);
            let func_name = self.parse_table_ref()?;
            self.expect(TokenType::LParen)?;
            let mut args = Vec::new();
            if !self.check(TokenType::RParen) {
                loop {
                    args.push(self.parse_expression()?);
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
            }
            self.expect(TokenType::RParen)?;
            TriggerBody::Execute {
                function: func_name,
                args,
            }
        } else if self.match_token(TokenType::Begin) {
            // Record start position (first token after BEGIN)
            let body_start = if !self.is_at_end() {
                self.tokens[self.current].span.start
            } else {
                0
            };
            let mut depth = 1;
            while depth > 0 && !self.is_at_end() {
                let tok = self.advance();
                if tok.token_type == TokenType::Begin {
                    depth += 1;
                } else if tok.token_type == TokenType::End {
                    depth -= 1;
                    if depth == 0 {
                        break;
                    }
                }
            }
            // Extract verbatim text from source if available
            let block_content = if let Some(ref source) = self.source {
                // End position is the start of the END token
                let body_end = if self.current > 0 {
                    self.tokens[self.current - 1].span.start
                } else {
                    body_start
                };
                source[body_start..body_end].trim().to_string()
            } else {
                // Fallback: no source available
                String::new()
            };
            TriggerBody::Block(block_content)
        } else {
            return Err(self.parse_error("Expected EXECUTE or BEGIN in trigger body"));
        };

        Ok(Expression::CreateTrigger(Box::new(CreateTrigger {
            name,
            table,
            timing,
            events,
            for_each,
            when,
            when_paren,
            body,
            or_replace,
            constraint,
            deferrable,
            initially_deferred,
            referencing,
        })))
    }

    /// Parse DROP TRIGGER statement
    fn parse_drop_trigger(&mut self) -> Result<Expression> {
        self.expect(TokenType::Trigger)?;

        let if_exists = self.match_keywords(&[TokenType::If, TokenType::Exists]);
        let name = Identifier::new(self.expect_identifier()?);

        let table = if self.match_token(TokenType::On) {
            Some(self.parse_table_ref()?)
        } else {
            None
        };

        let cascade = self.match_token(TokenType::Cascade);
        if !cascade {
            self.match_token(TokenType::Restrict);
        }

        Ok(Expression::DropTrigger(Box::new(DropTrigger {
            name,
            table,
            if_exists,
            cascade,
        })))
    }

    /// Parse CREATE TYPE statement
    fn parse_create_type(&mut self) -> Result<Expression> {
        self.expect(TokenType::Type)?;

        let if_not_exists =
            self.match_keywords(&[TokenType::If, TokenType::Not, TokenType::Exists]);
        let name = self.parse_table_ref()?;

        self.expect(TokenType::As)?;

        let definition = if self.match_token(TokenType::Enum) {
            // ENUM type
            self.expect(TokenType::LParen)?;
            let mut values = Vec::new();
            loop {
                let tok = self.expect(TokenType::String)?;
                values.push(tok.text.trim_matches('\'').to_string());
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            self.expect(TokenType::RParen)?;
            TypeDefinition::Enum(values)
        } else if self.match_token(TokenType::LParen) {
            // Composite type
            let mut attrs = Vec::new();
            loop {
                let attr_name = Identifier::new(self.expect_identifier()?);
                let data_type = self.parse_data_type()?;
                let collate = if self.match_identifier("COLLATE") {
                    Some(Identifier::new(self.expect_identifier()?))
                } else {
                    None
                };
                attrs.push(TypeAttribute {
                    name: attr_name,
                    data_type,
                    collate,
                });
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            self.expect(TokenType::RParen)?;
            TypeDefinition::Composite(attrs)
        } else if self.match_token(TokenType::Range) {
            // Range type
            self.expect(TokenType::LParen)?;
            self.match_identifier("SUBTYPE");
            self.match_token(TokenType::Eq);
            let subtype = self.parse_data_type()?;

            let mut subtype_diff = None;
            let mut canonical = None;

            while self.match_token(TokenType::Comma) {
                if self.match_identifier("SUBTYPE_DIFF") {
                    self.match_token(TokenType::Eq);
                    subtype_diff = Some(self.expect_identifier()?);
                } else if self.match_identifier("CANONICAL") {
                    self.match_token(TokenType::Eq);
                    canonical = Some(self.expect_identifier()?);
                }
            }
            self.expect(TokenType::RParen)?;

            TypeDefinition::Range {
                subtype,
                subtype_diff,
                canonical,
            }
        } else {
            return Err(
                self.parse_error("Expected ENUM, composite type definition, or RANGE after AS")
            );
        };

        Ok(Expression::CreateType(Box::new(CreateType {
            name,
            definition,
            if_not_exists,
        })))
    }

    /// Parse CREATE DOMAIN statement
    fn parse_create_domain(&mut self) -> Result<Expression> {
        self.expect(TokenType::Domain)?;

        let if_not_exists =
            self.match_keywords(&[TokenType::If, TokenType::Not, TokenType::Exists]);
        let name = self.parse_table_ref()?;

        self.expect(TokenType::As)?;
        let base_type = self.parse_data_type()?;

        let mut default = None;
        let mut constraints = Vec::new();

        // Parse domain options
        while !self.is_at_end() && !self.check(TokenType::Semicolon) {
            if self.match_token(TokenType::Default) {
                default = Some(self.parse_expression()?);
            } else if self.match_token(TokenType::Constraint) {
                let constr_name = Some(Identifier::new(self.expect_identifier()?));
                self.expect(TokenType::Check)?;
                self.expect(TokenType::LParen)?;
                let check_expr = self.parse_expression()?;
                self.expect(TokenType::RParen)?;
                constraints.push(DomainConstraint {
                    name: constr_name,
                    check: check_expr,
                });
            } else if self.match_token(TokenType::Check) {
                self.expect(TokenType::LParen)?;
                let check_expr = self.parse_expression()?;
                self.expect(TokenType::RParen)?;
                constraints.push(DomainConstraint {
                    name: None,
                    check: check_expr,
                });
            } else if self.match_keywords(&[TokenType::Not, TokenType::Null]) {
                // NOT NULL is a constraint - represented as VALUE IS NOT NULL
                constraints.push(DomainConstraint {
                    name: None,
                    check: Expression::IsNull(Box::new(IsNull {
                        this: Expression::Identifier(Identifier::new("VALUE")),
                        not: true,
                        postfix_form: false,
                    })),
                });
            } else {
                break;
            }
        }

        Ok(Expression::CreateType(Box::new(CreateType {
            name,
            definition: TypeDefinition::Domain {
                base_type,
                default,
                constraints,
            },
            if_not_exists,
        })))
    }

    /// Parse CREATE STAGE statement (Snowflake)
    fn parse_create_stage(&mut self, or_replace: bool, temporary: bool) -> Result<Expression> {
        self.advance(); // consume STAGE (identifier)
                        // Parse remaining tokens, normalizing FILE_FORMAT clause
        let start = self.current;
        while !self.is_at_end() && !self.check(TokenType::Semicolon) {
            self.advance();
        }
        let sql = self.tokens_to_sql_stage_format(start, self.current);

        // Build the CREATE prefix with modifiers
        let mut prefix = String::from("CREATE");
        if or_replace {
            prefix.push_str(" OR REPLACE");
        }
        if temporary {
            prefix.push_str(" TEMPORARY");
        }
        prefix.push_str(" STAGE");

        Ok(Expression::Raw(Raw {
            sql: format!("{} {}", prefix, sql),
        }))
    }

    /// Parse CREATE TAG statement (Snowflake)
    fn parse_create_tag(&mut self, or_replace: bool) -> Result<Expression> {
        self.advance(); // consume TAG
                        // Capture remaining tokens as raw SQL
        let start = self.current;
        while !self.is_at_end() && !self.check(TokenType::Semicolon) {
            self.advance();
        }
        let sql = self.tokens_to_sql(start, self.current);
        let prefix = if or_replace {
            "CREATE OR REPLACE TAG"
        } else {
            "CREATE TAG"
        };
        Ok(Expression::Raw(Raw {
            sql: format!("{} {}", prefix, sql),
        }))
    }

    /// Parse CREATE STREAM statement (Snowflake)
    fn parse_create_stream(&mut self, _or_replace: bool) -> Result<Expression> {
        self.advance(); // consume STREAM
                        // Capture remaining tokens as raw SQL
        let start = self.current;
        while !self.is_at_end() && !self.check(TokenType::Semicolon) {
            self.advance();
        }
        let sql = self.tokens_to_sql(start, self.current);
        Ok(Expression::Raw(Raw {
            sql: format!("CREATE STREAM {}", sql),
        }))
    }

    /// Parse CREATE FILE FORMAT statement (Snowflake)
    fn parse_create_file_format(
        &mut self,
        or_replace: bool,
        temporary: bool,
    ) -> Result<Expression> {
        self.advance(); // consume FILE
        self.advance(); // consume FORMAT
                        // Capture remaining tokens as raw SQL
        let start = self.current;
        while !self.is_at_end() && !self.check(TokenType::Semicolon) {
            self.advance();
        }
        let sql = self.tokens_to_sql(start, self.current);
        let mut prefix = String::from("CREATE");
        if or_replace {
            prefix.push_str(" OR REPLACE");
        }
        if temporary {
            prefix.push_str(" TEMPORARY");
        }
        prefix.push_str(" FILE FORMAT ");
        prefix.push_str(&sql);
        Ok(Expression::Raw(Raw { sql: prefix }))
    }

    /// Parse DROP TYPE statement
    fn parse_drop_type(&mut self) -> Result<Expression> {
        self.expect(TokenType::Type)?;

        let if_exists = self.match_keywords(&[TokenType::If, TokenType::Exists]);
        let name = self.parse_table_ref()?;

        let cascade = self.match_token(TokenType::Cascade);
        if !cascade {
            self.match_token(TokenType::Restrict);
        }

        Ok(Expression::DropType(Box::new(DropType {
            name,
            if_exists,
            cascade,
        })))
    }

    fn parse_alter_view_with_modifiers(
        &mut self,
        algorithm: Option<String>,
        definer: Option<String>,
        sql_security: Option<String>,
    ) -> Result<Expression> {
        self.expect(TokenType::View)?;

        let name = self.parse_table_ref()?;
        let mut actions = Vec::new();

        // Hive: Optional column aliases with optional COMMENT: (c1, c2) or (c1 COMMENT 'text', c2)
        // Only parse if we see LParen followed by identifier (not SELECT for subquery)
        let columns = if self.check(TokenType::LParen) {
            // Peek ahead to see if this looks like column aliases
            let saved = self.current;
            self.advance(); // consume LParen

            // Check if this is an identifier (column name) vs SELECT keyword
            let is_column_aliases = self.check(TokenType::Identifier)
                || self.check(TokenType::Var)
                || self.check(TokenType::QuotedIdentifier);

            if is_column_aliases {
                // Parse column aliases
                let mut cols = Vec::new();
                loop {
                    let col_name = self.expect_identifier()?;
                    // Optional COMMENT 'text'
                    let comment = if self.match_token(TokenType::Comment) {
                        Some(self.expect_string()?)
                    } else {
                        None
                    };
                    cols.push(ViewColumn {
                        name: Identifier::new(col_name),
                        comment,
                        options: Vec::new(),
                    });
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
                self.expect(TokenType::RParen)?;
                cols
            } else {
                self.current = saved; // retreat
                Vec::new()
            }
        } else {
            Vec::new()
        };

        // TSQL: WITH option (SCHEMABINDING, ENCRYPTION, VIEW_METADATA) before AS
        let with_option = if self.match_token(TokenType::With) {
            let opt = self.expect_identifier_or_keyword()?;
            Some(opt.to_uppercase())
        } else {
            None
        };

        // Parse actions
        if self.match_token(TokenType::Rename) {
            self.expect(TokenType::To)?;
            actions.push(AlterViewAction::Rename(self.parse_table_ref()?));
        } else if self.match_identifier("OWNER") {
            self.expect(TokenType::To)?;
            actions.push(AlterViewAction::OwnerTo(Identifier::new(
                self.expect_identifier()?,
            )));
        } else if self.match_token(TokenType::Set) {
            // Hive: SET TBLPROPERTIES ('key'='value', ...) or SET SCHEMA name
            // Trino: SET AUTHORIZATION [ROLE] user
            if self.match_identifier("TBLPROPERTIES") {
                let props = self.parse_tblproperties_key_value_list()?;
                actions.push(AlterViewAction::SetTblproperties(props));
            } else if self.match_token(TokenType::Authorization) {
                let mut auth_text = String::new();
                if self.match_texts(&["ROLE"]) {
                    auth_text.push_str("ROLE ");
                }
                let user = self.expect_identifier()?;
                auth_text.push_str(&user);
                actions.push(AlterViewAction::SetAuthorization(auth_text));
            } else {
                self.expect(TokenType::Schema)?;
                actions.push(AlterViewAction::SetSchema(Identifier::new(
                    self.expect_identifier()?,
                )));
            }
        } else if self.match_identifier("UNSET") {
            // Hive: UNSET TBLPROPERTIES ('key1', 'key2', ...)
            if !self.match_identifier("TBLPROPERTIES") {
                return Err(self.parse_error("Expected TBLPROPERTIES after UNSET"));
            }
            let keys = self.parse_tblproperties_key_list()?;
            actions.push(AlterViewAction::UnsetTblproperties(keys));
        } else if self.match_token(TokenType::Alter) {
            self.match_token(TokenType::Column);
            let col_name = Identifier::new(self.expect_identifier()?);
            let action = self.parse_alter_column_action()?;
            actions.push(AlterViewAction::AlterColumn {
                name: col_name,
                action,
            });
        } else if self.match_token(TokenType::As) {
            // AS SELECT ... or AS SELECT ... UNION ... (redefine view query)
            let query = self.parse_statement()?;
            actions.push(AlterViewAction::AsSelect(Box::new(query)));
        }

        Ok(Expression::AlterView(Box::new(AlterView {
            name,
            actions,
            algorithm,
            definer,
            sql_security,
            with_option,
            columns,
        })))
    }

    /// Parse TBLPROPERTIES key-value list: ('key1'='value1', 'key2'='value2', ...)
    fn parse_tblproperties_key_value_list(&mut self) -> Result<Vec<(String, String)>> {
        self.expect(TokenType::LParen)?;
        let mut props = Vec::new();
        loop {
            let key = self.expect_string()?;
            self.expect(TokenType::Eq)?;
            let value = self.expect_string()?;
            props.push((key, value));
            if !self.match_token(TokenType::Comma) {
                break;
            }
        }
        self.expect(TokenType::RParen)?;
        Ok(props)
    }

    /// Parse TBLPROPERTIES key list (for UNSET): ('key1', 'key2', ...)
    fn parse_tblproperties_key_list(&mut self) -> Result<Vec<String>> {
        self.expect(TokenType::LParen)?;
        let mut keys = Vec::new();
        loop {
            let key = self.expect_string()?;
            keys.push(key);
            if !self.match_token(TokenType::Comma) {
                break;
            }
        }
        self.expect(TokenType::RParen)?;
        Ok(keys)
    }

    /// Parse ALTER INDEX statement
    fn parse_alter_index(&mut self) -> Result<Expression> {
        self.expect(TokenType::Index)?;

        // Use expect_identifier_or_keyword_with_quoted to preserve quoted flag
        let name = self.expect_identifier_or_keyword_with_quoted()?;

        let table = if self.match_token(TokenType::On) {
            Some(self.parse_table_ref()?)
        } else {
            None
        };

        let mut actions = Vec::new();

        // Parse actions
        if self.match_token(TokenType::Rename) {
            self.expect(TokenType::To)?;
            // Also preserve quoted flag for the new name
            actions.push(AlterIndexAction::Rename(
                self.expect_identifier_or_keyword_with_quoted()?,
            ));
        } else if self.match_token(TokenType::Set) {
            self.match_identifier("TABLESPACE");
            actions.push(AlterIndexAction::SetTablespace(
                self.expect_identifier_or_keyword_with_quoted()?,
            ));
        } else if self.match_identifier("VISIBLE") {
            actions.push(AlterIndexAction::Visible(true));
        } else if self.match_identifier("INVISIBLE") {
            actions.push(AlterIndexAction::Visible(false));
        }

        Ok(Expression::AlterIndex(Box::new(AlterIndex {
            name,
            table,
            actions,
        })))
    }

    // ==================== End DDL Parsing ====================

    /// Parse an expression (with precedence)
    /// Assignment (:=) has lower precedence than OR, matching Python sqlglot's
    /// _parse_expression -> _parse_assignment -> _parse_disjunction chain
    fn parse_expression(&mut self) -> Result<Expression> {
        let mut left = self.parse_or()?;

        // Handle := assignment operator (MySQL @var := val, DuckDB named args/settings)
        // This has lower precedence than OR
        while self.match_token(TokenType::ColonEq) {
            let right = self.parse_or()?;
            left = Expression::PropertyEQ(Box::new(BinaryOp::new(left, right)));
        }

        // ClickHouse ternary operator: condition ? true_value : false_value
        // Parsed as: CASE WHEN condition THEN true_value ELSE false_value END
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) && self.match_token(TokenType::Parameter)
        {
            if self.check(TokenType::Colon) {
                return Err(
                    self.parse_error("Expected true expression after ? in ClickHouse ternary")
                );
            }
            let true_value = self.parse_or()?;
            let false_value = if self.match_token(TokenType::Colon) {
                self.parse_or()?
            } else {
                Expression::Null(Null)
            };
            left = Expression::IfFunc(Box::new(IfFunc {
                original_name: None,
                condition: left,
                true_value,
                false_value: Some(false_value),
                inferred_type: None,
            }));
        }

        // ClickHouse: APPLY(func) column transformer
        // e.g., COLUMNS('pattern') APPLY(toString) APPLY(length)
        // Also: APPLY func (no parens), APPLY(x -> expr) (lambda)
        // Only match APPLY when followed by ( — bare APPLY without ( is treated as an alias
        // by the select expression parser (e.g., SELECT col apply -> SELECT col AS apply)
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) {
            while self.check(TokenType::Apply) && self.check_next(TokenType::LParen) {
                self.advance(); // consume APPLY
                self.advance(); // consume (
                let expr = self.parse_expression()?;
                self.expect(TokenType::RParen)?;
                left = Expression::Apply(Box::new(crate::expressions::Apply {
                    this: Box::new(left),
                    expression: Box::new(expr),
                }));
            }
        }

        Ok(left)
    }

    /// Parse OR expressions
    fn parse_or(&mut self) -> Result<Expression> {
        let mut left = self.parse_xor()?;

        while self.check(TokenType::Or)
            || (self.dpipe_is_logical_or() && self.check(TokenType::DPipe))
        {
            let mut all_comments = self.previous_trailing_comments();
            // Also capture leading comments on the OR token (comments on a separate line before OR)
            all_comments.extend(self.current_leading_comments());
            self.advance(); // consume OR
            all_comments.extend(self.previous_trailing_comments());
            // Clear trailing_comments from left expression to avoid duplication
            if !all_comments.is_empty() {
                Self::clear_rightmost_trailing_comments(&mut left);
            }
            // Filter out empty/whitespace-only comments
            all_comments.retain(|c| !c.trim().is_empty());
            // Split: block comments go before operator, line comments go after
            let mut left_comments = Vec::new();
            let mut operator_comments = Vec::new();
            for comment in all_comments {
                if comment.starts_with("/*") {
                    left_comments.push(comment);
                } else {
                    operator_comments.push(comment);
                }
            }
            let mut right = self.parse_xor()?;
            // If parse_comparison stored pending leading comments, attach them
            if !self.pending_leading_comments.is_empty() {
                let pending = self.pending_leading_comments.drain(..).collect::<Vec<_>>();
                right = Expression::Annotated(Box::new(Annotated {
                    this: right,
                    trailing_comments: pending,
                }));
            }
            left = Expression::Or(Box::new(BinaryOp {
                left,
                right,
                left_comments,
                operator_comments,
                trailing_comments: Vec::new(),
                inferred_type: None,
            }));
        }

        Ok(Self::maybe_rebalance_boolean_chain(left, false))
    }

    /// Whether `||` should be parsed as logical OR for the active dialect.
    fn dpipe_is_logical_or(&self) -> bool {
        matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::MySQL | crate::dialects::DialectType::Solr)
        )
    }

    /// Parse XOR expressions (MySQL logical XOR)
    fn parse_xor(&mut self) -> Result<Expression> {
        let mut left = self.parse_and()?;

        while self.match_token(TokenType::Xor) {
            let right = self.parse_and()?;
            left = Expression::Xor(Box::new(Xor {
                this: Some(Box::new(left)),
                expression: Some(Box::new(right)),
                expressions: Vec::new(),
            }));
        }

        Ok(left)
    }

    /// Parse AND expressions
    fn parse_and(&mut self) -> Result<Expression> {
        let mut left = self.parse_not()?;

        while self.check(TokenType::And) {
            // Capture comments from the token before AND (left operand's last token)
            let mut all_comments = self.previous_trailing_comments();
            // Also capture leading comments on the AND token (comments on a separate line before AND)
            all_comments.extend(self.current_leading_comments());
            self.advance(); // consume AND
                            // Also capture any trailing comments on the AND token itself
            all_comments.extend(self.previous_trailing_comments());
            // Clear trailing_comments from left expression to avoid duplication
            if !all_comments.is_empty() {
                Self::clear_rightmost_trailing_comments(&mut left);
            }
            // Filter out empty/whitespace-only comments (e.g., bare "--" with no content)
            all_comments.retain(|c| !c.trim().is_empty());
            // Split comments: block comments (/*...*/) go BEFORE the operator (left_comments),
            // line comments (raw text from --) go AFTER the operator (operator_comments).
            // This matches Python sqlglot's behavior where inline block comments stay
            // in-place and line comments shift to after the operator.
            let mut left_comments = Vec::new();
            let mut operator_comments = Vec::new();
            for comment in all_comments {
                if comment.starts_with("/*") {
                    left_comments.push(comment);
                } else {
                    operator_comments.push(comment);
                }
            }
            let mut right = self.parse_not()?;
            // If parse_comparison stored pending leading comments (comments before
            // the right operand's first token with no comparison following),
            // attach them as trailing_comments on the right expression.
            if !self.pending_leading_comments.is_empty() {
                let pending = self.pending_leading_comments.drain(..).collect::<Vec<_>>();
                right = Expression::Annotated(Box::new(Annotated {
                    this: right,
                    trailing_comments: pending,
                }));
            }
            left = Expression::And(Box::new(BinaryOp {
                left,
                right,
                left_comments,
                operator_comments,
                trailing_comments: Vec::new(),
                inferred_type: None,
            }));
        }

        Ok(Self::maybe_rebalance_boolean_chain(left, true))
    }

    /// Rebalance AND/OR chains into a balanced tree when no connector comments are present.
    /// This keeps connector chain depth logarithmic for very large predicates.
    fn maybe_rebalance_boolean_chain(expr: Expression, is_and: bool) -> Expression {
        if !Self::should_rebalance_boolean_chain(&expr, is_and) {
            return expr;
        }

        let terms = Self::flatten_boolean_terms_owned(expr, is_and);
        if terms.len() <= 2 {
            return Self::build_balanced_boolean_tree(terms, is_and);
        }

        Self::build_balanced_boolean_tree(terms, is_and)
    }

    fn should_rebalance_boolean_chain(expr: &Expression, is_and: bool) -> bool {
        let mut leaf_count = 0usize;
        let mut stack = vec![expr];

        while let Some(node) = stack.pop() {
            match (is_and, node) {
                (true, Expression::And(op)) => {
                    if !op.left_comments.is_empty()
                        || !op.operator_comments.is_empty()
                        || !op.trailing_comments.is_empty()
                    {
                        return false;
                    }
                    stack.push(&op.right);
                    stack.push(&op.left);
                }
                (false, Expression::Or(op)) => {
                    if !op.left_comments.is_empty()
                        || !op.operator_comments.is_empty()
                        || !op.trailing_comments.is_empty()
                    {
                        return false;
                    }
                    stack.push(&op.right);
                    stack.push(&op.left);
                }
                _ => leaf_count += 1,
            }
        }

        leaf_count > 2
    }

    fn flatten_boolean_terms_owned(expr: Expression, is_and: bool) -> Vec<Expression> {
        let mut terms = Vec::new();
        let mut stack = vec![expr];

        while let Some(node) = stack.pop() {
            match (is_and, node) {
                (true, Expression::And(op)) => {
                    stack.push(op.right);
                    stack.push(op.left);
                }
                (false, Expression::Or(op)) => {
                    stack.push(op.right);
                    stack.push(op.left);
                }
                (_, other) => terms.push(other),
            }
        }

        terms
    }

    fn build_balanced_boolean_tree(mut terms: Vec<Expression>, is_and: bool) -> Expression {
        if terms.is_empty() {
            return Expression::Null(Null);
        }

        while terms.len() > 1 {
            let mut next = Vec::with_capacity((terms.len() + 1) / 2);
            let mut iter = terms.into_iter();

            while let Some(left) = iter.next() {
                if let Some(right) = iter.next() {
                    let combined = if is_and {
                        Expression::And(Box::new(BinaryOp::new(left, right)))
                    } else {
                        Expression::Or(Box::new(BinaryOp::new(left, right)))
                    };
                    next.push(combined);
                } else {
                    next.push(left);
                }
            }

            terms = next;
        }

        terms.pop().unwrap_or(Expression::Null(Null))
    }

    /// Parse NOT expressions
    fn parse_not(&mut self) -> Result<Expression> {
        if self.match_token(TokenType::Not) {
            let expr = self.parse_not()?;
            Ok(Expression::Not(Box::new(UnaryOp::new(expr))))
        } else {
            self.parse_comparison()
        }
    }

    /// Parse comparison expressions
    fn parse_comparison(&mut self) -> Result<Expression> {
        // Capture leading comments from the first token before parsing the left side.
        // If a comparison operator follows, these are placed after the left operand.
        let pre_left_comments = self.current_leading_comments();
        let mut left = self.parse_bitwise_or()?;

        // Only attach pre-left comments when a comparison operator follows.
        // When no comparison follows (e.g., in SELECT list expressions or AND operands),
        // the comments are returned to the caller by being accessible via the
        // `comparison_pre_left_comments` field, so they can be placed appropriately
        // (e.g., after an alias name, or after the expression in an AND chain).
        let has_comparison_op = self.check(TokenType::Eq)
            || self.check(TokenType::Neq)
            || self.check(TokenType::Lt)
            || self.check(TokenType::Gt)
            || self.check(TokenType::Lte)
            || self.check(TokenType::Gte)
            || self.check(TokenType::Is)
            || self.check(TokenType::In)
            || self.check(TokenType::Not)
            || self.check(TokenType::Between)
            || self.check(TokenType::Like)
            || self.check(TokenType::ILike)
            || self.check(TokenType::RLike)
            || self.check(TokenType::SimilarTo);

        if !pre_left_comments.is_empty() {
            if has_comparison_op {
                // Comparison follows: attach comments between left operand and operator
                match &mut left {
                    Expression::Column(col) => {
                        col.trailing_comments.extend(pre_left_comments);
                    }
                    Expression::Identifier(id) => {
                        id.trailing_comments.extend(pre_left_comments);
                    }
                    _ => {
                        left = Expression::Annotated(Box::new(Annotated {
                            this: left,
                            trailing_comments: pre_left_comments,
                        }));
                    }
                }
            } else {
                // No comparison operator: store comments for the caller to use.
                // Save them as "pending" comments that the caller can retrieve.
                self.pending_leading_comments = pre_left_comments;
            }
        }

        loop {
            let mut global_in = false;
            if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && self.check_identifier("GLOBAL")
                && (self.check_next(TokenType::Not) || self.check_next(TokenType::In))
            {
                self.advance();
                global_in = true;
            }

            let expr = if self.match_token(TokenType::Eq) {
                // Check for ANY/ALL subquery
                if self.match_token(TokenType::Any) || self.match_token(TokenType::Some) {
                    let was_any = self.previous_token_type() == Some(TokenType::Any);
                    self.expect(TokenType::LParen)?;
                    let inner = self.parse_statement()?;
                    self.expect(TokenType::RParen)?;
                    let subquery = if was_any {
                        self.maybe_wrap_in_subquery(inner)
                    } else {
                        inner
                    };
                    Expression::Any(Box::new(QuantifiedExpr {
                        this: left,
                        subquery,
                        op: Some(QuantifiedOp::Eq),
                    }))
                } else if self.match_token(TokenType::All) {
                    self.expect(TokenType::LParen)?;
                    let inner = self.parse_statement()?;
                    self.expect(TokenType::RParen)?;
                    let subquery = self.maybe_wrap_in_subquery(inner);
                    Expression::All(Box::new(QuantifiedExpr {
                        this: left,
                        subquery,
                        op: Some(QuantifiedOp::Eq),
                    }))
                } else {
                    let right = self.parse_bitwise_or()?;
                    let trailing_comments = self.previous_trailing_comments();
                    Expression::Eq(Box::new(BinaryOp {
                        left,
                        right,
                        left_comments: Vec::new(),
                        operator_comments: Vec::new(),
                        trailing_comments,
                        inferred_type: None,
                    }))
                }
            } else if self.match_token(TokenType::Neq) {
                // Check for ANY/ALL subquery
                if self.match_token(TokenType::Any) || self.match_token(TokenType::Some) {
                    let was_any = self.previous_token_type() == Some(TokenType::Any);
                    self.expect(TokenType::LParen)?;
                    let inner = self.parse_statement()?;
                    self.expect(TokenType::RParen)?;
                    let subquery = if was_any {
                        self.maybe_wrap_in_subquery(inner)
                    } else {
                        inner
                    };
                    Expression::Any(Box::new(QuantifiedExpr {
                        this: left,
                        subquery,
                        op: Some(QuantifiedOp::Neq),
                    }))
                } else if self.match_token(TokenType::All) {
                    self.expect(TokenType::LParen)?;
                    let inner = self.parse_statement()?;
                    self.expect(TokenType::RParen)?;
                    let subquery = self.maybe_wrap_in_subquery(inner);
                    Expression::All(Box::new(QuantifiedExpr {
                        this: left,
                        subquery,
                        op: Some(QuantifiedOp::Neq),
                    }))
                } else {
                    let right = self.parse_bitwise_or()?;
                    let trailing_comments = self.previous_trailing_comments();
                    Expression::Neq(Box::new(BinaryOp {
                        left,
                        right,
                        left_comments: Vec::new(),
                        operator_comments: Vec::new(),
                        trailing_comments,
                        inferred_type: None,
                    }))
                }
            } else if self.match_token(TokenType::Lt) {
                // Check for ANY/ALL subquery
                if self.match_token(TokenType::Any) || self.match_token(TokenType::Some) {
                    let was_any = self.previous_token_type() == Some(TokenType::Any);
                    self.expect(TokenType::LParen)?;
                    let inner = self.parse_statement()?;
                    self.expect(TokenType::RParen)?;
                    let subquery = if was_any {
                        self.maybe_wrap_in_subquery(inner)
                    } else {
                        inner
                    };
                    Expression::Any(Box::new(QuantifiedExpr {
                        this: left,
                        subquery,
                        op: Some(QuantifiedOp::Lt),
                    }))
                } else if self.match_token(TokenType::All) {
                    self.expect(TokenType::LParen)?;
                    let inner = self.parse_statement()?;
                    self.expect(TokenType::RParen)?;
                    let subquery = self.maybe_wrap_in_subquery(inner);
                    Expression::All(Box::new(QuantifiedExpr {
                        this: left,
                        subquery,
                        op: Some(QuantifiedOp::Lt),
                    }))
                } else {
                    let right = self.parse_bitwise_or()?;
                    let trailing_comments = self.previous_trailing_comments();
                    Expression::Lt(Box::new(BinaryOp {
                        left,
                        right,
                        left_comments: Vec::new(),
                        operator_comments: Vec::new(),
                        trailing_comments,
                        inferred_type: None,
                    }))
                }
            } else if self.match_token(TokenType::Lte) {
                // Check for ANY/ALL subquery
                if self.match_token(TokenType::Any) || self.match_token(TokenType::Some) {
                    let was_any = self.previous_token_type() == Some(TokenType::Any);
                    self.expect(TokenType::LParen)?;
                    let inner = self.parse_statement()?;
                    self.expect(TokenType::RParen)?;
                    let subquery = if was_any {
                        self.maybe_wrap_in_subquery(inner)
                    } else {
                        inner
                    };
                    Expression::Any(Box::new(QuantifiedExpr {
                        this: left,
                        subquery,
                        op: Some(QuantifiedOp::Lte),
                    }))
                } else if self.match_token(TokenType::All) {
                    self.expect(TokenType::LParen)?;
                    let inner = self.parse_statement()?;
                    self.expect(TokenType::RParen)?;
                    let subquery = self.maybe_wrap_in_subquery(inner);
                    Expression::All(Box::new(QuantifiedExpr {
                        this: left,
                        subquery,
                        op: Some(QuantifiedOp::Lte),
                    }))
                } else {
                    let right = self.parse_bitwise_or()?;
                    let trailing_comments = self.previous_trailing_comments();
                    Expression::Lte(Box::new(BinaryOp {
                        left,
                        right,
                        left_comments: Vec::new(),
                        operator_comments: Vec::new(),
                        trailing_comments,
                        inferred_type: None,
                    }))
                }
            } else if self.match_token(TokenType::Gt) {
                // Check for ANY/ALL subquery
                if self.match_token(TokenType::Any) || self.match_token(TokenType::Some) {
                    let was_any = self.previous_token_type() == Some(TokenType::Any);
                    self.expect(TokenType::LParen)?;
                    let inner = self.parse_statement()?;
                    self.expect(TokenType::RParen)?;
                    let subquery = if was_any {
                        self.maybe_wrap_in_subquery(inner)
                    } else {
                        inner
                    };
                    Expression::Any(Box::new(QuantifiedExpr {
                        this: left,
                        subquery,
                        op: Some(QuantifiedOp::Gt),
                    }))
                } else if self.match_token(TokenType::All) {
                    self.expect(TokenType::LParen)?;
                    let inner = self.parse_statement()?;
                    self.expect(TokenType::RParen)?;
                    let subquery = self.maybe_wrap_in_subquery(inner);
                    Expression::All(Box::new(QuantifiedExpr {
                        this: left,
                        subquery,
                        op: Some(QuantifiedOp::Gt),
                    }))
                } else {
                    let right = self.parse_bitwise_or()?;
                    let trailing_comments = self.previous_trailing_comments();
                    Expression::Gt(Box::new(BinaryOp {
                        left,
                        right,
                        left_comments: Vec::new(),
                        operator_comments: Vec::new(),
                        trailing_comments,
                        inferred_type: None,
                    }))
                }
            } else if self.match_token(TokenType::Gte) {
                // Check for ANY/ALL subquery
                if self.match_token(TokenType::Any) || self.match_token(TokenType::Some) {
                    let was_any = self.previous_token_type() == Some(TokenType::Any);
                    self.expect(TokenType::LParen)?;
                    let inner = self.parse_statement()?;
                    self.expect(TokenType::RParen)?;
                    let subquery = if was_any {
                        self.maybe_wrap_in_subquery(inner)
                    } else {
                        inner
                    };
                    Expression::Any(Box::new(QuantifiedExpr {
                        this: left,
                        subquery,
                        op: Some(QuantifiedOp::Gte),
                    }))
                } else if self.match_token(TokenType::All) {
                    self.expect(TokenType::LParen)?;
                    let inner = self.parse_statement()?;
                    self.expect(TokenType::RParen)?;
                    let subquery = self.maybe_wrap_in_subquery(inner);
                    Expression::All(Box::new(QuantifiedExpr {
                        this: left,
                        subquery,
                        op: Some(QuantifiedOp::Gte),
                    }))
                } else {
                    let right = self.parse_bitwise_or()?;
                    let trailing_comments = self.previous_trailing_comments();
                    Expression::Gte(Box::new(BinaryOp {
                        left,
                        right,
                        left_comments: Vec::new(),
                        operator_comments: Vec::new(),
                        trailing_comments,
                        inferred_type: None,
                    }))
                }
            } else if self.match_token(TokenType::NullsafeEq) {
                // <=> (MySQL NULL-safe equality)
                let right = self.parse_bitwise_or()?;
                let trailing_comments = self.previous_trailing_comments();
                Expression::NullSafeEq(Box::new(BinaryOp {
                    left,
                    right,
                    left_comments: Vec::new(),
                    operator_comments: Vec::new(),
                    trailing_comments,
                    inferred_type: None,
                }))
            } else if self.check_identifier("SOUNDS") && self.check_next(TokenType::Like) {
                // MySQL SOUNDS LIKE: expr SOUNDS LIKE expr -> SOUNDEX(expr) = SOUNDEX(expr)
                self.advance(); // consume SOUNDS
                self.advance(); // consume LIKE
                let right = self.parse_bitwise_or()?;
                // Transform: SOUNDEX(left) = SOUNDEX(right)
                let soundex_left = Expression::Function(Box::new(Function::new(
                    "SOUNDEX".to_string(),
                    vec![left],
                )));
                let soundex_right = Expression::Function(Box::new(Function::new(
                    "SOUNDEX".to_string(),
                    vec![right],
                )));
                Expression::Eq(Box::new(BinaryOp::new(soundex_left, soundex_right)))
            } else if self.match_token(TokenType::Like) {
                // Check for ANY/ALL/SOME quantifier
                let quantifier = if self.match_token(TokenType::Any) {
                    Some("ANY".to_string())
                } else if self.match_token(TokenType::All) {
                    Some("ALL".to_string())
                } else if self.match_token(TokenType::Some) {
                    Some("SOME".to_string())
                } else {
                    None
                };
                let right = self.parse_bitwise_or()?;
                let escape = if self.match_token(TokenType::Escape) {
                    Some(self.parse_primary()?)
                } else {
                    None
                };
                Expression::Like(Box::new(LikeOp {
                    left,
                    right,
                    escape,
                    quantifier,
                    inferred_type: None,
                }))
            } else if self.match_token(TokenType::ILike) {
                // Check for ANY/ALL/SOME quantifier
                let quantifier = if self.match_token(TokenType::Any) {
                    Some("ANY".to_string())
                } else if self.match_token(TokenType::All) {
                    Some("ALL".to_string())
                } else if self.match_token(TokenType::Some) {
                    Some("SOME".to_string())
                } else {
                    None
                };
                let right = self.parse_bitwise_or()?;
                let escape = if self.match_token(TokenType::Escape) {
                    Some(self.parse_primary()?)
                } else {
                    None
                };
                Expression::ILike(Box::new(LikeOp {
                    left,
                    right,
                    escape,
                    quantifier,
                    inferred_type: None,
                }))
            } else if self.check_identifier("SIMILAR") && self.check_next(TokenType::To) {
                // SIMILAR TO operator (PostgreSQL/Redshift regex-like pattern matching)
                self.advance(); // consume SIMILAR
                self.advance(); // consume TO
                let pattern = self.parse_bitwise_or()?;
                let escape = if self.match_token(TokenType::Escape) {
                    Some(self.parse_primary()?)
                } else {
                    None
                };
                Expression::SimilarTo(Box::new(SimilarToExpr {
                    this: left,
                    pattern,
                    escape,
                    not: false,
                }))
            } else if self.match_token(TokenType::Glob) {
                let right = self.parse_bitwise_or()?;
                Expression::Glob(Box::new(BinaryOp::new(left, right)))
            } else if self.match_token(TokenType::Match) {
                // SQLite MATCH operator (FTS full-text search)
                let right = self.parse_bitwise_or()?;
                Expression::Match(Box::new(BinaryOp::new(left, right)))
            } else if self.match_token(TokenType::RLike) || self.match_token(TokenType::Tilde) {
                // PostgreSQL ~ (regexp match) operator
                let right = self.parse_bitwise_or()?;
                Expression::RegexpLike(Box::new(RegexpFunc {
                    this: left,
                    pattern: right,
                    flags: None,
                }))
            } else if self.match_token(TokenType::IRLike) {
                // PostgreSQL ~* (case-insensitive regexp match) operator
                let right = self.parse_bitwise_or()?;
                Expression::RegexpILike(Box::new(RegexpILike {
                    this: Box::new(left),
                    expression: Box::new(right),
                    flag: None,
                }))
            } else if self.match_token(TokenType::NotLike) {
                // PostgreSQL !~~ (NOT LIKE) operator
                let right = self.parse_bitwise_or()?;
                let escape = if self.match_token(TokenType::Escape) {
                    Some(self.parse_primary()?)
                } else {
                    None
                };
                let like_expr = Expression::Like(Box::new(LikeOp {
                    left,
                    right,
                    escape,
                    quantifier: None,
                    inferred_type: None,
                }));
                Expression::Not(Box::new(UnaryOp::new(like_expr)))
            } else if self.match_token(TokenType::NotILike) {
                // PostgreSQL !~~* (NOT ILIKE) operator
                let right = self.parse_bitwise_or()?;
                let escape = if self.match_token(TokenType::Escape) {
                    Some(self.parse_primary()?)
                } else {
                    None
                };
                let ilike_expr = Expression::ILike(Box::new(LikeOp {
                    left,
                    right,
                    escape,
                    quantifier: None,
                    inferred_type: None,
                }));
                Expression::Not(Box::new(UnaryOp::new(ilike_expr)))
            } else if self.match_token(TokenType::NotRLike) {
                // PostgreSQL !~ (NOT regexp match) operator
                let right = self.parse_bitwise_or()?;
                let regexp_expr = Expression::RegexpLike(Box::new(RegexpFunc {
                    this: left,
                    pattern: right,
                    flags: None,
                }));
                Expression::Not(Box::new(UnaryOp::new(regexp_expr)))
            } else if self.match_token(TokenType::NotIRLike) {
                // PostgreSQL !~* (NOT case-insensitive regexp match) operator
                let right = self.parse_bitwise_or()?;
                let regexp_expr = Expression::RegexpILike(Box::new(RegexpILike {
                    this: Box::new(left),
                    expression: Box::new(right),
                    flag: None,
                }));
                Expression::Not(Box::new(UnaryOp::new(regexp_expr)))
            } else if self.check(TokenType::Is)
                && !self.is_last_expression_token(TokenType::Is)
                && self.match_token(TokenType::Is)
            {
                let not = self.match_token(TokenType::Not);
                if self.match_token(TokenType::Null) {
                    let expr = Expression::IsNull(Box::new(IsNull {
                        this: left,
                        not,
                        postfix_form: false,
                    }));
                    // ClickHouse: IS NULL :: Type — handle :: cast after IS NULL
                    if matches!(
                        self.config.dialect,
                        Some(crate::dialects::DialectType::ClickHouse)
                    ) && self.check(TokenType::DColon)
                    {
                        self.advance(); // consume ::
                        let data_type = self.parse_data_type_for_cast()?;
                        Expression::Cast(Box::new(Cast {
                            this: expr,
                            to: data_type,
                            trailing_comments: Vec::new(),
                            double_colon_syntax: true,
                            format: None,
                            default: None,
                            inferred_type: None,
                        }))
                    } else {
                        expr
                    }
                } else if self.match_token(TokenType::True) {
                    // IS TRUE / IS NOT TRUE
                    Expression::IsTrue(Box::new(IsTrueFalse { this: left, not }))
                } else if self.match_token(TokenType::False) {
                    // IS FALSE / IS NOT FALSE
                    Expression::IsFalse(Box::new(IsTrueFalse { this: left, not }))
                } else if self.match_token(TokenType::Distinct) {
                    // IS DISTINCT FROM / IS NOT DISTINCT FROM
                    self.expect(TokenType::From)?;
                    let right = self.parse_bitwise_or()?;
                    if not {
                        // IS NOT DISTINCT FROM → null-safe equality
                        Expression::NullSafeEq(Box::new(BinaryOp::new(left, right)))
                    } else {
                        // IS DISTINCT FROM → null-safe inequality
                        Expression::NullSafeNeq(Box::new(BinaryOp::new(left, right)))
                    }
                } else if self.match_identifier("UNKNOWN") {
                    // IS UNKNOWN
                    Expression::IsNull(Box::new(IsNull {
                        this: left,
                        not,
                        postfix_form: false,
                    }))
                } else if self.match_texts(&["JSON"]) {
                    // IS JSON [VALUE|SCALAR|OBJECT|ARRAY] [WITH UNIQUE KEYS|WITHOUT UNIQUE KEYS|UNIQUE KEYS]
                    let json_type = if self.match_texts(&["VALUE"]) {
                        Some("VALUE".to_string())
                    } else if self.match_texts(&["SCALAR"]) {
                        Some("SCALAR".to_string())
                    } else if self.match_texts(&["OBJECT"]) {
                        Some("OBJECT".to_string())
                    } else if self.match_texts(&["ARRAY"]) {
                        Some("ARRAY".to_string())
                    } else {
                        None
                    };

                    // Parse optional key uniqueness constraint
                    let unique_keys = if self.match_text_seq(&["WITH", "UNIQUE", "KEYS"]) {
                        Some(JsonUniqueKeys::With)
                    } else if self.match_text_seq(&["WITHOUT", "UNIQUE", "KEYS"]) {
                        Some(JsonUniqueKeys::Without)
                    } else if self.match_text_seq(&["UNIQUE", "KEYS"]) {
                        // Shorthand for WITH UNIQUE KEYS
                        Some(JsonUniqueKeys::Shorthand)
                    } else {
                        None
                    };

                    Expression::IsJson(Box::new(IsJson {
                        this: left,
                        json_type,
                        unique_keys,
                        negated: not,
                    }))
                } else {
                    // IS followed by an expression (e.g., IS ?)
                    // If we matched NOT, wrap the IS expression in NOT
                    let right = self.parse_primary()?;
                    let is_expr = Expression::Is(Box::new(BinaryOp::new(left, right)));
                    if not {
                        Expression::Not(Box::new(UnaryOp::new(is_expr)))
                    } else {
                        is_expr
                    }
                }
            } else if self.match_token(TokenType::Not) {
                // Handle NOT IN, NOT BETWEEN, NOT LIKE, NOT ILIKE, etc.
                if self.match_token(TokenType::In) {
                    // BigQuery: NOT IN UNNEST(expr)
                    if self.check_identifier("UNNEST") {
                        self.advance(); // consume UNNEST
                        self.expect(TokenType::LParen)?;
                        let unnest_expr = self.parse_expression()?;
                        self.expect(TokenType::RParen)?;
                        Expression::In(Box::new(In {
                            this: left,
                            expressions: Vec::new(),
                            query: None,
                            not: true,
                            global: global_in,
                            unnest: Some(Box::new(unnest_expr)),
                            is_field: false,
                        }))
                    } else if self.match_token(TokenType::LParen) {
                        if self.check(TokenType::Select) || self.check(TokenType::With) {
                            let subquery = self.parse_statement()?;
                            self.expect(TokenType::RParen)?;
                            Expression::In(Box::new(In {
                                this: left,
                                expressions: Vec::new(),
                                query: Some(subquery),
                                not: true,
                                global: global_in,
                                unnest: None,
                                is_field: false,
                            }))
                        } else if self.check(TokenType::RParen) {
                            // Empty NOT IN set: NOT IN ()
                            self.advance();
                            Expression::In(Box::new(In {
                                this: left,
                                expressions: Vec::new(),
                                query: None,
                                not: true,
                                global: global_in,
                                unnest: None,
                                is_field: false,
                            }))
                        } else {
                            let expressions = self.parse_expression_list()?;
                            self.expect(TokenType::RParen)?;
                            Expression::In(Box::new(In {
                                this: left,
                                expressions,
                                query: None,
                                not: true,
                                global: global_in,
                                unnest: None,
                                is_field: false,
                            }))
                        }
                    } else {
                        // ClickHouse/DuckDB: IN without parentheses: expr NOT IN table_name
                        let table_expr = self.parse_primary()?;
                        Expression::In(Box::new(In {
                            this: left,
                            expressions: vec![table_expr],
                            query: None,
                            not: true,
                            global: global_in,
                            unnest: None,
                            is_field: true,
                        }))
                    }
                } else if self.match_token(TokenType::Between) {
                    // Check for SYMMETRIC/ASYMMETRIC qualifier
                    let symmetric = if self.match_texts(&["SYMMETRIC"]) {
                        Some(true)
                    } else if self.match_texts(&["ASYMMETRIC"]) {
                        Some(false)
                    } else {
                        None
                    };
                    let low = self.parse_bitwise_or()?;
                    self.expect(TokenType::And)?;
                    let high = self.parse_bitwise_or()?;
                    Expression::Between(Box::new(Between {
                        this: left,
                        low,
                        high,
                        not: true,
                        symmetric,
                    }))
                } else if self.check_identifier("SOUNDS") && self.check_next(TokenType::Like) {
                    // MySQL NOT SOUNDS LIKE: expr NOT SOUNDS LIKE expr -> NOT SOUNDEX(expr) = SOUNDEX(expr)
                    self.advance(); // consume SOUNDS
                    self.advance(); // consume LIKE
                    let right = self.parse_bitwise_or()?;
                    let soundex_left = Expression::Function(Box::new(Function::new(
                        "SOUNDEX".to_string(),
                        vec![left],
                    )));
                    let soundex_right = Expression::Function(Box::new(Function::new(
                        "SOUNDEX".to_string(),
                        vec![right],
                    )));
                    let eq_expr =
                        Expression::Eq(Box::new(BinaryOp::new(soundex_left, soundex_right)));
                    Expression::Not(Box::new(UnaryOp::new(eq_expr)))
                } else if self.match_token(TokenType::Like) {
                    let right = self.parse_bitwise_or()?;
                    let escape = if self.match_token(TokenType::Escape) {
                        Some(self.parse_primary()?)
                    } else {
                        None
                    };
                    let like_expr = Expression::Like(Box::new(LikeOp {
                        left,
                        right,
                        escape,
                        quantifier: None,
                        inferred_type: None,
                    }));
                    Expression::Not(Box::new(UnaryOp::new(like_expr)))
                } else if self.match_token(TokenType::ILike) {
                    let right = self.parse_bitwise_or()?;
                    let escape = if self.match_token(TokenType::Escape) {
                        Some(self.parse_primary()?)
                    } else {
                        None
                    };
                    let ilike_expr = Expression::ILike(Box::new(LikeOp {
                        left,
                        right,
                        escape,
                        quantifier: None,
                        inferred_type: None,
                    }));
                    Expression::Not(Box::new(UnaryOp::new(ilike_expr)))
                } else if self.check_identifier("SIMILAR") && self.check_next(TokenType::To) {
                    // NOT SIMILAR TO
                    self.advance(); // consume SIMILAR
                    self.advance(); // consume TO
                    let pattern = self.parse_bitwise_or()?;
                    let escape = if self.match_token(TokenType::Escape) {
                        Some(self.parse_primary()?)
                    } else {
                        None
                    };
                    Expression::SimilarTo(Box::new(SimilarToExpr {
                        this: left,
                        pattern,
                        escape,
                        not: true,
                    }))
                } else if self.match_token(TokenType::RLike) {
                    let right = self.parse_bitwise_or()?;
                    let regexp_expr = Expression::RegexpLike(Box::new(RegexpFunc {
                        this: left,
                        pattern: right,
                        flags: None,
                    }));
                    Expression::Not(Box::new(UnaryOp::new(regexp_expr)))
                } else if self.match_token(TokenType::Null) {
                    // SQLite: a NOT NULL (postfix form, two separate tokens)
                    // Creates NOT(a IS NULL) which is semantically equivalent
                    let is_null =
                        Expression::Is(Box::new(BinaryOp::new(left, Expression::Null(Null))));
                    Expression::Not(Box::new(UnaryOp::new(is_null)))
                } else {
                    // NOT followed by something else - revert
                    return Ok(left);
                }
            } else if self.match_token(TokenType::In) {
                // BigQuery: IN UNNEST(expr)
                if self.check_identifier("UNNEST") {
                    self.advance(); // consume UNNEST
                    self.expect(TokenType::LParen)?;
                    let unnest_expr = self.parse_expression()?;
                    self.expect(TokenType::RParen)?;
                    Expression::In(Box::new(In {
                        this: left,
                        expressions: Vec::new(),
                        query: None,
                        not: false,
                        global: global_in,
                        unnest: Some(Box::new(unnest_expr)),
                        is_field: false,
                    }))
                } else if self.match_token(TokenType::LParen) {
                    // Standard IN (list) or IN (subquery)
                    // Check if this is a subquery (IN (SELECT ...) or IN (WITH ... SELECT ...))
                    if self.check(TokenType::Select) || self.check(TokenType::With) {
                        // Use parse_statement to handle both SELECT and WITH...SELECT
                        let subquery = self.parse_statement()?;
                        self.expect(TokenType::RParen)?;
                        Expression::In(Box::new(In {
                            this: left,
                            expressions: Vec::new(),
                            query: Some(subquery),
                            not: false,
                            global: global_in,
                            unnest: None,
                            is_field: false,
                        }))
                    } else if self.check(TokenType::RParen) {
                        // Empty IN set: IN ()
                        self.advance();
                        Expression::In(Box::new(In {
                            this: left,
                            expressions: Vec::new(),
                            query: None,
                            not: false,
                            global: global_in,
                            unnest: None,
                            is_field: false,
                        }))
                    } else {
                        let expressions = self.parse_expression_list()?;
                        self.expect(TokenType::RParen)?;
                        Expression::In(Box::new(In {
                            this: left,
                            expressions,
                            query: None,
                            not: false,
                            global: global_in,
                            unnest: None,
                            is_field: false,
                        }))
                    }
                } else {
                    // DuckDB: IN without parentheses for array/list membership: 'red' IN tbl.flags
                    let expr = self.parse_bitwise_or()?;
                    Expression::In(Box::new(In {
                        this: left,
                        expressions: vec![expr],
                        query: None,
                        not: false,
                        global: global_in,
                        unnest: None,
                        is_field: true,
                    }))
                }
            } else if self.match_token(TokenType::Between) {
                // Check for SYMMETRIC/ASYMMETRIC qualifier
                let symmetric = if self.match_texts(&["SYMMETRIC"]) {
                    Some(true)
                } else if self.match_texts(&["ASYMMETRIC"]) {
                    Some(false)
                } else {
                    None
                };
                let low = self.parse_bitwise_or()?;
                self.expect(TokenType::And)?;
                let high = self.parse_bitwise_or()?;
                Expression::Between(Box::new(Between {
                    this: left,
                    low,
                    high,
                    not: false,
                    symmetric,
                }))
            } else if self.match_token(TokenType::Adjacent) {
                let right = self.parse_bitwise_or()?;
                Expression::Adjacent(Box::new(BinaryOp::new(left, right)))
            } else if self.check(TokenType::Overlaps)
                && self.current + 1 < self.tokens.len()
                && !matches!(
                    self.tokens[self.current + 1].token_type,
                    TokenType::Semicolon
                        | TokenType::Comma
                        | TokenType::From
                        | TokenType::Where
                        | TokenType::RParen
                        | TokenType::As
                        | TokenType::Join
                        | TokenType::On
                        | TokenType::OrderBy
                        | TokenType::GroupBy
                        | TokenType::Having
                        | TokenType::Limit
                        | TokenType::Union
                        | TokenType::Except
                        | TokenType::Intersect
                        | TokenType::Eof
                )
            {
                self.advance(); // consume OVERLAPS
                let right = self.parse_bitwise_or()?;
                Expression::Overlaps(Box::new(OverlapsExpr {
                    this: Some(left),
                    expression: Some(right),
                    left_start: None,
                    left_end: None,
                    right_start: None,
                    right_end: None,
                }))
            } else if self.match_token(TokenType::IsNull) {
                // ISNULL postfix operator (PostgreSQL/SQLite)
                Expression::IsNull(Box::new(IsNull {
                    this: left,
                    not: false,
                    postfix_form: true,
                }))
            } else if self.match_token(TokenType::NotNull) {
                // NOTNULL postfix operator (PostgreSQL/SQLite)
                Expression::IsNull(Box::new(IsNull {
                    this: left,
                    not: true,
                    postfix_form: true,
                }))
            } else if self.match_token(TokenType::AtAt) {
                // PostgreSQL text search match operator (@@)
                let right = self.parse_bitwise_or()?;
                Expression::TsMatch(Box::new(BinaryOp::new(left, right)))
            } else if self.match_token(TokenType::AtGt) {
                // PostgreSQL array contains all operator (@>)
                let right = self.parse_bitwise_or()?;
                Expression::ArrayContainsAll(Box::new(BinaryOp::new(left, right)))
            } else if self.match_token(TokenType::LtAt) {
                // PostgreSQL array contained by operator (<@)
                let right = self.parse_bitwise_or()?;
                Expression::ArrayContainedBy(Box::new(BinaryOp::new(left, right)))
            } else if self.match_token(TokenType::DAmp) {
                // PostgreSQL array overlaps operator (&&)
                let right = self.parse_bitwise_or()?;
                Expression::ArrayOverlaps(Box::new(BinaryOp::new(left, right)))
            } else if self.match_token(TokenType::QMarkAmp) {
                // PostgreSQL JSONB contains all top keys operator (?&)
                let right = self.parse_bitwise_or()?;
                Expression::JSONBContainsAllTopKeys(Box::new(BinaryOp::new(left, right)))
            } else if self.match_token(TokenType::QMarkPipe) {
                // PostgreSQL JSONB contains any top key operator (?|)
                let right = self.parse_bitwise_or()?;
                Expression::JSONBContainsAnyTopKeys(Box::new(BinaryOp::new(left, right)))
            } else if !matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && self.match_token(TokenType::Parameter)
            {
                // PostgreSQL JSONB contains key operator (?)
                // Note: ? is tokenized as Parameter, but when used between expressions
                // it's the JSONB key existence operator
                // ClickHouse uses ? as ternary operator instead, handled in parse_assignment()
                let right = self.parse_bitwise_or()?;
                Expression::JSONBContains(Box::new(BinaryFunc {
                    original_name: Some("?".to_string()),
                    this: left,
                    expression: right,
                    inferred_type: None,
                }))
            } else if self.match_token(TokenType::HashDash) {
                // PostgreSQL JSONB delete at path operator (#-)
                let right = self.parse_bitwise_or()?;
                Expression::JSONBDeleteAtPath(Box::new(BinaryOp::new(left, right)))
            } else if self.match_token(TokenType::AmpLt) {
                // PostgreSQL range extends left operator (&<)
                let right = self.parse_bitwise_or()?;
                Expression::ExtendsLeft(Box::new(BinaryOp::new(left, right)))
            } else if self.match_token(TokenType::AmpGt) {
                // PostgreSQL range extends right operator (&>)
                let right = self.parse_bitwise_or()?;
                Expression::ExtendsRight(Box::new(BinaryOp::new(left, right)))
            } else if self.match_identifier("MEMBER") {
                // MySQL MEMBER OF(expr) operator - JSON membership test
                self.expect(TokenType::Of)?;
                self.expect(TokenType::LParen)?;
                let right = self.parse_expression()?;
                self.expect(TokenType::RParen)?;
                Expression::MemberOf(Box::new(BinaryOp::new(left, right)))
            } else if self.match_token(TokenType::CaretAt) {
                // DuckDB/PostgreSQL starts-with operator (^@)
                let right = self.parse_bitwise_or()?;
                Expression::StartsWith(Box::new(BinaryFunc {
                    original_name: Some("^@".to_string()),
                    this: left,
                    expression: right,
                    inferred_type: None,
                }))
            } else if self.match_token(TokenType::LrArrow) {
                // PostgreSQL distance operator (<->)
                let right = self.parse_bitwise_or()?;
                Expression::EuclideanDistance(Box::new(EuclideanDistance {
                    this: Box::new(left),
                    expression: Box::new(right),
                }))
            } else if self.match_token(TokenType::Operator) {
                // PostgreSQL OPERATOR(schema.op) syntax for schema-qualified operators
                // Example: col1 OPERATOR(pg_catalog.~) col2
                self.expect(TokenType::LParen)?;

                // Collect all tokens between parentheses as the operator text
                // This can include schema names, dots, and operator symbols like ~
                let mut op_text = String::new();
                while !self.check(TokenType::RParen) && !self.is_at_end() {
                    op_text.push_str(&self.peek().text);
                    self.advance();
                }
                self.expect(TokenType::RParen)?;

                // Collect any inline comments (e.g., /* foo */) between OPERATOR() and the RHS
                // Try trailing comments of the RParen (previous token) first,
                // then leading comments of the next token
                let mut comments = if self.current > 0 {
                    std::mem::take(&mut self.tokens[self.current - 1].trailing_comments)
                } else {
                    Vec::new()
                };
                if comments.is_empty() && !self.is_at_end() {
                    comments = std::mem::take(&mut self.tokens[self.current].comments);
                }

                // Parse the right-hand side expression
                let right = self.parse_bitwise_or()?;

                Expression::Operator(Box::new(Operator {
                    this: Box::new(left),
                    operator: Some(Box::new(Expression::Identifier(Identifier::new(op_text)))),
                    expression: Box::new(right),
                    comments,
                }))
            } else {
                return Ok(left);
            };

            left = expr;
        }
    }

    /// Parse bitwise OR expressions (|)
    fn parse_bitwise_or(&mut self) -> Result<Expression> {
        let mut left = self.parse_bitwise_xor()?;

        loop {
            if self.match_token(TokenType::Pipe) {
                let right = self.parse_bitwise_xor()?;
                left = Expression::BitwiseOr(Box::new(BinaryOp::new(left, right)));
            } else {
                return Ok(left);
            }
        }
    }

    /// Parse bitwise operators with an existing left expression
    /// Used for DuckDB's @ operator when @col is tokenized as a single Var token
    /// We already have the column, now need to continue parsing any binary operators
    /// Follows the same precedence chain: bitwise -> shift -> addition -> multiplication
    fn parse_bitwise_continuation(&mut self, left: Expression) -> Result<Expression> {
        // Start from multiplication level since we have a primary expression (col)
        // Then work up through addition, shift, bitwise AND/XOR/OR
        let mult_result = self.parse_multiplication_continuation(left)?;
        let add_result = self.parse_addition_continuation(mult_result)?;
        self.parse_bitwise_or_continuation(add_result)
    }

    /// Parse bitwise OR with an existing left expression
    fn parse_bitwise_or_continuation(&mut self, mut left: Expression) -> Result<Expression> {
        loop {
            if self.match_token(TokenType::Pipe) {
                let right = self.parse_bitwise_xor()?;
                left = Expression::BitwiseOr(Box::new(BinaryOp::new(left, right)));
            } else {
                return Ok(left);
            }
        }
    }

    /// Parse multiplication/division with an existing left expression
    fn parse_multiplication_continuation(&mut self, mut left: Expression) -> Result<Expression> {
        loop {
            let expr = if self.match_token(TokenType::Star) {
                let right = self.parse_power()?;
                Expression::Mul(Box::new(BinaryOp::new(left, right)))
            } else if self.match_token(TokenType::Slash) {
                let right = self.parse_power()?;
                Expression::Div(Box::new(BinaryOp::new(left, right)))
            } else if self.match_token(TokenType::Percent) {
                let right = self.parse_power()?;
                Expression::Mod(Box::new(BinaryOp::new(left, right)))
            } else if !self.check(TokenType::QuotedIdentifier)
                && (self.match_identifier("DIV") || self.match_token(TokenType::Div))
            {
                // DIV keyword for integer division (Hive/Spark/MySQL/ClickHouse)
                // Don't match QuotedIdentifier — `DIV` is an identifier alias, not an operator
                // If DIV was matched as a Var (not keyword Div token), verify it's actually
                // an operator by checking that a right operand follows. Otherwise it's an alias.
                let matched_as_var = self.previous().token_type == TokenType::Var;
                if matched_as_var
                    && (self.is_at_end()
                        || self.check(TokenType::Semicolon)
                        || self.check(TokenType::From)
                        || self.check(TokenType::Where)
                        || self.check(TokenType::Comma)
                        || self.check(TokenType::RParen))
                {
                    // Backtrack: DIV is being used as an alias, not an operator
                    self.current -= 1;
                    return Ok(left);
                }
                let right = self.parse_power()?;
                Expression::IntDiv(Box::new(crate::expressions::BinaryFunc {
                    this: left,
                    expression: right,
                    original_name: None,
                    inferred_type: None,
                }))
            } else {
                return Ok(left);
            };
            left = expr;
        }
    }

    /// Parse addition/subtraction with an existing left expression
    fn parse_addition_continuation(&mut self, mut left: Expression) -> Result<Expression> {
        loop {
            let left_comments = self.previous_trailing_comments();

            let expr = if self.match_token(TokenType::Plus) {
                let operator_comments = self.previous_trailing_comments();
                let right = self.parse_at_time_zone()?;
                let trailing_comments = self.previous_trailing_comments();
                Expression::Add(Box::new(BinaryOp {
                    left,
                    right,
                    left_comments,
                    operator_comments,
                    trailing_comments,
                    inferred_type: None,
                }))
            } else if self.match_token(TokenType::Dash) {
                let operator_comments = self.previous_trailing_comments();
                let right = self.parse_at_time_zone()?;
                let trailing_comments = self.previous_trailing_comments();
                Expression::Sub(Box::new(BinaryOp {
                    left,
                    right,
                    left_comments,
                    operator_comments,
                    trailing_comments,
                    inferred_type: None,
                }))
            } else if !self.dpipe_is_logical_or() && self.match_token(TokenType::DPipe) {
                let operator_comments = self.previous_trailing_comments();
                let right = self.parse_at_time_zone()?;
                let trailing_comments = self.previous_trailing_comments();
                Expression::Concat(Box::new(BinaryOp {
                    left,
                    right,
                    left_comments,
                    operator_comments,
                    trailing_comments,
                    inferred_type: None,
                }))
            } else if self.match_token(TokenType::DQMark) {
                let right = self.parse_at_time_zone()?;
                Expression::Coalesce(Box::new(crate::expressions::VarArgFunc {
                    expressions: vec![left, right],
                    original_name: None,
                    inferred_type: None,
                }))
            } else {
                return Ok(left);
            };

            left = expr;
        }
    }

    /// Parse bitwise XOR expressions (^)
    fn parse_bitwise_xor(&mut self) -> Result<Expression> {
        let mut left = self.parse_bitwise_and()?;

        loop {
            // In PostgreSQL, ^ is POWER (handled at parse_power level), and # is BitwiseXor
            if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::PostgreSQL)
                    | Some(crate::dialects::DialectType::Redshift)
            ) {
                if self.match_token(TokenType::Hash) {
                    let right = self.parse_bitwise_and()?;
                    left = Expression::BitwiseXor(Box::new(BinaryOp::new(left, right)));
                } else {
                    return Ok(left);
                }
            } else if self.match_token(TokenType::Caret) {
                let right = self.parse_bitwise_and()?;
                left = Expression::BitwiseXor(Box::new(BinaryOp::new(left, right)));
            } else {
                return Ok(left);
            }
        }
    }

    /// Parse bitwise AND expressions (&)
    fn parse_bitwise_and(&mut self) -> Result<Expression> {
        let mut left = self.parse_shift()?;

        loop {
            if self.match_token(TokenType::Amp) {
                let right = self.parse_shift()?;
                left = Expression::BitwiseAnd(Box::new(BinaryOp::new(left, right)));
            } else {
                return Ok(left);
            }
        }
    }

    /// Parse shift expressions (<< and >>)
    fn parse_shift(&mut self) -> Result<Expression> {
        let mut left = self.parse_addition()?;

        loop {
            if self.match_token(TokenType::LtLt) {
                let right = self.parse_addition()?;
                left = Expression::BitwiseLeftShift(Box::new(BinaryOp::new(left, right)));
            } else if self.match_token(TokenType::GtGt) {
                let right = self.parse_addition()?;
                left = Expression::BitwiseRightShift(Box::new(BinaryOp::new(left, right)));
            } else {
                return Ok(left);
            }
        }
    }

    /// Parse addition/subtraction
    fn parse_addition(&mut self) -> Result<Expression> {
        let mut left = self.parse_at_time_zone()?;

        loop {
            // Capture comments after left operand before consuming operator
            let left_comments = self.previous_trailing_comments();

            let expr = if self.match_token(TokenType::Plus) {
                // Capture comments after operator (before right operand)
                let operator_comments = self.previous_trailing_comments();
                let right = self.parse_at_time_zone()?;
                let trailing_comments = self.previous_trailing_comments();
                Expression::Add(Box::new(BinaryOp {
                    left,
                    right,
                    left_comments,
                    operator_comments,
                    trailing_comments,
                    inferred_type: None,
                }))
            } else if self.match_token(TokenType::Dash) {
                let operator_comments = self.previous_trailing_comments();
                let right = self.parse_at_time_zone()?;
                let trailing_comments = self.previous_trailing_comments();
                Expression::Sub(Box::new(BinaryOp {
                    left,
                    right,
                    left_comments,
                    operator_comments,
                    trailing_comments,
                    inferred_type: None,
                }))
            } else if !self.dpipe_is_logical_or() && self.match_token(TokenType::DPipe) {
                let operator_comments = self.previous_trailing_comments();
                let right = self.parse_at_time_zone()?;
                let trailing_comments = self.previous_trailing_comments();
                Expression::Concat(Box::new(BinaryOp {
                    left,
                    right,
                    left_comments,
                    operator_comments,
                    trailing_comments,
                    inferred_type: None,
                }))
            } else if self.match_token(TokenType::DQMark) {
                let right = self.parse_at_time_zone()?;
                Expression::Coalesce(Box::new(crate::expressions::VarArgFunc {
                    expressions: vec![left, right],
                    original_name: None,
                    inferred_type: None,
                }))
            } else {
                return Ok(left);
            };

            left = expr;
        }
    }

    /// Parse AT TIME ZONE expression
    fn parse_at_time_zone(&mut self) -> Result<Expression> {
        let mut expr = self.parse_multiplication()?;

        // Check for AT TIME ZONE (can be chained)
        while self.check(TokenType::Var) && self.peek().text.to_uppercase() == "AT" {
            self.advance(); // consume AT
                            // Check for TIME ZONE
            if self.check(TokenType::Time) {
                self.advance(); // consume TIME
                if self.check(TokenType::Var) && self.peek().text.to_uppercase() == "ZONE" {
                    self.advance(); // consume ZONE
                    let zone = self.parse_unary()?;
                    expr = Expression::AtTimeZone(Box::new(AtTimeZone { this: expr, zone }));
                } else {
                    return Err(self.parse_error("Expected ZONE after AT TIME"));
                }
            } else {
                return Err(self.parse_error("Expected TIME after AT"));
            }
        }

        Ok(expr)
    }

    /// Parse multiplication/division
    fn parse_multiplication(&mut self) -> Result<Expression> {
        let mut left = self.parse_power()?;

        loop {
            let expr = if self.match_token(TokenType::Star) {
                let right = self.parse_power()?;
                Expression::Mul(Box::new(BinaryOp::new(left, right)))
            } else if self.match_token(TokenType::Slash) {
                let right = self.parse_power()?;
                Expression::Div(Box::new(BinaryOp::new(left, right)))
            } else if self.match_token(TokenType::Percent) {
                let right = self.parse_power()?;
                Expression::Mod(Box::new(BinaryOp::new(left, right)))
            } else if !self.check(TokenType::QuotedIdentifier)
                && (self.match_identifier("MOD") || self.match_token(TokenType::Mod))
            {
                // MySQL/Teradata: x MOD y (infix modulo operator)
                // Don't match QuotedIdentifier — `MOD` is an identifier alias, not an operator
                let right = self.parse_power()?;
                Expression::Mod(Box::new(BinaryOp::new(left, right)))
            } else if !self.check(TokenType::QuotedIdentifier)
                && (self.match_identifier("DIV") || self.match_token(TokenType::Div))
            {
                // DIV keyword for integer division (Hive/Spark/MySQL/ClickHouse)
                // Don't match QuotedIdentifier — `DIV` is an identifier alias, not an operator
                // If DIV was matched as a Var (not keyword Div token), verify it's actually
                // an operator by checking that a right operand follows. Otherwise it's an alias.
                let matched_as_var = self.previous().token_type == TokenType::Var;
                if matched_as_var
                    && (self.is_at_end()
                        || self.check(TokenType::Semicolon)
                        || self.check(TokenType::From)
                        || self.check(TokenType::Where)
                        || self.check(TokenType::Comma)
                        || self.check(TokenType::RParen))
                {
                    // Backtrack: DIV is being used as an alias, not an operator
                    self.current -= 1;
                    return Ok(left);
                }
                let right = self.parse_power()?;
                Expression::IntDiv(Box::new(crate::expressions::BinaryFunc {
                    this: left,
                    expression: right,
                    original_name: None,
                    inferred_type: None,
                }))
            } else {
                return Ok(left);
            };

            left = expr;
        }
    }

    /// Parse power/exponentiation (**) operator
    /// In PostgreSQL/Redshift, ^ (Caret) is POWER, not BitwiseXor
    fn parse_power(&mut self) -> Result<Expression> {
        let mut left = self.parse_unary()?;

        loop {
            if self.match_token(TokenType::DStar) {
                let right = self.parse_unary()?;
                left = Expression::Power(Box::new(BinaryFunc {
                    original_name: Some("**".to_string()),
                    this: left,
                    expression: right,
                    inferred_type: None,
                }));
            } else if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::PostgreSQL)
                    | Some(crate::dialects::DialectType::Redshift)
                    | Some(crate::dialects::DialectType::DuckDB)
            ) && self.match_token(TokenType::Caret)
            {
                let right = self.parse_unary()?;
                left = Expression::Power(Box::new(BinaryFunc {
                    original_name: None,
                    this: left,
                    expression: right,
                    inferred_type: None,
                }));
            } else {
                return Ok(left);
            }
        }
    }

    /// Try to parse a type literal expression like: point '(4,4)', timestamp '2024-01-01'
    /// PostgreSQL allows type name followed by string literal as a cast shorthand.
    /// Returns None if not a type literal pattern, so caller can fall through to parse_primary.
    fn try_parse_type_literal(&mut self) -> Result<Option<Expression>> {
        // Save position for backtracking
        let start_pos = self.current;

        // Check if we're at an identifier or Var token that could be a type name
        if !self.check(TokenType::Identifier) && !self.check(TokenType::Var) {
            return Ok(None);
        }

        // Get the potential type name without consuming
        let type_name = self.peek().text.to_uppercase();

        // Check if this looks like a known data type that supports literal syntax
        // These are types where PostgreSQL allows TYPE 'value' syntax
        // NOTE: DATE, TIME, TIMESTAMP, INTERVAL are NOT here because they have their own
        // token types and are handled specially in parse_primary
        let is_type_literal_type = matches!(
            type_name.as_str(),
            // Geometric types (PostgreSQL)
            "POINT" | "LINE" | "LSEG" | "BOX" | "PATH" | "POLYGON" | "CIRCLE" |
            // Network types (PostgreSQL)
            "INET" | "CIDR" | "MACADDR" | "MACADDR8" |
            // Other types that support literal syntax
            "UUID" | "JSON" | "JSONB" | "XML" | "BIT" | "VARBIT" |
            // Range types (PostgreSQL)
            "INT4RANGE" | "INT8RANGE" | "NUMRANGE" | "TSRANGE" | "TSTZRANGE" | "DATERANGE"
        );

        if !is_type_literal_type {
            return Ok(None);
        }

        // Check if the next token (after type name) is a string literal
        if self.current + 1 >= self.tokens.len() {
            return Ok(None);
        }

        if self.tokens[self.current + 1].token_type != TokenType::String {
            return Ok(None);
        }

        // This looks like a type literal! Parse it.
        // Consume the type name
        self.advance();

        // Try to parse the data type from the name
        let data_type = match self.parse_data_type_from_name(&type_name) {
            Ok(dt) => dt,
            Err(_) => {
                // If we can't parse the type, backtrack
                self.current = start_pos;
                return Ok(None);
            }
        };

        // Parse the string literal
        if !self.check(TokenType::String) {
            // Backtrack - something went wrong
            self.current = start_pos;
            return Ok(None);
        }

        let string_token = self.advance();
        let value = Expression::Literal(Literal::String(string_token.text.clone()));

        // JSON literal: JSON '"foo"' -> ParseJson expression (matches Python sqlglot)
        if matches!(data_type, DataType::Json | DataType::JsonB)
            || matches!(type_name.as_str(), "JSON" | "JSONB")
        {
            return Ok(Some(Expression::ParseJson(Box::new(UnaryFunc {
                this: value,
                original_name: None,
                inferred_type: None,
            }))));
        }

        // Create the Cast expression
        Ok(Some(Expression::Cast(Box::new(Cast {
            this: value,
            to: data_type,
            trailing_comments: Vec::new(),
            double_colon_syntax: false,
            format: None,
            default: None,
            inferred_type: None,
        }))))
    }

    /// Try to parse type shorthand CAST: INT 1, VARCHAR 'x', STRING 'x', TEXT 'y', etc.
    /// In generic mode (no dialect), a type keyword followed by a literal becomes CAST(literal AS type).
    /// This matches Python sqlglot's `_parse_types()` behavior.
    fn try_parse_type_shorthand_cast(&mut self) -> Result<Option<Expression>> {
        // Only apply in generic mode
        let is_generic = self.config.dialect.is_none()
            || matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::Generic)
            );
        if !is_generic {
            return Ok(None);
        }

        let start_pos = self.current;

        // Check if current token is a type keyword
        if !self.is_type_keyword() {
            return Ok(None);
        }

        // Don't apply if the type keyword is followed by a left paren (function call)
        // or is not followed by a literal
        if self.current + 1 >= self.tokens.len() {
            return Ok(None);
        }

        let next_type = self.tokens[self.current + 1].token_type;
        // The value after the type keyword must be a literal (number or string)
        if !matches!(next_type, TokenType::Number | TokenType::String) {
            return Ok(None);
        }

        // Get the type name
        let type_token = self.advance();
        let type_name = type_token.text.to_uppercase();

        // Parse the data type
        let data_type = match type_name.as_str() {
            "INT" | "INTEGER" => DataType::Int {
                length: None,
                integer_spelling: type_name == "INTEGER",
            },
            "BIGINT" => DataType::BigInt { length: None },
            "SMALLINT" => DataType::SmallInt { length: None },
            "TINYINT" => DataType::TinyInt { length: None },
            "FLOAT" => DataType::Float {
                precision: None,
                scale: None,
                real_spelling: false,
            },
            "DOUBLE" => DataType::Double {
                precision: None,
                scale: None,
            },
            "DECIMAL" | "NUMERIC" => DataType::Decimal {
                precision: None,
                scale: None,
            },
            "REAL" => DataType::Float {
                precision: None,
                scale: None,
                real_spelling: true,
            },
            "VARCHAR" => DataType::VarChar {
                length: None,
                parenthesized_length: false,
            },
            "CHAR" => DataType::Char { length: None },
            "TEXT" | "STRING" => DataType::Text,
            "BOOLEAN" | "BOOL" => DataType::Boolean,
            "BINARY" => DataType::Binary { length: None },
            "VARBINARY" => DataType::VarBinary { length: None },
            _ => {
                // Unknown type, backtrack
                self.current = start_pos;
                return Ok(None);
            }
        };

        // Parse the literal value
        let value = if self.check(TokenType::String) {
            let tok = self.advance();
            Expression::Literal(Literal::String(tok.text.clone()))
        } else if self.check(TokenType::Number) {
            let tok = self.advance();
            Expression::Literal(Literal::Number(tok.text.clone()))
        } else {
            self.current = start_pos;
            return Ok(None);
        };

        // Create the Cast expression
        Ok(Some(Expression::Cast(Box::new(Cast {
            this: value,
            to: data_type,
            trailing_comments: Vec::new(),
            double_colon_syntax: false,
            format: None,
            default: None,
            inferred_type: None,
        }))))
    }

    /// Parse unary expressions
    fn parse_unary(&mut self) -> Result<Expression> {
        if self.match_token(TokenType::Plus) {
            // Unary plus is a no-op - just parse the inner expression
            // This handles +++1 -> 1, +-1 -> -1, etc.
            self.parse_unary()
        } else if self.match_token(TokenType::Dash) {
            let expr = self.parse_unary()?;
            Ok(Expression::Neg(Box::new(UnaryOp::new(expr))))
        } else if self.match_token(TokenType::Plus) {
            // Unary plus: +1, +expr — just return the inner expression (no-op)
            self.parse_unary()
        } else if self.match_token(TokenType::Tilde) {
            let expr = self.parse_unary()?;
            Ok(Expression::BitwiseNot(Box::new(UnaryOp::new(expr))))
        } else if self.match_token(TokenType::DPipeSlash) {
            // ||/ (Cube root - PostgreSQL)
            let expr = self.parse_unary()?;
            Ok(Expression::Cbrt(Box::new(UnaryFunc::with_name(
                expr,
                "||/".to_string(),
            ))))
        } else if self.match_token(TokenType::PipeSlash) {
            // |/ (Square root - PostgreSQL)
            let expr = self.parse_unary()?;
            Ok(Expression::Sqrt(Box::new(UnaryFunc::with_name(
                expr,
                "|/".to_string(),
            ))))
        } else if self.check(TokenType::DAt)
            && matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::DuckDB)
            )
        {
            // DuckDB @ operator: @(-1), @(expr), @-1
            // @ is the ABS operator in DuckDB with low precedence
            // Python sqlglot: "@": lambda self: exp.Abs(this=self._parse_bitwise())
            // This means @col + 1 parses as ABS(col + 1), not ABS(col) + 1
            self.advance(); // consume @
                            // Parse at bitwise level for correct precedence (matches Python sqlglot)
            let expr = self.parse_bitwise_or()?;
            Ok(Expression::Abs(Box::new(UnaryFunc::new(expr))))
        } else if self.check(TokenType::Var)
            && self.peek().text.starts_with('@')
            && matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::DuckDB)
            )
        {
            // DuckDB @ operator with identifier: @col, @col + 1
            // Tokenizer creates "@col" as a single Var token, so we need to handle it here
            // Python sqlglot: "@": lambda self: exp.Abs(this=self._parse_bitwise())
            let token = self.advance(); // consume @col token
            let col_name = &token.text[1..]; // strip leading @

            // Create column expression for the identifier part
            let col_expr = Expression::Column(Column {
                name: Identifier::new(col_name),
                table: None,
                join_mark: false,
                trailing_comments: Vec::new(),
                span: None,
                inferred_type: None,
            });

            // Check if followed by operators that should be included in the ABS
            // We need to parse any remaining operators at bitwise level
            // First, check if there's a binary operator after this column
            if self.check(TokenType::Plus)
                || self.check(TokenType::Dash)
                || self.check(TokenType::Star)
                || self.check(TokenType::Slash)
                || self.check(TokenType::Percent)
                || self.check(TokenType::Amp)
                || self.check(TokenType::Pipe)
                || self.check(TokenType::Caret)
                || self.check(TokenType::LtLt)
                || self.check(TokenType::GtGt)
            {
                // There are more operators - we need to continue parsing at bitwise level
                // But parse_bitwise_or expects to start fresh, not continue with existing left
                // So we use a helper approach: parse_bitwise_continuation
                let full_expr = self.parse_bitwise_continuation(col_expr)?;
                Ok(Expression::Abs(Box::new(UnaryFunc::new(full_expr))))
            } else {
                // Just the column, no more operators
                Ok(Expression::Abs(Box::new(UnaryFunc::new(col_expr))))
            }
        } else if self.check(TokenType::DAt)
            && (self.check_next(TokenType::LParen) || self.check_next(TokenType::Dash))
        {
            // Non-DuckDB dialects: only handle @(expr) and @-expr as ABS
            self.advance(); // consume @
            let expr = self.parse_bitwise_or()?;
            Ok(Expression::Abs(Box::new(UnaryFunc::new(expr))))
        } else if self.check(TokenType::Prior)
            && !self.check_next(TokenType::As)
            && !self.check_next(TokenType::Comma)
            && !self.check_next(TokenType::RParen)
            && !self.check_next(TokenType::Semicolon)
            && self.current + 1 < self.tokens.len()
        {
            // Oracle PRIOR expression - references parent row's value in hierarchical queries
            // Can appear in SELECT list, CONNECT BY, or other expression contexts
            // Python sqlglot: "PRIOR": lambda self: self.expression(exp.Prior, this=self._parse_bitwise())
            // When followed by AS/comma/rparen/end, treat PRIOR as an identifier (column name)
            self.advance(); // consume PRIOR
            let expr = self.parse_bitwise_or()?;
            Ok(Expression::Prior(Box::new(Prior { this: expr })))
        } else {
            // Try to parse type literals like: point '(4,4)', timestamp '2024-01-01', interval '1 day'
            // PostgreSQL allows type name followed by string literal as a cast shorthand
            if let Some(type_literal) = self.try_parse_type_literal()? {
                return self.parse_postfix_operators(type_literal);
            }
            // Try to parse type shorthand CAST: INT 1, VARCHAR 'x', STRING 'x', TEXT 'y', etc.
            // In generic mode, type keyword followed by literal -> CAST(literal AS type)
            if let Some(type_cast) = self.try_parse_type_shorthand_cast()? {
                return self.parse_postfix_operators(type_cast);
            }
            let expr = self.parse_primary()?;
            // Handle postfix exclamation mark for Snowflake model attribute syntax: model!PREDICT(...)
            self.parse_postfix_operators(expr)
        }
    }

    /// Parse postfix operators like ! (model attribute in Snowflake) and : (JSON path in Snowflake)
    fn parse_postfix_operators(&mut self, mut expr: Expression) -> Result<Expression> {
        // Handle Oracle/Redshift outer join marker (+) after column reference
        // Syntax: column_ref (+) indicates optional side of join
        if self.check(TokenType::LParen) && self.check_next(TokenType::Plus) {
            // Look ahead to verify it's ( + )
            let saved_pos = self.current;
            if self.match_token(TokenType::LParen)
                && self.match_token(TokenType::Plus)
                && self.match_token(TokenType::RParen)
            {
                // Set join_mark on the column expression
                if let Expression::Column(ref mut col) = expr {
                    col.join_mark = true;
                }
            } else {
                self.current = saved_pos;
            }
        }

        // Handle EXCLAMATION for Snowflake model attribute syntax: model!PREDICT(...)
        while self.match_token(TokenType::Exclamation) {
            // Parse the attribute/function after the exclamation mark
            // This can be either a simple identifier (model!admin) or a function call (model!PREDICT(1))
            let attr = self.parse_primary()?;
            expr = Expression::ModelAttribute(Box::new(ModelAttribute {
                this: Box::new(expr),
                expression: Box::new(attr),
            }));
        }

        // Handle COLON for Snowflake JSON path extraction: a:field or a:field.subfield
        // This creates JSONExtract expressions that transform to GET_PATH(a, 'field') in Snowflake
        expr = self.parse_colon_json_path(expr)?;

        // Handle DCOLON (::) - in SingleStore it's JSON extraction, in other dialects it's cast
        // SingleStore JSON path syntax:
        //   a::b -> JSON_EXTRACT_JSON(a, 'b')
        //   a::$b -> JSON_EXTRACT_STRING(a, 'b')
        //   a::%b -> JSON_EXTRACT_DOUBLE(a, 'b')
        //   a::?names -> JSON match syntax
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::SingleStore)
        ) {
            expr = self.parse_singlestore_json_path(expr)?;
        } else {
            // For other dialects, :: is cast syntax
            // IMPORTANT: Use parse_data_type_for_cast to avoid consuming subscripts as array dimensions
            // e.g., ::VARIANT[0] should be cast to VARIANT followed by subscript [0]
            while self.match_token(TokenType::DColon) {
                let data_type = self.parse_data_type_for_cast()?;
                expr = Expression::Cast(Box::new(Cast {
                    this: expr,
                    to: data_type,
                    trailing_comments: Vec::new(),
                    double_colon_syntax: true,
                    format: None,
                    default: None,
                    inferred_type: None,
                }));
            }
        }

        // Teradata: (FORMAT '...') phrase after an expression
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::Teradata)
        ) && self.check(TokenType::LParen)
            && self.check_next(TokenType::Format)
        {
            self.advance(); // consume (
            self.advance(); // consume FORMAT
            let format = self.expect_string()?;
            self.expect(TokenType::RParen)?;
            expr = Expression::FormatPhrase(Box::new(FormatPhrase {
                this: Box::new(expr),
                format,
            }));
        }

        Ok(expr)
    }

    /// Parse SingleStore JSON path extraction syntax
    /// Examples:
    ///   a::b -> JSON_EXTRACT_JSON(a, 'b')
    ///   a::$b -> JSON_EXTRACT_STRING(a, 'b')
    ///   a::%b -> JSON_EXTRACT_DOUBLE(a, 'b')
    ///   a::`b`::`2` -> nested JSON extraction
    fn parse_singlestore_json_path(&mut self, mut expr: Expression) -> Result<Expression> {
        loop {
            if self.match_token(TokenType::DColon) {
                // :: followed by identifier -> JSON_EXTRACT_JSON
                // Check if next is a backtick-quoted identifier or regular identifier
                let path_key = if self.check(TokenType::Identifier) || self.check(TokenType::Var) {
                    self.advance().text
                } else if self.check(TokenType::Number) {
                    // a::2 -> JSON_EXTRACT_JSON(a, '2')
                    self.advance().text
                } else {
                    return Err(self.parse_error("Expected identifier after ::"));
                };

                expr = Expression::Function(Box::new(Function::new(
                    "JSON_EXTRACT_JSON".to_string(),
                    vec![expr, Expression::string(&path_key)],
                )));
            } else if self.match_token(TokenType::DColonDollar) {
                // ::$ followed by identifier -> JSON_EXTRACT_STRING
                let path_key = if self.check(TokenType::Identifier) || self.check(TokenType::Var) {
                    self.advance().text
                } else {
                    return Err(self.parse_error("Expected identifier after ::$"));
                };

                expr = Expression::Function(Box::new(Function::new(
                    "JSON_EXTRACT_STRING".to_string(),
                    vec![expr, Expression::string(&path_key)],
                )));
            } else if self.match_token(TokenType::DColonPercent) {
                // ::% followed by identifier -> JSON_EXTRACT_DOUBLE
                let path_key = if self.check(TokenType::Identifier) || self.check(TokenType::Var) {
                    self.advance().text
                } else {
                    return Err(self.parse_error("Expected identifier after ::%"));
                };

                expr = Expression::Function(Box::new(Function::new(
                    "JSON_EXTRACT_DOUBLE".to_string(),
                    vec![expr, Expression::string(&path_key)],
                )));
            } else if self.match_token(TokenType::DColonQMark) {
                // ::? followed by identifier -> Keep as JSONMatchAny expression for now
                let path_key = if self.check(TokenType::Identifier) || self.check(TokenType::Var) {
                    self.advance().text
                } else {
                    return Err(self.parse_error("Expected identifier after ::?"));
                };

                // For now, create a function that will be handled specially
                expr = Expression::Function(Box::new(Function::new(
                    "JSON_EXTRACT_JSON".to_string(), // placeholder
                    vec![expr, Expression::string(&format!("?{}", path_key))],
                )));
            } else {
                break;
            }
        }
        Ok(expr)
    }

    /// Parse colon-separated JSON path syntax (Snowflake variant extraction)
    /// Examples:
    ///   a:from -> GET_PATH(a, 'from')
    ///   a:b.c.d -> GET_PATH(a, 'b.c.d')
    ///   a:from::STRING -> CAST(GET_PATH(a, 'from') AS VARCHAR)
    ///   a:b:c.d -> GET_PATH(a, 'b.c.d') (multiple colons joined into single path)
    fn parse_colon_json_path(&mut self, this: Expression) -> Result<Expression> {
        // DuckDB uses colon for prefix alias syntax (e.g., "alias: expr" means "expr AS alias")
        // Skip JSON path extraction for DuckDB - it's handled separately in parse_select_expressions
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::DuckDB)
        ) {
            return Ok(this);
        }

        // ClickHouse uses : as part of the ternary operator (condition ? true : false)
        // Skip JSON path extraction for ClickHouse to avoid consuming the ternary separator
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) {
            return Ok(this);
        }

        // Only apply colon JSON path parsing to identifiers, columns, and function results
        // This prevents {'key': 'value'} object literals from being misinterpreted
        let is_valid_json_path_base = matches!(
            &this,
            Expression::Column(_) |
            Expression::Identifier(_) |
            Expression::Dot(_) |
            Expression::JSONExtract(_) |  // Allow chained paths like a:b:c
            Expression::Function(_) |     // Allow function results like PARSE_JSON(...):x
            Expression::ParseJson(_) |    // Allow PARSE_JSON specifically
            Expression::Parameter(_) // Allow positional params like $1:name
        );

        if !is_valid_json_path_base {
            return Ok(this);
        }

        // Check if we have a colon (but NOT double-colon which is cast syntax)
        if !self.check(TokenType::Colon) {
            return Ok(this);
        }

        // Make sure this is not a double-colon (::) which is cast syntax
        if self.check_next(TokenType::Colon) {
            // This is :: (DColon should have been tokenized, but just in case)
            return Ok(this);
        }

        // Collect ALL the JSON path parts across multiple colons
        // a:b.c:d.e -> GET_PATH(a, 'b.c.d.e')
        // a:b[0].c -> GET_PATH(a, 'b[0].c')
        let mut path_string = String::new();

        // Parse all colon-separated path segments
        while self.check(TokenType::Colon) && !self.check_next(TokenType::Colon) {
            // Save position before consuming colon so we can backtrack
            // if what follows isn't a valid JSON path component (e.g., DuckDB's "foo: 1" label syntax)
            let saved_pos = self.current;
            let saved_path_len = path_string.len();

            // Consume the colon
            self.advance();

            // Parse first path component (required) - can be any identifier including keywords
            // Also handle backtick-quoted identifiers like `zip code` or `fb:testid`
            // Also handle bracket notation directly after colon: c1:['price'] or c1:["foo bar"]
            // IMPORTANT: Check QuotedIdentifier FIRST since is_identifier_token() includes QuotedIdentifier
            let mut had_initial_component = false;
            if self.check(TokenType::QuotedIdentifier) {
                // Quoted field name in variant access
                // Snowflake: v:"fruit" → double-quoted key → stored as plain text 'fruit'
                // Databricks: raw:`zip code` → backtick-quoted key → stored as bracket notation '["zip code"]'
                let quoted_name = self.advance().text.clone();
                let is_snowflake = matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::Snowflake)
                );
                let needs_bracket = quoted_name.contains(' ') || quoted_name.contains('\'');
                if is_snowflake && !needs_bracket {
                    // Snowflake double-quoted keys without special chars are stored as plain text
                    // Add dot separator for plain segments
                    if !path_string.is_empty() {
                        path_string.push('.');
                    }
                    path_string.push_str(&quoted_name);
                } else if is_snowflake && needs_bracket {
                    // Snowflake keys with spaces/apostrophes use bracket notation: ["key with spaces"]
                    // No dot before bracket notation
                    path_string.push_str("[\"");
                    // Don't escape single quotes here - the generator will handle escaping
                    // when outputting the string literal
                    path_string.push_str(&quoted_name);
                    path_string.push_str("\"]");
                } else {
                    // Other dialects (Databricks): wrap in bracket notation
                    // No dot before bracket notation
                    path_string.push_str("[\"");
                    for c in quoted_name.chars() {
                        if c == '"' {
                            path_string.push_str("\\\"");
                        } else {
                            path_string.push(c);
                        }
                    }
                    path_string.push_str("\"]");
                }
                had_initial_component = true;
            } else if self.is_identifier_token()
                || self.is_safe_keyword_as_identifier()
                || self.is_reserved_keyword_as_identifier()
            {
                // Add a dot separator for plain identifier segments
                if !path_string.is_empty() {
                    path_string.push('.');
                }
                let first_part = self.advance().text;
                path_string.push_str(&first_part);
                had_initial_component = true;
            } else if self.check(TokenType::LBracket) {
                // Bracket notation directly after colon: c1:['price'] or c1:["foo bar"]
                // Mark that we have a valid path start - the bracket will be parsed in the loop below
                had_initial_component = true;
            }

            if !had_initial_component {
                // Not a valid JSON path component - backtrack and stop
                // This handles cases like DuckDB's "foo: 1" label/alias syntax
                // where the colon is followed by a non-identifier (e.g., a number)
                self.current = saved_pos;
                path_string.truncate(saved_path_len);
                break;
            }

            // Parse optional array indices and additional path components
            loop {
                // Handle array index: [0], [1], [*], ['key'], ["key"], etc.
                if self.match_token(TokenType::LBracket) {
                    // Parse the index expression (typically a number, identifier, * for wildcard, or string key)
                    if self.check(TokenType::Number) {
                        path_string.push('[');
                        let idx = self.advance().text;
                        path_string.push_str(&idx);
                        self.expect(TokenType::RBracket)?;
                        path_string.push(']');
                    } else if self.check(TokenType::Star) {
                        // Wildcard array access: [*] matches all array elements
                        path_string.push('[');
                        self.advance();
                        path_string.push('*');
                        self.expect(TokenType::RBracket)?;
                        path_string.push(']');
                    } else if self.check(TokenType::String) {
                        // Single-quoted string key access: ['bicycle']
                        // Convert to dot notation for simple keys, keep bracket notation for keys with spaces
                        let key = self.advance().text;
                        self.expect(TokenType::RBracket)?;
                        // Check if the key contains spaces or special characters that require bracket notation
                        let needs_brackets =
                            key.contains(' ') || key.contains('"') || key.contains('\'');
                        if needs_brackets {
                            // Keep bracket notation with double quotes: ["zip code"]
                            path_string.push_str("[\"");
                            for c in key.chars() {
                                if c == '"' {
                                    path_string.push_str("\\\"");
                                } else {
                                    path_string.push(c);
                                }
                            }
                            path_string.push_str("\"]");
                        } else {
                            // Convert to dot notation: store['bicycle'] -> store.bicycle
                            // But only add dot if path_string is not empty (handles c1:['price'] -> c1:price)
                            if !path_string.is_empty() {
                                path_string.push('.');
                            }
                            path_string.push_str(&key);
                        }
                    } else if self.check(TokenType::QuotedIdentifier) {
                        // Double-quoted string key access: ["zip code"]
                        // These are tokenized as QuotedIdentifier, not String
                        // Must be checked BEFORE is_identifier_token() since it includes QuotedIdentifier
                        let key = self.advance().text;
                        self.expect(TokenType::RBracket)?;
                        // Always use bracket notation with double quotes for quoted identifiers
                        path_string.push_str("[\"");
                        for c in key.chars() {
                            if c == '"' {
                                path_string.push_str("\\\"");
                            } else {
                                path_string.push(c);
                            }
                        }
                        path_string.push_str("\"]");
                    } else if self.is_identifier_token() {
                        path_string.push('[');
                        let idx = self.advance().text;
                        path_string.push_str(&idx);
                        self.expect(TokenType::RBracket)?;
                        path_string.push(']');
                    } else {
                        // Empty brackets or unexpected token - just close the bracket
                        path_string.push('[');
                        self.expect(TokenType::RBracket)?;
                        path_string.push(']');
                    }
                } else if self.match_token(TokenType::Dot) {
                    // Handle dot access
                    path_string.push('.');
                    if self.is_identifier_token()
                        || self.is_safe_keyword_as_identifier()
                        || self.is_reserved_keyword_as_identifier()
                    {
                        let part = self.advance().text;
                        path_string.push_str(&part);
                    } else {
                        return Err(self.parse_error("Expected identifier after . in JSON path"));
                    }
                } else {
                    break;
                }
            }
        }

        // If no path was parsed (e.g., backtracked on first colon), return the original expression
        if path_string.is_empty() {
            return Ok(this);
        }

        // Create the JSONExtract expression with variant_extract marker
        let path_expr = Expression::Literal(Literal::String(path_string));
        let json_extract = Expression::JSONExtract(Box::new(JSONExtract {
            this: Box::new(this),
            expression: Box::new(path_expr),
            only_json_types: None,
            expressions: Vec::new(),
            variant_extract: Some(Box::new(Expression::Boolean(BooleanLiteral {
                value: true,
            }))),
            json_query: None,
            option: None,
            quote: None,
            on_condition: None,
            requires_json: None,
        }));

        Ok(json_extract)
    }

    /// Check if the current token is a reserved keyword that can be used as identifier in JSON path
    fn is_reserved_keyword_as_identifier(&self) -> bool {
        if self.is_at_end() {
            return false;
        }
        let token = self.peek();
        // Allow reserved keywords like FROM, SELECT, etc. as JSON path components
        matches!(
            token.token_type,
            TokenType::From
                | TokenType::Select
                | TokenType::Where
                | TokenType::And
                | TokenType::Or
                | TokenType::Not
                | TokenType::In
                | TokenType::As
                | TokenType::On
                | TokenType::Join
                | TokenType::Left
                | TokenType::Right
                | TokenType::Inner
                | TokenType::Outer
                | TokenType::Cross
                | TokenType::Full
                | TokenType::Group
                | TokenType::Order
                | TokenType::By
                | TokenType::Having
                | TokenType::Limit
                | TokenType::Offset
                | TokenType::Union
                | TokenType::Except
                | TokenType::Intersect
                | TokenType::All
                | TokenType::Distinct
                | TokenType::Case
                | TokenType::When
                | TokenType::Then
                | TokenType::Else
                | TokenType::End
                | TokenType::Null
                | TokenType::True
                | TokenType::False
                | TokenType::Between
                | TokenType::Like
                | TokenType::Is
                | TokenType::Exists
                | TokenType::Insert
                | TokenType::Update
                | TokenType::Delete
                | TokenType::Create
                | TokenType::Alter
                | TokenType::Drop
                | TokenType::Table
                | TokenType::View
                | TokenType::Index
                | TokenType::Set
                | TokenType::Values
                | TokenType::Into
                | TokenType::Default
                | TokenType::Key
                | TokenType::Unique
                | TokenType::Check
                | TokenType::Constraint
                | TokenType::References
        )
    }

    /// Parse primary expressions
    fn parse_primary(&mut self) -> Result<Expression> {
        // Handle APPROXIMATE COUNT(DISTINCT expr) - Redshift syntax
        // Parses as ApproxDistinct expression
        if self.check(TokenType::Var) && self.peek().text.to_uppercase() == "APPROXIMATE" {
            let saved_pos = self.current;
            self.advance(); // consume APPROXIMATE
                            // Parse the COUNT(DISTINCT ...) that follows
            let func = self.parse_primary()?;
            // Check if it's COUNT with DISTINCT
            if let Expression::Count(ref count_expr) = func {
                if count_expr.distinct {
                    let this_expr = count_expr.this.clone().unwrap_or_else(|| {
                        Expression::Star(crate::expressions::Star {
                            table: None,
                            except: None,
                            replace: None,
                            rename: None,
                            trailing_comments: Vec::new(),
                            span: None,
                        })
                    });
                    return Ok(Expression::ApproxDistinct(Box::new(
                        crate::expressions::AggFunc {
                            this: this_expr,
                            distinct: false,
                            filter: None,
                            order_by: Vec::new(),
                            name: Some("APPROX_DISTINCT".to_string()),
                            ignore_nulls: None,
                            having_max: None,
                            limit: None,
                            inferred_type: None,
                        },
                    )));
                }
            }
            // Not COUNT(DISTINCT ...) - backtrack
            self.current = saved_pos;
        }

        if let Some(connect_by_root) = self.try_parse_connect_by_root_expression()? {
            return Ok(connect_by_root);
        }

        // PostgreSQL VARIADIC prefix in function call arguments
        // e.g., SELECT MLEAST(VARIADIC ARRAY[10, -1, 5, 4.4])
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::PostgreSQL)
                | Some(crate::dialects::DialectType::Redshift)
        ) {
            if self.check(TokenType::Var) && self.peek().text.eq_ignore_ascii_case("VARIADIC") {
                self.advance(); // consume VARIADIC
                let expr = self.parse_bitwise_or()?;
                return Ok(Expression::Variadic(Box::new(
                    crate::expressions::Variadic {
                        this: Box::new(expr),
                    },
                )));
            }
        }

        // MySQL charset introducer: _utf8mb4 'string', _latin1 x'hex', etc.
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::MySQL)
                | Some(crate::dialects::DialectType::SingleStore)
                | Some(crate::dialects::DialectType::Doris)
                | Some(crate::dialects::DialectType::StarRocks)
        ) {
            if self.check(TokenType::Var) || self.check(TokenType::Identifier) {
                let text = self.peek().text.to_uppercase();
                if text.starts_with('_') && Self::is_mysql_charset_introducer(&text) {
                    // Check if next token is a string literal or hex string
                    if self.current + 1 < self.tokens.len() {
                        let next_tt = self.tokens[self.current + 1].token_type;
                        if matches!(
                            next_tt,
                            TokenType::String | TokenType::HexString | TokenType::BitString
                        ) {
                            let charset_token = self.advance(); // consume charset name
                            let charset_name = charset_token.text.clone();
                            let literal = self.parse_primary()?; // parse the string/hex literal
                            return Ok(Expression::Introducer(Box::new(
                                crate::expressions::Introducer {
                                    this: Box::new(Expression::Column(
                                        crate::expressions::Column {
                                            name: crate::expressions::Identifier {
                                                name: charset_name,
                                                quoted: false,
                                                trailing_comments: Vec::new(),
                                                span: None,
                                            },
                                            table: None,
                                            join_mark: false,
                                            trailing_comments: Vec::new(),
                                            span: None,
                                            inferred_type: None,
                                        },
                                    )),
                                    expression: Box::new(literal),
                                },
                            )));
                        }
                    }
                }
            }
        }

        // Array literal: [1, 2, 3] or comprehension: [expr FOR var IN iterator]
        if self.match_token(TokenType::LBracket) {
            // Parse empty array: []
            if self.match_token(TokenType::RBracket) {
                return Ok(Expression::ArrayFunc(Box::new(ArrayConstructor {
                    expressions: Vec::new(),
                    bracket_notation: true,
                    use_list_keyword: false,
                })));
            }

            // Parse first expression
            let first_expr = self.parse_expression()?;

            // Check for comprehension syntax: [expr FOR var IN iterator [IF condition]]
            if self.match_token(TokenType::For) {
                // Parse loop variable - typically a simple identifier like 'x'
                let loop_var = self.parse_primary()?;

                // Parse optional position (second variable after comma)
                let position = if self.match_token(TokenType::Comma) {
                    Some(self.parse_primary()?)
                } else {
                    None
                };

                // Expect IN keyword
                if !self.match_token(TokenType::In) {
                    return Err(self.parse_error("Expected IN in comprehension"));
                }

                // Parse iterator expression
                let iterator = self.parse_expression()?;

                // Parse optional condition after IF
                let condition = if self.match_token(TokenType::If) {
                    Some(self.parse_expression()?)
                } else {
                    None
                };

                // Expect closing bracket
                self.expect(TokenType::RBracket)?;

                // Return Comprehension
                return Ok(Expression::Comprehension(Box::new(Comprehension {
                    this: Box::new(first_expr),
                    expression: Box::new(loop_var),
                    position: position.map(Box::new),
                    iterator: Some(Box::new(iterator)),
                    condition: condition.map(Box::new),
                })));
            }

            // Regular array - continue parsing elements
            // ClickHouse allows AS aliases in array: [1 AS a, 2 AS b]
            let first_expr = if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && self.check(TokenType::As)
                && !self.check_next(TokenType::RBracket)
            {
                self.advance(); // consume AS
                let alias = self.expect_identifier()?;
                Expression::Alias(Box::new(Alias::new(first_expr, Identifier::new(alias))))
            } else {
                first_expr
            };
            let mut expressions = vec![first_expr];
            while self.match_token(TokenType::Comma) {
                // Handle trailing comma
                if self.check(TokenType::RBracket) {
                    break;
                }
                let expr = self.parse_expression()?;
                // ClickHouse: handle AS alias on array elements
                let expr = if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) && self.check(TokenType::As)
                    && !self.check_next(TokenType::RBracket)
                {
                    self.advance(); // consume AS
                    let alias = self.expect_identifier()?;
                    Expression::Alias(Box::new(Alias::new(expr, Identifier::new(alias))))
                } else {
                    expr
                };
                expressions.push(expr);
            }
            self.expect(TokenType::RBracket)?;
            return self.maybe_parse_subscript(Expression::ArrayFunc(Box::new(ArrayConstructor {
                expressions,
                bracket_notation: true,
                use_list_keyword: false,
            })));
        }

        // Map/Struct literal with curly braces: {'a': 1, 'b': 2}
        // Or Snowflake wildcard syntax: {*}, {tbl.*}, {* EXCLUDE (...)}, {* ILIKE '...'}
        if self.match_token(TokenType::LBrace) {
            // ClickHouse query parameter: {name: Type}
            // We consumed `{` above, so rewind and let the dedicated parser consume it.
            if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) {
                self.current -= 1;
                if let Some(param) = self.parse_clickhouse_braced_parameter()? {
                    return self.maybe_parse_subscript(param);
                }
                // Not a ClickHouse query parameter, restore position after `{` for map/wildcard parsing.
                self.current += 1;
            }

            // Parse empty map: {}
            if self.match_token(TokenType::RBrace) {
                return self.maybe_parse_subscript(Expression::MapFunc(Box::new(MapConstructor {
                    keys: Vec::new(),
                    values: Vec::new(),
                    curly_brace_syntax: true,
                    with_map_keyword: false,
                })));
            }

            // Check for ODBC escape syntax: {fn function_name(args)}
            // This must be checked before wildcards and map literals
            if self.check_identifier("fn") {
                self.advance(); // consume 'fn'
                                // Parse function call
                let func_name = self.expect_identifier_or_keyword_with_quoted()?;
                self.expect(TokenType::LParen)?;

                // Parse function arguments
                let mut args = Vec::new();
                if !self.check(TokenType::RParen) {
                    loop {
                        args.push(self.parse_expression()?);
                        if !self.match_token(TokenType::Comma) {
                            break;
                        }
                    }
                }
                self.expect(TokenType::RParen)?;
                self.expect(TokenType::RBrace)?;

                // Return as a regular function call (the ODBC escape is just syntax sugar)
                return Ok(Expression::Function(Box::new(Function::new(
                    func_name.name,
                    args,
                ))));
            }

            // Check for ODBC datetime literals: {d'2024-01-01'}, {t'12:00:00'}, {ts'2024-01-01 12:00:00'}
            if self.check(TokenType::Identifier) || self.check(TokenType::Var) {
                let type_text = self.peek().text.to_lowercase();
                if (type_text == "d" || type_text == "t" || type_text == "ts")
                    && self.check_next(TokenType::String)
                {
                    self.advance(); // consume type indicator (d, t, or ts)
                    let value = self.expect_string()?;
                    self.expect(TokenType::RBrace)?;

                    // Return appropriate expression based on type
                    return match type_text.as_str() {
                        "d" => Ok(Expression::Date(Box::new(
                            crate::expressions::UnaryFunc::new(Expression::Literal(
                                crate::expressions::Literal::String(value),
                            )),
                        ))),
                        "t" => Ok(Expression::Time(Box::new(
                            crate::expressions::UnaryFunc::new(Expression::Literal(
                                crate::expressions::Literal::String(value),
                            )),
                        ))),
                        "ts" => Ok(Expression::Timestamp(Box::new(
                            crate::expressions::TimestampFunc {
                                this: Some(Box::new(Expression::Literal(
                                    crate::expressions::Literal::String(value),
                                ))),
                                zone: None,
                                with_tz: None,
                                safe: None,
                            },
                        ))),
                        _ => {
                            Err(self
                                .parse_error(format!("Unknown ODBC datetime type: {}", type_text)))
                        }
                    };
                }
            }

            // Check for Snowflake wildcard syntax: {*}, {tbl.*}, {* EXCLUDE (...)}, {* ILIKE '...'}
            // Pattern: either {*...} or {identifier/var followed by .*}
            // Note: Identifiers may be tokenized as Var or Identifier
            let is_table_star = (self.check(TokenType::Identifier) || self.check(TokenType::Var))
                && self.check_next(TokenType::Dot)
                && self
                    .tokens
                    .get(self.current + 2)
                    .map(|t| t.token_type == TokenType::Star)
                    .unwrap_or(false);
            let is_wildcard = self.check(TokenType::Star) || is_table_star;

            if is_wildcard {
                // Parse the wildcard expression
                let wildcard_expr = if self.match_token(TokenType::Star) {
                    // {*} or {* EXCLUDE ...} or {* ILIKE ...}
                    // Check for ILIKE first since it's different from standard star modifiers
                    if self.check_keyword_text("ILIKE") {
                        self.advance();
                        let pattern = self.parse_expression()?;
                        // Create an ILike expression with Star as left side
                        Expression::ILike(Box::new(LikeOp {
                            left: Expression::Star(Star {
                                table: None,
                                except: None,
                                replace: None,
                                rename: None,
                                trailing_comments: Vec::new(),
                                span: None,
                            }),
                            right: pattern,
                            escape: None,
                            quantifier: None,
                            inferred_type: None,
                        }))
                    } else {
                        // {*} or {* EXCLUDE ...}
                        let star = self.parse_star_modifiers(None)?;
                        Expression::Star(star)
                    }
                } else {
                    // {tbl.*} - table qualified wildcard
                    let table_name = self.expect_identifier_or_keyword_with_quoted()?;
                    self.expect(TokenType::Dot)?;
                    self.expect(TokenType::Star)?;
                    let star = self.parse_star_modifiers(Some(table_name))?;
                    Expression::Star(star)
                };

                self.expect(TokenType::RBrace)?;

                // Wrap in BracedWildcard for generation
                return Ok(Expression::BracedWildcard(Box::new(wildcard_expr)));
            }

            // Parse key-value pairs: key: value, ...
            let mut keys = Vec::new();
            let mut values = Vec::new();
            loop {
                let key = self.parse_expression()?;
                self.expect(TokenType::Colon)?;
                let value = self.parse_expression()?;
                keys.push(key);
                values.push(value);
                if !self.match_token(TokenType::Comma) {
                    break;
                }
                // Handle trailing comma
                if self.check(TokenType::RBrace) {
                    break;
                }
            }
            self.expect(TokenType::RBrace)?;
            return self.maybe_parse_subscript(Expression::MapFunc(Box::new(MapConstructor {
                keys,
                values,
                curly_brace_syntax: true,
                with_map_keyword: false,
            })));
        }

        // Parenthesized expression or subquery
        if self.match_token(TokenType::LParen) {
            // Capture comments from the ( token (e.g., "(/* comment */ 1)")
            let lparen_comments = self.previous_trailing_comments();

            // Empty parens () — could be empty tuple or zero-param lambda () -> body
            if self.check(TokenType::RParen) {
                self.advance(); // consume )
                                // Check for lambda: () -> body
                if self.match_token(TokenType::Arrow) || self.match_token(TokenType::FArrow) {
                    let body = self.parse_expression()?;
                    return Ok(Expression::Lambda(Box::new(LambdaExpr {
                        parameters: Vec::new(),
                        body,
                        colon: false,
                        parameter_types: Vec::new(),
                    })));
                }
                // Otherwise empty tuple
                return self.maybe_parse_subscript(Expression::Tuple(Box::new(Tuple {
                    expressions: Vec::new(),
                })));
            }

            // Check if this is a VALUES expression inside parens: (VALUES ...)
            if self.check(TokenType::Values) {
                let values = self.parse_values()?;
                self.expect(TokenType::RParen)?;
                return Ok(Expression::Subquery(Box::new(Subquery {
                    this: values,
                    alias: None,
                    column_aliases: Vec::new(),
                    order_by: None,
                    limit: None,
                    offset: None,
                    distribute_by: None,
                    sort_by: None,
                    cluster_by: None,
                    lateral: false,
                    modifiers_inside: false,
                    trailing_comments: self.previous_trailing_comments(),
                    inferred_type: None,
                })));
            }

            // Check if this is a subquery (SELECT, WITH, DuckDB FROM-first, or ClickHouse EXPLAIN)
            let is_explain_subquery = self.check(TokenType::Var)
                && self.peek().text.eq_ignore_ascii_case("EXPLAIN")
                && self.peek_nth(1).map_or(false, |t| {
                    // EXPLAIN followed by statement/style keywords is a subquery
                    matches!(
                        t.token_type,
                        TokenType::Select
                            | TokenType::Insert
                            | TokenType::Create
                            | TokenType::Alter
                            | TokenType::Drop
                            | TokenType::Set
                            | TokenType::System
                            | TokenType::Table
                    ) || matches!(
                        t.text.to_uppercase().as_str(),
                        "SYNTAX" | "AST" | "PLAN" | "PIPELINE" | "ESTIMATE" | "CURRENT" | "QUERY"
                    ) || (t.token_type == TokenType::Var
                        && self
                            .peek_nth(2)
                            .map_or(false, |t2| t2.token_type == TokenType::Eq))
                });
            // ClickHouse: (from, to, ...) -> body is a tuple-lambda with keyword params
            // Detect pattern: (keyword/ident, keyword/ident, ...) ->
            if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) {
                let mut look = self.current;
                let mut is_tuple_lambda = true;
                let mut param_count = 0;
                loop {
                    if look >= self.tokens.len() {
                        is_tuple_lambda = false;
                        break;
                    }
                    let tt = self.tokens[look].token_type;
                    if tt == TokenType::Identifier
                        || tt == TokenType::Var
                        || tt == TokenType::QuotedIdentifier
                        || tt.is_keyword()
                    {
                        param_count += 1;
                        look += 1;
                    } else {
                        is_tuple_lambda = false;
                        break;
                    }
                    if look >= self.tokens.len() {
                        is_tuple_lambda = false;
                        break;
                    }
                    if self.tokens[look].token_type == TokenType::Comma {
                        look += 1;
                    } else if self.tokens[look].token_type == TokenType::RParen {
                        look += 1;
                        break;
                    } else {
                        is_tuple_lambda = false;
                        break;
                    }
                }
                if is_tuple_lambda
                    && param_count >= 1
                    && look < self.tokens.len()
                    && self.tokens[look].token_type == TokenType::Arrow
                {
                    // Parse as lambda: consume params
                    let mut params = Vec::new();
                    loop {
                        let tok = self.advance();
                        params.push(Identifier::new(tok.text));
                        if self.match_token(TokenType::Comma) {
                            continue;
                        }
                        break;
                    }
                    self.expect(TokenType::RParen)?;
                    self.expect(TokenType::Arrow)?;
                    let body = self.parse_expression()?;
                    return Ok(Expression::Lambda(Box::new(LambdaExpr {
                        parameters: params,
                        body,
                        colon: false,
                        parameter_types: Vec::new(),
                    })));
                }
            }
            if self.check(TokenType::Select)
                || self.check(TokenType::With)
                || self.check(TokenType::From)
                || is_explain_subquery
            {
                let query = self.parse_statement()?;

                // Parse LIMIT/OFFSET that may appear after set operations INSIDE the parentheses
                // e.g., (SELECT 1 EXCEPT (SELECT 2) LIMIT 1)
                let limit = if self.match_token(TokenType::Limit) {
                    Some(Limit {
                        this: self.parse_expression()?,
                        percent: false,
                        comments: Vec::new(),
                    })
                } else {
                    None
                };
                let offset = if self.match_token(TokenType::Offset) {
                    Some(Offset {
                        this: self.parse_expression()?,
                        rows: None,
                    })
                } else {
                    None
                };

                self.expect(TokenType::RParen)?;

                // Wrap in Subquery to preserve parentheses in set operations
                let subquery = if limit.is_some() || offset.is_some() {
                    // If we have limit/offset INSIDE the parens, set modifiers_inside = true
                    Expression::Subquery(Box::new(Subquery {
                        this: query,
                        alias: None,
                        column_aliases: Vec::new(),
                        order_by: None,
                        limit,
                        offset,
                        distribute_by: None,
                        sort_by: None,
                        cluster_by: None,
                        lateral: false,
                        modifiers_inside: true,
                        trailing_comments: self.previous_trailing_comments(),
                        inferred_type: None,
                    }))
                } else {
                    Expression::Subquery(Box::new(Subquery {
                        this: query,
                        alias: None,
                        column_aliases: Vec::new(),
                        order_by: None,
                        limit: None,
                        offset: None,
                        distribute_by: None,
                        sort_by: None,
                        cluster_by: None,
                        lateral: false,
                        modifiers_inside: false,
                        trailing_comments: self.previous_trailing_comments(),
                        inferred_type: None,
                    }))
                };

                // Check for set operations after the subquery (e.g., (SELECT 1) UNION (SELECT 2))
                let set_result = self.parse_set_operation(subquery)?;

                // Only parse ORDER BY/LIMIT/OFFSET after set operations if there WAS a set operation
                // (for cases like ((SELECT 0) UNION (SELECT 1) ORDER BY 1 OFFSET 1))
                // If there's no set operation, we should NOT consume these - they belong to outer context
                let had_set_operation = matches!(
                    &set_result,
                    Expression::Union(_) | Expression::Intersect(_) | Expression::Except(_)
                );

                let result = if had_set_operation {
                    let order_by = if self.check(TokenType::Order) {
                        self.expect(TokenType::Order)?;
                        self.expect(TokenType::By)?;
                        Some(self.parse_order_by()?)
                    } else {
                        None
                    };
                    let limit_after = if self.match_token(TokenType::Limit) {
                        Some(Limit {
                            this: self.parse_expression()?,
                            percent: false,
                            comments: Vec::new(),
                        })
                    } else {
                        None
                    };
                    let offset_after = if self.match_token(TokenType::Offset) {
                        Some(Offset {
                            this: self.parse_expression()?,
                            rows: None,
                        })
                    } else {
                        None
                    };

                    // If we have any modifiers, wrap in a Subquery with the modifiers OUTSIDE the paren
                    if order_by.is_some() || limit_after.is_some() || offset_after.is_some() {
                        Expression::Subquery(Box::new(Subquery {
                            this: set_result,
                            alias: None,
                            column_aliases: Vec::new(),
                            order_by,
                            limit: limit_after,
                            offset: offset_after,
                            lateral: false,
                            modifiers_inside: false,
                            trailing_comments: Vec::new(),
                            distribute_by: None,
                            sort_by: None,
                            cluster_by: None,
                            inferred_type: None,
                        }))
                    } else {
                        set_result
                    }
                } else {
                    set_result
                };
                // Allow postfix operators on subquery expressions (e.g., (SELECT 1, 2).1 for tuple element access)
                return self.maybe_parse_subscript(result);
            }

            // Check if this starts with another paren that might be a subquery
            // e.g., ((SELECT 1))
            if self.check(TokenType::LParen) {
                let expr = self.parse_expression()?;

                // Handle aliasing of expression inside outer parens (e.g., ((a, b) AS c))
                let first_expr = if self.match_token(TokenType::As) {
                    let alias = self.expect_identifier_or_alias_keyword_with_quoted()?;
                    Expression::Alias(Box::new(Alias::new(expr, alias)))
                } else {
                    expr
                };

                // Check for tuple of tuples: ((1, 2), (3, 4))
                // Also handles ClickHouse: ((SELECT 1) AS x, (SELECT 2) AS y)
                if self.match_token(TokenType::Comma) {
                    let mut expressions = vec![first_expr];
                    loop {
                        if self.check(TokenType::RParen) {
                            break;
                        } // trailing comma
                        let elem = self.parse_expression()?;
                        // Handle AS alias after each element (ClickHouse tuple CTE pattern)
                        let elem = if self.match_token(TokenType::As) {
                            let alias = self.expect_identifier_or_keyword()?;
                            Expression::Alias(Box::new(Alias::new(elem, Identifier::new(alias))))
                        } else {
                            elem
                        };
                        expressions.push(elem);
                        if !self.match_token(TokenType::Comma) {
                            break;
                        }
                    }
                    self.expect(TokenType::RParen)?;
                    let tuple_expr = Expression::Tuple(Box::new(Tuple { expressions }));
                    return self.maybe_parse_subscript(tuple_expr);
                }

                let result = first_expr;

                self.expect(TokenType::RParen)?;
                let mut nested_paren_comments = lparen_comments.clone();
                nested_paren_comments.extend(self.previous_trailing_comments());
                // Check for set operations after parenthesized expression
                if self.check(TokenType::Union)
                    || self.check(TokenType::Intersect)
                    || self.check(TokenType::Except)
                {
                    // This is a set operation - need to handle specially
                    if let Expression::Subquery(subq) = &result {
                        let set_result = self.parse_set_operation(subq.this.clone())?;

                        // Parse ORDER BY/LIMIT/OFFSET after set operations
                        let order_by = if self.check(TokenType::Order) {
                            self.expect(TokenType::Order)?;
                            self.expect(TokenType::By)?;
                            Some(self.parse_order_by()?)
                        } else {
                            None
                        };
                        let limit = if self.match_token(TokenType::Limit) {
                            Some(Limit {
                                this: self.parse_expression()?,
                                percent: false,
                                comments: Vec::new(),
                            })
                        } else {
                            None
                        };
                        let offset = if self.match_token(TokenType::Offset) {
                            Some(Offset {
                                this: self.parse_expression()?,
                                rows: None,
                            })
                        } else {
                            None
                        };

                        return Ok(Expression::Subquery(Box::new(Subquery {
                            this: set_result,
                            alias: None,
                            column_aliases: Vec::new(),
                            order_by,
                            limit,
                            offset,
                            lateral: false,
                            modifiers_inside: false,
                            trailing_comments: Vec::new(),
                            distribute_by: None,
                            sort_by: None,
                            cluster_by: None,
                            inferred_type: None,
                        })));
                    }
                }
                return self.maybe_parse_over(Expression::Paren(Box::new(Paren {
                    this: result,
                    trailing_comments: nested_paren_comments,
                })));
            }

            let expr = self.parse_expression()?;

            // Check for AS alias on the first element (e.g., (x AS y, ...))
            let first_expr = if self.match_token(TokenType::As) {
                let alias = self.expect_identifier_or_keyword_with_quoted()?;
                Expression::Alias(Box::new(Alias::new(expr, alias)))
            } else {
                expr
            };

            // Check for tuple (multiple expressions separated by commas)
            if self.match_token(TokenType::Comma) {
                let mut expressions = vec![first_expr];
                // ClickHouse: trailing comma creates single-element tuple, e.g., (1,)
                if self.check(TokenType::RParen) {
                    self.advance(); // consume )
                    let tuple_expr = Expression::Tuple(Box::new(Tuple { expressions }));
                    return self.maybe_parse_subscript(tuple_expr);
                }
                // Parse remaining tuple elements, each can have AS alias
                loop {
                    let elem = self.parse_expression()?;
                    let elem_with_alias = if self.match_token(TokenType::As) {
                        let alias = self.expect_identifier_or_keyword_with_quoted()?;
                        Expression::Alias(Box::new(Alias::new(elem, alias)))
                    } else {
                        elem
                    };
                    expressions.push(elem_with_alias);
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                    // ClickHouse: trailing comma in multi-element tuple, e.g., (1, 2,)
                    if self.check(TokenType::RParen) {
                        break;
                    }
                }

                self.expect(TokenType::RParen)?;

                // Check for lambda expression: (a, b) -> body
                if self.match_token(TokenType::Arrow) {
                    let parameters = expressions
                        .into_iter()
                        .filter_map(|e| {
                            if let Expression::Column(c) = e {
                                Some(c.name)
                            } else if let Expression::Identifier(id) = e {
                                Some(id)
                            } else {
                                None
                            }
                        })
                        .collect();
                    let body = self.parse_expression()?;
                    return Ok(Expression::Lambda(Box::new(LambdaExpr {
                        parameters,
                        body,
                        colon: false,
                        parameter_types: Vec::new(),
                    })));
                }

                // Check for optional alias on the whole tuple
                // But NOT when AS is followed by a type constructor like Tuple(a Int8, ...)
                // or STRUCT<a TINYINT, ...> which would be part of a CAST expression: CAST((1, 2) AS Tuple(a Int8, b Int16))
                // Also NOT when AS is followed by a type name then ) like: CAST((1, 2) AS String)
                let tuple_expr = Expression::Tuple(Box::new(Tuple { expressions }));
                let result = if self.check(TokenType::As) {
                    // Look ahead: AS + type_keyword + ( or < → likely a type, not an alias
                    let after_as = self.current + 1;
                    let after_ident = self.current + 2;
                    let is_type_constructor = after_ident < self.tokens.len()
                        && (self.tokens[after_as].token_type == TokenType::Identifier
                            || self.tokens[after_as].token_type == TokenType::Var
                            || self.tokens[after_as].token_type == TokenType::Nullable
                            || self.tokens[after_as].token_type == TokenType::Struct
                            || self.tokens[after_as].token_type == TokenType::Array)
                        && (self.tokens[after_ident].token_type == TokenType::LParen
                            || self.tokens[after_ident].token_type == TokenType::Lt);
                    // Check if AS is followed by identifier/keyword then ), indicating CAST(tuple AS Type)
                    let is_cast_type = after_ident < self.tokens.len()
                        && (self.tokens[after_as].token_type == TokenType::Identifier
                            || self.tokens[after_as].token_type == TokenType::Var
                            || self.tokens[after_as].token_type.is_keyword())
                        && self.tokens[after_ident].token_type == TokenType::RParen;
                    if is_type_constructor || is_cast_type {
                        tuple_expr
                    } else {
                        self.advance(); // consume AS
                        let alias = self.expect_identifier()?;
                        Expression::Alias(Box::new(Alias::new(tuple_expr, Identifier::new(alias))))
                    }
                } else {
                    tuple_expr
                };

                // Allow postfix operators on tuple expressions (e.g., ('a', 'b').1 for tuple element access)
                return self.maybe_parse_subscript(result);
            }

            // ClickHouse: (x -> body) — lambda inside parentheses
            if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && self.match_token(TokenType::Arrow)
            {
                let parameters = if let Expression::Column(c) = first_expr {
                    vec![c.name]
                } else if let Expression::Identifier(id) = first_expr {
                    vec![id]
                } else {
                    return Err(self.parse_error("Expected identifier as lambda parameter"));
                };
                let body = self.parse_expression()?;
                self.expect(TokenType::RParen)?;
                return Ok(Expression::Paren(Box::new(Paren {
                    this: Expression::Lambda(Box::new(LambdaExpr {
                        parameters,
                        body,
                        colon: false,
                        parameter_types: Vec::new(),
                    })),
                    trailing_comments: Vec::new(),
                })));
            }

            self.expect(TokenType::RParen)?;
            // Combine comments from ( and ) tokens
            let mut paren_comments = lparen_comments.clone();
            paren_comments.extend(self.previous_trailing_comments());

            // Check for lambda expression: (x) -> body or single identifier case
            if self.match_token(TokenType::Arrow) {
                // first_expr should be a single identifier for the parameter
                let parameters = if let Expression::Column(c) = first_expr {
                    vec![c.name]
                } else if let Expression::Identifier(id) = first_expr {
                    vec![id]
                } else {
                    return Err(self.parse_error("Expected identifier as lambda parameter"));
                };
                let body = self.parse_expression()?;
                return Ok(Expression::Lambda(Box::new(LambdaExpr {
                    parameters,
                    body,
                    colon: false,
                    parameter_types: Vec::new(),
                })));
            }

            return self.maybe_parse_over(Expression::Paren(Box::new(Paren {
                this: first_expr,
                trailing_comments: paren_comments,
            })));
        }

        // NULL
        if self.match_token(TokenType::Null) {
            return Ok(Expression::Null(Null));
        }

        // TRUE
        if self.match_token(TokenType::True) {
            return Ok(Expression::Boolean(BooleanLiteral { value: true }));
        }

        // FALSE
        if self.match_token(TokenType::False) {
            return Ok(Expression::Boolean(BooleanLiteral { value: false }));
        }

        // LAMBDA expression (DuckDB syntax: LAMBDA x : expr)
        if self.check(TokenType::Lambda) {
            if let Some(lambda) = self.parse_lambda()? {
                return Ok(lambda);
            }
        }

        // CASE expression - but not if followed by DOT (then it's an identifier like case.column)
        if self.check(TokenType::Case) && !self.check_next(TokenType::Dot) {
            let case_expr = self.parse_case()?;
            return self.maybe_parse_over(case_expr);
        }

        // CAST expression
        if self.check(TokenType::Cast) {
            let cast_expr = self.parse_cast()?;
            return self.maybe_parse_subscript(cast_expr);
        }

        // TRY_CAST expression
        if self.check(TokenType::TryCast) {
            let cast_expr = self.parse_try_cast()?;
            return self.maybe_parse_subscript(cast_expr);
        }

        // SAFE_CAST expression (BigQuery)
        if self.check(TokenType::SafeCast) {
            let cast_expr = self.parse_safe_cast()?;
            return self.maybe_parse_subscript(cast_expr);
        }

        // EXISTS - either subquery predicate EXISTS(SELECT ...) or Hive array function EXISTS(array, lambda)
        // ClickHouse: EXISTS without ( is a column name/identifier
        if self.check(TokenType::Exists)
            && matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            )
            && !self.check_next(TokenType::LParen)
        {
            let tok = self.advance();
            return Ok(Expression::Identifier(Identifier::new(tok.text)));
        }
        if self.match_token(TokenType::Exists) {
            self.expect(TokenType::LParen)?;

            // Check if this is a subquery EXISTS (SELECT, WITH, or FROM for DuckDB)
            // ClickHouse: also handle EXISTS((SELECT ...)) with double parens
            if self.check(TokenType::Select)
                || self.check(TokenType::With)
                || self.check(TokenType::From)
                || (self.check(TokenType::LParen)
                    && self
                        .peek_nth(1)
                        .map(|t| {
                            matches!(
                                t.token_type,
                                TokenType::Select | TokenType::With | TokenType::From
                            )
                        })
                        .unwrap_or(false))
            {
                let query = self.parse_statement()?;
                self.expect(TokenType::RParen)?;
                return Ok(Expression::Exists(Box::new(Exists {
                    this: query,
                    not: false,
                })));
            }

            // Otherwise it's Hive's array EXISTS function: EXISTS(array, lambda_predicate)
            // This function checks if any element in the array matches the predicate
            let array_expr = self.parse_expression()?;
            self.expect(TokenType::Comma)?;
            let predicate = self.parse_expression()?;
            self.expect(TokenType::RParen)?;
            return Ok(Expression::Function(Box::new(Function {
                name: "EXISTS".to_string(),
                args: vec![array_expr, predicate],
                distinct: false,
                trailing_comments: Vec::new(),
                use_bracket_syntax: false,
                no_parens: false,
                quoted: false,
                span: None,
                inferred_type: None,
            })));
        }

        // INTERVAL expression or identifier
        if self.check(TokenType::Interval) {
            if let Some(interval_expr) = self.try_parse_interval()? {
                return Ok(interval_expr);
            }
            // INTERVAL is used as an identifier
            let token = self.advance();
            return Ok(Expression::Identifier(Identifier::new(token.text)));
        }

        // DATE literal: DATE '2024-01-15' or DATE function: DATE(expr)
        if self.check(TokenType::Date) {
            let token = self.advance();
            let original_text = token.text.clone();
            if self.check(TokenType::String) {
                let str_token = self.advance();
                if self.config.dialect.is_none() {
                    // Generic (no dialect): DATE 'literal' -> CAST('literal' AS DATE)
                    return Ok(Expression::Cast(Box::new(Cast {
                        this: Expression::Literal(Literal::String(str_token.text)),
                        to: DataType::Date,
                        trailing_comments: Vec::new(),
                        double_colon_syntax: false,
                        format: None,
                        default: None,
                        inferred_type: None,
                    })));
                }
                return Ok(Expression::Literal(Literal::Date(str_token.text)));
            }
            // Check for DATE() function call
            if self.match_token(TokenType::LParen) {
                let func_expr = self.parse_typed_function(&original_text, "DATE", false)?;
                return self.maybe_parse_over(func_expr);
            }
            // Fallback to DATE as identifier/type - preserve original case
            return Ok(Expression::Identifier(Identifier::new(original_text)));
        }

        // TIME literal: TIME '10:30:00' or TIME function: TIME(expr)
        if self.check(TokenType::Time) {
            let token = self.advance();
            let original_text = token.text.clone();
            if self.check(TokenType::String) {
                let str_token = self.advance();
                return Ok(Expression::Literal(Literal::Time(str_token.text)));
            }
            // Check for TIME() function call
            if self.match_token(TokenType::LParen) {
                let func_expr = self.parse_typed_function(&original_text, "TIME", false)?;
                return self.maybe_parse_over(func_expr);
            }
            // Fallback to TIME as identifier/type - preserve original case
            return self
                .maybe_parse_subscript(Expression::Identifier(Identifier::new(original_text)));
        }

        // TIMESTAMP literal: TIMESTAMP '2024-01-15 10:30:00' or TIMESTAMP function: TIMESTAMP(expr)
        // Also handles TIMESTAMP(n) WITH TIME ZONE as a data type expression
        if self.check(TokenType::Timestamp) {
            let token = self.advance();
            let original_text = token.text.clone();
            if self.check(TokenType::String) {
                let str_token = self.advance();
                if self.config.dialect.is_none() {
                    // Generic (no dialect): TIMESTAMP 'literal' -> CAST('literal' AS TIMESTAMP)
                    return Ok(Expression::Cast(Box::new(Cast {
                        this: Expression::Literal(Literal::String(str_token.text)),
                        to: DataType::Timestamp {
                            precision: None,
                            timezone: false,
                        },
                        trailing_comments: Vec::new(),
                        double_colon_syntax: false,
                        format: None,
                        default: None,
                        inferred_type: None,
                    })));
                }
                // Dialect-specific: keep as Literal::Timestamp for dialect transforms
                return Ok(Expression::Literal(Literal::Timestamp(str_token.text)));
            }
            // Check for TIMESTAMP(n) WITH/WITHOUT TIME ZONE or TIMESTAMP(n) 'literal' as data type
            // This is a data type, not a function call
            if self.check(TokenType::LParen) {
                // Look ahead to see if this is TIMESTAMP(number) WITH/WITHOUT/String (data type)
                // vs TIMESTAMP(expr) (function call)
                let is_data_type = self.check_next(TokenType::Number) && {
                    // Check if after (number) there's WITH, WITHOUT, or String literal
                    let mut lookahead = self.current + 2;
                    // Skip the number
                    while lookahead < self.tokens.len()
                        && self.tokens[lookahead].token_type == TokenType::RParen
                    {
                        lookahead += 1;
                        break;
                    }
                    // Check for WITH, WITHOUT, or String after the closing paren
                    lookahead < self.tokens.len()
                        && (self.tokens[lookahead].token_type == TokenType::With
                            || self.tokens[lookahead].text.to_uppercase() == "WITHOUT"
                            || self.tokens[lookahead].token_type == TokenType::String)
                };

                if is_data_type {
                    // Parse as data type: TIMESTAMP(precision) [WITH/WITHOUT TIME ZONE] ['literal']
                    self.advance(); // consume (
                    let precision = Some(self.expect_number()? as u32);
                    self.expect(TokenType::RParen)?;

                    let data_type = if self.match_token(TokenType::With) {
                        if self.match_token(TokenType::Local) {
                            // WITH LOCAL TIME ZONE -> TIMESTAMPLTZ
                            self.match_keyword("TIME");
                            self.match_keyword("ZONE");
                            DataType::Custom {
                                name: format!("TIMESTAMPLTZ({})", precision.unwrap()),
                            }
                        } else {
                            self.match_keyword("TIME");
                            self.match_keyword("ZONE");
                            DataType::Timestamp {
                                precision,
                                timezone: true,
                            }
                        }
                    } else if self.match_keyword("WITHOUT") {
                        self.match_keyword("TIME");
                        self.match_keyword("ZONE");
                        DataType::Timestamp {
                            precision,
                            timezone: false,
                        }
                    } else {
                        DataType::Timestamp {
                            precision,
                            timezone: false,
                        }
                    };

                    // Check for following string literal -> wrap in CAST
                    if self.check(TokenType::String) {
                        let str_token = self.advance();
                        return Ok(Expression::Cast(Box::new(Cast {
                            this: Expression::Literal(Literal::String(str_token.text)),
                            to: data_type,
                            trailing_comments: Vec::new(),
                            double_colon_syntax: false,
                            format: None,
                            default: None,
                            inferred_type: None,
                        })));
                    }

                    return Ok(Expression::DataType(data_type));
                }

                // Otherwise parse as function call
                self.advance(); // consume (
                let func_expr = self.parse_typed_function(&original_text, "TIMESTAMP", false)?;
                return self.maybe_parse_over(func_expr);
            }
            // Check for TIMESTAMP WITH/WITHOUT TIME ZONE (no precision) as data type
            // Use lookahead to verify WITH is followed by TIME (not WITH FILL, WITH TOTALS, etc.)
            if (self.check(TokenType::With)
                && self.peek_nth(1).map_or(false, |t| {
                    t.text.eq_ignore_ascii_case("TIME") || t.text.eq_ignore_ascii_case("LOCAL")
                }))
                || self.check_keyword_text("WITHOUT")
            {
                let data_type = if self.match_token(TokenType::With) {
                    if self.match_token(TokenType::Local) {
                        // WITH LOCAL TIME ZONE -> TIMESTAMPLTZ
                        self.match_keyword("TIME");
                        self.match_keyword("ZONE");
                        DataType::Custom {
                            name: "TIMESTAMPLTZ".to_string(),
                        }
                    } else {
                        self.match_keyword("TIME");
                        self.match_keyword("ZONE");
                        DataType::Timestamp {
                            precision: None,
                            timezone: true,
                        }
                    }
                } else if self.match_keyword("WITHOUT") {
                    self.match_keyword("TIME");
                    self.match_keyword("ZONE");
                    DataType::Timestamp {
                        precision: None,
                        timezone: false,
                    }
                } else {
                    DataType::Timestamp {
                        precision: None,
                        timezone: false,
                    }
                };

                // Check for following string literal -> wrap in CAST
                if self.check(TokenType::String) {
                    let str_token = self.advance();
                    return Ok(Expression::Cast(Box::new(Cast {
                        this: Expression::Literal(Literal::String(str_token.text)),
                        to: data_type,
                        trailing_comments: Vec::new(),
                        double_colon_syntax: false,
                        format: None,
                        default: None,
                        inferred_type: None,
                    })));
                }

                return Ok(Expression::DataType(data_type));
            }
            // Fallback to TIMESTAMP as identifier/type - preserve original case
            return Ok(Expression::Identifier(Identifier::new(original_text)));
        }

        // DATETIME literal: DATETIME '2024-01-15 10:30:00' or DATETIME function: DATETIME(expr)
        if self.check(TokenType::DateTime) {
            let token = self.advance();
            let original_text = token.text.clone();
            if self.check(TokenType::String) {
                let str_token = self.advance();
                return Ok(Expression::Literal(Literal::Datetime(str_token.text)));
            }
            // Check for DATETIME() function call
            if self.match_token(TokenType::LParen) {
                let func_expr = self.parse_typed_function(&original_text, "DATETIME", false)?;
                return self.maybe_parse_over(func_expr);
            }
            // Fallback to DATETIME as identifier/type - preserve original case
            return Ok(Expression::Identifier(Identifier::new(original_text)));
        }

        // ROW() function (window function for row number)
        if self.check(TokenType::Row) && self.check_next(TokenType::LParen) {
            self.advance(); // consume ROW
            self.expect(TokenType::LParen)?;
            // ROW() typically takes no arguments
            let args = if !self.check(TokenType::RParen) {
                self.parse_expression_list()?
            } else {
                Vec::new()
            };
            self.expect(TokenType::RParen)?;
            let func_expr = Expression::Function(Box::new(Function {
                name: "ROW".to_string(),
                args,
                distinct: false,
                trailing_comments: Vec::new(),
                use_bracket_syntax: false,
                no_parens: false,
                quoted: false,
                span: None,
                inferred_type: None,
            }));
            return self.maybe_parse_over(func_expr);
        }

        // Number - support postfix operators like ::type
        if self.check(TokenType::Number) {
            let token = self.advance();
            if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::MySQL)
            ) {
                let text = token.text.as_str();
                if text.len() > 2
                    && (text.starts_with("0x") || text.starts_with("0X"))
                    && !text[2..].chars().all(|c| c.is_ascii_hexdigit())
                {
                    let ident = Expression::Identifier(Identifier {
                        name: token.text,
                        quoted: true,
                        trailing_comments: Vec::new(),
                        span: None,
                    });
                    return self.maybe_parse_subscript(ident);
                }
            }
            if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::Teradata)
            ) && token.text == "0"
            {
                if let Some(next) = self.tokens.get(self.current) {
                    let is_adjacent = token.span.end == next.span.start;
                    let next_text = next.text.as_str();
                    let is_hex_prefix = next_text.starts_with('x') || next_text.starts_with('X');
                    if is_adjacent
                        && matches!(next.token_type, TokenType::Identifier | TokenType::Var)
                        && is_hex_prefix
                        && next_text.len() > 1
                        && next_text[1..].chars().all(|c| c.is_ascii_hexdigit())
                    {
                        // Consume the hex suffix token and emit a HexString literal
                        let hex_token = self.advance();
                        let hex = hex_token.text[1..].to_string();
                        let literal = Expression::Literal(Literal::HexString(hex));
                        return self.maybe_parse_subscript(literal);
                    }
                }
            }
            if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) {
                if let Some(next) = self.tokens.get(self.current) {
                    let is_adjacent = token.span.end == next.span.start;
                    if is_adjacent
                        && matches!(next.token_type, TokenType::Identifier | TokenType::Var)
                        && next.text.starts_with('_')
                    {
                        let suffix = next.text.clone();
                        self.advance(); // consume suffix token
                        let combined = format!("{}{}", token.text, suffix);
                        let literal = Expression::Literal(Literal::Number(combined));
                        return self.maybe_parse_subscript(literal);
                    }
                }
            }
            // Check for numeric literal suffix encoded as "number::TYPE" by tokenizer
            let literal = if let Some(sep_pos) = token.text.find("::") {
                let num_part = &token.text[..sep_pos];
                let type_name = &token.text[sep_pos + 2..];
                let num_expr = Expression::Literal(Literal::Number(num_part.to_string()));
                let data_type = match type_name {
                    "BIGINT" => crate::expressions::DataType::BigInt { length: None },
                    "SMALLINT" => crate::expressions::DataType::SmallInt { length: None },
                    "TINYINT" => crate::expressions::DataType::TinyInt { length: None },
                    "DOUBLE" => crate::expressions::DataType::Double {
                        precision: None,
                        scale: None,
                    },
                    "FLOAT" => crate::expressions::DataType::Float {
                        precision: None,
                        scale: None,
                        real_spelling: false,
                    },
                    "DECIMAL" => crate::expressions::DataType::Decimal {
                        precision: None,
                        scale: None,
                    },
                    _ => crate::expressions::DataType::Custom {
                        name: type_name.to_string(),
                    },
                };
                Expression::Cast(Box::new(crate::expressions::Cast {
                    this: num_expr,
                    to: data_type,
                    trailing_comments: Vec::new(),
                    double_colon_syntax: false,
                    format: None,
                    default: None,
                    inferred_type: None,
                }))
            } else {
                Expression::Literal(Literal::Number(token.text))
            };
            return self.maybe_parse_subscript(literal);
        }

        // String - support postfix operators like ::type, ->, ->>
        // Also handle adjacent string literals (SQL standard) which concatenate: 'x' 'y' 'z' -> CONCAT('x', 'y', 'z')
        if self.check(TokenType::String) {
            let token = self.advance();
            let first_literal = Expression::Literal(Literal::String(token.text));

            // Check for adjacent string literals (PostgreSQL and SQL standard feature)
            // 'x' 'y' 'z' should be treated as string concatenation
            if self.check(TokenType::String) {
                let mut expressions = vec![first_literal];
                while self.check(TokenType::String) {
                    let next_token = self.advance();
                    expressions.push(Expression::Literal(Literal::String(next_token.text)));
                }
                // Create CONCAT function call with all adjacent strings
                let concat_func =
                    Expression::Function(Box::new(Function::new("CONCAT", expressions)));
                return self.maybe_parse_subscript(concat_func);
            }

            return self.maybe_parse_subscript(first_literal);
        }

        // Dollar-quoted string: $$...$$ or $tag$...$tag$ -- preserve as DollarString
        // so the generator can handle dialect-specific conversion
        if self.check(TokenType::DollarString) {
            let token = self.advance();
            let literal = Expression::Literal(Literal::DollarString(token.text));
            return self.maybe_parse_subscript(literal);
        }

        // Triple-quoted string with double quotes: """..."""
        if self.check(TokenType::TripleDoubleQuotedString) {
            let token = self.advance();
            let literal = Expression::Literal(Literal::TripleQuotedString(token.text, '"'));
            return self.maybe_parse_subscript(literal);
        }

        // Triple-quoted string with single quotes: '''...'''
        if self.check(TokenType::TripleSingleQuotedString) {
            let token = self.advance();
            let literal = Expression::Literal(Literal::TripleQuotedString(token.text, '\''));
            return self.maybe_parse_subscript(literal);
        }

        // National String (N'...')
        if self.check(TokenType::NationalString) {
            let token = self.advance();
            let literal = Expression::Literal(Literal::NationalString(token.text));
            return self.maybe_parse_subscript(literal);
        }

        // Hex String (X'...')
        if self.check(TokenType::HexString) {
            let token = self.advance();
            let literal = Expression::Literal(Literal::HexString(token.text));
            return self.maybe_parse_subscript(literal);
        }

        // Hex Number (0xA from BigQuery/SQLite) - integer in hex notation
        if self.check(TokenType::HexNumber) {
            let token = self.advance();
            if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::MySQL)
            ) {
                let text = token.text.as_str();
                if text.len() > 2
                    && (text.starts_with("0x") || text.starts_with("0X"))
                    && !text[2..].chars().all(|c| c.is_ascii_hexdigit())
                {
                    let ident = Expression::Identifier(Identifier {
                        name: token.text,
                        quoted: true,
                        trailing_comments: Vec::new(),
                        span: None,
                    });
                    return self.maybe_parse_subscript(ident);
                }
            }
            let literal = Expression::Literal(Literal::HexNumber(token.text));
            return self.maybe_parse_subscript(literal);
        }

        // Bit String (B'...')
        if self.check(TokenType::BitString) {
            let token = self.advance();
            let literal = Expression::Literal(Literal::BitString(token.text));
            return self.maybe_parse_subscript(literal);
        }

        // Byte String (b"..." - BigQuery style)
        if self.check(TokenType::ByteString) {
            let token = self.advance();
            let literal = Expression::Literal(Literal::ByteString(token.text));
            return self.maybe_parse_subscript(literal);
        }

        // Raw String (r"..." - BigQuery style, backslashes are literal)
        if self.check(TokenType::RawString) {
            let token = self.advance();
            // Raw strings preserve backslashes as literal characters.
            // The generator will handle escaping when converting to a regular string.
            let literal = Expression::Literal(Literal::RawString(token.text));
            return self.maybe_parse_subscript(literal);
        }

        // Escape String (E'...' - PostgreSQL)
        if self.check(TokenType::EscapeString) {
            let token = self.advance();
            // EscapeString is stored as "E'content'" - extract just the content
            let literal = Expression::Literal(Literal::EscapeString(token.text));
            return self.maybe_parse_subscript(literal);
        }

        // Star - check for DuckDB *COLUMNS(...) syntax first
        if self.check(TokenType::Star) {
            // DuckDB *COLUMNS(...) syntax: *COLUMNS(*), *COLUMNS('regex'), *COLUMNS(['col1', 'col2'])
            // Check if * is followed by COLUMNS and (
            if self.check_next_identifier("COLUMNS") {
                // Check if there's a ( after COLUMNS
                if self
                    .tokens
                    .get(self.current + 2)
                    .map(|t| t.token_type == TokenType::LParen)
                    .unwrap_or(false)
                {
                    self.advance(); // consume *
                    self.advance(); // consume COLUMNS
                    self.advance(); // consume (

                    // Parse the argument: can be *, a regex string, or an array of column names
                    let arg = if self.check(TokenType::Star) {
                        self.advance(); // consume *
                        Expression::Star(Star {
                            table: None,
                            except: None,
                            replace: None,
                            rename: None,
                            trailing_comments: Vec::new(),
                            span: None,
                        })
                    } else {
                        self.parse_expression()?
                    };

                    self.expect(TokenType::RParen)?;

                    // Create Columns expression with unpack=true
                    return Ok(Expression::Columns(Box::new(Columns {
                        this: Box::new(arg),
                        unpack: Some(Box::new(Expression::Boolean(BooleanLiteral {
                            value: true,
                        }))),
                    })));
                }
            }

            // Regular star
            self.advance(); // consume *
            let star = self.parse_star_modifiers(None)?;
            return Ok(Expression::Star(star));
        }

        // Generic type expressions: ARRAY<T>, MAP<K,V>, STRUCT<...>
        // These are standalone type expressions (not in CAST context)
        // But also handle STRUCT<TYPE>(args) which becomes CAST(STRUCT(args) AS STRUCT<TYPE>)
        if self.is_identifier_token() || self.is_safe_keyword_as_identifier() {
            let name_upper = self.peek().text.to_uppercase();
            if (name_upper == "ARRAY" || name_upper == "MAP" || name_upper == "STRUCT")
                && self.check_next(TokenType::Lt)
            {
                self.advance(); // consume ARRAY/MAP/STRUCT
                let data_type = self.parse_data_type_from_name(&name_upper)?;

                // Check for typed constructor: STRUCT<TYPE>(args) or ARRAY<TYPE>(args)
                // These become CAST(STRUCT(args) AS TYPE) or CAST(ARRAY(args) AS TYPE)
                if self.match_token(TokenType::LParen) {
                    if name_upper == "STRUCT" {
                        // Parse struct constructor arguments
                        let args = if self.check(TokenType::RParen) {
                            Vec::new()
                        } else {
                            self.parse_struct_args()?
                        };
                        self.expect(TokenType::RParen)?;

                        // Convert args to Struct fields (all unnamed)
                        let fields: Vec<(Option<String>, Expression)> =
                            args.into_iter().map(|e| (None, e)).collect();

                        // Create CAST(STRUCT(args) AS STRUCT<TYPE>)
                        let struct_expr = Expression::Struct(Box::new(Struct { fields }));
                        let cast_expr = Expression::Cast(Box::new(Cast {
                            this: struct_expr,
                            to: data_type,
                            trailing_comments: Vec::new(),
                            double_colon_syntax: false,
                            format: None,
                            default: None,
                            inferred_type: None,
                        }));
                        return self.maybe_parse_subscript(cast_expr);
                    } else if name_upper == "ARRAY" {
                        // Parse array constructor arguments
                        let mut expressions = Vec::new();
                        if !self.check(TokenType::RParen) {
                            loop {
                                expressions.push(self.parse_expression()?);
                                if !self.match_token(TokenType::Comma) {
                                    break;
                                }
                            }
                        }
                        self.expect(TokenType::RParen)?;

                        // Create CAST(ARRAY[args] AS ARRAY<TYPE>)
                        let array_expr = Expression::Array(Box::new(Array { expressions }));
                        let cast_expr = Expression::Cast(Box::new(Cast {
                            this: array_expr,
                            to: data_type,
                            trailing_comments: Vec::new(),
                            double_colon_syntax: false,
                            format: None,
                            default: None,
                            inferred_type: None,
                        }));
                        return self.maybe_parse_subscript(cast_expr);
                    }
                } else if self.match_token(TokenType::LBracket) {
                    // ARRAY<TYPE>[values] or ARRAY<TYPE>[] - bracket-style array constructor
                    let expressions = if self.check(TokenType::RBracket) {
                        Vec::new()
                    } else {
                        self.parse_expression_list()?
                    };
                    self.expect(TokenType::RBracket)?;
                    // Create CAST(Array(values) AS DataType)
                    let array_expr = Expression::Array(Box::new(Array { expressions }));
                    let cast_expr = Expression::Cast(Box::new(Cast {
                        this: array_expr,
                        to: data_type,
                        trailing_comments: Vec::new(),
                        double_colon_syntax: false,
                        format: None,
                        default: None,
                        inferred_type: None,
                    }));
                    return self.maybe_parse_subscript(cast_expr);
                }

                return Ok(Expression::DataType(data_type));
            }
            // DuckDB-style MAP with curly brace literals: MAP {'key': value}
            if name_upper == "MAP" && self.check_next(TokenType::LBrace) {
                self.advance(); // consume MAP
                self.expect(TokenType::LBrace)?;

                // Handle empty: MAP {}
                if self.match_token(TokenType::RBrace) {
                    return self.maybe_parse_subscript(Expression::MapFunc(Box::new(
                        MapConstructor {
                            keys: Vec::new(),
                            values: Vec::new(),
                            curly_brace_syntax: true,
                            with_map_keyword: true,
                        },
                    )));
                }

                // Parse key-value pairs
                let mut keys = Vec::new();
                let mut values = Vec::new();
                loop {
                    let key = self.parse_primary()?;
                    self.expect(TokenType::Colon)?;
                    let value = self.parse_expression()?;
                    keys.push(key);
                    values.push(value);
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                    // Handle trailing comma
                    if self.check(TokenType::RBrace) {
                        break;
                    }
                }
                self.expect(TokenType::RBrace)?;

                return self.maybe_parse_subscript(Expression::MapFunc(Box::new(MapConstructor {
                    keys,
                    values,
                    curly_brace_syntax: true,
                    with_map_keyword: true,
                })));
            }
        }

        // Keywords as identifiers when followed by DOT (e.g., case.x, top.y)
        // These keywords can be table/column names when used with dot notation
        if (self.check(TokenType::Case) || self.check(TokenType::Top))
            && self.check_next(TokenType::Dot)
        {
            let token = self.advance();
            let ident = Identifier::new(token.text);
            self.expect(TokenType::Dot)?;
            if self.match_token(TokenType::Star) {
                // case.* or top.*
                let star = self.parse_star_modifiers(Some(ident))?;
                return Ok(Expression::Star(star));
            }
            // case.column or top.column
            let col_ident = self.expect_identifier_or_keyword_with_quoted()?;
            // Capture trailing comments from the column name token
            let trailing_comments = self.previous_trailing_comments();
            let mut col = Expression::Column(Column {
                name: col_ident,
                table: Some(ident),
                join_mark: false,
                trailing_comments,
                span: None,
                inferred_type: None,
            });
            // Handle Oracle/Redshift outer join marker (+) after column reference
            if self.check(TokenType::LParen) && self.check_next(TokenType::Plus) {
                let saved_pos = self.current;
                if self.match_token(TokenType::LParen)
                    && self.match_token(TokenType::Plus)
                    && self.match_token(TokenType::RParen)
                {
                    if let Expression::Column(ref mut c) = col {
                        c.join_mark = true;
                    }
                } else {
                    self.current = saved_pos;
                }
            }
            return self.maybe_parse_subscript(col);
        }

        // MySQL BINARY prefix operator: BINARY expr -> CAST(expr AS BINARY)
        // Only treat as prefix operator when followed by an expression (not ( which would be BINARY() function,
        // and not when it would be a data type like BINARY in column definitions)
        if self.check(TokenType::Var)
            && self.peek().text.eq_ignore_ascii_case("BINARY")
            && !self.check_next(TokenType::LParen)
            && !self.check_next(TokenType::Dot)
            && !self.check_next(TokenType::RParen)
            && !self.check_next(TokenType::Comma)
            && !self.is_at_end()
        {
            // Check if this is actually followed by an expression token (not end of statement)
            let next_idx = self.current + 1;
            let has_expr = next_idx < self.tokens.len()
                && !matches!(
                    self.tokens[next_idx].token_type,
                    TokenType::Semicolon | TokenType::Eof | TokenType::RParen | TokenType::Comma
                );
            if has_expr {
                self.advance(); // consume BINARY
                let expr = self.parse_unary()?;
                return Ok(Expression::Cast(Box::new(Cast {
                    this: expr,
                    to: DataType::Binary { length: None },
                    trailing_comments: Vec::new(),
                    double_colon_syntax: false,
                    format: None,
                    default: None,
                    inferred_type: None,
                })));
            }
        }

        // RLIKE/REGEXP as function call: RLIKE(expr, pattern, flags)
        // Normally RLIKE is an operator, but Snowflake allows function syntax
        if self.check(TokenType::RLike) && self.check_next(TokenType::LParen) {
            let token = self.advance(); // consume RLIKE
            self.advance(); // consume LParen
            let args = if self.check(TokenType::RParen) {
                Vec::new()
            } else {
                self.parse_function_arguments()?
            };
            self.expect(TokenType::RParen)?;
            let func = Expression::Function(Box::new(Function {
                name: token.text.clone(), // Preserve original case; generator handles normalization
                args,
                distinct: false,
                trailing_comments: Vec::new(),
                use_bracket_syntax: false,
                no_parens: false,
                quoted: false,
                span: None,
                inferred_type: None,
            }));
            return self.maybe_parse_over(func);
        }

        // INSERT as function call: INSERT(str, pos, len, newstr)
        // Snowflake/MySQL have INSERT as a string function, but INSERT is also a DML keyword.
        // When followed by ( in expression context, treat as function call.
        if self.check(TokenType::Insert) && self.check_next(TokenType::LParen) {
            let token = self.advance(); // consume INSERT
            self.advance(); // consume LParen
            let args = if self.check(TokenType::RParen) {
                Vec::new()
            } else {
                self.parse_function_arguments()?
            };
            self.expect(TokenType::RParen)?;
            let func = Expression::Function(Box::new(Function {
                name: token.text.clone(),
                args,
                distinct: false,
                trailing_comments: Vec::new(),
                use_bracket_syntax: false,
                no_parens: false,
                quoted: false,
                span: None,
                inferred_type: None,
            }));
            return self.maybe_parse_over(func);
        }

        // ClickHouse: MINUS/EXCEPT/INTERSECT/REGEXP as function names (e.g., minus(a, b), REGEXP('^db'))
        // MINUS is tokenized as TokenType::Except (Oracle alias), REGEXP as TokenType::RLike
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) && (self.check(TokenType::Except)
            || self.check(TokenType::Intersect)
            || self.check(TokenType::RLike))
            && self.check_next(TokenType::LParen)
        {
            let token = self.advance(); // consume keyword
            self.advance(); // consume LParen
            let args = if self.check(TokenType::RParen) {
                Vec::new()
            } else {
                self.parse_function_arguments()?
            };
            self.expect(TokenType::RParen)?;
            let func = Expression::Function(Box::new(Function {
                name: token.text.clone(),
                args,
                distinct: false,
                trailing_comments: Vec::new(),
                use_bracket_syntax: false,
                no_parens: false,
                quoted: false,
                span: None,
                inferred_type: None,
            }));
            return self.maybe_parse_over(func);
        }

        // Handle CURRENT_DATE/CURRENT_TIMESTAMP/CURRENT_TIME/CURRENT_DATETIME with parentheses
        // These have special token types but BigQuery and others use them as function calls with args
        if matches!(
            self.peek().token_type,
            TokenType::CurrentDate
                | TokenType::CurrentTimestamp
                | TokenType::CurrentTime
                | TokenType::CurrentDateTime
        ) {
            // Snowflake: CURRENT_TIME / CURRENT_TIME(n) -> Localtime (so DuckDB can output LOCALTIME)
            if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::Snowflake)
            ) && self.peek().token_type == TokenType::CurrentTime
            {
                self.advance(); // consume CURRENT_TIME
                if self.match_token(TokenType::LParen) {
                    // CURRENT_TIME(n) - consume args but ignore precision
                    if !self.check(TokenType::RParen) {
                        let _ = self.parse_function_arguments()?;
                    }
                    self.expect(TokenType::RParen)?;
                }
                return self.maybe_parse_subscript(Expression::Localtime(Box::new(
                    crate::expressions::Localtime { this: None },
                )));
            }
            if self.check_next(TokenType::LParen) {
                // Parse as function call: CURRENT_DATE('UTC'), CURRENT_TIMESTAMP(), etc.
                let token = self.advance(); // consume CURRENT_DATE etc.
                self.advance(); // consume LParen
                let args = if self.check(TokenType::RParen) {
                    Vec::new()
                } else {
                    self.parse_function_arguments()?
                };
                self.expect(TokenType::RParen)?;
                let func = Expression::Function(Box::new(Function {
                    name: token.text.clone(),
                    args,
                    distinct: false,
                    trailing_comments: Vec::new(),
                    use_bracket_syntax: false,
                    no_parens: false,
                    quoted: false,
                    span: None,
                    inferred_type: None,
                }));
                return self.maybe_parse_subscript(func);
            } else {
                // No parens - parse as no-paren function
                let token = self.advance();
                let func = Expression::Function(Box::new(Function {
                    name: token.text.clone(),
                    args: Vec::new(),
                    distinct: false,
                    trailing_comments: Vec::new(),
                    use_bracket_syntax: false,
                    no_parens: true,
                    quoted: false,
                    span: None,
                    inferred_type: None,
                }));
                return self.maybe_parse_subscript(func);
            }
        }

        // Type keyword followed by string literal -> CAST('value' AS TYPE)
        // E.g., NUMERIC '2.25' -> CAST('2.25' AS NUMERIC)
        if self.is_identifier_token() && self.check_next(TokenType::String) {
            let upper_name = self.peek().text.to_uppercase();
            if matches!(
                upper_name.as_str(),
                "NUMERIC" | "DECIMAL" | "BIGNUMERIC" | "BIGDECIMAL"
            ) {
                self.advance(); // consume the type keyword
                let str_token = self.advance(); // consume the string literal
                let data_type = match upper_name.as_str() {
                    "NUMERIC" | "DECIMAL" | "BIGNUMERIC" | "BIGDECIMAL" => {
                        crate::expressions::DataType::Decimal {
                            precision: None,
                            scale: None,
                        }
                    }
                    _ => unreachable!("type keyword already matched in outer if-condition"),
                };
                return Ok(Expression::Cast(Box::new(crate::expressions::Cast {
                    this: Expression::Literal(Literal::String(str_token.text)),
                    to: data_type,
                    trailing_comments: Vec::new(),
                    double_colon_syntax: false,
                    format: None,
                    default: None,
                    inferred_type: None,
                })));
            }
        }

        // Identifier, Column, or Function
        if self.is_identifier_token() {
            // Check for no-paren functions like CURRENT_TIMESTAMP, CURRENT_DATE, etc.
            // These should be parsed as functions even without parentheses
            let upper_name = self.peek().text.to_uppercase();
            if !self.check_next(TokenType::LParen)
                && !self.check_next(TokenType::Dot)
                && crate::function_registry::is_no_paren_function_name_upper(upper_name.as_str())
                && !(matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) && upper_name.as_str() == "CURRENT_TIMESTAMP")
            {
                let token = self.advance();
                let func = Expression::Function(Box::new(Function {
                    name: token.text.clone(), // Preserve original case; generator handles normalization
                    args: Vec::new(),
                    distinct: false,
                    trailing_comments: Vec::new(),
                    use_bracket_syntax: false,
                    no_parens: true, // These functions were called without parentheses
                    quoted: false,
                    span: None,
                    inferred_type: None,
                }));
                return self.maybe_parse_subscript(func);
            }

            let ident = self.expect_identifier_with_quoted()?;
            let name = ident.name.clone();
            let quoted = ident.quoted;

            // Check for function call (skip Teradata FORMAT phrase)
            let is_teradata_format_phrase = matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::Teradata)
            ) && self.check(TokenType::LParen)
                && self.check_next(TokenType::Format);
            if !is_teradata_format_phrase && self.match_token(TokenType::LParen) {
                let upper_name = name.to_uppercase();
                let func_expr = self.parse_typed_function(&name, &upper_name, quoted)?;
                let func_expr = self.maybe_parse_clickhouse_parameterized_agg(func_expr)?;
                // Check for OVER clause (window function)
                return self.maybe_parse_over(func_expr);
            }

            // Check for qualified name (table.column or table.method())
            if self.match_token(TokenType::Dot) {
                if self.match_token(TokenType::Star) {
                    // table.* with potential modifiers
                    let star = self.parse_star_modifiers(Some(ident))?;
                    let mut star_expr = Expression::Star(star);
                    // ClickHouse: a.* APPLY(func) EXCEPT(col) REPLACE(expr AS col) in any order
                    if matches!(
                        self.config.dialect,
                        Some(crate::dialects::DialectType::ClickHouse)
                    ) {
                        loop {
                            if self.check(TokenType::Apply) {
                                self.advance();
                                let apply_expr = if self.match_token(TokenType::LParen) {
                                    let e = self.parse_expression()?;
                                    self.expect(TokenType::RParen)?;
                                    e
                                } else {
                                    self.parse_expression()?
                                };
                                star_expr =
                                    Expression::Apply(Box::new(crate::expressions::Apply {
                                        this: Box::new(star_expr),
                                        expression: Box::new(apply_expr),
                                    }));
                            } else if self.check(TokenType::Except)
                                || self.check(TokenType::Exclude)
                            {
                                self.advance();
                                self.match_identifier("STRICT");
                                if self.match_token(TokenType::LParen) {
                                    loop {
                                        if self.check(TokenType::RParen) {
                                            break;
                                        }
                                        let _ = self.parse_expression()?;
                                        if !self.match_token(TokenType::Comma) {
                                            break;
                                        }
                                    }
                                    self.expect(TokenType::RParen)?;
                                } else if self.is_identifier_token()
                                    || self.is_safe_keyword_as_identifier()
                                {
                                    let _ = self.parse_expression()?;
                                }
                            } else if self.check(TokenType::Replace) {
                                self.advance();
                                self.match_identifier("STRICT");
                                if self.match_token(TokenType::LParen) {
                                    loop {
                                        if self.check(TokenType::RParen) {
                                            break;
                                        }
                                        let _ = self.parse_expression()?;
                                        if self.match_token(TokenType::As) {
                                            if self.is_identifier_token()
                                                || self.is_safe_keyword_as_identifier()
                                            {
                                                self.advance();
                                            }
                                        }
                                        if !self.match_token(TokenType::Comma) {
                                            break;
                                        }
                                    }
                                    self.expect(TokenType::RParen)?;
                                } else {
                                    let _ = self.parse_expression()?;
                                    if self.match_token(TokenType::As) {
                                        if self.is_identifier_token()
                                            || self.is_safe_keyword_as_identifier()
                                        {
                                            self.advance();
                                        }
                                    }
                                }
                            } else {
                                break;
                            }
                        }
                    }
                    return Ok(star_expr);
                }
                // Handle numeric field access: a.1, t.2 (ClickHouse tuple field access)
                // Also handle negative: a.-1 (ClickHouse negative tuple index)
                if self.check(TokenType::Number) {
                    let field_name = self.advance().text;
                    let col_expr = Expression::Dot(Box::new(DotAccess {
                        this: Expression::Column(Column {
                            name: ident,
                            table: None,
                            join_mark: false,
                            trailing_comments: Vec::new(),
                            span: None,
                            inferred_type: None,
                        }),
                        field: Identifier::new(field_name),
                    }));
                    return self.maybe_parse_subscript(col_expr);
                }
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) && self.check(TokenType::Dash)
                    && self.current + 1 < self.tokens.len()
                    && self.tokens[self.current + 1].token_type == TokenType::Number
                {
                    self.advance(); // consume -
                    let num = self.advance().text;
                    let field_name = format!("-{}", num);
                    let col_expr = Expression::Dot(Box::new(DotAccess {
                        this: Expression::Column(Column {
                            name: ident,
                            table: None,
                            join_mark: false,
                            trailing_comments: Vec::new(),
                            span: None,
                            inferred_type: None,
                        }),
                        field: Identifier::new(field_name),
                    }));
                    return self.maybe_parse_subscript(col_expr);
                }
                // ClickHouse: json.^path — the ^ prefix means "get all nested subcolumns"
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) && self.check(TokenType::Caret)
                {
                    self.advance(); // consume ^
                    let mut field_name = "^".to_string();
                    if self.check(TokenType::Identifier)
                        || self.check(TokenType::Var)
                        || self.check_keyword()
                    {
                        field_name.push_str(&self.advance().text);
                    }
                    let col_expr = Expression::Dot(Box::new(DotAccess {
                        this: Expression::Column(Column {
                            name: ident,
                            table: None,
                            join_mark: false,
                            trailing_comments: Vec::new(),
                            span: None,
                            inferred_type: None,
                        }),
                        field: Identifier::new(field_name),
                    }));
                    return self.maybe_parse_subscript(col_expr);
                }
                // Allow keywords as column names (e.g., a.filter, x.update)
                let col_ident = self.expect_identifier_or_keyword_with_quoted()?;

                // Handle Oracle/Redshift outer join marker (+) BEFORE checking for method call
                // This is critical: (+) looks like a method call but is actually a join marker
                if self.check(TokenType::LParen) && self.check_next(TokenType::Plus) {
                    let saved_pos = self.current;
                    if self.match_token(TokenType::LParen)
                        && self.match_token(TokenType::Plus)
                        && self.match_token(TokenType::RParen)
                    {
                        let trailing_comments = self.previous_trailing_comments();
                        let col = Expression::Column(Column {
                            name: col_ident,
                            table: Some(ident),
                            join_mark: true,
                            trailing_comments,
                            span: None,
                            inferred_type: None,
                        });
                        return self.maybe_parse_subscript(col);
                    } else {
                        self.current = saved_pos;
                    }
                }

                // Check if this is a method call (column followed by parentheses)
                if self.check(TokenType::LParen) {
                    // This is a method call like table.EXTRACT() or obj.INT()
                    self.advance(); // consume (
                    let args = if self.check(TokenType::RParen) {
                        Vec::new()
                    } else {
                        self.parse_expression_list()?
                    };
                    self.expect(TokenType::RParen)?;
                    let method_call = Expression::MethodCall(Box::new(MethodCall {
                        this: Expression::Column(Column {
                            name: ident.clone(),
                            table: None,
                            join_mark: false,
                            trailing_comments: Vec::new(),
                            span: None,
                            inferred_type: None,
                        }),
                        method: col_ident,
                        args,
                    }));
                    return self.maybe_parse_subscript(method_call);
                }

                // Capture trailing comments from the column name token
                let trailing_comments = self.previous_trailing_comments();
                let col = Expression::Column(Column {
                    name: col_ident,
                    table: Some(ident),
                    join_mark: false,
                    trailing_comments,
                    span: None,
                    inferred_type: None,
                });
                return self.maybe_parse_subscript(col);
            }

            // Check for Oracle pseudocolumns (ROWNUM, ROWID, LEVEL, SYSDATE, etc.)
            // Note: SQLite treats rowid as a regular column name, not a pseudocolumn
            // ClickHouse: skip pseudocolumn parsing as these are regular identifiers
            if !quoted
                && !matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::SQLite)
                        | Some(crate::dialects::DialectType::ClickHouse)
                )
            {
                if let Some(pseudocolumn_type) = PseudocolumnType::from_str(&name) {
                    return Ok(Expression::Pseudocolumn(Pseudocolumn {
                        kind: pseudocolumn_type,
                    }));
                }
            }

            // Check for lambda expression: x -> body
            // But NOT if followed by a string literal (that's JSON extract: col -> '$.path')
            if self.check(TokenType::Arrow)
                && !self
                    .peek_nth(1)
                    .map_or(false, |t| t.token_type == TokenType::String)
            {
                self.advance(); // consume the Arrow token
                let body = self.parse_expression()?;
                return Ok(Expression::Lambda(Box::new(LambdaExpr {
                    parameters: vec![ident],
                    body,
                    colon: false,
                    parameter_types: Vec::new(),
                })));
            }

            // Capture trailing comments from the identifier token
            let trailing_comments = self.previous_trailing_comments();
            let col = Expression::Column(Column {
                name: ident,
                table: None,
                join_mark: false,
                trailing_comments,
                span: None,
                inferred_type: None,
            });
            return self.maybe_parse_subscript(col);
        }

        // Exasol-style IF expression: IF condition THEN true_value ELSE false_value ENDIF
        // Check for IF not followed by ( (which would be IF function call handled elsewhere)
        // This handles: IF age < 18 THEN 'minor' ELSE 'adult' ENDIF
        // IMPORTANT: This must be checked BEFORE is_safe_keyword_as_identifier() which would
        // treat IF as a column name when not followed by ( or .
        // For TSQL/Fabric: IF (cond) BEGIN ... END is an IF statement, not function
        if self.check(TokenType::If)
            && !self.check_next(TokenType::Dot)
            && (!self.check_next(TokenType::LParen) || matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::TSQL) | Some(crate::dialects::DialectType::Fabric)
            ))
        {
            let saved_pos = self.current;
            self.advance(); // consume IF
            if let Some(if_expr) = self.parse_if()? {
                return Ok(if_expr);
            }
            // parse_if() returned None — IF is not an IF expression here,
            // restore position so it can be treated as an identifier
            self.current = saved_pos;
        }

        // NEXT VALUE FOR sequence_name [OVER (ORDER BY ...)]
        // Must check before treating NEXT as a standalone identifier via is_safe_keyword_as_identifier
        if self.check(TokenType::Next)
            && self.current + 2 < self.tokens.len()
            && self.tokens[self.current + 1]
                .text
                .eq_ignore_ascii_case("VALUE")
            && self.tokens[self.current + 2]
                .text
                .eq_ignore_ascii_case("FOR")
        {
            self.advance(); // consume NEXT
            if let Some(expr) = self.parse_next_value_for()? {
                return Ok(expr);
            }
        }

        // ClickHouse: `from` can be a column name when followed by comma or dot
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) && self.check(TokenType::From)
            && (self.check_next(TokenType::Comma) || self.check_next(TokenType::Dot))
        {
            let token = self.advance();
            let name = token.text.clone();
            if self.match_token(TokenType::Dot) {
                // from.col qualified reference
                let col_name = self.expect_identifier_or_keyword()?;
                return Ok(Expression::Column(crate::expressions::Column {
                    name: Identifier::new(col_name),
                    table: Some(Identifier::new(name)),
                    join_mark: false,
                    trailing_comments: Vec::new(),
                    span: None,
                    inferred_type: None,
                }));
            }
            return Ok(Expression::Column(crate::expressions::Column {
                name: Identifier::new(name),
                table: None,
                join_mark: false,
                trailing_comments: Vec::new(),
                span: None,
                inferred_type: None,
            }));
        }

        // ClickHouse: `except` as identifier in expression context (set operations are handled at statement level)
        // except(args) is already handled above in the MINUS/EXCEPT/INTERSECT function block
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) && self.check(TokenType::Except)
            && !self.check_next(TokenType::LParen)
        {
            let token = self.advance();
            let name = token.text.clone();
            if self.match_token(TokenType::Dot) {
                let col_name = self.expect_identifier_or_keyword()?;
                return Ok(Expression::Column(crate::expressions::Column {
                    name: Identifier::new(col_name),
                    table: Some(Identifier::new(name)),
                    join_mark: false,
                    trailing_comments: Vec::new(),
                    span: None,
                    inferred_type: None,
                }));
            }
            return Ok(Expression::Column(crate::expressions::Column {
                name: Identifier::new(name),
                table: None,
                join_mark: false,
                trailing_comments: Vec::new(),
                span: None,
                inferred_type: None,
            }));
        }

        // ClickHouse: structural keywords like FROM, ON, JOIN can be used as identifiers
        // in expression context when followed by an operator (e.g., from + 1, on.col)
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) && self.peek().token_type.is_keyword()
            && !self.is_safe_keyword_as_identifier()
        {
            let next_tt = self
                .peek_nth(1)
                .map(|t| t.token_type)
                .unwrap_or(TokenType::Semicolon);
            // A structural keyword can be used as an identifier when it appears
            // in expression context. We detect this by checking what follows.
            // Essentially: it's NOT an identifier only if the keyword itself starts
            // a clause (e.g., FROM followed by a table name). But when it's followed
            // by an operator, comma, close-paren, or even another clause keyword
            // (meaning it's the last token in an expression), it's an identifier.
            let is_expr_context = !matches!(
                next_tt,
                TokenType::Identifier
                    | TokenType::Var
                    | TokenType::QuotedIdentifier
                    | TokenType::LParen
                    | TokenType::Number
                    | TokenType::String
            );
            if is_expr_context {
                let token = self.advance();
                return Ok(Expression::Column(Column {
                    name: Identifier::new(token.text),
                    table: None,
                    join_mark: false,
                    trailing_comments: Vec::new(),
                    span: None,
                    inferred_type: None,
                }));
            }
        }
        // %s or %(name)s percent parameter (PostgreSQL psycopg2 style)
        // Must be checked BEFORE the keyword-as-identifier handler below, since
        // Percent is in is_keyword() and is_safe_keyword_as_identifier() returns true for it.
        if self.check(TokenType::Percent)
            && (
                self.check_next(TokenType::Var)  // %s
            || self.check_next(TokenType::LParen)
                // %(name)s
            )
        {
            self.advance(); // consume %
                            // Check for %(name)s - named parameter
            if self.match_token(TokenType::LParen) {
                // Get the parameter name
                if self.is_identifier_token() || self.is_safe_keyword_as_identifier() {
                    let name = self.advance().text;
                    self.expect(TokenType::RParen)?;
                    // Expect 's' after the closing paren
                    if self.check(TokenType::Var) && self.peek().text == "s" {
                        self.advance(); // consume 's'
                    }
                    return Ok(Expression::Parameter(Box::new(Parameter {
                        name: Some(name),
                        index: None,
                        style: ParameterStyle::Percent,
                        quoted: false,
                        string_quoted: false,
                        expression: None,
                    })));
                } else {
                    return Err(self.parse_error("Expected parameter name after %("));
                }
            }
            // Check for %s - anonymous parameter
            if self.check(TokenType::Var) && self.peek().text == "s" {
                self.advance(); // consume 's'
                return Ok(Expression::Parameter(Box::new(Parameter {
                    name: None,
                    index: None,
                    style: ParameterStyle::Percent,
                    quoted: false,
                    string_quoted: false,
                    expression: None,
                })));
            }
            // Not a parameter - backtrack
            self.current -= 1;
        }

        // Some keywords can be used as identifiers (column names, table names, etc.)
        // when they are "safe" keywords that don't affect query structure.
        // Structural keywords like FROM, WHERE, JOIN should NOT be usable as identifiers.
        if self.is_safe_keyword_as_identifier() {
            let token = self.advance();
            let name = token.text.clone();

            // Check for function call (keyword followed by paren) - skip Teradata FORMAT phrase
            let is_teradata_format_phrase = matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::Teradata)
            ) && self.check(TokenType::LParen)
                && self.check_next(TokenType::Format);
            if !is_teradata_format_phrase && self.match_token(TokenType::LParen) {
                let upper_name = name.to_uppercase();
                let func_expr = self.parse_typed_function(&name, &upper_name, false)?;
                let func_expr = self.maybe_parse_clickhouse_parameterized_agg(func_expr)?;
                return self.maybe_parse_over(func_expr);
            }

            // Check for qualified name (keyword.column or keyword.method())
            if self.match_token(TokenType::Dot) {
                if self.match_token(TokenType::Star) {
                    // keyword.* with potential modifiers
                    let ident = Identifier::new(name);
                    let star = self.parse_star_modifiers(Some(ident))?;
                    return Ok(Expression::Star(star));
                }
                // ClickHouse: json.^path — the ^ prefix means "get all nested subcolumns"
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) && self.check(TokenType::Caret)
                {
                    self.advance(); // consume ^
                    let mut field_name = "^".to_string();
                    if self.check(TokenType::Identifier)
                        || self.check(TokenType::Var)
                        || self.check_keyword()
                    {
                        field_name.push_str(&self.advance().text);
                    }
                    let col = Expression::Dot(Box::new(DotAccess {
                        this: Expression::Column(Column {
                            name: Identifier::new(name),
                            table: None,
                            join_mark: false,
                            trailing_comments: Vec::new(),
                            span: None,
                            inferred_type: None,
                        }),
                        field: Identifier::new(field_name),
                    }));
                    return self.maybe_parse_subscript(col);
                }

                // Handle numeric field access: keyword.1, keyword.2 (ClickHouse tuple field access)
                if self.check(TokenType::Number) {
                    let field_name = self.advance().text;
                    let col_expr = Expression::Dot(Box::new(DotAccess {
                        this: Expression::Column(Column {
                            name: Identifier::new(name),
                            table: None,
                            join_mark: false,
                            trailing_comments: Vec::new(),
                            span: None,
                            inferred_type: None,
                        }),
                        field: Identifier::new(field_name),
                    }));
                    return self.maybe_parse_subscript(col_expr);
                }

                // Allow keywords as column names
                let col_ident = self.expect_identifier_or_keyword_with_quoted()?;

                // Check if this is a method call
                if self.check(TokenType::LParen) {
                    self.advance(); // consume (
                    let args = if self.check(TokenType::RParen) {
                        Vec::new()
                    } else {
                        self.parse_expression_list()?
                    };
                    self.expect(TokenType::RParen)?;
                    let method_call = Expression::MethodCall(Box::new(MethodCall {
                        this: Expression::Identifier(Identifier::new(name)),
                        method: col_ident,
                        args,
                    }));
                    return self.maybe_parse_subscript(method_call);
                }

                // Capture trailing comments from the column name token
                let trailing_comments = self.previous_trailing_comments();
                let mut col = Expression::Column(Column {
                    name: col_ident,
                    table: Some(Identifier::new(name)),
                    join_mark: false,
                    trailing_comments,
                    span: None,
                    inferred_type: None,
                });
                // Handle Oracle/Redshift outer join marker (+) after column reference
                if self.check(TokenType::LParen) && self.check_next(TokenType::Plus) {
                    let saved_pos = self.current;
                    if self.match_token(TokenType::LParen)
                        && self.match_token(TokenType::Plus)
                        && self.match_token(TokenType::RParen)
                    {
                        if let Expression::Column(ref mut c) = col {
                            c.join_mark = true;
                        }
                    } else {
                        self.current = saved_pos;
                    }
                }
                return self.maybe_parse_subscript(col);
            }

            // Simple identifier (keyword used as column name)
            // Capture trailing comments from the keyword token
            let trailing_comments = self.previous_trailing_comments();
            let ident = Identifier::new(name);
            let col = Expression::Column(Column {
                name: ident,
                table: None,
                join_mark: false,
                trailing_comments,
                span: None,
                inferred_type: None,
            });
            return self.maybe_parse_subscript(col);
        }

        // @@ system variable (MySQL/SQL Server): @@version, @@IDENTITY, @@GLOBAL.var
        if self.match_token(TokenType::AtAt) {
            // Get the variable name
            let name = if self.check(TokenType::Identifier) || self.check(TokenType::Var) {
                let mut n = self.advance().text;
                // Handle @@scope.variable (e.g., @@GLOBAL.max_connections, @@SESSION.sql_mode)
                if self.match_token(TokenType::Dot) {
                    if self.check(TokenType::Identifier)
                        || self.check(TokenType::Var)
                        || self.is_safe_keyword_as_identifier()
                    {
                        n.push('.');
                        n.push_str(&self.advance().text);
                    }
                }
                n
            } else if self.check_keyword() {
                // Handle @@keyword (e.g., @@sql_mode when sql_mode is a keyword)
                self.advance().text
            } else {
                return Err(self.parse_error("Expected variable name after @@"));
            };
            return Ok(Expression::Parameter(Box::new(Parameter {
                name: Some(name),
                index: None,
                style: ParameterStyle::DoubleAt,
                quoted: false,
                string_quoted: false,
                expression: None,
            })));
        }

        // @ user variable/parameter: @x, @"x", @JOIN, @'foo'
        if self.match_token(TokenType::DAt) {
            // Get the variable name - can be identifier, quoted identifier, keyword, or string
            let (name, quoted, string_quoted) =
                if self.check(TokenType::Identifier) || self.check(TokenType::Var) {
                    (self.advance().text, false, false)
                } else if self.check(TokenType::QuotedIdentifier) {
                    // Quoted identifier like @"x"
                    let token = self.advance();
                    (token.text, true, false)
                } else if self.check(TokenType::String) {
                    // String-quoted like @'foo'
                    let token = self.advance();
                    (token.text, false, true)
                } else if self.check(TokenType::Number) {
                    // Numeric like @1
                    let token = self.advance();
                    (token.text, false, false)
                } else if self.peek().token_type.is_keyword() {
                    // Keyword used as variable name like @JOIN
                    let token = self.advance();
                    (token.text, false, false)
                } else {
                    return Err(self.parse_error("Expected variable name after @"));
                };
            return Ok(Expression::Parameter(Box::new(Parameter {
                name: Some(name),
                index: None,
                style: ParameterStyle::At,
                quoted,
                string_quoted,
                expression: None,
            })));
        }

        // Parameter: ? placeholder or $n positional parameter
        if self.check(TokenType::Parameter) {
            let token = self.advance();
            // Check if this is a positional parameter ($1, $2, etc.) or a plain ? placeholder
            if let Ok(index) = token.text.parse::<u32>() {
                // Positional parameter like $1, $2 (token text is just the number)
                let param = Expression::Parameter(Box::new(Parameter {
                    name: None,
                    index: Some(index),
                    style: ParameterStyle::Dollar,
                    quoted: false,
                    string_quoted: false,
                    expression: None,
                }));
                // Check for JSON path access: $1:name or dot access: $1.c1
                let result = self.parse_colon_json_path(param)?;
                return self.maybe_parse_subscript(result);
            } else {
                // Plain ? placeholder
                return Ok(Expression::Placeholder(Placeholder { index: None }));
            }
        }

        // :name or :1 colon parameter
        if self.match_token(TokenType::Colon) {
            // Check for numeric parameter :1, :2, etc.
            if self.check(TokenType::Number) {
                let num_token = self.advance();
                if let Ok(index) = num_token.text.parse::<u32>() {
                    return Ok(Expression::Parameter(Box::new(Parameter {
                        name: None,
                        index: Some(index),
                        style: ParameterStyle::Colon,
                        quoted: false,
                        string_quoted: false,
                        expression: None,
                    })));
                }
                return Err(
                    self.parse_error(format!("Invalid colon parameter: :{}", num_token.text))
                );
            }
            // Get the parameter name
            if self.is_identifier_token() || self.is_safe_keyword_as_identifier() {
                let name = self.advance().text;
                return Ok(Expression::Parameter(Box::new(Parameter {
                    name: Some(name),
                    index: None,
                    style: ParameterStyle::Colon,
                    quoted: false,
                    string_quoted: false,
                    expression: None,
                })));
            } else {
                return Err(self.parse_error("Expected parameter name after :"));
            }
        }

        // $n dollar parameter: $1, $2, etc.
        if self.match_token(TokenType::Dollar) {
            // Check for ${identifier} or ${kind:name} template variable syntax (Databricks, Hive)
            // Hive supports ${hiveconf:variable_name} syntax
            if self.match_token(TokenType::LBrace) {
                // Parse the variable name - can be identifier or keyword
                if self.is_identifier_token() || self.is_safe_keyword_as_identifier() {
                    let name_token = self.advance();
                    // Check for ${kind:name} syntax (e.g., ${hiveconf:some_var})
                    let expression = if self.match_token(TokenType::Colon) {
                        if self.is_identifier_token() || self.is_safe_keyword_as_identifier() {
                            let expr_token = self.advance();
                            Some(expr_token.text.clone())
                        } else {
                            return Err(self.parse_error("Expected identifier after : in ${...}"));
                        }
                    } else {
                        None
                    };
                    self.expect(TokenType::RBrace)?;
                    return Ok(Expression::Parameter(Box::new(Parameter {
                        name: Some(name_token.text.clone()),
                        index: None,
                        style: ParameterStyle::DollarBrace,
                        quoted: false,
                        string_quoted: false,
                        expression,
                    })));
                } else {
                    return Err(self.parse_error("Expected identifier after ${"));
                }
            }
            // Check for number following the dollar sign → positional parameter ($1, $2, etc.)
            if self.check(TokenType::Number) {
                let num_token = self.advance();
                // Parse the number as an index
                if let Ok(index) = num_token.text.parse::<u32>() {
                    let param_expr = Expression::Parameter(Box::new(Parameter {
                        name: None,
                        index: Some(index),
                        style: ParameterStyle::Dollar,
                        quoted: false,
                        string_quoted: false,
                        expression: None,
                    }));
                    // Check for JSON path access: $1:name or $1:name:subname
                    let result = self.parse_colon_json_path(param_expr)?;
                    // Also check for dot access: $1.c1 or $1:name.field
                    return self.maybe_parse_subscript(result);
                }
                // If it's not a valid integer, treat as error
                return Err(
                    self.parse_error(format!("Invalid dollar parameter: ${}", num_token.text))
                );
            }
            // Check for identifier following the dollar sign → session variable ($x, $query_id, etc.)
            if self.check(TokenType::Identifier)
                || self.check(TokenType::Var)
                || self.is_safe_keyword_as_identifier()
            {
                let name_token = self.advance();
                return Ok(Expression::Parameter(Box::new(Parameter {
                    name: Some(name_token.text.clone()),
                    index: None,
                    style: ParameterStyle::Dollar,
                    quoted: false,
                    string_quoted: false,
                    expression: None,
                })));
            }
            // Just a $ by itself - treat as error
            return Err(self.parse_error("Expected number or identifier after $"));
        }

        // %s or %(name)s percent parameter (PostgreSQL psycopg2 style)
        if self.match_token(TokenType::Percent) {
            // Check for %(name)s - named parameter
            if self.match_token(TokenType::LParen) {
                // Get the parameter name
                if self.is_identifier_token() || self.is_safe_keyword_as_identifier() {
                    let name = self.advance().text;
                    self.expect(TokenType::RParen)?;
                    // Expect 's' after the closing paren
                    if self.check(TokenType::Var) && self.peek().text == "s" {
                        self.advance(); // consume 's'
                    }
                    return Ok(Expression::Parameter(Box::new(Parameter {
                        name: Some(name),
                        index: None,
                        style: ParameterStyle::Percent,
                        quoted: false,
                        string_quoted: false,
                        expression: None,
                    })));
                } else {
                    return Err(self.parse_error("Expected parameter name after %("));
                }
            }
            // Check for %s - anonymous parameter
            if self.check(TokenType::Var) && self.peek().text == "s" {
                self.advance(); // consume 's'
                return Ok(Expression::Parameter(Box::new(Parameter {
                    name: None,
                    index: None,
                    style: ParameterStyle::Percent,
                    quoted: false,
                    string_quoted: false,
                    expression: None,
                })));
            }
            // If not followed by 's' or '(', it's not a parameter - error
            return Err(self.parse_error("Expected 's' or '(' after % for parameter"));
        }

        // LEFT, RIGHT, OUTER, FULL, ALL etc. keywords as identifiers when followed by DOT
        // e.g., SELECT LEFT.FOO FROM ... or SELECT all.count FROM ...
        if (self.check(TokenType::Left)
            || self.check(TokenType::Right)
            || self.check(TokenType::Outer)
            || self.check(TokenType::Full)
            || self.check(TokenType::All)
            || self.check(TokenType::Only)
            || self.check(TokenType::Next)
            || self.check(TokenType::If))
            && self.check_next(TokenType::Dot)
        {
            let token = self.advance();
            let ident = Identifier::new(token.text);
            self.expect(TokenType::Dot)?;
            if self.match_token(TokenType::Star) {
                let star = self.parse_star_modifiers(Some(ident))?;
                return Ok(Expression::Star(star));
            }
            let col_ident = self.expect_identifier_or_keyword_with_quoted()?;
            let trailing_comments = self.previous_trailing_comments();
            let mut col = Expression::Column(Column {
                name: col_ident,
                table: Some(ident),
                join_mark: false,
                trailing_comments,
                span: None,
                inferred_type: None,
            });
            // Handle Oracle/Redshift outer join marker (+) after column reference
            if self.check(TokenType::LParen) && self.check_next(TokenType::Plus) {
                let saved_pos = self.current;
                if self.match_token(TokenType::LParen)
                    && self.match_token(TokenType::Plus)
                    && self.match_token(TokenType::RParen)
                {
                    if let Expression::Column(ref mut c) = col {
                        c.join_mark = true;
                    }
                } else {
                    self.current = saved_pos;
                }
            }
            return self.maybe_parse_subscript(col);
        }

        // NEXT VALUE FOR sequence_name [OVER (ORDER BY ...)]
        // Must check before treating NEXT as a standalone identifier
        if self.check(TokenType::Next) {
            // NEXT(arg) - pattern navigation function in MATCH_RECOGNIZE
            if self.check_next(TokenType::LParen) {
                let token = self.advance();
                self.advance(); // consume LParen
                let args = self.parse_function_args_list()?;
                self.expect(TokenType::RParen)?;
                return Ok(Expression::Function(Box::new(Function {
                    name: token.text,
                    args,
                    distinct: false,
                    trailing_comments: Vec::new(),
                    use_bracket_syntax: false,
                    no_parens: false,
                    quoted: false,
                    span: None,
                    inferred_type: None,
                })));
            }
        }

        // LEFT, RIGHT, OUTER, FULL, ONLY, NEXT as standalone identifiers (not followed by JOIN or LParen)
        // e.g., SELECT LEFT FROM ... or SELECT only FROM ...
        // If followed by LParen, it's a function call (e.g., NEXT(bar) in MATCH_RECOGNIZE)
        if self.can_be_alias_keyword()
            && !self.check_next(TokenType::Join)
            && !self.check_next(TokenType::LParen)
        {
            let token = self.advance();
            let trailing_comments = self.previous_trailing_comments();
            let col = Expression::Column(Column {
                name: Identifier::new(token.text),
                table: None,
                join_mark: false,
                trailing_comments,
                span: None,
                inferred_type: None,
            });
            return self.maybe_parse_subscript(col);
        }

        Err(self.parse_error(format!("Unexpected token: {:?}", self.peek().token_type)))
    }

    /// Check if function name is a known aggregate function
    fn is_aggregate_function(name: &str) -> bool {
        crate::function_registry::is_aggregate_function_name(name)
    }

    /// Whether the source dialect uses LOG(base, value) order (base first).
    /// Default is true. BigQuery, TSQL, Tableau, Fabric use LOG(value, base).
    fn log_base_first(&self) -> bool {
        !matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::BigQuery)
                | Some(crate::dialects::DialectType::TSQL)
                | Some(crate::dialects::DialectType::Tableau)
                | Some(crate::dialects::DialectType::Fabric)
        )
    }

    /// Whether the source dialect treats single-arg LOG(x) as LN(x).
    /// These dialects have LOG_DEFAULTS_TO_LN = True in Python sqlglot.
    fn log_defaults_to_ln(&self) -> bool {
        matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::MySQL)
                | Some(crate::dialects::DialectType::BigQuery)
                | Some(crate::dialects::DialectType::TSQL)
                | Some(crate::dialects::DialectType::ClickHouse)
                | Some(crate::dialects::DialectType::Hive)
                | Some(crate::dialects::DialectType::Spark)
                | Some(crate::dialects::DialectType::Databricks)
                | Some(crate::dialects::DialectType::Drill)
                | Some(crate::dialects::DialectType::Dremio)
        )
    }

    /// Parse the subset of typed functions that are handled via function-registry metadata.
    fn try_parse_registry_typed_function(
        &mut self,
        name: &str,
        upper_name: &str,
        canonical_upper_name: &str,
        quoted: bool,
    ) -> Result<Option<Expression>> {
        let Some(spec) =
            crate::function_registry::typed_function_spec_by_canonical_upper(canonical_upper_name)
        else {
            return Ok(None);
        };

        match (spec.parse_kind, spec.canonical_name) {
            (crate::function_registry::TypedParseKind::AggregateLike, "COUNT_IF") => {
                let distinct = self.match_token(TokenType::Distinct);
                let this = self.parse_expression()?;
                // ClickHouse: handle AS alias inside countIf args: countIf(expr AS d, pred)
                let this = if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) && self.check(TokenType::As)
                {
                    let next_idx = self.current + 1;
                    let after_alias_idx = self.current + 2;
                    let is_alias = next_idx < self.tokens.len()
                        && (matches!(
                            self.tokens[next_idx].token_type,
                            TokenType::Identifier | TokenType::Var | TokenType::QuotedIdentifier
                        ) || self.tokens[next_idx].token_type.is_keyword())
                        && after_alias_idx < self.tokens.len()
                        && matches!(
                            self.tokens[after_alias_idx].token_type,
                            TokenType::RParen | TokenType::Comma
                        );
                    if is_alias {
                        self.advance(); // consume AS
                        let alias_token = self.advance();
                        Expression::Alias(Box::new(crate::expressions::Alias {
                            this,
                            alias: Identifier::new(alias_token.text.clone()),
                            column_aliases: Vec::new(),
                            pre_alias_comments: Vec::new(),
                            trailing_comments: Vec::new(),
                            inferred_type: None,
                        }))
                    } else {
                        this
                    }
                } else {
                    this
                };
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) && self.match_token(TokenType::Comma)
                {
                    let mut args = vec![this];
                    let arg = self.parse_expression()?;
                    // Handle AS alias on subsequent args too
                    let arg = if self.check(TokenType::As) {
                        let next_idx = self.current + 1;
                        let after_alias_idx = self.current + 2;
                        let is_alias = next_idx < self.tokens.len()
                            && (matches!(
                                self.tokens[next_idx].token_type,
                                TokenType::Identifier
                                    | TokenType::Var
                                    | TokenType::QuotedIdentifier
                            ) || self.tokens[next_idx].token_type.is_keyword())
                            && after_alias_idx < self.tokens.len()
                            && matches!(
                                self.tokens[after_alias_idx].token_type,
                                TokenType::RParen | TokenType::Comma
                            );
                        if is_alias {
                            self.advance(); // consume AS
                            let alias_token = self.advance();
                            Expression::Alias(Box::new(crate::expressions::Alias {
                                this: arg,
                                alias: Identifier::new(alias_token.text.clone()),
                                column_aliases: Vec::new(),
                                pre_alias_comments: Vec::new(),
                                trailing_comments: Vec::new(),
                                inferred_type: None,
                            }))
                        } else {
                            arg
                        }
                    } else {
                        arg
                    };
                    args.push(arg);
                    while self.match_token(TokenType::Comma) {
                        args.push(self.parse_expression()?);
                    }
                    self.expect(TokenType::RParen)?;
                    return Ok(Some(Expression::CombinedAggFunc(Box::new(
                        CombinedAggFunc {
                            this: Box::new(Expression::Identifier(Identifier::new("countIf"))),
                            expressions: args,
                        },
                    ))));
                }
                self.expect(TokenType::RParen)?;
                let filter = self.parse_filter_clause()?;
                Ok(Some(Expression::CountIf(Box::new(AggFunc {
                    ignore_nulls: None,
                    this,
                    distinct,
                    filter,
                    order_by: Vec::new(),
                    having_max: None,
                    name: Some(name.to_string()),
                    limit: None,
                    inferred_type: None,
                }))))
            }
            (crate::function_registry::TypedParseKind::Binary, "STARTS_WITH")
            | (crate::function_registry::TypedParseKind::Binary, "ENDS_WITH") => {
                let this = self.parse_expression()?;
                self.expect(TokenType::Comma)?;
                let expression = self.parse_expression()?;
                self.expect(TokenType::RParen)?;
                let func = BinaryFunc {
                    original_name: None,
                    this,
                    expression,
                    inferred_type: None,
                };
                let expr = match spec.canonical_name {
                    "STARTS_WITH" => Expression::StartsWith(Box::new(func)),
                    "ENDS_WITH" => Expression::EndsWith(Box::new(func)),
                    _ => unreachable!("binary typed parse kind already matched in caller"),
                };
                Ok(Some(expr))
            }
            (crate::function_registry::TypedParseKind::Binary, "ATAN2") => {
                let this = self.parse_expression()?;
                self.expect(TokenType::Comma)?;
                let expression = self.parse_expression()?;
                self.expect(TokenType::RParen)?;
                Ok(Some(Expression::Atan2(Box::new(BinaryFunc {
                    original_name: None,
                    this,
                    expression,
                    inferred_type: None,
                }))))
            }
            (crate::function_registry::TypedParseKind::Binary, "MAP_FROM_ARRAYS")
            | (crate::function_registry::TypedParseKind::Binary, "MAP_CONTAINS_KEY")
            | (crate::function_registry::TypedParseKind::Binary, "ELEMENT_AT") => {
                let this = self.parse_expression()?;
                self.expect(TokenType::Comma)?;
                let expression = self.parse_expression()?;
                self.expect(TokenType::RParen)?;
                let func = BinaryFunc {
                    original_name: None,
                    this,
                    expression,
                    inferred_type: None,
                };
                let expr = match spec.canonical_name {
                    "MAP_FROM_ARRAYS" => Expression::MapFromArrays(Box::new(func)),
                    "MAP_CONTAINS_KEY" => Expression::MapContainsKey(Box::new(func)),
                    "ELEMENT_AT" => Expression::ElementAt(Box::new(func)),
                    _ => unreachable!("binary map parse kind already matched in caller"),
                };
                Ok(Some(expr))
            }
            (crate::function_registry::TypedParseKind::Binary, "CONTAINS")
            | (crate::function_registry::TypedParseKind::Binary, "MOD")
            | (crate::function_registry::TypedParseKind::Binary, "POW") => {
                let this = self.parse_expression()?;
                self.expect(TokenType::Comma)?;
                let expression = self.parse_expression()?;
                self.expect(TokenType::RParen)?;
                let expr = match spec.canonical_name {
                    "CONTAINS" => Expression::Contains(Box::new(BinaryFunc {
                        original_name: None,
                        this,
                        expression,
                        inferred_type: None,
                    })),
                    "MOD" => Expression::ModFunc(Box::new(BinaryFunc {
                        original_name: None,
                        this,
                        expression,
                        inferred_type: None,
                    })),
                    "POW" => Expression::Power(Box::new(BinaryFunc {
                        original_name: None,
                        this,
                        expression,
                        inferred_type: None,
                    })),
                    _ => unreachable!("binary scalar parse kind already matched in caller"),
                };
                Ok(Some(expr))
            }
            (crate::function_registry::TypedParseKind::Binary, "ADD_MONTHS")
            | (crate::function_registry::TypedParseKind::Binary, "MONTHS_BETWEEN")
            | (crate::function_registry::TypedParseKind::Binary, "NEXT_DAY") => {
                let this = self.parse_expression()?;
                self.expect(TokenType::Comma)?;
                let expression = self.parse_expression()?;
                if spec.canonical_name == "MONTHS_BETWEEN" && self.match_token(TokenType::Comma) {
                    let round_off = self.parse_expression()?;
                    self.expect(TokenType::RParen)?;
                    return Ok(Some(Expression::Function(Box::new(
                        crate::expressions::Function::new(
                            "MONTHS_BETWEEN".to_string(),
                            vec![this, expression, round_off],
                        ),
                    ))));
                }
                self.expect(TokenType::RParen)?;
                let func = BinaryFunc {
                    original_name: None,
                    this,
                    expression,
                    inferred_type: None,
                };
                let expr = match spec.canonical_name {
                    "ADD_MONTHS" => Expression::AddMonths(Box::new(func)),
                    "MONTHS_BETWEEN" => Expression::MonthsBetween(Box::new(func)),
                    "NEXT_DAY" => Expression::NextDay(Box::new(func)),
                    _ => unreachable!("date binary parse kind already matched in caller"),
                };
                Ok(Some(expr))
            }
            (crate::function_registry::TypedParseKind::Binary, "ARRAY_CONTAINS")
            | (crate::function_registry::TypedParseKind::Binary, "ARRAY_POSITION")
            | (crate::function_registry::TypedParseKind::Binary, "ARRAY_APPEND")
            | (crate::function_registry::TypedParseKind::Binary, "ARRAY_PREPEND")
            | (crate::function_registry::TypedParseKind::Binary, "ARRAY_UNION")
            | (crate::function_registry::TypedParseKind::Binary, "ARRAY_EXCEPT")
            | (crate::function_registry::TypedParseKind::Binary, "ARRAY_REMOVE") => {
                let this = self.parse_expression()?;
                self.expect(TokenType::Comma)?;
                let expression = self.parse_expression()?;
                self.expect(TokenType::RParen)?;
                let func = BinaryFunc {
                    original_name: None,
                    this,
                    expression,
                    inferred_type: None,
                };
                let expr = match spec.canonical_name {
                    "ARRAY_CONTAINS" => Expression::ArrayContains(Box::new(func)),
                    "ARRAY_POSITION" => Expression::ArrayPosition(Box::new(func)),
                    "ARRAY_APPEND" => Expression::ArrayAppend(Box::new(func)),
                    "ARRAY_PREPEND" => Expression::ArrayPrepend(Box::new(func)),
                    "ARRAY_UNION" => Expression::ArrayUnion(Box::new(func)),
                    "ARRAY_EXCEPT" => Expression::ArrayExcept(Box::new(func)),
                    "ARRAY_REMOVE" => Expression::ArrayRemove(Box::new(func)),
                    _ => unreachable!("array binary parse kind already matched in caller"),
                };
                Ok(Some(expr))
            }
            (crate::function_registry::TypedParseKind::Unary, "LENGTH") => {
                let this = self.parse_expression()?;
                // PostgreSQL: LENGTH(string, encoding) accepts optional second argument
                if self.match_token(TokenType::Comma) {
                    let encoding = self.parse_expression()?;
                    self.expect(TokenType::RParen)?;
                    // Store as a regular function to preserve both arguments
                    Ok(Some(Expression::Function(Box::new(Function::new(
                        upper_name,
                        vec![this, encoding],
                    )))))
                } else {
                    self.expect(TokenType::RParen)?;
                    Ok(Some(Expression::Length(Box::new(UnaryFunc::new(this)))))
                }
            }
            (crate::function_registry::TypedParseKind::Unary, "LOWER") => {
                let this = self.parse_expression_with_clickhouse_alias()?;
                self.expect(TokenType::RParen)?;
                Ok(Some(Expression::Lower(Box::new(UnaryFunc::new(this)))))
            }
            (crate::function_registry::TypedParseKind::Unary, "UPPER") => {
                let this = self.parse_expression_with_clickhouse_alias()?;
                self.expect(TokenType::RParen)?;
                Ok(Some(Expression::Upper(Box::new(UnaryFunc::new(this)))))
            }
            (crate::function_registry::TypedParseKind::Unary, "TYPEOF") => {
                let this = self.parse_expression()?;
                // ClickHouse: expr AS alias inside function args
                let this = self.maybe_clickhouse_alias(this);
                if self.match_token(TokenType::Comma) {
                    // Preserve additional args via generic function form
                    let mut all_args = vec![this];
                    let remaining = self.parse_function_arguments()?;
                    all_args.extend(remaining);
                    self.expect(TokenType::RParen)?;
                    Ok(Some(Expression::Function(Box::new(Function {
                        name: name.to_string(),
                        args: all_args,
                        distinct: false,
                        trailing_comments: Vec::new(),
                        use_bracket_syntax: false,
                        no_parens: false,
                        quoted: false,
                        span: None,
                        inferred_type: None,
                    }))))
                } else {
                    self.expect(TokenType::RParen)?;
                    Ok(Some(Expression::Typeof(Box::new(UnaryFunc::new(this)))))
                }
            }
            (crate::function_registry::TypedParseKind::Unary, "DAYOFWEEK")
            | (crate::function_registry::TypedParseKind::Unary, "DAYOFYEAR")
            | (crate::function_registry::TypedParseKind::Unary, "DAYOFMONTH")
            | (crate::function_registry::TypedParseKind::Unary, "WEEKOFYEAR") => {
                let this = self.parse_expression()?;
                self.expect(TokenType::RParen)?;
                let func = UnaryFunc::new(this);
                let expr = match spec.canonical_name {
                    "DAYOFWEEK" => Expression::DayOfWeek(Box::new(func)),
                    "DAYOFYEAR" => Expression::DayOfYear(Box::new(func)),
                    "DAYOFMONTH" => Expression::DayOfMonth(Box::new(func)),
                    "WEEKOFYEAR" => Expression::WeekOfYear(Box::new(func)),
                    _ => unreachable!("date-part unary parse kind already matched in caller"),
                };
                Ok(Some(expr))
            }
            (crate::function_registry::TypedParseKind::Unary, "SIN")
            | (crate::function_registry::TypedParseKind::Unary, "COS")
            | (crate::function_registry::TypedParseKind::Unary, "TAN")
            | (crate::function_registry::TypedParseKind::Unary, "ASIN")
            | (crate::function_registry::TypedParseKind::Unary, "ACOS")
            | (crate::function_registry::TypedParseKind::Unary, "ATAN")
            | (crate::function_registry::TypedParseKind::Unary, "RADIANS")
            | (crate::function_registry::TypedParseKind::Unary, "DEGREES") => {
                let this = self.parse_expression()?;
                // MySQL: ATAN(y, x) with 2 args is equivalent to ATAN2(y, x)
                if spec.canonical_name == "ATAN" && self.match_token(TokenType::Comma) {
                    let expression = self.parse_expression()?;
                    self.expect(TokenType::RParen)?;
                    return Ok(Some(Expression::Atan2(Box::new(BinaryFunc {
                        original_name: Some("ATAN".to_string()),
                        this,
                        expression,
                        inferred_type: None,
                    }))));
                }
                self.expect(TokenType::RParen)?;
                let func = UnaryFunc::new(this);
                let expr = match spec.canonical_name {
                    "SIN" => Expression::Sin(Box::new(func)),
                    "COS" => Expression::Cos(Box::new(func)),
                    "TAN" => Expression::Tan(Box::new(func)),
                    "ASIN" => Expression::Asin(Box::new(func)),
                    "ACOS" => Expression::Acos(Box::new(func)),
                    "ATAN" => Expression::Atan(Box::new(func)),
                    "RADIANS" => Expression::Radians(Box::new(func)),
                    "DEGREES" => Expression::Degrees(Box::new(func)),
                    _ => unreachable!("trig unary parse kind already matched in caller"),
                };
                Ok(Some(expr))
            }
            (crate::function_registry::TypedParseKind::Unary, "YEAR")
            | (crate::function_registry::TypedParseKind::Unary, "MONTH")
            | (crate::function_registry::TypedParseKind::Unary, "DAY")
            | (crate::function_registry::TypedParseKind::Unary, "HOUR")
            | (crate::function_registry::TypedParseKind::Unary, "MINUTE")
            | (crate::function_registry::TypedParseKind::Unary, "SECOND")
            | (crate::function_registry::TypedParseKind::Unary, "DAYOFWEEK_ISO")
            | (crate::function_registry::TypedParseKind::Unary, "QUARTER")
            | (crate::function_registry::TypedParseKind::Unary, "EPOCH")
            | (crate::function_registry::TypedParseKind::Unary, "EPOCH_MS") => {
                let this = self.parse_expression()?;
                self.expect(TokenType::RParen)?;
                let func = UnaryFunc::new(this);
                let expr = match spec.canonical_name {
                    "YEAR" => Expression::Year(Box::new(func)),
                    "MONTH" => Expression::Month(Box::new(func)),
                    "DAY" => Expression::Day(Box::new(func)),
                    "HOUR" => Expression::Hour(Box::new(func)),
                    "MINUTE" => Expression::Minute(Box::new(func)),
                    "SECOND" => Expression::Second(Box::new(func)),
                    "DAYOFWEEK_ISO" => Expression::DayOfWeekIso(Box::new(func)),
                    "QUARTER" => Expression::Quarter(Box::new(func)),
                    "EPOCH" => Expression::Epoch(Box::new(func)),
                    "EPOCH_MS" => Expression::EpochMs(Box::new(func)),
                    _ => unreachable!("date unary parse kind already matched in caller"),
                };
                Ok(Some(expr))
            }
            (crate::function_registry::TypedParseKind::Unary, "ARRAY_LENGTH")
            | (crate::function_registry::TypedParseKind::Unary, "ARRAY_SIZE")
            | (crate::function_registry::TypedParseKind::Unary, "CARDINALITY")
            | (crate::function_registry::TypedParseKind::Unary, "ARRAY_REVERSE")
            | (crate::function_registry::TypedParseKind::Unary, "ARRAY_DISTINCT")
            | (crate::function_registry::TypedParseKind::Unary, "ARRAY_COMPACT")
            | (crate::function_registry::TypedParseKind::Unary, "EXPLODE")
            | (crate::function_registry::TypedParseKind::Unary, "EXPLODE_OUTER") => {
                let this = self.parse_expression()?;
                // PostgreSQL ARRAY_LENGTH and ARRAY_SIZE can take a second dimension arg.
                // Preserve that by falling back to generic function form for 2-arg usage.
                if (spec.canonical_name == "ARRAY_LENGTH" || spec.canonical_name == "ARRAY_SIZE")
                    && self.match_token(TokenType::Comma)
                {
                    let dimension = self.parse_expression()?;
                    self.expect(TokenType::RParen)?;
                    return Ok(Some(Expression::Function(Box::new(Function {
                        name: name.to_string(),
                        args: vec![this, dimension],
                        distinct: false,
                        trailing_comments: Vec::new(),
                        use_bracket_syntax: false,
                        no_parens: false,
                        quoted: false,
                        span: None,
                        inferred_type: None,
                    }))));
                }
                self.expect(TokenType::RParen)?;
                let func = UnaryFunc::new(this);
                let expr = match spec.canonical_name {
                    "ARRAY_LENGTH" => Expression::ArrayLength(Box::new(func)),
                    "ARRAY_SIZE" => Expression::ArraySize(Box::new(func)),
                    "CARDINALITY" => Expression::Cardinality(Box::new(func)),
                    "ARRAY_REVERSE" => Expression::ArrayReverse(Box::new(func)),
                    "ARRAY_DISTINCT" => Expression::ArrayDistinct(Box::new(func)),
                    "ARRAY_COMPACT" => Expression::ArrayCompact(Box::new(func)),
                    "EXPLODE" => Expression::Explode(Box::new(func)),
                    "EXPLODE_OUTER" => Expression::ExplodeOuter(Box::new(func)),
                    _ => unreachable!("array unary parse kind already matched in caller"),
                };
                Ok(Some(expr))
            }
            (crate::function_registry::TypedParseKind::Unary, "MAP_FROM_ENTRIES")
            | (crate::function_registry::TypedParseKind::Unary, "MAP_KEYS")
            | (crate::function_registry::TypedParseKind::Unary, "MAP_VALUES") => {
                let this = self.parse_expression()?;
                self.expect(TokenType::RParen)?;
                let func = UnaryFunc::new(this);
                let expr = match spec.canonical_name {
                    "MAP_FROM_ENTRIES" => Expression::MapFromEntries(Box::new(func)),
                    "MAP_KEYS" => Expression::MapKeys(Box::new(func)),
                    "MAP_VALUES" => Expression::MapValues(Box::new(func)),
                    _ => unreachable!("map unary parse kind already matched in caller"),
                };
                Ok(Some(expr))
            }
            (crate::function_registry::TypedParseKind::Unary, "ABS") => {
                let this = self.parse_expression_with_clickhouse_alias()?;
                self.expect(TokenType::RParen)?;
                Ok(Some(Expression::Abs(Box::new(UnaryFunc::new(this)))))
            }
            (crate::function_registry::TypedParseKind::Unary, "SQRT")
            | (crate::function_registry::TypedParseKind::Unary, "EXP")
            | (crate::function_registry::TypedParseKind::Unary, "LN") => {
                let this = self.parse_expression()?;
                self.expect(TokenType::RParen)?;
                let expr = match spec.canonical_name {
                    "SQRT" => Expression::Sqrt(Box::new(UnaryFunc::new(this))),
                    "EXP" => Expression::Exp(Box::new(UnaryFunc::new(this))),
                    "LN" => Expression::Ln(Box::new(UnaryFunc::new(this))),
                    _ => unreachable!("math unary parse kind already matched in caller"),
                };
                Ok(Some(expr))
            }
            (crate::function_registry::TypedParseKind::Variadic, "TO_NUMBER")
            | (crate::function_registry::TypedParseKind::Variadic, "TRY_TO_NUMBER") => {
                let args = self.parse_expression_list()?;
                self.expect(TokenType::RParen)?;
                let this = args.get(0).cloned().unwrap_or(Expression::Null(Null {}));
                let format = args.get(1).cloned().map(Box::new);
                let precision = args.get(2).cloned().map(Box::new);
                let scale = args.get(3).cloned().map(Box::new);
                let safe = if spec.canonical_name == "TRY_TO_NUMBER" {
                    Some(Box::new(Expression::Boolean(BooleanLiteral {
                        value: true,
                    })))
                } else {
                    None
                };
                Ok(Some(Expression::ToNumber(Box::new(ToNumber {
                    this: Box::new(this),
                    format,
                    nlsparam: None,
                    precision,
                    scale,
                    safe,
                    safe_name: None,
                }))))
            }
            (crate::function_registry::TypedParseKind::Variadic, "SUBSTRING") => {
                let this = self.parse_expression()?;
                // ClickHouse: implicit/explicit alias: substring('1234' lhs FROM 2) or substring('1234' AS lhs FROM 2)
                let this = self.try_clickhouse_func_arg_alias(this);

                // Check for SQL standard FROM syntax: SUBSTRING(str FROM pos [FOR len])
                if self.match_token(TokenType::From) {
                    let start = self.parse_expression()?;
                    let start = self.try_clickhouse_func_arg_alias(start);
                    let length = if self.match_token(TokenType::For) {
                        let len = self.parse_expression()?;
                        Some(self.try_clickhouse_func_arg_alias(len))
                    } else {
                        None
                    };
                    self.expect(TokenType::RParen)?;
                    Ok(Some(Expression::Substring(Box::new(SubstringFunc {
                        this,
                        start,
                        length,
                        from_for_syntax: true,
                    }))))
                } else if self.match_token(TokenType::For) {
                    // PostgreSQL: SUBSTRING(str FOR len) or SUBSTRING(str FOR len FROM pos)
                    let length_expr = self.parse_expression()?;
                    let length_expr = self.try_clickhouse_func_arg_alias(length_expr);
                    let start = if self.match_token(TokenType::From) {
                        let s = self.parse_expression()?;
                        self.try_clickhouse_func_arg_alias(s)
                    } else {
                        // No FROM, use 1 as default start position
                        Expression::Literal(Literal::Number("1".to_string()))
                    };
                    self.expect(TokenType::RParen)?;
                    Ok(Some(Expression::Substring(Box::new(SubstringFunc {
                        this,
                        start,
                        length: Some(length_expr),
                        from_for_syntax: true,
                    }))))
                } else if self.match_token(TokenType::Comma) {
                    // Comma-separated syntax: SUBSTRING(str, pos) or SUBSTRING(str, pos, len)
                    let start = self.parse_expression()?;
                    let start = self.try_clickhouse_func_arg_alias(start);
                    let length = if self.match_token(TokenType::Comma) {
                        let len = self.parse_expression()?;
                        Some(self.try_clickhouse_func_arg_alias(len))
                    } else {
                        None
                    };
                    self.expect(TokenType::RParen)?;
                    Ok(Some(Expression::Substring(Box::new(SubstringFunc {
                        this,
                        start,
                        length,
                        from_for_syntax: false,
                    }))))
                } else {
                    // Just SUBSTRING(str) with no other args - unusual but handle it
                    self.expect(TokenType::RParen)?;
                    // Treat as function call
                    Ok(Some(Expression::Function(Box::new(Function {
                        name: name.to_string(),
                        args: vec![this],
                        distinct: false,
                        trailing_comments: Vec::new(),
                        use_bracket_syntax: false,
                        no_parens: false,
                        quoted: false,
                        span: None,
                        inferred_type: None,
                    }))))
                }
            }
            (crate::function_registry::TypedParseKind::Variadic, "DATE_PART") => {
                let part = self.parse_expression()?;
                // For TSQL/Fabric, normalize date part aliases (e.g., "dd" -> DAY)
                let mut part = if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::TSQL)
                        | Some(crate::dialects::DialectType::Fabric)
                ) {
                    self.normalize_tsql_date_part(part)
                } else {
                    part
                };
                // Accept both FROM and comma as separator (Snowflake supports both syntaxes)
                if !self.match_token(TokenType::From) && !self.match_token(TokenType::Comma) {
                    return Err(self.parse_error("Expected FROM or comma in DATE_PART"));
                }
                let from_expr = self.parse_expression()?;
                self.expect(TokenType::RParen)?;
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::Snowflake)
                ) {
                    if self
                        .try_parse_date_part_field_identifier_expr(&part)
                        .is_some()
                    {
                        part = self.convert_date_part_identifier_expr_to_var(part);
                    }
                }
                Ok(Some(Expression::Function(Box::new(Function {
                    name: "DATE_PART".to_string(),
                    args: vec![part, from_expr],
                    distinct: false,
                    trailing_comments: Vec::new(),
                    use_bracket_syntax: false,
                    no_parens: false,
                    quoted: false,
                    span: None,
                    inferred_type: None,
                }))))
            }
            (crate::function_registry::TypedParseKind::Variadic, "DATEADD") => {
                let mut first_arg = self.parse_expression()?;
                first_arg = self.try_clickhouse_func_arg_alias(first_arg);
                self.expect(TokenType::Comma)?;
                let second_arg = self.parse_expression()?;
                let second_arg = self.try_clickhouse_func_arg_alias(second_arg);

                // Check if there's a third argument (traditional 3-arg syntax)
                if self.match_token(TokenType::Comma) {
                    let third_arg = self.parse_expression()?;
                    let third_arg = self.try_clickhouse_func_arg_alias(third_arg);
                    self.expect(TokenType::RParen)?;
                    if matches!(
                        self.config.dialect,
                        Some(crate::dialects::DialectType::Snowflake)
                    ) {
                        if self
                            .try_parse_date_part_unit_identifier_expr(&first_arg)
                            .is_some()
                        {
                            first_arg = self.convert_date_part_identifier_expr_to_var(first_arg);
                        }
                    }
                    Ok(Some(Expression::Function(Box::new(Function {
                        name: name.to_string(),
                        args: vec![first_arg, second_arg, third_arg],
                        distinct: false,
                        trailing_comments: Vec::new(),
                        use_bracket_syntax: false,
                        no_parens: false,
                        quoted: false,
                        span: None,
                        inferred_type: None,
                    }))))
                } else {
                    // BigQuery 2-arg syntax: DATE_ADD(date, interval)
                    self.expect(TokenType::RParen)?;
                    Ok(Some(Expression::Function(Box::new(Function {
                        name: name.to_string(),
                        args: vec![first_arg, second_arg],
                        distinct: false,
                        trailing_comments: Vec::new(),
                        use_bracket_syntax: false,
                        no_parens: false,
                        quoted: false,
                        span: None,
                        inferred_type: None,
                    }))))
                }
            }
            (crate::function_registry::TypedParseKind::Variadic, "DATEDIFF") => {
                // First argument (can be unit for DATEDIFF/TIMESTAMPDIFF or datetime for TIMEDIFF)
                let first_arg = self.parse_expression()?;
                let first_arg = self.try_clickhouse_func_arg_alias(first_arg);
                self.expect(TokenType::Comma)?;
                let second_arg = self.parse_expression()?;
                let second_arg = self.try_clickhouse_func_arg_alias(second_arg);
                // Third argument is optional (SQLite TIMEDIFF only takes 2 args)
                let mut args = if self.match_token(TokenType::Comma) {
                    let third_arg = self.parse_expression()?;
                    let third_arg = self.try_clickhouse_func_arg_alias(third_arg);
                    vec![first_arg, second_arg, third_arg]
                } else {
                    vec![first_arg, second_arg]
                };
                // ClickHouse: optional 4th timezone argument for dateDiff
                while self.match_token(TokenType::Comma) {
                    let arg = self.parse_expression()?;
                    args.push(self.try_clickhouse_func_arg_alias(arg));
                }
                self.expect(TokenType::RParen)?;
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::Snowflake)
                ) && args.len() == 3
                {
                    if let Some(unit) = self.try_parse_date_part_unit_expr(&args[0]) {
                        return Ok(Some(Expression::DateDiff(Box::new(DateDiffFunc {
                            this: args[2].clone(),
                            expression: args[1].clone(),
                            unit: Some(unit),
                        }))));
                    }
                }
                Ok(Some(Expression::Function(Box::new(Function {
                    name: name.to_string(),
                    args,
                    distinct: false,
                    trailing_comments: Vec::new(),
                    use_bracket_syntax: false,
                    no_parens: false,
                    quoted: false,
                    span: None,
                    inferred_type: None,
                }))))
            }
            (crate::function_registry::TypedParseKind::Variadic, "RANDOM") => {
                // RANDOM() - no args, RANDOM(seed) - Snowflake, RANDOM(lower, upper) - Teradata
                if self.check(TokenType::RParen) {
                    self.expect(TokenType::RParen)?;
                    Ok(Some(Expression::Random(Random)))
                } else {
                    let first = self.parse_expression()?;
                    if self.match_token(TokenType::Comma) {
                        let second = self.parse_expression()?;
                        self.expect(TokenType::RParen)?;
                        Ok(Some(Expression::Rand(Box::new(Rand {
                            seed: None,
                            lower: Some(Box::new(first)),
                            upper: Some(Box::new(second)),
                        }))))
                    } else {
                        self.expect(TokenType::RParen)?;
                        Ok(Some(Expression::Rand(Box::new(Rand {
                            seed: Some(Box::new(first)),
                            lower: None,
                            upper: None,
                        }))))
                    }
                }
            }
            (crate::function_registry::TypedParseKind::Variadic, "RAND") => {
                let seed = if self.check(TokenType::RParen) {
                    None
                } else {
                    Some(Box::new(self.parse_expression()?))
                };
                self.expect(TokenType::RParen)?;
                Ok(Some(Expression::Rand(Box::new(Rand {
                    seed,
                    lower: None,
                    upper: None,
                }))))
            }
            (crate::function_registry::TypedParseKind::Variadic, "PI") => {
                self.expect(TokenType::RParen)?;
                Ok(Some(Expression::Pi(Pi)))
            }
            (crate::function_registry::TypedParseKind::Variadic, "LAST_DAY") => {
                let this = self.parse_expression()?;
                let unit = if self.match_token(TokenType::Comma) {
                    Some(self.parse_datetime_field()?)
                } else {
                    None
                };
                self.expect(TokenType::RParen)?;
                Ok(Some(Expression::LastDay(Box::new(LastDayFunc {
                    this,
                    unit,
                }))))
            }
            (crate::function_registry::TypedParseKind::Variadic, "POSITION") => {
                let expr = self
                    .parse_position()?
                    .ok_or_else(|| self.parse_error("Expected expression in POSITION"))?;
                self.expect(TokenType::RParen)?;
                Ok(Some(expr))
            }
            (crate::function_registry::TypedParseKind::Variadic, "STRPOS") => {
                let this = self.parse_expression()?;
                self.expect(TokenType::Comma)?;
                let substr = self.parse_expression()?;
                let occurrence = if self.match_token(TokenType::Comma) {
                    Some(Box::new(self.parse_expression()?))
                } else {
                    None
                };
                self.expect(TokenType::RParen)?;
                Ok(Some(Expression::StrPosition(Box::new(StrPosition {
                    this: Box::new(this),
                    substr: Some(Box::new(substr)),
                    position: None,
                    occurrence,
                }))))
            }
            (crate::function_registry::TypedParseKind::Variadic, "LOCATE") => {
                if self.check(TokenType::RParen) {
                    self.advance();
                    return Ok(Some(Expression::Function(Box::new(Function {
                        name: name.to_string(),
                        args: vec![],
                        distinct: false,
                        trailing_comments: Vec::new(),
                        use_bracket_syntax: false,
                        no_parens: false,
                        quoted: false,
                        span: None,
                        inferred_type: None,
                    }))));
                }
                let first = self.parse_expression()?;
                if !self.check(TokenType::Comma) && self.check(TokenType::RParen) {
                    self.advance();
                    return Ok(Some(Expression::Function(Box::new(Function {
                        name: name.to_string(),
                        args: vec![first],
                        distinct: false,
                        trailing_comments: Vec::new(),
                        use_bracket_syntax: false,
                        no_parens: false,
                        quoted: false,
                        span: None,
                        inferred_type: None,
                    }))));
                }
                self.expect(TokenType::Comma)?;
                let second = self.parse_expression()?;
                let position = if self.match_token(TokenType::Comma) {
                    Some(Box::new(self.parse_expression()?))
                } else {
                    None
                };
                self.expect(TokenType::RParen)?;
                Ok(Some(Expression::StrPosition(Box::new(StrPosition {
                    this: Box::new(second),
                    substr: Some(Box::new(first)),
                    position,
                    occurrence: None,
                }))))
            }
            (crate::function_registry::TypedParseKind::Variadic, "INSTR") => {
                let first = self.parse_expression()?;
                self.expect(TokenType::Comma)?;
                let second = self.parse_expression()?;
                let position = if self.match_token(TokenType::Comma) {
                    Some(Box::new(self.parse_expression()?))
                } else {
                    None
                };
                self.expect(TokenType::RParen)?;
                Ok(Some(Expression::StrPosition(Box::new(StrPosition {
                    this: Box::new(first),
                    substr: Some(Box::new(second)),
                    position,
                    occurrence: None,
                }))))
            }
            (crate::function_registry::TypedParseKind::Variadic, "NORMALIZE") => {
                let this = self.parse_expression()?;
                let form = if self.match_token(TokenType::Comma) {
                    Some(Box::new(self.parse_expression()?))
                } else {
                    None
                };
                self.expect(TokenType::RParen)?;
                Ok(Some(Expression::Normalize(Box::new(Normalize {
                    this: Box::new(this),
                    form,
                    is_casefold: None,
                }))))
            }
            (crate::function_registry::TypedParseKind::Variadic, "INITCAP") => {
                let this = self.parse_expression()?;
                let delimiter = if self.match_token(TokenType::Comma) {
                    Some(Box::new(self.parse_expression()?))
                } else {
                    None
                };
                self.expect(TokenType::RParen)?;
                if let Some(delim) = delimiter {
                    Ok(Some(Expression::Function(Box::new(Function::new(
                        "INITCAP".to_string(),
                        vec![this, *delim],
                    )))))
                } else {
                    Ok(Some(Expression::Initcap(Box::new(UnaryFunc::new(this)))))
                }
            }
            (crate::function_registry::TypedParseKind::Variadic, "FLOOR") => {
                let this = self.parse_expression()?;
                let to = if self.match_token(TokenType::To) {
                    self.parse_var()?
                } else {
                    None
                };
                let scale = if to.is_none() && self.match_token(TokenType::Comma) {
                    Some(self.parse_expression()?)
                } else {
                    None
                };
                if self.check(TokenType::Comma) {
                    let mut args = vec![this];
                    if let Some(s) = scale {
                        args.push(s);
                    }
                    while self.match_token(TokenType::Comma) {
                        args.push(self.parse_expression()?);
                    }
                    self.expect(TokenType::RParen)?;
                    return Ok(Some(Expression::Function(Box::new(Function {
                        name: name.to_string(),
                        args,
                        distinct: false,
                        trailing_comments: Vec::new(),
                        use_bracket_syntax: false,
                        no_parens: false,
                        quoted: false,
                        span: None,
                        inferred_type: None,
                    }))));
                }
                self.expect(TokenType::RParen)?;
                Ok(Some(Expression::Floor(Box::new(FloorFunc {
                    this,
                    scale,
                    to,
                }))))
            }
            (crate::function_registry::TypedParseKind::Variadic, "LOG") => {
                let first = self.parse_expression()?;
                if self.match_token(TokenType::Comma) {
                    let second = self.parse_expression()?;
                    self.expect(TokenType::RParen)?;
                    let (value, base) = if self.log_base_first() {
                        (second, first)
                    } else {
                        (first, second)
                    };
                    Ok(Some(Expression::Log(Box::new(LogFunc {
                        this: value,
                        base: Some(base),
                    }))))
                } else {
                    self.expect(TokenType::RParen)?;
                    if self.log_defaults_to_ln() {
                        Ok(Some(Expression::Ln(Box::new(UnaryFunc::new(first)))))
                    } else {
                        Ok(Some(Expression::Log(Box::new(LogFunc {
                            this: first,
                            base: None,
                        }))))
                    }
                }
            }
            (crate::function_registry::TypedParseKind::Variadic, "FLATTEN") => {
                let args = self.parse_function_arguments()?;
                self.expect(TokenType::RParen)?;
                Ok(Some(Expression::Function(Box::new(Function {
                    name: name.to_string(),
                    args,
                    distinct: false,
                    trailing_comments: Vec::new(),
                    use_bracket_syntax: false,
                    no_parens: false,
                    quoted: false,
                    span: None,
                    inferred_type: None,
                }))))
            }
            (crate::function_registry::TypedParseKind::Variadic, "ARRAY_INTERSECT") => {
                let mut expressions = vec![self.parse_expression()?];
                while self.match_token(TokenType::Comma) {
                    expressions.push(self.parse_expression()?);
                }
                self.expect(TokenType::RParen)?;
                Ok(Some(Expression::ArrayIntersect(Box::new(VarArgFunc {
                    expressions,
                    original_name: Some(name.to_string()),
                    inferred_type: None,
                }))))
            }
            (crate::function_registry::TypedParseKind::Variadic, "CURRENT_SCHEMAS") => {
                let args = if self.check(TokenType::RParen) {
                    Vec::new()
                } else {
                    vec![self.parse_expression()?]
                };
                self.expect(TokenType::RParen)?;
                Ok(Some(Expression::CurrentSchemas(Box::new(CurrentSchemas {
                    this: args.into_iter().next().map(Box::new),
                }))))
            }
            (crate::function_registry::TypedParseKind::Variadic, "COALESCE") => {
                let args = if self.check(TokenType::RParen) {
                    Vec::new()
                } else {
                    self.parse_expression_list()?
                };
                self.expect(TokenType::RParen)?;
                Ok(Some(Expression::Coalesce(Box::new(
                    crate::expressions::VarArgFunc {
                        original_name: None,
                        expressions: args,
                        inferred_type: None,
                    },
                ))))
            }
            (crate::function_registry::TypedParseKind::Variadic, "IFNULL") => {
                let args = self.parse_expression_list()?;
                self.expect(TokenType::RParen)?;
                if args.len() >= 2 {
                    Ok(Some(Expression::Coalesce(Box::new(
                        crate::expressions::VarArgFunc {
                            original_name: Some("IFNULL".to_string()),
                            expressions: args,
                            inferred_type: None,
                        },
                    ))))
                } else {
                    Ok(Some(Expression::Function(Box::new(Function {
                        name: name.to_string(),
                        args,
                        distinct: false,
                        trailing_comments: Vec::new(),
                        use_bracket_syntax: false,
                        no_parens: false,
                        quoted: false,
                        span: None,
                        inferred_type: None,
                    }))))
                }
            }
            (crate::function_registry::TypedParseKind::Variadic, "NVL") => {
                let args = self.parse_expression_list()?;
                self.expect(TokenType::RParen)?;
                if args.len() > 2 {
                    Ok(Some(Expression::Function(Box::new(Function {
                        name: "COALESCE".to_string(),
                        args,
                        distinct: false,
                        trailing_comments: Vec::new(),
                        use_bracket_syntax: false,
                        no_parens: false,
                        quoted: false,
                        span: None,
                        inferred_type: None,
                    }))))
                } else if args.len() == 2 {
                    Ok(Some(Expression::Nvl(Box::new(
                        crate::expressions::BinaryFunc {
                            original_name: Some("NVL".to_string()),
                            this: args[0].clone(),
                            expression: args[1].clone(),
                            inferred_type: None,
                        },
                    ))))
                } else {
                    Ok(Some(Expression::Function(Box::new(Function {
                        name: name.to_string(),
                        args,
                        distinct: false,
                        trailing_comments: Vec::new(),
                        use_bracket_syntax: false,
                        no_parens: false,
                        quoted: false,
                        span: None,
                        inferred_type: None,
                    }))))
                }
            }
            (crate::function_registry::TypedParseKind::Variadic, "NVL2") => {
                let args = self.parse_expression_list()?;
                self.expect(TokenType::RParen)?;
                if args.len() >= 3 {
                    Ok(Some(Expression::Nvl2(Box::new(
                        crate::expressions::Nvl2Func {
                            this: args[0].clone(),
                            true_value: args[1].clone(),
                            false_value: args[2].clone(),
                            inferred_type: None,
                        },
                    ))))
                } else {
                    Ok(Some(Expression::Function(Box::new(Function {
                        name: name.to_string(),
                        args,
                        distinct: false,
                        trailing_comments: Vec::new(),
                        use_bracket_syntax: false,
                        no_parens: false,
                        quoted: false,
                        span: None,
                        inferred_type: None,
                    }))))
                }
            }
            (crate::function_registry::TypedParseKind::Variadic, "EXTRACT") => {
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) && (self.check(TokenType::Identifier)
                    || self.check(TokenType::Var)
                    || self.peek().token_type.is_keyword()
                    || self.check(TokenType::String)
                    || self.check(TokenType::Number))
                    && (self.check_next(TokenType::Comma)
                        || self.check_next(TokenType::LParen)
                        || self.check_next(TokenType::Var)
                        || self.check_next(TokenType::Identifier))
                {
                    let args = self.parse_function_arguments()?;
                    self.expect(TokenType::RParen)?;
                    return Ok(Some(Expression::Function(Box::new(Function {
                        name: name.to_string(),
                        args,
                        distinct: false,
                        trailing_comments: Vec::new(),
                        use_bracket_syntax: false,
                        no_parens: false,
                        quoted: false,
                        span: None,
                        inferred_type: None,
                    }))));
                }

                if self.check(TokenType::String) {
                    let args = self.parse_expression_list()?;
                    self.expect(TokenType::RParen)?;
                    return Ok(Some(Expression::Function(Box::new(Function {
                        name: name.to_string(),
                        args,
                        distinct: false,
                        trailing_comments: Vec::new(),
                        use_bracket_syntax: false,
                        no_parens: false,
                        quoted: false,
                        span: None,
                        inferred_type: None,
                    }))));
                }

                let field = self.parse_datetime_field()?;
                if !self.match_token(TokenType::From) && !self.match_token(TokenType::Comma) {
                    return Err(self.parse_error("Expected FROM or comma after EXTRACT field"));
                }
                let this = self.parse_expression()?;
                let this = self.try_clickhouse_func_arg_alias(this);
                self.expect(TokenType::RParen)?;
                Ok(Some(Expression::Extract(Box::new(ExtractFunc {
                    this,
                    field,
                }))))
            }
            (crate::function_registry::TypedParseKind::Variadic, "STRUCT") => {
                let args = if self.check(TokenType::RParen) {
                    Vec::new()
                } else {
                    self.parse_struct_args()?
                };
                self.expect(TokenType::RParen)?;
                Ok(Some(Expression::Function(Box::new(Function {
                    name: name.to_string(),
                    args,
                    distinct: false,
                    trailing_comments: Vec::new(),
                    use_bracket_syntax: false,
                    no_parens: false,
                    quoted: false,
                    span: None,
                    inferred_type: None,
                }))))
            }
            (crate::function_registry::TypedParseKind::Variadic, "CHAR") => {
                let args = self.parse_expression_list()?;
                let charset = if self.match_token(TokenType::Using) {
                    if !self.is_at_end() {
                        let charset_token = self.advance();
                        Some(charset_token.text.clone())
                    } else {
                        None
                    }
                } else {
                    None
                };
                self.expect(TokenType::RParen)?;
                if charset.is_some() {
                    Ok(Some(Expression::CharFunc(Box::new(
                        crate::expressions::CharFunc {
                            args,
                            charset,
                            name: None,
                        },
                    ))))
                } else {
                    Ok(Some(Expression::Function(Box::new(Function {
                        name: name.to_string(),
                        args,
                        distinct: false,
                        trailing_comments: Vec::new(),
                        use_bracket_syntax: false,
                        no_parens: false,
                        quoted: false,
                        span: None,
                        inferred_type: None,
                    }))))
                }
            }
            (crate::function_registry::TypedParseKind::Variadic, "CHR") => {
                let args = self.parse_expression_list()?;
                let charset = if self.match_token(TokenType::Using) {
                    if !self.is_at_end() {
                        let charset_token = self.advance();
                        Some(charset_token.text.clone())
                    } else {
                        None
                    }
                } else {
                    None
                };
                self.expect(TokenType::RParen)?;
                if charset.is_some() {
                    Ok(Some(Expression::CharFunc(Box::new(
                        crate::expressions::CharFunc {
                            args,
                            charset,
                            name: Some("CHR".to_string()),
                        },
                    ))))
                } else {
                    Ok(Some(Expression::Function(Box::new(Function {
                        name: name.to_string(),
                        args,
                        distinct: false,
                        trailing_comments: Vec::new(),
                        use_bracket_syntax: false,
                        no_parens: false,
                        quoted: false,
                        span: None,
                        inferred_type: None,
                    }))))
                }
            }
            (crate::function_registry::TypedParseKind::Variadic, "RANGE_N") => {
                let this = self.parse_bitwise_or()?;
                self.expect(TokenType::Between)?;
                let mut expressions = Vec::new();
                while !self.check(TokenType::Each) && !self.check(TokenType::RParen) {
                    expressions.push(self.parse_expression()?);
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
                let each = if self.match_token(TokenType::Each) {
                    Some(Box::new(self.parse_expression()?))
                } else {
                    None
                };
                self.expect(TokenType::RParen)?;
                Ok(Some(Expression::RangeN(Box::new(RangeN {
                    this: Box::new(this),
                    expressions,
                    each,
                }))))
            }
            (crate::function_registry::TypedParseKind::Variadic, "XMLTABLE") => {
                if let Some(xml_table) = self.parse_xml_table()? {
                    self.expect(TokenType::RParen)?;
                    Ok(Some(xml_table))
                } else {
                    Err(self.parse_error("Failed to parse XMLTABLE"))
                }
            }
            (crate::function_registry::TypedParseKind::Variadic, "XMLELEMENT") => {
                if let Some(elem) = self.parse_xml_element()? {
                    self.expect(TokenType::RParen)?;
                    Ok(Some(elem))
                } else {
                    self.expect(TokenType::RParen)?;
                    Ok(Some(Expression::Function(Box::new(Function {
                        name: name.to_string(),
                        args: Vec::new(),
                        distinct: false,
                        trailing_comments: Vec::new(),
                        use_bracket_syntax: false,
                        no_parens: false,
                        quoted: false,
                        span: None,
                        inferred_type: None,
                    }))))
                }
            }
            (crate::function_registry::TypedParseKind::Variadic, "XMLATTRIBUTES") => {
                let mut attrs = Vec::new();
                if !self.check(TokenType::RParen) {
                    loop {
                        let expr = self.parse_expression()?;
                        if self.match_token(TokenType::As) {
                            let alias_ident = self.expect_identifier_or_keyword_with_quoted()?;
                            attrs.push(Expression::Alias(Box::new(Alias {
                                this: expr,
                                alias: alias_ident,
                                column_aliases: Vec::new(),
                                pre_alias_comments: Vec::new(),
                                trailing_comments: Vec::new(),
                                inferred_type: None,
                            })));
                        } else {
                            attrs.push(expr);
                        }
                        if !self.match_token(TokenType::Comma) {
                            break;
                        }
                    }
                }
                self.expect(TokenType::RParen)?;
                Ok(Some(Expression::Function(Box::new(Function {
                    name: "XMLATTRIBUTES".to_string(),
                    args: attrs,
                    distinct: false,
                    trailing_comments: Vec::new(),
                    use_bracket_syntax: false,
                    no_parens: false,
                    quoted: false,
                    span: None,
                    inferred_type: None,
                }))))
            }
            (crate::function_registry::TypedParseKind::Variadic, "XMLCOMMENT") => {
                let args = if self.check(TokenType::RParen) {
                    Vec::new()
                } else {
                    self.parse_expression_list()?
                };
                self.expect(TokenType::RParen)?;
                Ok(Some(Expression::Function(Box::new(Function {
                    name: "XMLCOMMENT".to_string(),
                    args,
                    distinct: false,
                    trailing_comments: Vec::new(),
                    use_bracket_syntax: false,
                    no_parens: false,
                    quoted: false,
                    span: None,
                    inferred_type: None,
                }))))
            }
            (crate::function_registry::TypedParseKind::Variadic, "MATCH") => {
                let expressions = if self.check(TokenType::Table)
                    && !matches!(
                        self.config.dialect,
                        Some(crate::dialects::DialectType::ClickHouse)
                    ) {
                    self.advance();
                    let table_name = self.expect_identifier_or_keyword()?;
                    vec![Expression::Var(Box::new(Var {
                        this: format!("TABLE {}", table_name),
                    }))]
                } else {
                    self.parse_expression_list()?
                };

                self.expect(TokenType::RParen)?;

                if !self.check_keyword_text("AGAINST") {
                    return Ok(Some(Expression::Function(Box::new(Function {
                        name: "MATCH".to_string(),
                        args: expressions,
                        distinct: false,
                        trailing_comments: Vec::new(),
                        use_bracket_syntax: false,
                        no_parens: false,
                        quoted: false,
                        span: None,
                        inferred_type: None,
                    }))));
                }

                self.advance();
                self.expect(TokenType::LParen)?;
                let search_expr = self.parse_primary()?;

                let modifier = if self.match_text_seq(&["IN", "NATURAL", "LANGUAGE", "MODE"]) {
                    if self.match_text_seq(&["WITH", "QUERY", "EXPANSION"]) {
                        Some(Box::new(Expression::Var(Box::new(Var {
                            this: "IN NATURAL LANGUAGE MODE WITH QUERY EXPANSION".to_string(),
                        }))))
                    } else {
                        Some(Box::new(Expression::Var(Box::new(Var {
                            this: "IN NATURAL LANGUAGE MODE".to_string(),
                        }))))
                    }
                } else if self.match_text_seq(&["IN", "BOOLEAN", "MODE"]) {
                    Some(Box::new(Expression::Var(Box::new(Var {
                        this: "IN BOOLEAN MODE".to_string(),
                    }))))
                } else if self.match_text_seq(&["WITH", "QUERY", "EXPANSION"]) {
                    Some(Box::new(Expression::Var(Box::new(Var {
                        this: "WITH QUERY EXPANSION".to_string(),
                    }))))
                } else {
                    None
                };

                self.expect(TokenType::RParen)?;

                Ok(Some(Expression::MatchAgainst(Box::new(MatchAgainst {
                    this: Box::new(search_expr),
                    expressions,
                    modifier,
                }))))
            }
            (crate::function_registry::TypedParseKind::Variadic, "TRANSFORM") => {
                let expressions = if self.check(TokenType::RParen) {
                    Vec::new()
                } else {
                    self.parse_function_args_with_lambda()?
                };
                self.expect(TokenType::RParen)?;

                let row_format_before = if self.match_token(TokenType::Row) {
                    self.parse_row()?
                } else {
                    None
                };

                let record_writer = if self.match_text_seq(&["RECORDWRITER"]) {
                    Some(Box::new(self.parse_expression()?))
                } else {
                    None
                };

                if self.match_token(TokenType::Using) {
                    let command_script = Some(Box::new(self.parse_expression()?));
                    let schema = if self.match_token(TokenType::As) {
                        self.parse_schema()?
                    } else {
                        None
                    };

                    let row_format_after = if self.match_token(TokenType::Row) {
                        self.parse_row()?
                    } else {
                        None
                    };

                    let record_reader = if self.match_text_seq(&["RECORDREADER"]) {
                        Some(Box::new(self.parse_expression()?))
                    } else {
                        None
                    };

                    Ok(Some(Expression::QueryTransform(Box::new(QueryTransform {
                        expressions,
                        command_script,
                        schema: schema.map(Box::new),
                        row_format_before: row_format_before.map(Box::new),
                        record_writer,
                        row_format_after: row_format_after.map(Box::new),
                        record_reader,
                    }))))
                } else {
                    Ok(Some(Expression::Function(Box::new(Function {
                        name: name.to_string(),
                        args: expressions,
                        distinct: false,
                        trailing_comments: Vec::new(),
                        use_bracket_syntax: false,
                        no_parens: false,
                        quoted,
                        span: None,
                        inferred_type: None,
                    }))))
                }
            }
            (crate::function_registry::TypedParseKind::Variadic, "CONVERT") => {
                let is_try = upper_name == "TRY_CONVERT";
                let is_tsql = matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::TSQL)
                        | Some(crate::dialects::DialectType::Fabric)
                );

                if is_tsql {
                    let saved = self.current;
                    let orig_type_text = if self.current < self.tokens.len() {
                        self.tokens[self.current].text.to_uppercase()
                    } else {
                        String::new()
                    };
                    let dt = self.parse_data_type();
                    if let Ok(mut dt) = dt {
                        if self.match_token(TokenType::Comma) {
                            if orig_type_text == "NVARCHAR" || orig_type_text == "NCHAR" {
                                dt = match dt {
                                    crate::expressions::DataType::VarChar { length, .. } => {
                                        if let Some(len) = length {
                                            crate::expressions::DataType::Custom {
                                                name: format!("{}({})", orig_type_text, len),
                                            }
                                        } else {
                                            crate::expressions::DataType::Custom {
                                                name: orig_type_text.clone(),
                                            }
                                        }
                                    }
                                    crate::expressions::DataType::Char { length } => {
                                        if let Some(len) = length {
                                            crate::expressions::DataType::Custom {
                                                name: format!("{}({})", orig_type_text, len),
                                            }
                                        } else {
                                            crate::expressions::DataType::Custom {
                                                name: orig_type_text.clone(),
                                            }
                                        }
                                    }
                                    other => other,
                                };
                            }
                            let value = self.parse_expression()?;
                            let style = if self.match_token(TokenType::Comma) {
                                Some(self.parse_expression()?)
                            } else {
                                None
                            };
                            self.expect(TokenType::RParen)?;
                            let func_name = if is_try { "TRY_CONVERT" } else { "CONVERT" };
                            let mut args = vec![Expression::DataType(dt), value];
                            if let Some(s) = style {
                                args.push(s);
                            }
                            return Ok(Some(Expression::Function(Box::new(Function {
                                name: func_name.to_string(),
                                args,
                                distinct: false,
                                trailing_comments: Vec::new(),
                                use_bracket_syntax: false,
                                no_parens: false,
                                quoted: false,
                                span: None,
                                inferred_type: None,
                            }))));
                        }
                        self.current = saved;
                    } else {
                        self.current = saved;
                    }
                }

                let this = self.parse_expression()?;
                if self.match_token(TokenType::Using) {
                    let charset = self.expect_identifier()?;
                    self.expect(TokenType::RParen)?;
                    Ok(Some(Expression::Cast(Box::new(Cast {
                        this,
                        to: DataType::CharacterSet { name: charset },
                        trailing_comments: Vec::new(),
                        double_colon_syntax: false,
                        format: None,
                        default: None,
                        inferred_type: None,
                    }))))
                } else if self.match_token(TokenType::Comma) {
                    let mut args = vec![this];
                    args.push(self.parse_expression()?);
                    while self.match_token(TokenType::Comma) {
                        args.push(self.parse_expression()?);
                    }
                    self.expect(TokenType::RParen)?;
                    let func_name = if is_try { "TRY_CONVERT" } else { "CONVERT" };
                    Ok(Some(Expression::Function(Box::new(Function {
                        name: func_name.to_string(),
                        args,
                        distinct: false,
                        trailing_comments: Vec::new(),
                        use_bracket_syntax: false,
                        no_parens: false,
                        quoted: false,
                        span: None,
                        inferred_type: None,
                    }))))
                } else {
                    self.expect(TokenType::RParen)?;
                    let func_name = if is_try { "TRY_CONVERT" } else { "CONVERT" };
                    Ok(Some(Expression::Function(Box::new(Function {
                        name: func_name.to_string(),
                        args: vec![this],
                        distinct: false,
                        trailing_comments: Vec::new(),
                        use_bracket_syntax: false,
                        no_parens: false,
                        quoted: false,
                        span: None,
                        inferred_type: None,
                    }))))
                }
            }
            (crate::function_registry::TypedParseKind::Variadic, "TRIM") => {
                let (position, position_explicit) = if self.match_token(TokenType::Leading) {
                    (TrimPosition::Leading, true)
                } else if self.match_token(TokenType::Trailing) {
                    (TrimPosition::Trailing, true)
                } else if self.match_token(TokenType::Both) {
                    (TrimPosition::Both, true)
                } else {
                    (TrimPosition::Both, false)
                };

                if position_explicit || self.check(TokenType::From) {
                    if self.match_token(TokenType::From) {
                        let this = self.parse_expression()?;
                        self.expect(TokenType::RParen)?;
                        Ok(Some(Expression::Trim(Box::new(TrimFunc {
                            this,
                            characters: None,
                            position,
                            sql_standard_syntax: true,
                            position_explicit,
                        }))))
                    } else {
                        let first_expr = self.parse_bitwise_or()?;
                        let first_expr = self.try_clickhouse_func_arg_alias(first_expr);
                        if self.match_token(TokenType::From) {
                            let this = self.parse_bitwise_or()?;
                            let this = self.try_clickhouse_func_arg_alias(this);
                            self.expect(TokenType::RParen)?;
                            Ok(Some(Expression::Trim(Box::new(TrimFunc {
                                this,
                                characters: Some(first_expr),
                                position,
                                sql_standard_syntax: true,
                                position_explicit,
                            }))))
                        } else {
                            self.expect(TokenType::RParen)?;
                            Ok(Some(Expression::Trim(Box::new(TrimFunc {
                                this: first_expr,
                                characters: None,
                                position,
                                sql_standard_syntax: true,
                                position_explicit,
                            }))))
                        }
                    }
                } else {
                    let first_expr = self.parse_expression()?;
                    let first_expr = self.try_clickhouse_func_arg_alias(first_expr);
                    if self.match_token(TokenType::From) {
                        let this = self.parse_expression()?;
                        let this = self.try_clickhouse_func_arg_alias(this);
                        self.expect(TokenType::RParen)?;
                        Ok(Some(Expression::Trim(Box::new(TrimFunc {
                            this,
                            characters: Some(first_expr),
                            position: TrimPosition::Both,
                            sql_standard_syntax: true,
                            position_explicit: false,
                        }))))
                    } else if self.match_token(TokenType::Comma) {
                        let second_expr = self.parse_expression()?;
                        self.expect(TokenType::RParen)?;
                        let trim_pattern_first = matches!(
                            self.config.dialect,
                            Some(crate::dialects::DialectType::Spark)
                        );
                        let (this, characters) = if trim_pattern_first {
                            (second_expr, first_expr)
                        } else {
                            (first_expr, second_expr)
                        };
                        Ok(Some(Expression::Trim(Box::new(TrimFunc {
                            this,
                            characters: Some(characters),
                            position: TrimPosition::Both,
                            sql_standard_syntax: false,
                            position_explicit: false,
                        }))))
                    } else {
                        self.expect(TokenType::RParen)?;
                        Ok(Some(Expression::Trim(Box::new(TrimFunc {
                            this: first_expr,
                            characters: None,
                            position: TrimPosition::Both,
                            sql_standard_syntax: false,
                            position_explicit: false,
                        }))))
                    }
                }
            }
            (crate::function_registry::TypedParseKind::Variadic, "OVERLAY") => {
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) {
                    let args = self.parse_function_arguments()?;
                    self.expect(TokenType::RParen)?;
                    return Ok(Some(Expression::Function(Box::new(Function {
                        name: name.to_string(),
                        args,
                        distinct: false,
                        trailing_comments: Vec::new(),
                        use_bracket_syntax: false,
                        no_parens: false,
                        quoted: false,
                        span: None,
                        inferred_type: None,
                    }))));
                }

                let this = self.parse_expression()?;
                if self.match_token(TokenType::Placing) {
                    let replacement = self.parse_expression()?;
                    self.expect(TokenType::From)?;
                    let from = self.parse_expression()?;
                    let length = if self.match_token(TokenType::For) {
                        Some(self.parse_expression()?)
                    } else {
                        None
                    };
                    self.expect(TokenType::RParen)?;
                    Ok(Some(Expression::Overlay(Box::new(OverlayFunc {
                        this,
                        replacement,
                        from,
                        length,
                    }))))
                } else if self.match_token(TokenType::Comma) {
                    let replacement = self.parse_expression()?;
                    if self.match_token(TokenType::Comma) {
                        let from = self.parse_expression()?;
                        let length = if self.match_token(TokenType::Comma) {
                            Some(self.parse_expression()?)
                        } else {
                            None
                        };
                        self.expect(TokenType::RParen)?;
                        Ok(Some(Expression::Overlay(Box::new(OverlayFunc {
                            this,
                            replacement,
                            from,
                            length,
                        }))))
                    } else {
                        self.expect(TokenType::RParen)?;
                        Ok(Some(Expression::Function(Box::new(Function {
                            name: name.to_string(),
                            args: vec![this, replacement],
                            distinct: false,
                            trailing_comments: Vec::new(),
                            use_bracket_syntax: false,
                            no_parens: false,
                            quoted: false,
                            span: None,
                            inferred_type: None,
                        }))))
                    }
                } else {
                    self.expect(TokenType::RParen)?;
                    Ok(Some(Expression::Function(Box::new(Function {
                        name: name.to_string(),
                        args: vec![this],
                        distinct: false,
                        trailing_comments: Vec::new(),
                        use_bracket_syntax: false,
                        no_parens: false,
                        quoted: false,
                        span: None,
                        inferred_type: None,
                    }))))
                }
            }
            (crate::function_registry::TypedParseKind::Variadic, "CEIL") => {
                let this = self.parse_expression()?;
                // Check for TO unit syntax (Druid: CEIL(__time TO WEEK))
                let to = if self.match_token(TokenType::To) {
                    // Parse the time unit as a variable/identifier
                    self.parse_var()?
                } else {
                    None
                };
                let decimals = if to.is_none() && self.match_token(TokenType::Comma) {
                    Some(self.parse_expression()?)
                } else {
                    None
                };
                self.expect(TokenType::RParen)?;
                Ok(Some(Expression::Ceil(Box::new(CeilFunc {
                    this,
                    decimals,
                    to,
                }))))
            }
            (crate::function_registry::TypedParseKind::Variadic, "TIMESTAMP_FROM_PARTS")
            | (crate::function_registry::TypedParseKind::Variadic, "TIMESTAMP_NTZ_FROM_PARTS")
            | (crate::function_registry::TypedParseKind::Variadic, "TIMESTAMP_LTZ_FROM_PARTS")
            | (crate::function_registry::TypedParseKind::Variadic, "TIMESTAMP_TZ_FROM_PARTS")
            | (crate::function_registry::TypedParseKind::Variadic, "DATE_FROM_PARTS")
            | (crate::function_registry::TypedParseKind::Variadic, "TIME_FROM_PARTS") => {
                let args = self.parse_expression_list()?;
                self.expect(TokenType::RParen)?;
                Ok(Some(Expression::Function(Box::new(Function {
                    name: name.to_string(),
                    args,
                    distinct: false,
                    trailing_comments: Vec::new(),
                    use_bracket_syntax: false,
                    no_parens: false,
                    quoted: false,
                    span: None,
                    inferred_type: None,
                }))))
            }
            (crate::function_registry::TypedParseKind::CastLike, "TRY_CAST") => {
                let this = self.parse_expression()?;
                self.expect(TokenType::As)?;
                let to = self.parse_data_type()?;
                self.expect(TokenType::RParen)?;
                Ok(Some(Expression::TryCast(Box::new(Cast {
                    this,
                    to,
                    trailing_comments: Vec::new(),
                    double_colon_syntax: false,
                    format: None,
                    default: None,
                    inferred_type: None,
                }))))
            }
            (crate::function_registry::TypedParseKind::Conditional, "IF") => {
                // ClickHouse: if() with zero args is valid in test queries
                if self.check(TokenType::RParen) {
                    self.advance();
                    return Ok(Some(Expression::Function(Box::new(Function {
                        name: name.to_string(),
                        args: vec![],
                        distinct: false,
                        trailing_comments: Vec::new(),
                        use_bracket_syntax: false,
                        no_parens: false,
                        quoted: false,
                        span: None,
                        inferred_type: None,
                    }))));
                }
                let args = self.parse_expression_list()?;
                self.expect(TokenType::RParen)?;
                let expr = if args.len() == 3 {
                    Expression::IfFunc(Box::new(crate::expressions::IfFunc {
                        original_name: Some(upper_name.to_string()),
                        condition: args[0].clone(),
                        true_value: args[1].clone(),
                        false_value: Some(args[2].clone()),
                        inferred_type: None,
                    }))
                } else if args.len() == 2 {
                    // IF with 2 args: condition, true_value (no false_value)
                    Expression::IfFunc(Box::new(crate::expressions::IfFunc {
                        original_name: Some(upper_name.to_string()),
                        condition: args[0].clone(),
                        true_value: args[1].clone(),
                        false_value: None,
                        inferred_type: None,
                    }))
                } else {
                    return Err(self.parse_error("IF function requires 2 or 3 arguments"));
                };
                Ok(Some(expr))
            }
            _ => {
                self.try_parse_registry_grouped_typed_family(name, upper_name, canonical_upper_name)
            }
        }
    }

    /// Route heavy typed-function families via registry metadata groups.
    fn try_parse_registry_grouped_typed_family(
        &mut self,
        name: &str,
        upper_name: &str,
        canonical_upper_name: &str,
    ) -> Result<Option<Expression>> {
        use crate::function_registry::TypedDispatchGroup;

        match crate::function_registry::typed_dispatch_group_by_name_upper(canonical_upper_name) {
            Some(TypedDispatchGroup::AggregateFamily) => self
                .parse_typed_aggregate_family(name, upper_name, canonical_upper_name)
                .map(Some),
            Some(TypedDispatchGroup::WindowFamily) => self
                .parse_typed_window_family(name, upper_name, canonical_upper_name)
                .map(Some),
            Some(TypedDispatchGroup::JsonFamily) => self
                .parse_typed_json_family(name, upper_name, canonical_upper_name)
                .map(Some),
            Some(TypedDispatchGroup::TranslateTeradataFamily) => {
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::Teradata)
                ) {
                    self.parse_typed_translate_teradata_family(
                        name,
                        upper_name,
                        canonical_upper_name,
                    )
                    .map(Some)
                } else {
                    Ok(None)
                }
            }
            None => Ok(None),
        }
    }

    fn make_unquoted_function(name: &str, args: Vec<Expression>) -> Expression {
        Expression::Function(Box::new(Function {
            name: name.to_string(),
            args,
            distinct: false,
            trailing_comments: Vec::new(),
            use_bracket_syntax: false,
            no_parens: false,
            quoted: false,
            span: None,
            inferred_type: None,
        }))
    }

    fn make_simple_aggregate(
        name: &str,
        args: Vec<Expression>,
        distinct: bool,
        filter: Option<Expression>,
    ) -> Expression {
        Expression::AggregateFunction(Box::new(AggregateFunction {
            name: name.to_string(),
            args,
            distinct,
            filter,
            order_by: Vec::new(),
            limit: None,
            ignore_nulls: None,
            inferred_type: None,
        }))
    }

    /// Parse phase-3 typed-function slices that are straightforward pass-throughs.
    fn try_parse_phase3_typed_function(
        &mut self,
        name: &str,
        _upper_name: &str,
        canonical_upper_name: &str,
    ) -> Result<Option<Expression>> {
        let Some(behavior) =
            crate::function_registry::parser_dispatch_behavior_by_name_upper(canonical_upper_name)
        else {
            return Ok(None);
        };

        match behavior {
            crate::function_registry::ParserDispatchBehavior::ExprListFunction => {
                let args = self.parse_expression_list()?;
                self.expect(TokenType::RParen)?;
                Ok(Some(Self::make_unquoted_function(name, args)))
            }
            crate::function_registry::ParserDispatchBehavior::OptionalExprListFunction => {
                let args = if self.check(TokenType::RParen) {
                    Vec::new()
                } else {
                    self.parse_expression_list()?
                };
                self.expect(TokenType::RParen)?;
                Ok(Some(Self::make_unquoted_function(name, args)))
            }
            crate::function_registry::ParserDispatchBehavior::FunctionArgumentsFunction => {
                let args = self.parse_function_arguments()?;
                self.expect(TokenType::RParen)?;
                Ok(Some(Self::make_unquoted_function(name, args)))
            }
            crate::function_registry::ParserDispatchBehavior::ZeroArgFunction => {
                self.expect(TokenType::RParen)?;
                Ok(Some(Self::make_unquoted_function(name, Vec::new())))
            }
            crate::function_registry::ParserDispatchBehavior::ExprListMaybeAggregateByFilter => {
                let args = if self.check(TokenType::RParen) {
                    Vec::new()
                } else {
                    self.parse_expression_list()?
                };
                self.expect(TokenType::RParen)?;
                let filter = self.parse_filter_clause()?;
                if filter.is_some() {
                    Ok(Some(Self::make_simple_aggregate(name, args, false, filter)))
                } else {
                    Ok(Some(Self::make_unquoted_function(name, args)))
                }
            }
            crate::function_registry::ParserDispatchBehavior::ExprListMaybeAggregateByAggSuffix => {
                let args = self.parse_expression_list()?;
                self.expect(TokenType::RParen)?;
                let filter = self.parse_filter_clause()?;
                if canonical_upper_name.ends_with("_AGG") || filter.is_some() {
                    Ok(Some(Self::make_simple_aggregate(name, args, false, filter)))
                } else {
                    Ok(Some(Self::make_unquoted_function(name, args)))
                }
            }
            crate::function_registry::ParserDispatchBehavior::HashLike => {
                let args = self.parse_expression_list()?;
                self.expect(TokenType::RParen)?;
                let filter = self.parse_filter_clause()?;
                if canonical_upper_name == "HASH_AGG" || filter.is_some() {
                    Ok(Some(Self::make_simple_aggregate(name, args, false, filter)))
                } else {
                    Ok(Some(Self::make_unquoted_function(name, args)))
                }
            }
            crate::function_registry::ParserDispatchBehavior::HllAggregate => {
                let distinct = self.match_token(TokenType::Distinct);
                let args = if self.match_token(TokenType::Star) {
                    vec![Expression::Star(Star {
                        table: None,
                        except: None,
                        replace: None,
                        rename: None,
                        trailing_comments: Vec::new(),
                        span: None,
                    })]
                } else if self.check(TokenType::RParen) {
                    Vec::new()
                } else {
                    self.parse_expression_list()?
                };
                self.expect(TokenType::RParen)?;
                let filter = self.parse_filter_clause()?;
                Ok(Some(Self::make_simple_aggregate(
                    name, args, distinct, filter,
                )))
            }
            crate::function_registry::ParserDispatchBehavior::PercentileAggregate => {
                let distinct = self.match_token(TokenType::Distinct);
                if !distinct {
                    self.match_token(TokenType::All);
                }
                let args = self.parse_expression_list()?;
                self.expect(TokenType::RParen)?;
                let filter = self.parse_filter_clause()?;
                Ok(Some(Self::make_simple_aggregate(
                    name, args, distinct, filter,
                )))
            }
            crate::function_registry::ParserDispatchBehavior::ExprListAggregate => {
                let args = self.parse_expression_list()?;
                self.expect(TokenType::RParen)?;
                let filter = self.parse_filter_clause()?;
                Ok(Some(Self::make_simple_aggregate(name, args, false, filter)))
            }
            crate::function_registry::ParserDispatchBehavior::UnaryAggregate => {
                let this = self.parse_expression()?;
                self.expect(TokenType::RParen)?;
                let filter = self.parse_filter_clause()?;
                Ok(Some(Self::make_simple_aggregate(
                    name,
                    vec![this],
                    false,
                    filter,
                )))
            }
            crate::function_registry::ParserDispatchBehavior::TranslateNonTeradata => {
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::Teradata)
                ) {
                    return Ok(None);
                }
                let args = self.parse_expression_list()?;
                self.expect(TokenType::RParen)?;
                Ok(Some(Self::make_unquoted_function(name, args)))
            }
        }
    }

    /// Parse a typed function call (after the opening paren)
    /// Following Python SQLGlot pattern: match all function aliases to typed expressions
    fn parse_typed_function(
        &mut self,
        name: &str,
        upper_name: &str,
        quoted: bool,
    ) -> Result<Expression> {
        let canonical_upper_name =
            crate::function_registry::canonical_typed_function_name_upper(upper_name);

        // Handle internal function rewrites (sqlglot internal functions that map to CAST)
        if canonical_upper_name == "TIME_TO_TIME_STR" {
            let arg = self.parse_expression()?;
            self.expect(TokenType::RParen)?;
            return Ok(Expression::Cast(Box::new(Cast {
                this: arg,
                to: DataType::Text,
                trailing_comments: Vec::new(),
                double_colon_syntax: false,
                format: None,
                default: None,
                inferred_type: None,
            })));
        }

        if let Some(expr) =
            self.try_parse_registry_typed_function(name, upper_name, canonical_upper_name, quoted)?
        {
            return Ok(expr);
        }
        if let Some(expr) =
            self.try_parse_phase3_typed_function(name, upper_name, canonical_upper_name)?
        {
            return Ok(expr);
        }

        self.parse_generic_function(name, quoted)
    }

    fn parse_typed_aggregate_family(
        &mut self,
        name: &str,
        upper_name: &str,
        canonical_upper_name: &str,
    ) -> Result<Expression> {
        match canonical_upper_name {
            // COUNT function
            "COUNT" => {
                let (this, star, distinct) = if self.check(TokenType::RParen) {
                    (None, false, false)
                } else if self.match_token(TokenType::Star) {
                    (None, true, false)
                } else if self.match_token(TokenType::All) {
                    // COUNT(ALL expr) - ALL is the default, just consume it
                    (Some(self.parse_expression()?), false, false)
                } else if self.match_token(TokenType::Distinct) {
                    let first_expr = self.parse_expression()?;
                    // Check for multiple columns: COUNT(DISTINCT a, b, c)
                    if self.match_token(TokenType::Comma) {
                        let mut args = vec![first_expr];
                        loop {
                            args.push(self.parse_expression()?);
                            if !self.match_token(TokenType::Comma) {
                                break;
                            }
                        }
                        // Return as a tuple expression for COUNT DISTINCT over multiple columns
                        (
                            Some(Expression::Tuple(Box::new(Tuple { expressions: args }))),
                            false,
                            true,
                        )
                    } else {
                        (Some(first_expr), false, true)
                    }
                } else {
                    let first_expr = self.parse_expression()?;
                    // ClickHouse: consume optional AS alias inside function args (e.g., count(NULL AS a))
                    let first_expr = if matches!(
                        self.config.dialect,
                        Some(crate::dialects::DialectType::ClickHouse)
                    ) && self.check(TokenType::As)
                    {
                        self.advance(); // consume AS
                        let alias = self.expect_identifier_or_keyword_with_quoted()?;
                        Expression::Alias(Box::new(Alias {
                            this: first_expr,
                            alias,
                            column_aliases: Vec::new(),
                            pre_alias_comments: Vec::new(),
                            trailing_comments: Vec::new(),
                            inferred_type: None,
                        }))
                    } else {
                        first_expr
                    };
                    // Check for multiple arguments (rare but possible)
                    if self.match_token(TokenType::Comma) {
                        let mut args = vec![first_expr];
                        loop {
                            args.push(self.parse_expression()?);
                            if !self.match_token(TokenType::Comma) {
                                break;
                            }
                        }
                        self.expect(TokenType::RParen)?;
                        // Multiple args without DISTINCT - treat as generic function
                        return Ok(Expression::Function(Box::new(Function {
                            name: name.to_string(),
                            args,
                            distinct: false,
                            trailing_comments: Vec::new(),
                            use_bracket_syntax: false,
                            no_parens: false,
                            quoted: false,
                            span: None,
                            inferred_type: None,
                        })));
                    }
                    (Some(first_expr), false, false)
                };
                // BigQuery: RESPECT NULLS / IGNORE NULLS inside COUNT
                let ignore_nulls = if self.match_token(TokenType::Ignore)
                    && self.match_token(TokenType::Nulls)
                {
                    Some(true)
                } else if self.match_token(TokenType::Respect) && self.match_token(TokenType::Nulls)
                {
                    Some(false)
                } else {
                    None
                };
                self.expect(TokenType::RParen)?;
                let filter = self.parse_filter_clause()?;
                // Also check for IGNORE NULLS / RESPECT NULLS after the closing paren
                let ignore_nulls = if ignore_nulls.is_some() {
                    ignore_nulls
                } else if self.match_keywords(&[TokenType::Ignore, TokenType::Nulls]) {
                    Some(true)
                } else if self.match_keywords(&[TokenType::Respect, TokenType::Nulls]) {
                    Some(false)
                } else {
                    None
                };
                Ok(Expression::Count(Box::new(CountFunc {
                    this,
                    star,
                    distinct,
                    filter,
                    ignore_nulls,
                    original_name: Some(name.to_string()),
                    inferred_type: None,
                })))
            }

            // LIST function: LIST(SELECT ...) in Materialize - list constructor with subquery
            "LIST" => {
                let is_materialize = matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::Materialize)
                );
                if is_materialize && self.check(TokenType::Select) {
                    let query = self.parse_select()?;
                    self.expect(TokenType::RParen)?;
                    return Ok(Expression::List(Box::new(List {
                        expressions: vec![query],
                    })));
                }
                // For non-Materialize or non-subquery, parse as either generic function or aggregate.
                let distinct = self.match_token(TokenType::Distinct);
                let args = if self.check(TokenType::RParen) {
                    Vec::new()
                } else {
                    self.parse_function_arguments()?
                };
                let order_by = if self.match_token(TokenType::Order) {
                    self.expect(TokenType::By)?;
                    self.parse_order_by_list()?
                } else {
                    Vec::new()
                };
                let limit = if self.match_token(TokenType::Limit) {
                    Some(Box::new(self.parse_expression()?))
                } else {
                    None
                };
                self.expect(TokenType::RParen)?;
                let filter = self.parse_filter_clause()?;

                if distinct || !order_by.is_empty() || limit.is_some() || filter.is_some() {
                    Ok(Expression::AggregateFunction(Box::new(AggregateFunction {
                        name: name.to_string(),
                        args,
                        distinct,
                        filter,
                        order_by,
                        limit,
                        ignore_nulls: None,
                        inferred_type: None,
                    })))
                } else {
                    Ok(Expression::Function(Box::new(Function {
                        name: name.to_string(),
                        args,
                        distinct: false,
                        trailing_comments: Vec::new(),
                        use_bracket_syntax: false,
                        no_parens: false,
                        quoted: false,
                        span: None,
                        inferred_type: None,
                    })))
                }
            }

            // MAP function: MAP(SELECT ...) in Materialize - map constructor with subquery
            "MAP" => {
                let is_materialize = matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::Materialize)
                );
                if is_materialize && self.check(TokenType::Select) {
                    let query = self.parse_select()?;
                    self.expect(TokenType::RParen)?;
                    return Ok(Expression::ToMap(Box::new(ToMap {
                        this: Box::new(query),
                    })));
                }
                // For non-Materialize or non-subquery, fall through to generic handling
                let args = if self.check(TokenType::RParen) {
                    Vec::new()
                } else {
                    self.parse_function_arguments()?
                };
                self.expect(TokenType::RParen)?;
                Ok(Expression::Function(Box::new(Function {
                    name: name.to_string(),
                    args,
                    distinct: false,
                    trailing_comments: Vec::new(),
                    use_bracket_syntax: false,
                    no_parens: false,
                    quoted: false,
                    span: None,
                    inferred_type: None,
                })))
            }

            // ARRAY function: ARRAY(SELECT ...) or ARRAY((SELECT ...) LIMIT n) is an array constructor with subquery
            // Different from ARRAY<type> which is a data type
            "ARRAY" => {
                // Check if this is ARRAY(SELECT ...) - array subquery constructor
                if self.check(TokenType::Select) {
                    let query = self.parse_select()?;
                    self.expect(TokenType::RParen)?;
                    // Pass the query directly as an argument to ARRAY function
                    // The generator will handle it correctly
                    return Ok(Expression::Function(Box::new(Function {
                        name: name.to_string(),
                        args: vec![query],
                        distinct: false,
                        trailing_comments: Vec::new(),
                        use_bracket_syntax: false,
                        no_parens: false,
                        quoted: false,
                        span: None,
                        inferred_type: None,
                    })));
                }
                // Check if this is ARRAY((SELECT ...) LIMIT n) - BigQuery allows LIMIT outside the subquery parens
                // This is common for constructs like ARRAY((SELECT AS STRUCT ...) LIMIT 10)
                if self.check(TokenType::LParen) {
                    // This could be a parenthesized subquery with modifiers after it
                    // Save position in case we need to backtrack
                    let saved_pos = self.current;
                    self.advance(); // consume opening paren

                    // Check if there's a SELECT or WITH inside
                    if self.check(TokenType::Select) || self.check(TokenType::With) {
                        let inner_query = self.parse_statement()?;
                        self.expect(TokenType::RParen)?; // close inner parens

                        // Now check for LIMIT/OFFSET modifiers outside the inner parens
                        let limit = if self.match_token(TokenType::Limit) {
                            let expr = self.parse_expression()?;
                            Some(Limit {
                                this: expr,
                                percent: false,
                                comments: Vec::new(),
                            })
                        } else {
                            None
                        };

                        let offset = if self.match_token(TokenType::Offset) {
                            let expr = self.parse_expression()?;
                            let rows = if self.match_token(TokenType::Row)
                                || self.match_token(TokenType::Rows)
                            {
                                Some(true)
                            } else {
                                None
                            };
                            Some(Offset { this: expr, rows })
                        } else {
                            None
                        };

                        self.expect(TokenType::RParen)?; // close ARRAY parens

                        // Wrap the inner query in a Subquery with the modifiers
                        let subquery = Expression::Subquery(Box::new(Subquery {
                            this: inner_query,
                            alias: None,
                            column_aliases: Vec::new(),
                            order_by: None,
                            limit,
                            offset,
                            lateral: false,
                            modifiers_inside: false,
                            trailing_comments: Vec::new(),
                            distribute_by: None,
                            sort_by: None,
                            cluster_by: None,
                            inferred_type: None,
                        }));

                        return Ok(Expression::Function(Box::new(Function {
                            name: name.to_string(),
                            args: vec![subquery],
                            distinct: false,
                            trailing_comments: Vec::new(),
                            use_bracket_syntax: false,
                            no_parens: false,
                            quoted: false,
                            span: None,
                            inferred_type: None,
                        })));
                    } else {
                        // Not a subquery, backtrack and parse as regular arguments
                        self.current = saved_pos;
                    }
                }
                // Otherwise fall through to parse as generic function or error
                // This could be ARRAY(...values...) or invalid syntax
                let args = if self.check(TokenType::RParen) {
                    Vec::new()
                } else {
                    self.parse_function_arguments()?
                };
                self.expect(TokenType::RParen)?;
                Ok(Expression::Function(Box::new(Function {
                    name: name.to_string(),
                    args,
                    distinct: false,
                    trailing_comments: Vec::new(),
                    use_bracket_syntax: false,
                    no_parens: false,
                    quoted: false,
                    span: None,
                    inferred_type: None,
                })))
            }

            // Simple aggregate functions (SUM, AVG, MIN, MAX, etc.)
            // These can have multiple arguments in some contexts (e.g., MAX(a, b) is a scalar function)
            "SUM"
            | "AVG"
            | "MIN"
            | "MAX"
            | "ARRAY_AGG"
            | "ARRAY_CONCAT_AGG"
            | "STDDEV"
            | "STDDEV_POP"
            | "STDDEV_SAMP"
            | "VARIANCE"
            | "VAR_POP"
            | "VAR_SAMP"
            | "MEDIAN"
            | "MODE"
            | "FIRST"
            | "LAST"
            | "ANY_VALUE"
            | "APPROX_DISTINCT"
            | "APPROX_COUNT_DISTINCT"
            | "BIT_AND"
            | "BIT_OR"
            | "BIT_XOR" => {
                let distinct = if self.match_token(TokenType::Distinct) {
                    true
                } else {
                    self.match_token(TokenType::All); // ALL is the default, just consume it
                    false
                };

                // MODE() can have zero arguments when used with WITHIN GROUP
                // e.g., MODE() WITHIN GROUP (ORDER BY col)
                if self.check(TokenType::RParen) {
                    // Empty args - will likely be followed by WITHIN GROUP
                    self.expect(TokenType::RParen)?;
                    let filter = self.parse_filter_clause()?;
                    let agg = AggFunc {
                        ignore_nulls: None,
                        this: Expression::Null(Null {}), // Placeholder for 0-arg aggregate
                        distinct: false,
                        filter,
                        order_by: Vec::new(),
                        having_max: None,
                        name: Some(name.to_string()),
                        limit: None,
                        inferred_type: None,
                    };
                    return Ok(match upper_name {
                        "MODE" => Expression::Mode(Box::new(agg)),
                        _ => {
                            // ClickHouse: allow zero-arg aggregates (server will validate)
                            if matches!(
                                self.config.dialect,
                                Some(crate::dialects::DialectType::ClickHouse)
                            ) {
                                Expression::Function(Box::new(Function {
                                    name: name.to_string(),
                                    args: Vec::new(),
                                    distinct: false,
                                    trailing_comments: Vec::new(),
                                    use_bracket_syntax: false,
                                    no_parens: false,
                                    quoted: false,
                                    span: None,
                                    inferred_type: None,
                                }))
                            } else {
                                return Err(self.parse_error(format!(
                                    "{} cannot have zero arguments",
                                    upper_name
                                )));
                            }
                        }
                    });
                }

                let first_arg = self.parse_expression_with_clickhouse_alias()?;

                // Check if there are more arguments (multi-arg scalar function like MAX(a, b))
                if self.match_token(TokenType::Comma) {
                    // Special handling for FIRST, LAST, ANY_VALUE with boolean second arg
                    // In Spark/Hive: first(col, true) means FIRST(col) IGNORE NULLS
                    let is_ignore_nulls_func = matches!(upper_name, "FIRST" | "LAST" | "ANY_VALUE");

                    let second_arg = self.parse_expression()?;

                    // Check if this is the IGNORE NULLS pattern: func(col, true)
                    if is_ignore_nulls_func && self.check(TokenType::RParen) {
                        if let Expression::Boolean(BooleanLiteral { value: true }) = &second_arg {
                            // This is func(col, true) -> FUNC(col) IGNORE NULLS
                            self.expect(TokenType::RParen)?;
                            let filter = self.parse_filter_clause()?;
                            let agg = AggFunc {
                                ignore_nulls: Some(true),
                                this: first_arg,
                                distinct,
                                filter,
                                order_by: Vec::new(),
                                having_max: None,
                                name: Some(name.to_string()),
                                limit: None,
                                inferred_type: None,
                            };
                            return Ok(match upper_name {
                                "FIRST" => Expression::First(Box::new(agg)),
                                "LAST" => Expression::Last(Box::new(agg)),
                                "ANY_VALUE" => Expression::AnyValue(Box::new(agg)),
                                _ => unreachable!(
                                    "function name already matched by is_ignore_nulls_func guard"
                                ),
                            });
                        }
                    }

                    // Multiple arguments - treat as generic function call
                    let mut args = vec![first_arg, second_arg];
                    while self.match_token(TokenType::Comma) {
                        args.push(self.parse_expression()?);
                    }
                    self.expect(TokenType::RParen)?;
                    Ok(Expression::Function(Box::new(Function {
                        name: name.to_string(),
                        args,
                        distinct: false,
                        trailing_comments: Vec::new(),
                        use_bracket_syntax: false,
                        no_parens: false,
                        quoted: false,
                        span: None,
                        inferred_type: None,
                    })))
                } else {
                    // Check for IGNORE NULLS / RESPECT NULLS (BigQuery style)
                    let ignore_nulls = if self.match_token(TokenType::Ignore)
                        && self.match_token(TokenType::Nulls)
                    {
                        Some(true)
                    } else if self.match_token(TokenType::Respect)
                        && self.match_token(TokenType::Nulls)
                    {
                        Some(false)
                    } else {
                        None
                    };

                    // Check for HAVING MAX/MIN inside aggregate (BigQuery syntax)
                    // e.g., ANY_VALUE(fruit HAVING MAX sold)
                    let having_max = if self.match_token(TokenType::Having) {
                        let is_max = if self.check_keyword_text("MAX") {
                            self.advance();
                            true
                        } else if self.check_keyword_text("MIN") {
                            self.advance();
                            false
                        } else {
                            return Err(
                                self.parse_error("Expected MAX or MIN after HAVING in aggregate")
                            );
                        };
                        let expr = self.parse_expression()?;
                        Some((Box::new(expr), is_max))
                    } else {
                        None
                    };

                    // Check for ORDER BY inside aggregate (e.g., ARRAY_AGG(x ORDER BY y))
                    let order_by = if self.match_keywords(&[TokenType::Order, TokenType::By]) {
                        self.parse_order_by_list()?
                    } else {
                        Vec::new()
                    };
                    // Check for LIMIT inside aggregate (e.g., ARRAY_AGG(x ORDER BY y LIMIT 2))
                    // Also supports LIMIT offset, count (e.g., ARRAY_AGG(x ORDER BY y LIMIT 1, 10))
                    let limit = if self.match_token(TokenType::Limit) {
                        let first = self.parse_expression()?;
                        if self.match_token(TokenType::Comma) {
                            let second = self.parse_expression()?;
                            // Store as Tuple(offset, count)
                            Some(Box::new(Expression::Tuple(Box::new(Tuple {
                                expressions: vec![first, second],
                            }))))
                        } else {
                            Some(Box::new(first))
                        }
                    } else {
                        None
                    };
                    // Single argument - treat as aggregate function
                    self.expect(TokenType::RParen)?;
                    let filter = self.parse_filter_clause()?;
                    // Also check for IGNORE NULLS / RESPECT NULLS after the closing paren
                    // e.g., FIRST(col) IGNORE NULLS (Hive/Spark/generic SQL syntax)
                    let ignore_nulls = if ignore_nulls.is_some() {
                        ignore_nulls
                    } else if self.match_keywords(&[TokenType::Ignore, TokenType::Nulls]) {
                        Some(true)
                    } else if self.match_keywords(&[TokenType::Respect, TokenType::Nulls]) {
                        Some(false)
                    } else {
                        None
                    };
                    let agg = AggFunc {
                        ignore_nulls,
                        this: first_arg,
                        distinct,
                        filter,
                        order_by,
                        having_max,
                        name: Some(name.to_string()),
                        limit,
                        inferred_type: None,
                    };
                    Ok(match upper_name {
                        "SUM" => Expression::Sum(Box::new(agg)),
                        "AVG" => Expression::Avg(Box::new(agg)),
                        "MIN" => Expression::Min(Box::new(agg)),
                        "MAX" => Expression::Max(Box::new(agg)),
                        "ARRAY_AGG" => Expression::ArrayAgg(Box::new(agg)),
                        "ARRAY_CONCAT_AGG" => Expression::ArrayConcatAgg(Box::new(agg)),
                        "STDDEV" => Expression::Stddev(Box::new(agg)),
                        "STDDEV_POP" => Expression::StddevPop(Box::new(agg)),
                        "STDDEV_SAMP" => Expression::StddevSamp(Box::new(agg)),
                        "VARIANCE" => Expression::Variance(Box::new(agg)),
                        "VAR_POP" => Expression::VarPop(Box::new(agg)),
                        "VAR_SAMP" => Expression::VarSamp(Box::new(agg)),
                        "MEDIAN" => Expression::Median(Box::new(agg)),
                        "MODE" => Expression::Mode(Box::new(agg)),
                        "FIRST" => Expression::First(Box::new(agg)),
                        "LAST" => Expression::Last(Box::new(agg)),
                        "ANY_VALUE" => Expression::AnyValue(Box::new(agg)),
                        "APPROX_DISTINCT" => Expression::ApproxDistinct(Box::new(agg)),
                        "APPROX_COUNT_DISTINCT" => Expression::ApproxCountDistinct(Box::new(agg)),
                        "BIT_AND" => Expression::BitwiseAndAgg(Box::new(agg)),
                        "BIT_OR" => Expression::BitwiseOrAgg(Box::new(agg)),
                        "BIT_XOR" => Expression::BitwiseXorAgg(Box::new(agg)),
                        _ => unreachable!("aggregate function name already matched in caller"),
                    })
                }
            }

            // STRING_AGG - STRING_AGG([DISTINCT] expr [, separator] [ORDER BY order_list])
            "STRING_AGG" => {
                let distinct = self.match_token(TokenType::Distinct);
                let this = self.parse_expression()?;
                // Separator is optional
                let separator = if self.match_token(TokenType::Comma) {
                    Some(self.parse_expression()?)
                } else {
                    None
                };
                let order_by = if self.match_keywords(&[TokenType::Order, TokenType::By]) {
                    Some(self.parse_order_by_list()?)
                } else {
                    None
                };
                // BigQuery: LIMIT inside STRING_AGG
                let limit = if self.match_token(TokenType::Limit) {
                    Some(Box::new(self.parse_expression()?))
                } else {
                    None
                };
                self.expect(TokenType::RParen)?;
                let filter = self.parse_filter_clause()?;
                Ok(Expression::StringAgg(Box::new(StringAggFunc {
                    this,
                    separator,
                    order_by,
                    distinct,
                    filter,
                    limit,
                    inferred_type: None,
                })))
            }

            // GROUP_CONCAT - GROUP_CONCAT([DISTINCT] expr [, expr...] [ORDER BY order_list] [SEPARATOR 'sep'])
            // MySQL allows multiple args which get wrapped in CONCAT:
            // GROUP_CONCAT(a, b, c SEPARATOR ',') -> GroupConcat(CONCAT(a, b, c), SEPARATOR=',')
            "GROUP_CONCAT" => {
                let distinct = self.match_token(TokenType::Distinct);
                let first = self.parse_expression()?;
                // Check for additional comma-separated expressions (before ORDER BY or SEPARATOR)
                let mut exprs = vec![first];
                while self.match_token(TokenType::Comma) {
                    // Check if the next tokens are ORDER BY or SEPARATOR
                    // If so, the comma was part of the separator syntax (not more args)
                    if self.check(TokenType::Order) || self.check(TokenType::Separator) {
                        // This shouldn't happen normally in valid SQL, backtrack
                        break;
                    }
                    exprs.push(self.parse_expression()?);
                }
                // If multiple expressions, wrap in CONCAT (matches Python sqlglot behavior)
                let this = if exprs.len() == 1 {
                    exprs.pop().unwrap()
                } else {
                    Expression::Function(Box::new(Function::new("CONCAT".to_string(), exprs)))
                };
                // Parse optional ORDER BY
                let order_by = if self.match_keywords(&[TokenType::Order, TokenType::By]) {
                    Some(self.parse_order_by_list()?)
                } else {
                    None
                };
                // Parse optional SEPARATOR - can be a string literal or expression (e.g., variable)
                let separator = if self.match_token(TokenType::Separator) {
                    Some(self.parse_expression()?)
                } else {
                    None
                };
                self.expect(TokenType::RParen)?;
                let filter = self.parse_filter_clause()?;
                Ok(Expression::GroupConcat(Box::new(GroupConcatFunc {
                    this,
                    separator,
                    order_by,
                    distinct,
                    filter,
                    inferred_type: None,
                })))
            }

            // LISTAGG - LISTAGG([DISTINCT] expr [, separator [ON OVERFLOW ...]]) WITHIN GROUP (ORDER BY ...)
            "LISTAGG" => {
                // Check for optional DISTINCT
                let distinct = self.match_token(TokenType::Distinct);
                let this = self.parse_expression()?;
                let separator = if self.match_token(TokenType::Comma) {
                    Some(self.parse_expression()?)
                } else {
                    None
                };
                // Parse optional ON OVERFLOW clause
                let on_overflow = if self.match_token(TokenType::On) {
                    if self.match_identifier("OVERFLOW") {
                        if self.match_identifier("ERROR") {
                            Some(ListAggOverflow::Error)
                        } else if self.match_token(TokenType::Truncate) {
                            // Optional filler string
                            let filler = if self.check(TokenType::String) {
                                Some(self.parse_expression()?)
                            } else {
                                None
                            };
                            // WITH COUNT or WITHOUT COUNT
                            let with_count = if self.match_token(TokenType::With) {
                                self.match_identifier("COUNT");
                                true
                            } else if self.match_identifier("WITHOUT") {
                                self.match_identifier("COUNT");
                                false
                            } else {
                                true // default is WITH COUNT
                            };
                            Some(ListAggOverflow::Truncate { filler, with_count })
                        } else {
                            None
                        }
                    } else {
                        None
                    }
                } else {
                    None
                };
                self.expect(TokenType::RParen)?;
                // WITHIN GROUP (ORDER BY ...) is handled by maybe_parse_over
                Ok(Expression::ListAgg(Box::new(ListAggFunc {
                    this,
                    separator,
                    on_overflow,
                    order_by: None,
                    distinct,
                    filter: None,
                    inferred_type: None,
                })))
            }
            _ => unreachable!(
                "phase-6 aggregate parser called with non-aggregate family name '{}'",
                canonical_upper_name
            ),
        }
    }

    fn parse_typed_window_family(
        &mut self,
        name: &str,
        upper_name: &str,
        canonical_upper_name: &str,
    ) -> Result<Expression> {
        match canonical_upper_name {
            // Window functions with no arguments (ClickHouse allows args in row_number)
            "ROW_NUMBER" => {
                if self.check(TokenType::RParen) {
                    self.advance();
                    Ok(Expression::RowNumber(RowNumber))
                } else {
                    // ClickHouse: row_number(column1) — parse as regular function
                    let args = self.parse_function_args_list()?;
                    self.expect(TokenType::RParen)?;
                    let trailing_comments = self.previous_trailing_comments();
                    Ok(Expression::Function(Box::new(Function {
                        name: name.to_string(),
                        args,
                        distinct: false,
                        trailing_comments,
                        use_bracket_syntax: false,
                        no_parens: false,
                        quoted: false,
                        span: None,
                        inferred_type: None,
                    })))
                }
            }
            "RANK" => {
                // DuckDB allows: RANK(ORDER BY col) OVER (...)
                // Oracle allows: RANK(val1, val2, ...) WITHIN GROUP (ORDER BY ...)
                let (order_by, args) = if self.check(TokenType::RParen) {
                    // RANK() - no arguments
                    (None, Vec::new())
                } else if self.match_token(TokenType::Order) {
                    // DuckDB: RANK(ORDER BY col)
                    self.expect(TokenType::By)?;
                    (Some(self.parse_order_by()?.expressions), Vec::new())
                } else {
                    // Oracle hypothetical: RANK(val1, val2, ...)
                    let mut args = vec![self.parse_expression()?];
                    while self.match_token(TokenType::Comma) {
                        args.push(self.parse_expression()?);
                    }
                    (None, args)
                };
                self.expect(TokenType::RParen)?;
                Ok(Expression::Rank(Rank { order_by, args }))
            }
            "DENSE_RANK" => {
                // Oracle allows: DENSE_RANK(val1, val2, ...) WITHIN GROUP (ORDER BY ...)
                let args = if self.check(TokenType::RParen) {
                    Vec::new()
                } else {
                    let mut args = vec![self.parse_expression()?];
                    while self.match_token(TokenType::Comma) {
                        args.push(self.parse_expression()?);
                    }
                    args
                };
                self.expect(TokenType::RParen)?;
                Ok(Expression::DenseRank(DenseRank { args }))
            }
            "PERCENT_RANK" => {
                // DuckDB allows: PERCENT_RANK(ORDER BY col) OVER (...)
                // Oracle allows: PERCENT_RANK(val1, val2, ...) WITHIN GROUP (ORDER BY ...)
                let (order_by, args) = if self.check(TokenType::RParen) {
                    // PERCENT_RANK() - no arguments
                    (None, Vec::new())
                } else if self.match_token(TokenType::Order) {
                    // DuckDB: PERCENT_RANK(ORDER BY col)
                    self.expect(TokenType::By)?;
                    (Some(self.parse_order_by()?.expressions), Vec::new())
                } else {
                    // Oracle hypothetical: PERCENT_RANK(val1, val2, ...)
                    let mut args = vec![self.parse_expression()?];
                    while self.match_token(TokenType::Comma) {
                        args.push(self.parse_expression()?);
                    }
                    (None, args)
                };
                self.expect(TokenType::RParen)?;
                Ok(Expression::PercentRank(PercentRank { order_by, args }))
            }
            "CUME_DIST" => {
                // DuckDB allows: CUME_DIST(ORDER BY col) OVER (...)
                // Oracle allows: CUME_DIST(val1, val2, ...) WITHIN GROUP (ORDER BY ...)
                let (order_by, args) = if self.check(TokenType::RParen) {
                    // CUME_DIST() - no arguments
                    (None, Vec::new())
                } else if self.match_token(TokenType::Order) {
                    // DuckDB: CUME_DIST(ORDER BY col)
                    self.expect(TokenType::By)?;
                    (Some(self.parse_order_by()?.expressions), Vec::new())
                } else {
                    // Oracle hypothetical: CUME_DIST(val1, val2, ...)
                    let mut args = vec![self.parse_expression()?];
                    while self.match_token(TokenType::Comma) {
                        args.push(self.parse_expression()?);
                    }
                    (None, args)
                };
                self.expect(TokenType::RParen)?;
                Ok(Expression::CumeDist(CumeDist { order_by, args }))
            }

            // NTILE
            "NTILE" => {
                // num_buckets is optional (Databricks allows NTILE() with no args)
                let num_buckets = if self.check(TokenType::RParen) {
                    None
                } else {
                    Some(self.parse_expression()?)
                };

                // ClickHouse: NTILE can have extra args (e.g., ntile(3, 2)) — skip them
                while matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) && self.match_token(TokenType::Comma)
                {
                    let _ = self.parse_expression()?;
                }

                // DuckDB allows: NTILE(n ORDER BY col) OVER (...)
                let order_by = if self.match_token(TokenType::Order) {
                    self.expect(TokenType::By)?;
                    Some(self.parse_order_by()?.expressions)
                } else {
                    None
                };
                self.expect(TokenType::RParen)?;
                Ok(Expression::NTile(Box::new(NTileFunc {
                    num_buckets,
                    order_by,
                })))
            }

            // LEAD / LAG
            "LEAD" | "LAG" => {
                let this = self.parse_expression()?;
                let (offset, default) = if self.match_token(TokenType::Comma) {
                    let off = self.parse_expression()?;
                    let def = if self.match_token(TokenType::Comma) {
                        Some(self.parse_expression()?)
                    } else {
                        None
                    };
                    (Some(off), def)
                } else {
                    (None, None)
                };
                self.expect(TokenType::RParen)?;
                // Check for IGNORE NULLS / RESPECT NULLS
                let ignore_nulls = if self.match_keywords(&[TokenType::Ignore, TokenType::Nulls]) {
                    Some(true)
                } else if self.match_keywords(&[TokenType::Respect, TokenType::Nulls]) {
                    Some(false)
                } else {
                    None
                };
                let func = LeadLagFunc {
                    this,
                    offset,
                    default,
                    ignore_nulls,
                };
                Ok(if upper_name == "LEAD" {
                    Expression::Lead(Box::new(func))
                } else {
                    Expression::Lag(Box::new(func))
                })
            }

            // FIRST_VALUE / LAST_VALUE
            "FIRST_VALUE" | "LAST_VALUE" => {
                let this = self.parse_expression()?;
                // Check for IGNORE NULLS / RESPECT NULLS inside the parens
                let mut ignore_nulls_inside = if self.match_token(TokenType::Ignore)
                    && self.match_token(TokenType::Nulls)
                {
                    Some(true)
                } else if self.match_token(TokenType::Respect) && self.match_token(TokenType::Nulls)
                {
                    Some(false) // RESPECT NULLS explicitly sets to false
                } else {
                    None
                };
                // Spark/Hive: first_value(col, true) means FIRST_VALUE(col) IGNORE NULLS
                if ignore_nulls_inside.is_none() && self.match_token(TokenType::Comma) {
                    let second_arg = self.parse_expression()?;
                    if let Expression::Boolean(BooleanLiteral { value: true }) = &second_arg {
                        ignore_nulls_inside = Some(true);
                    }
                    // If second arg is not true, just ignore it (not standard)
                }
                self.expect(TokenType::RParen)?;
                // Also check for IGNORE NULLS / RESPECT NULLS after the parens (some dialects use this syntax)
                let ignore_nulls: Option<bool> = if ignore_nulls_inside.is_some() {
                    ignore_nulls_inside
                } else if self.match_keywords(&[TokenType::Ignore, TokenType::Nulls]) {
                    Some(true)
                } else if self.match_keywords(&[TokenType::Respect, TokenType::Nulls]) {
                    Some(false)
                } else {
                    None
                };
                let func = ValueFunc { this, ignore_nulls };
                Ok(if upper_name == "FIRST_VALUE" {
                    Expression::FirstValue(Box::new(func))
                } else {
                    Expression::LastValue(Box::new(func))
                })
            }

            // NTH_VALUE
            "NTH_VALUE" => {
                let this = self.parse_expression()?;
                self.expect(TokenType::Comma)?;
                let offset = self.parse_expression()?;
                // Check for IGNORE NULLS / RESPECT NULLS inside the parens
                let ignore_nulls_inside = if self.match_token(TokenType::Ignore)
                    && self.match_token(TokenType::Nulls)
                {
                    Some(true)
                } else if self.match_token(TokenType::Respect) && self.match_token(TokenType::Nulls)
                {
                    Some(false)
                } else {
                    None
                };
                self.expect(TokenType::RParen)?;
                // Check for Snowflake FROM FIRST / FROM LAST after the parens
                let from_first = if self.match_keywords(&[TokenType::From, TokenType::First]) {
                    Some(true)
                } else if self.match_keywords(&[TokenType::From, TokenType::Last]) {
                    Some(false)
                } else {
                    None
                };
                // Also check for IGNORE NULLS / RESPECT NULLS after the parens (and after FROM FIRST/LAST)
                let ignore_nulls: Option<bool> = if ignore_nulls_inside.is_some() {
                    ignore_nulls_inside
                } else if self.match_keywords(&[TokenType::Ignore, TokenType::Nulls]) {
                    Some(true)
                } else if self.match_keywords(&[TokenType::Respect, TokenType::Nulls]) {
                    Some(false)
                } else {
                    None
                };
                Ok(Expression::NthValue(Box::new(NthValueFunc {
                    this,
                    offset,
                    ignore_nulls,
                    from_first,
                })))
            }
            _ => unreachable!(
                "phase-6 window parser called with non-window family name '{}'",
                canonical_upper_name
            ),
        }
    }

    fn parse_typed_json_family(
        &mut self,
        name: &str,
        upper_name: &str,
        canonical_upper_name: &str,
    ) -> Result<Expression> {
        match canonical_upper_name {
            // JSON functions
            "JSON_EXTRACT" | "JSON_EXTRACT_SCALAR" | "JSON_QUERY" | "JSON_VALUE" => {
                let this = self.parse_expression()?;
                // Path is optional for some dialects (e.g., TSQL JSON_QUERY with 1 arg defaults to '$')
                let path = if self.match_token(TokenType::Comma) {
                    self.parse_expression()?
                } else {
                    // Default path is '$' when not provided
                    Expression::Literal(Literal::String("$".to_string()))
                };

                // SQLite JSON_EXTRACT supports multiple paths - check for additional paths
                // If multiple paths, use generic Function instead of typed expression
                if self.check(TokenType::Comma)
                    && !self.check_identifier("WITH")
                    && !self.check_identifier("WITHOUT")
                    && !self.check_identifier("KEEP")
                    && !self.check_identifier("OMIT")
                    && !self.check_identifier("NULL")
                    && !self.check_identifier("ERROR")
                    && !self.check_identifier("EMPTY")
                    && !self.check(TokenType::Returning)
                {
                    let mut args = vec![this, path];
                    while self.match_token(TokenType::Comma) {
                        args.push(self.parse_expression()?);
                    }
                    self.expect(TokenType::RParen)?;
                    return Ok(Expression::Function(Box::new(Function {
                        name: name.to_string(),
                        args,
                        distinct: false,
                        trailing_comments: Vec::new(),
                        use_bracket_syntax: false,
                        no_parens: false,
                        quoted: false,
                        span: None,
                        inferred_type: None,
                    })));
                }

                // Parse JSON_QUERY/JSON_VALUE options (Trino/Presto style)
                // Options: WITH/WITHOUT [CONDITIONAL|UNCONDITIONAL] [ARRAY] WRAPPER
                //          KEEP QUOTES / OMIT QUOTES [ON SCALAR STRING]
                //          NULL ON ERROR / ERROR ON ERROR / EMPTY ON ERROR
                //          RETURNING type
                let mut wrapper_option: Option<String> = None;
                let mut quotes_option: Option<String> = None;
                let mut on_scalar_string = false;
                let mut on_error: Option<String> = None;
                let mut returning: Option<DataType> = None;

                // Keep parsing options until we see RParen
                while !self.check(TokenType::RParen) {
                    // WITH [CONDITIONAL|UNCONDITIONAL] [ARRAY] WRAPPER - match in order of specificity
                    if self.match_text_seq(&["WITH", "UNCONDITIONAL", "ARRAY", "WRAPPER"]) {
                        wrapper_option = Some("WITH UNCONDITIONAL ARRAY WRAPPER".to_string());
                    } else if self.match_text_seq(&["WITH", "CONDITIONAL", "ARRAY", "WRAPPER"]) {
                        wrapper_option = Some("WITH CONDITIONAL ARRAY WRAPPER".to_string());
                    } else if self.match_text_seq(&["WITH", "UNCONDITIONAL", "WRAPPER"]) {
                        wrapper_option = Some("WITH UNCONDITIONAL WRAPPER".to_string());
                    } else if self.match_text_seq(&["WITH", "CONDITIONAL", "WRAPPER"]) {
                        wrapper_option = Some("WITH CONDITIONAL WRAPPER".to_string());
                    } else if self.match_text_seq(&["WITH", "ARRAY", "WRAPPER"]) {
                        wrapper_option = Some("WITH ARRAY WRAPPER".to_string());
                    } else if self.match_text_seq(&["WITH", "WRAPPER"]) {
                        wrapper_option = Some("WITH WRAPPER".to_string());
                    // WITHOUT [CONDITIONAL] [ARRAY] WRAPPER
                    } else if self.match_text_seq(&["WITHOUT", "CONDITIONAL", "ARRAY", "WRAPPER"]) {
                        wrapper_option = Some("WITHOUT CONDITIONAL ARRAY WRAPPER".to_string());
                    } else if self.match_text_seq(&["WITHOUT", "CONDITIONAL", "WRAPPER"]) {
                        wrapper_option = Some("WITHOUT CONDITIONAL WRAPPER".to_string());
                    } else if self.match_text_seq(&["WITHOUT", "ARRAY", "WRAPPER"]) {
                        wrapper_option = Some("WITHOUT ARRAY WRAPPER".to_string());
                    } else if self.match_text_seq(&["WITHOUT", "WRAPPER"]) {
                        wrapper_option = Some("WITHOUT WRAPPER".to_string());
                    } else if self.match_text_seq(&["KEEP", "QUOTES"]) {
                        // KEEP QUOTES
                        quotes_option = Some("KEEP QUOTES".to_string());
                    } else if self.match_text_seq(&["OMIT", "QUOTES", "ON", "SCALAR", "STRING"]) {
                        // OMIT QUOTES ON SCALAR STRING
                        quotes_option = Some("OMIT QUOTES".to_string());
                        on_scalar_string = true;
                    } else if self.match_text_seq(&["OMIT", "QUOTES"]) {
                        // OMIT QUOTES
                        quotes_option = Some("OMIT QUOTES".to_string());
                    } else if self.match_text_seq(&["NULL", "ON", "ERROR"]) {
                        on_error = Some("NULL ON ERROR".to_string());
                    } else if self.match_text_seq(&["ERROR", "ON", "ERROR"]) {
                        on_error = Some("ERROR ON ERROR".to_string());
                    } else if self.match_text_seq(&["EMPTY", "ON", "ERROR"]) {
                        on_error = Some("EMPTY ON ERROR".to_string());
                    } else if self.match_token(TokenType::Returning) {
                        // RETURNING type
                        returning = Some(self.parse_data_type()?);
                    } else {
                        // No more options recognized, break
                        break;
                    }
                }

                self.expect(TokenType::RParen)?;
                let func = JsonExtractFunc {
                    this,
                    path,
                    returning,
                    arrow_syntax: false,
                    hash_arrow_syntax: false,
                    wrapper_option,
                    quotes_option,
                    on_scalar_string,
                    on_error,
                };
                Ok(match upper_name {
                    "JSON_EXTRACT" => Expression::JsonExtract(Box::new(func)),
                    "JSON_EXTRACT_SCALAR" => Expression::JsonExtractScalar(Box::new(func)),
                    "JSON_QUERY" => Expression::JsonQuery(Box::new(func)),
                    "JSON_VALUE" => Expression::JsonValue(Box::new(func)),
                    _ => unreachable!("JSON function name already matched in caller"),
                })
            }
            // JSON_KEYS, TO_JSON, PARSE_JSON etc. support additional args including named args (BigQuery)
            // e.g., JSON_KEYS(expr, depth, mode => 'lax'), TO_JSON(expr, stringify_wide_numbers => FALSE)
            // e.g., PARSE_JSON('{}', wide_number_mode => 'exact')
            "JSON_ARRAY_LENGTH" | "JSON_KEYS" | "JSON_TYPE" | "TO_JSON" | "PARSE_JSON" => {
                let this = self.parse_expression()?;
                // ClickHouse: expr AS alias inside function args
                let this = self.maybe_clickhouse_alias(this);

                // Check for additional arguments (comma-separated, possibly named)
                if self.match_token(TokenType::Comma) {
                    // Has additional arguments - parse as generic Function to preserve all args
                    let mut all_args = vec![this];
                    let remaining = self.parse_function_arguments()?;
                    all_args.extend(remaining);
                    self.expect(TokenType::RParen)?;
                    Ok(Expression::Function(Box::new(Function {
                        name: name.to_string(),
                        args: all_args,
                        distinct: false,
                        trailing_comments: Vec::new(),
                        use_bracket_syntax: false,
                        no_parens: false,
                        quoted: false,
                        span: None,
                        inferred_type: None,
                    })))
                } else {
                    // Single argument - use typed expression
                    self.expect(TokenType::RParen)?;
                    let func = UnaryFunc::new(this);
                    Ok(match canonical_upper_name {
                        "JSON_ARRAY_LENGTH" => Expression::JsonArrayLength(Box::new(func)),
                        "JSON_KEYS" => Expression::JsonKeys(Box::new(func)),
                        "JSON_TYPE" => Expression::JsonType(Box::new(func)),
                        "TO_JSON" => Expression::ToJson(Box::new(func)),
                        "PARSE_JSON" => Expression::ParseJson(Box::new(func)),
                        _ => unreachable!("JSON function name already matched in caller"),
                    })
                }
            }

            // JSON_OBJECT with SQL standard syntax: JSON_OBJECT('key': value, ...) or JSON_OBJECT(*)
            "JSON_OBJECT" => {
                let mut pairs = Vec::new();
                let mut star = false;
                if !self.check(TokenType::RParen) {
                    // Check for JSON_OBJECT(*) syntax
                    if self.check(TokenType::Star) && self.check_next(TokenType::RParen) {
                        self.advance(); // consume *
                        star = true;
                    } else {
                        loop {
                            // Check for KEY keyword for KEY 'key' IS value syntax (KEY is a keyword token)
                            let has_key_keyword = self.match_token(TokenType::Key);
                            // Parse key: try string first (for 'key' syntax), then column
                            let key = if let Some(s) = self.parse_string()? {
                                s
                            } else {
                                // Use parse_column for key to avoid interpreting colon as JSON path
                                self.parse_column()?.ok_or_else(|| {
                                    self.parse_error("Expected key expression in JSON_OBJECT")
                                })?
                            };

                            // Support colon, VALUE keyword (identifier), and IS keyword (for KEY...IS syntax)
                            let has_separator = self.match_token(TokenType::Colon)
                                || self.match_identifier("VALUE")
                                || (has_key_keyword && self.match_token(TokenType::Is));

                            if has_separator {
                                let value = self.parse_bitwise()?.ok_or_else(|| {
                                    self.parse_error("Expected value expression in JSON_OBJECT")
                                })?;
                                // Check for FORMAT JSON after value
                                let value_with_format = if self.match_text_seq(&["FORMAT", "JSON"])
                                {
                                    Expression::JSONFormat(Box::new(JSONFormat {
                                        this: Some(Box::new(value)),
                                        options: Vec::new(),
                                        is_json: None,
                                        to_json: None,
                                    }))
                                } else {
                                    value
                                };
                                pairs.push((key, value_with_format));
                            } else {
                                // Just key/value pairs without separator
                                if self.match_token(TokenType::Comma) {
                                    let value = self.parse_bitwise()?.ok_or_else(|| {
                                        self.parse_error("Expected value expression in JSON_OBJECT")
                                    })?;
                                    pairs.push((key, value));
                                } else {
                                    return Err(self
                                        .parse_error("Expected value expression in JSON_OBJECT"));
                                }
                            }
                            if !self.match_token(TokenType::Comma) {
                                break;
                            }
                        }
                    }
                }
                // Parse optional modifiers: NULL ON NULL, ABSENT ON NULL, WITH UNIQUE KEYS
                let null_handling = if self.match_token(TokenType::Null) {
                    self.match_token(TokenType::On);
                    self.match_token(TokenType::Null);
                    Some(JsonNullHandling::NullOnNull)
                } else if self.match_identifier("ABSENT") {
                    self.match_token(TokenType::On);
                    self.match_token(TokenType::Null);
                    Some(JsonNullHandling::AbsentOnNull)
                } else {
                    None
                };
                let with_unique_keys = if self.match_token(TokenType::With) {
                    self.match_token(TokenType::Unique);
                    self.match_identifier("KEYS");
                    true
                } else {
                    false
                };
                // Parse optional RETURNING clause: RETURNING type [FORMAT JSON] [ENCODING encoding]
                let (returning_type, format_json, encoding) = if self
                    .match_token(TokenType::Returning)
                {
                    let return_type = self.parse_data_type()?;
                    // Optional FORMAT JSON
                    let has_format_json = if self.match_token(TokenType::Format) {
                        // JSON might be a keyword or identifier
                        let _ = self.match_token(TokenType::Json) || self.match_identifier("JSON");
                        true
                    } else {
                        false
                    };
                    // Optional ENCODING encoding
                    let enc = if self.match_identifier("ENCODING") {
                        Some(self.expect_identifier_or_keyword()?)
                    } else {
                        None
                    };
                    (Some(return_type), has_format_json, enc)
                } else {
                    (None, false, None)
                };
                self.expect(TokenType::RParen)?;
                Ok(Expression::JsonObject(Box::new(JsonObjectFunc {
                    pairs,
                    null_handling,
                    with_unique_keys,
                    returning_type,
                    format_json,
                    encoding,
                    star,
                })))
            }

            // JSON_ARRAY function with Oracle-specific options
            // JSON_ARRAY(expr [FORMAT JSON], ... [NULL ON NULL | ABSENT ON NULL] [RETURNING type] [STRICT])
            "JSON_ARRAY" => {
                let mut expressions = Vec::new();
                if !self.check(TokenType::RParen) {
                    loop {
                        let expr = self.parse_bitwise()?.unwrap_or(Expression::Null(Null));
                        // Check for FORMAT JSON after each expression
                        let expr_with_format = if self.match_text_seq(&["FORMAT", "JSON"]) {
                            Expression::JSONFormat(Box::new(JSONFormat {
                                this: Some(Box::new(expr)),
                                options: Vec::new(),
                                is_json: None,
                                to_json: None,
                            }))
                        } else {
                            expr
                        };
                        expressions.push(expr_with_format);
                        if !self.match_token(TokenType::Comma) {
                            break;
                        }
                    }
                }
                // Parse NULL ON NULL or ABSENT ON NULL
                let null_handling = if self.match_text_seq(&["NULL", "ON", "NULL"]) {
                    Some(Box::new(Expression::Var(Box::new(Var {
                        this: "NULL ON NULL".to_string(),
                    }))))
                } else if self.match_text_seq(&["ABSENT", "ON", "NULL"]) {
                    Some(Box::new(Expression::Var(Box::new(Var {
                        this: "ABSENT ON NULL".to_string(),
                    }))))
                } else {
                    None
                };
                // Parse RETURNING type
                let return_type = if self.match_token(TokenType::Returning) {
                    let dt = self.parse_data_type()?;
                    Some(Box::new(Expression::DataType(dt)))
                } else {
                    None
                };
                // Parse STRICT
                let strict = if self.match_identifier("STRICT") {
                    Some(Box::new(Expression::Boolean(BooleanLiteral {
                        value: true,
                    })))
                } else {
                    None
                };
                self.expect(TokenType::RParen)?;
                Ok(Expression::JSONArray(Box::new(JSONArray {
                    expressions,
                    null_handling,
                    return_type,
                    strict,
                })))
            }

            // JSON_ARRAYAGG function with Oracle-specific options
            // JSON_ARRAYAGG(expr [FORMAT JSON] [ORDER BY ...] [NULL ON NULL | ABSENT ON NULL] [RETURNING type] [STRICT])
            "JSON_ARRAYAGG" => {
                let this = self.parse_bitwise()?.unwrap_or(Expression::Null(Null));
                // Check for FORMAT JSON after the expression
                let this_with_format = if self.match_text_seq(&["FORMAT", "JSON"]) {
                    Expression::JSONFormat(Box::new(JSONFormat {
                        this: Some(Box::new(this)),
                        options: Vec::new(),
                        is_json: None,
                        to_json: None,
                    }))
                } else {
                    this
                };
                // Parse ORDER BY clause
                let order = if self.match_token(TokenType::Order) {
                    self.match_token(TokenType::By);
                    // Parse comma-separated ordered expressions
                    let mut order_exprs = Vec::new();
                    loop {
                        if let Some(ordered) = self.parse_ordered_item()? {
                            order_exprs.push(ordered);
                        } else {
                            break;
                        }
                        if !self.match_token(TokenType::Comma) {
                            break;
                        }
                    }
                    if !order_exprs.is_empty() {
                        Some(Box::new(Expression::OrderBy(Box::new(OrderBy {
                            expressions: order_exprs,
                            siblings: false,
                            comments: Vec::new(),
                        }))))
                    } else {
                        None
                    }
                } else {
                    None
                };
                // Parse NULL ON NULL or ABSENT ON NULL
                let null_handling = if self.match_text_seq(&["NULL", "ON", "NULL"]) {
                    Some(Box::new(Expression::Var(Box::new(Var {
                        this: "NULL ON NULL".to_string(),
                    }))))
                } else if self.match_text_seq(&["ABSENT", "ON", "NULL"]) {
                    Some(Box::new(Expression::Var(Box::new(Var {
                        this: "ABSENT ON NULL".to_string(),
                    }))))
                } else {
                    None
                };
                // Parse RETURNING type
                let return_type = if self.match_token(TokenType::Returning) {
                    let dt = self.parse_data_type()?;
                    Some(Box::new(Expression::DataType(dt)))
                } else {
                    None
                };
                // Parse STRICT
                let strict = if self.match_identifier("STRICT") {
                    Some(Box::new(Expression::Boolean(BooleanLiteral {
                        value: true,
                    })))
                } else {
                    None
                };
                self.expect(TokenType::RParen)?;
                Ok(Expression::JSONArrayAgg(Box::new(JSONArrayAgg {
                    this: Box::new(this_with_format),
                    order,
                    null_handling,
                    return_type,
                    strict,
                })))
            }

            // JSON_OBJECTAGG with KEY...VALUE syntax
            // JSON_OBJECTAGG(KEY key VALUE value) or JSON_OBJECTAGG(key: value)
            "JSON_OBJECTAGG" => {
                // Check for KEY keyword (KEY is a keyword token, not an identifier)
                let _has_key_keyword = self.match_token(TokenType::Key);
                // Parse key: use column parsing to avoid colon being interpreted as JSON path
                let key = self.parse_column()?.unwrap_or(Expression::Null(Null));

                // Support colon or VALUE keyword (VALUE is an identifier, not a keyword)
                let _ = self.match_token(TokenType::Colon) || self.match_identifier("VALUE");

                let value = self.parse_bitwise()?.unwrap_or(Expression::Null(Null));
                // Check for FORMAT JSON after value
                let value_with_format = if self.match_text_seq(&["FORMAT", "JSON"]) {
                    Expression::JSONFormat(Box::new(JSONFormat {
                        this: Some(Box::new(value)),
                        options: Vec::new(),
                        is_json: None,
                        to_json: None,
                    }))
                } else {
                    value
                };
                // Parse NULL ON NULL or ABSENT ON NULL
                let null_handling = if self.match_text_seq(&["NULL", "ON", "NULL"]) {
                    Some(Box::new(Expression::Var(Box::new(Var {
                        this: "NULL ON NULL".to_string(),
                    }))))
                } else if self.match_text_seq(&["ABSENT", "ON", "NULL"]) {
                    Some(Box::new(Expression::Var(Box::new(Var {
                        this: "ABSENT ON NULL".to_string(),
                    }))))
                } else {
                    None
                };
                // Parse WITH/WITHOUT UNIQUE KEYS
                let unique_keys = if self.match_text_seq(&["WITH", "UNIQUE"]) {
                    self.match_identifier("KEYS");
                    Some(Box::new(Expression::Boolean(BooleanLiteral {
                        value: true,
                    })))
                } else if self.match_text_seq(&["WITHOUT", "UNIQUE"]) {
                    self.match_identifier("KEYS");
                    Some(Box::new(Expression::Boolean(BooleanLiteral {
                        value: false,
                    })))
                } else {
                    None
                };
                // Parse RETURNING type
                let return_type = if self.match_token(TokenType::Returning) {
                    let dt = self.parse_data_type()?;
                    Some(Box::new(Expression::DataType(dt)))
                } else {
                    None
                };
                self.expect(TokenType::RParen)?;
                Ok(Expression::JSONObjectAgg(Box::new(JSONObjectAgg {
                    expressions: vec![Expression::JSONKeyValue(Box::new(JSONKeyValue {
                        this: Box::new(key),
                        expression: Box::new(value_with_format),
                    }))],
                    null_handling,
                    unique_keys,
                    return_type,
                    encoding: None,
                })))
            }

            // JSON_TABLE function - MySQL/Oracle table function for JSON data
            // JSON_TABLE(json_doc [FORMAT JSON], path COLUMNS (column_list)) [AS alias]
            "JSON_TABLE" => {
                // Parse the JSON expression
                let this = self.parse_bitwise()?.unwrap_or(Expression::Null(Null));
                // Check for FORMAT JSON after the expression
                let this_with_format = if self.match_text_seq(&["FORMAT", "JSON"]) {
                    Expression::JSONFormat(Box::new(JSONFormat {
                        this: Some(Box::new(this)),
                        options: Vec::new(),
                        is_json: None,
                        to_json: None,
                    }))
                } else {
                    this
                };

                // Parse path (after comma)
                let path = if self.match_token(TokenType::Comma) {
                    if let Some(s) = self.parse_string()? {
                        Some(Box::new(s))
                    } else {
                        None
                    }
                } else {
                    None
                };

                // Oracle uses "ERROR ON ERROR" (value then behavior) instead of "ON ERROR ERROR"
                // Parse error handling: ERROR ON ERROR or NULL ON ERROR
                let error_handling =
                    if self.match_identifier("ERROR") && self.match_text_seq(&["ON", "ERROR"]) {
                        Some(Box::new(Expression::Var(Box::new(Var {
                            this: "ERROR ON ERROR".to_string(),
                        }))))
                    } else if self.match_text_seq(&["NULL", "ON", "ERROR"]) {
                        Some(Box::new(Expression::Var(Box::new(Var {
                            this: "NULL ON ERROR".to_string(),
                        }))))
                    } else {
                        None
                    };

                // Parse empty handling: ERROR ON EMPTY or NULL ON EMPTY
                let empty_handling =
                    if self.match_identifier("ERROR") && self.match_text_seq(&["ON", "EMPTY"]) {
                        Some(Box::new(Expression::Var(Box::new(Var {
                            this: "ERROR ON EMPTY".to_string(),
                        }))))
                    } else if self.match_text_seq(&["NULL", "ON", "EMPTY"]) {
                        Some(Box::new(Expression::Var(Box::new(Var {
                            this: "NULL ON EMPTY".to_string(),
                        }))))
                    } else {
                        None
                    };

                // Parse COLUMNS clause
                let schema = self.parse_json_table_columns()?;

                self.expect(TokenType::RParen)?;

                Ok(Expression::JSONTable(Box::new(JSONTable {
                    this: Box::new(this_with_format),
                    schema: schema.map(Box::new),
                    path,
                    error_handling,
                    empty_handling,
                })))
            }
            _ => unreachable!(
                "phase-6 json parser called with non-json family name '{}'",
                canonical_upper_name
            ),
        }
    }

    fn parse_typed_translate_teradata_family(
        &mut self,
        name: &str,
        _upper_name: &str,
        canonical_upper_name: &str,
    ) -> Result<Expression> {
        match canonical_upper_name {
            // Teradata: TRANSLATE(x USING charset [WITH ERROR])
            "TRANSLATE"
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::Teradata)
                ) =>
            {
                let this = self.parse_expression()?;
                if self.match_token(TokenType::Using) {
                    let expression = self.parse_expression()?;
                    let with_error = if self.match_text_seq(&["WITH", "ERROR"]) {
                        Some(Box::new(Expression::Boolean(BooleanLiteral {
                            value: true,
                        })))
                    } else {
                        None
                    };
                    self.expect(TokenType::RParen)?;
                    Ok(Expression::TranslateCharacters(Box::new(
                        TranslateCharacters {
                            this: Box::new(this),
                            expression: Box::new(expression),
                            with_error,
                        },
                    )))
                } else {
                    let mut args = vec![this];
                    if self.match_token(TokenType::Comma) {
                        let mut rest = self.parse_expression_list()?;
                        args.append(&mut rest);
                    }
                    self.expect(TokenType::RParen)?;
                    Ok(Expression::Function(Box::new(Function {
                        name: name.to_string(),
                        args,
                        distinct: false,
                        trailing_comments: Vec::new(),
                        use_bracket_syntax: false,
                        no_parens: false,
                        quoted: false,
                        span: None,
                        inferred_type: None,
                    })))
                }
            }

            _ => unreachable!(
                "phase-6 translate parser called with non-translate family name '{}'",
                canonical_upper_name
            ),
        }
    }

    /// Parse a generic function call (fallback for unrecognized functions)
    fn parse_generic_function(&mut self, name: &str, quoted: bool) -> Result<Expression> {
        let is_known_agg = Self::is_aggregate_function(name);

        let (args, distinct) = if self.check(TokenType::RParen) {
            (Vec::new(), false)
        } else if self.check(TokenType::Star) {
            // Check for DuckDB *COLUMNS(...) syntax first
            if self.check_next_identifier("COLUMNS")
                && self
                    .tokens
                    .get(self.current + 2)
                    .map(|t| t.token_type == TokenType::LParen)
                    .unwrap_or(false)
            {
                // Parse *COLUMNS(...) as a function argument
                (self.parse_function_arguments()?, false)
            } else {
                // Regular star: parse star modifiers like EXCLUDE/EXCEPT/REPLACE/RENAME
                // e.g., COLUMNS(* EXCLUDE (empid, dept))
                self.advance(); // consume *
                let star = self.parse_star_modifiers(None)?;
                let mut args = vec![Expression::Star(star)];
                // ClickHouse: func(*, col1, col2) — star followed by more args
                if self.match_token(TokenType::Comma) {
                    let rest = self.parse_function_arguments()?;
                    args.extend(rest);
                }
                (args, false)
            }
        } else if self.check(TokenType::Distinct)
            && !self.check_next(TokenType::Comma)
            && !self.check_next(TokenType::RParen)
        {
            // DISTINCT as aggregate modifier: func(DISTINCT expr)
            // Not when followed by comma or rparen — then DISTINCT is used as an identifier value
            self.advance(); // consume DISTINCT
            (self.parse_function_arguments()?, true)
        } else if is_known_agg && self.match_token(TokenType::All) {
            // ALL is the default quantifier, just consume it
            (self.parse_function_arguments()?, false)
        } else {
            (self.parse_function_arguments()?, false)
        };

        // For known aggregate functions, check for IGNORE NULLS, ORDER BY, LIMIT inside parens
        let (ignore_nulls, order_by, agg_limit) = if is_known_agg {
            let ignore_nulls = if self.match_token(TokenType::Ignore)
                && self.match_token(TokenType::Nulls)
            {
                Some(true)
            } else if self.match_token(TokenType::Respect) && self.match_token(TokenType::Nulls) {
                Some(false)
            } else {
                None
            };

            let order_by = if self.match_keywords(&[TokenType::Order, TokenType::By]) {
                self.parse_order_by_list()?
            } else {
                Vec::new()
            };
            let limit = if self.match_token(TokenType::Limit) {
                Some(Box::new(self.parse_expression()?))
            } else {
                None
            };
            (ignore_nulls, order_by, limit)
        } else {
            (None, Vec::new(), None)
        };

        // ClickHouse: SETTINGS key=value, ... before closing paren in function calls
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) && self.check(TokenType::Settings)
            && self.current + 2 < self.tokens.len()
            && (self.tokens[self.current + 1].token_type == TokenType::Var
                || self.tokens[self.current + 1].token_type == TokenType::Identifier)
            && self.tokens[self.current + 2].token_type == TokenType::Eq
        {
            self.advance(); // consume SETTINGS
            loop {
                let _key = if self.is_identifier_token() || self.is_safe_keyword_as_identifier() {
                    self.advance().text
                } else {
                    break;
                };
                if self.match_token(TokenType::Eq) {
                    let _value = self.parse_primary()?;
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
        }

        self.expect(TokenType::RParen)?;
        let trailing_comments = self.previous_trailing_comments();

        // Check for WITHIN GROUP (ORDER BY ...)
        if self.match_identifier("WITHIN") {
            if self.match_identifier("GROUP") {
                self.expect(TokenType::LParen)?;
                self.expect(TokenType::Order)?;
                self.expect(TokenType::By)?;
                let within_order = self.parse_order_by_list()?;
                self.expect(TokenType::RParen)?;

                let func_expr = Expression::AggregateFunction(Box::new(AggregateFunction {
                    name: name.to_string(),
                    args,
                    distinct,
                    filter: None,
                    order_by: Vec::new(),
                    limit: None,
                    ignore_nulls: None,
                    inferred_type: None,
                }));

                let within = Expression::WithinGroup(Box::new(WithinGroup {
                    this: func_expr,
                    order_by: within_order,
                }));

                // Check for FILTER after WITHIN GROUP
                let filter = self.parse_filter_clause()?;
                if let Some(filter_expr) = filter {
                    return Ok(Expression::AggregateFunction(Box::new(AggregateFunction {
                        name: format!("__WITHIN_GROUP_{}", name),
                        args: vec![within, filter_expr],
                        distinct: false,
                        filter: None,
                        order_by: Vec::new(),
                        limit: None,
                        ignore_nulls: None,
                        inferred_type: None,
                    })));
                }

                return Ok(within);
            }
        }

        let filter = self.parse_filter_clause()?;

        // Check for postfix IGNORE NULLS / RESPECT NULLS after RParen
        let ignore_nulls = if ignore_nulls.is_some() {
            ignore_nulls
        } else if self.match_keywords(&[TokenType::Ignore, TokenType::Nulls]) {
            Some(true)
        } else if self.match_keywords(&[TokenType::Respect, TokenType::Nulls]) {
            Some(false)
        } else {
            None
        };

        if filter.is_some() || is_known_agg || ignore_nulls.is_some() {
            Ok(Expression::AggregateFunction(Box::new(AggregateFunction {
                name: name.to_string(),
                args,
                distinct,
                filter,
                order_by,
                limit: agg_limit,
                ignore_nulls,
                inferred_type: None,
            })))
        } else {
            let mut func = Function::new(name.to_string(), args);
            func.distinct = distinct;
            func.trailing_comments = trailing_comments;
            func.quoted = quoted;
            Ok(Expression::Function(Box::new(func)))
        }
    }

    /// Check for an AS alias after an expression in ClickHouse function arg context.
    fn maybe_clickhouse_alias(&mut self, expr: Expression) -> Expression {
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) && self.check(TokenType::As)
            && !self.check_next(TokenType::RParen)
            && !self.check_next(TokenType::Comma)
        {
            let next_idx = self.current + 1;
            let is_alias = next_idx < self.tokens.len()
                && matches!(
                    self.tokens[next_idx].token_type,
                    TokenType::Identifier | TokenType::Var | TokenType::QuotedIdentifier
                );
            if is_alias {
                self.advance(); // consume AS
                let alias_token = self.advance();
                let alias_name = Identifier {
                    name: alias_token.text.clone(),
                    quoted: alias_token.token_type == TokenType::QuotedIdentifier,
                    trailing_comments: Vec::new(),
                    span: None,
                };
                return Expression::Alias(Box::new(crate::expressions::Alias {
                    this: expr,
                    alias: alias_name,
                    column_aliases: Vec::new(),
                    pre_alias_comments: Vec::new(),
                    trailing_comments: Vec::new(),
                    inferred_type: None,
                }));
            }
        }
        expr
    }

    /// Parse an expression, then check for AS alias in ClickHouse function arg context.
    /// ClickHouse allows: func(expr AS alias, ...) where AS creates a named alias inside function args.
    fn parse_expression_with_clickhouse_alias(&mut self) -> Result<Expression> {
        let expr = self.parse_expression()?;
        Ok(self.maybe_clickhouse_alias(expr))
    }

    /// Parse function arguments, handling named arguments (name => value, name := value)
    /// and TABLE/MODEL prefixed arguments (BigQuery)
    fn parse_function_arguments(&mut self) -> Result<Vec<Expression>> {
        let mut args = Vec::new();

        loop {
            // ClickHouse: SETTINGS key=value, ... terminates function args
            // Only break if SETTINGS is followed by identifier = value pattern
            if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && self.check(TokenType::Settings)
                && self.current + 2 < self.tokens.len()
                && (self.tokens[self.current + 1].token_type == TokenType::Var
                    || self.tokens[self.current + 1].token_type == TokenType::Identifier)
                && self.tokens[self.current + 2].token_type == TokenType::Eq
            {
                break; // will be consumed by SETTINGS handler after loop
            }

            // ClickHouse: bare SELECT/WITH as function argument (e.g., view(SELECT 1), remote(..., view(SELECT ...)))
            if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && (self.check(TokenType::Select) || self.check(TokenType::With))
            {
                let query = self.parse_statement()?;
                args.push(query);
                if !self.match_token(TokenType::Comma) {
                    break;
                }
                continue;
            }

            // Check for TABLE ref or MODEL ref as function argument (BigQuery)
            // e.g., GAP_FILL(TABLE device_data, ...) or ML.PREDICT(MODEL mydataset.mymodel, ...)
            let is_table_or_model_arg = if !self.is_at_end() {
                self.check(TokenType::Table) || self.peek().text.eq_ignore_ascii_case("MODEL")
            } else {
                false
            };
            let arg = if is_table_or_model_arg {
                let prefix = self.peek().text.to_uppercase();
                let saved_pos = self.current;
                self.advance(); // consume TABLE or MODEL

                // Only treat as TABLE/MODEL argument if followed by an identifier (table name),
                // not by => (which would be a named arg like "table => value")
                if !self.is_at_end()
                    && !self.check(TokenType::FArrow)
                    && !self.check(TokenType::ColonEq)
                {
                    // Parse the table/model reference (supports dotted names like dataset.table)
                    if let Some(table_expr) = self.parse_table_parts()? {
                        Expression::TableArgument(Box::new(TableArgument {
                            prefix,
                            this: table_expr,
                        }))
                    } else {
                        // Failed to parse table parts, backtrack and treat as regular expression
                        self.current = saved_pos;
                        self.parse_expression()?
                    }
                } else {
                    // TABLE/MODEL followed by => or :=, backtrack and handle as named arg
                    self.current = saved_pos;
                    if self.is_identifier_token() || self.is_safe_keyword_as_identifier() {
                        let ident_token = self.advance();
                        let ident_name = ident_token.text.clone();
                        if self.match_token(TokenType::FArrow) {
                            let value = self.parse_expression()?;
                            Expression::NamedArgument(Box::new(NamedArgument {
                                name: Identifier::new(ident_name),
                                value,
                                separator: NamedArgSeparator::DArrow,
                            }))
                        } else if self.match_token(TokenType::ColonEq) {
                            let value = self.parse_expression()?;
                            Expression::NamedArgument(Box::new(NamedArgument {
                                name: Identifier::new(ident_name),
                                value,
                                separator: NamedArgSeparator::ColonEq,
                            }))
                        } else {
                            self.current = saved_pos;
                            self.parse_expression()?
                        }
                    } else {
                        self.parse_expression()?
                    }
                }
            } else if self.is_identifier_token() || self.is_safe_keyword_as_identifier() {
                // Try to parse:
                // 1. Named argument: identifier => value or identifier := value
                // 2. Snowflake lambda with type: identifier type -> body (e.g., a int -> a + 1)
                // Save position to backtrack if not a named argument
                let saved_pos = self.current;

                // Try to get identifier
                let ident_token = self.advance();
                let ident_name = ident_token.text.clone();

                // PostgreSQL/Redshift VARIADIC keyword: backtrack and let parse_expression handle it
                // VARIADIC ARRAY[...] must not be misinterpreted as a lambda with type annotation
                if ident_name.eq_ignore_ascii_case("VARIADIC")
                    && matches!(
                        self.config.dialect,
                        Some(crate::dialects::DialectType::PostgreSQL)
                            | Some(crate::dialects::DialectType::Redshift)
                    )
                {
                    self.current = saved_pos;
                    self.parse_expression()?
                }
                // Check for Snowflake lambda with type annotation: a int -> body
                // Look ahead to see if we have a type token followed by ->
                else if !self.is_at_end()
                    && self.is_type_keyword()
                    && !self.check(TokenType::FArrow)
                    && !self.check(TokenType::ColonEq)
                {
                    // Parse type annotation
                    let type_annotation = self.parse_data_type()?;

                    // Check for arrow
                    if self.match_token(TokenType::Arrow) {
                        // This is a Snowflake lambda: param type -> body
                        let body = self.parse_expression()?;
                        Expression::Lambda(Box::new(LambdaExpr {
                            parameters: vec![Identifier::new(ident_name)],
                            body,
                            colon: false,
                            parameter_types: vec![Some(type_annotation)],
                        }))
                    } else {
                        // Not a lambda, backtrack and parse as regular expression
                        self.current = saved_pos;
                        self.parse_expression()?
                    }
                }
                // ClickHouse: simple lambda without type annotation: ident -> body
                else if self.match_token(TokenType::Arrow) {
                    let body = self.parse_expression()?;
                    Expression::Lambda(Box::new(LambdaExpr {
                        parameters: vec![Identifier::new(ident_name)],
                        body,
                        colon: false,
                        parameter_types: Vec::new(),
                    }))
                }
                // Check for named argument separator (=> is FArrow)
                else if self.match_token(TokenType::FArrow) {
                    // name => value
                    let value = self.parse_expression()?;
                    Expression::NamedArgument(Box::new(NamedArgument {
                        name: Identifier::new(ident_name),
                        value,
                        separator: NamedArgSeparator::DArrow,
                    }))
                } else if self.match_token(TokenType::ColonEq) {
                    // name := value
                    let value = self.parse_expression()?;
                    Expression::NamedArgument(Box::new(NamedArgument {
                        name: Identifier::new(ident_name),
                        value,
                        separator: NamedArgSeparator::ColonEq,
                    }))
                } else {
                    // Not a named argument, backtrack and parse as regular expression
                    self.current = saved_pos;
                    self.parse_expression()?
                }
            } else {
                // Regular expression
                self.parse_expression()?
            };

            // Handle AS alias inside function arguments (e.g. ClickHouse: arrayJoin([1,2,3] AS src))
            let arg = if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && self.check(TokenType::As)
                && !self.check_next(TokenType::RParen)
                && !self.check_next(TokenType::Comma)
            {
                // Look ahead: AS followed by identifier/keyword, then ) or , means it's an alias
                let next_idx = self.current + 1;
                let after_alias_idx = self.current + 2;
                let is_alias_token = next_idx < self.tokens.len()
                    && (matches!(
                        self.tokens[next_idx].token_type,
                        TokenType::Identifier | TokenType::Var | TokenType::QuotedIdentifier
                    ) || self.tokens[next_idx].token_type.is_keyword());
                // Ensure the token AFTER the alias is ) or , (function arg boundary)
                let is_alias = is_alias_token
                    && after_alias_idx < self.tokens.len()
                    && matches!(
                        self.tokens[after_alias_idx].token_type,
                        TokenType::RParen | TokenType::Comma
                    );
                if is_alias {
                    self.advance(); // consume AS
                    let alias_token = self.advance();
                    let alias_name = if alias_token.token_type == TokenType::QuotedIdentifier {
                        let mut ident = Identifier::new(alias_token.text.clone());
                        ident.quoted = true;
                        ident
                    } else {
                        Identifier::new(alias_token.text.clone())
                    };
                    Expression::Alias(Box::new(crate::expressions::Alias {
                        this: arg,
                        alias: alias_name,
                        column_aliases: Vec::new(),
                        pre_alias_comments: Vec::new(),
                        trailing_comments: Vec::new(),
                        inferred_type: None,
                    }))
                } else {
                    arg
                }
            } else {
                arg
            };

            // ClickHouse: implicit alias without AS keyword: func(expr identifier, ...)
            let arg = self.try_clickhouse_implicit_alias(arg);

            // Handle trailing comments
            let trailing_comments = self.previous_trailing_comments();
            let arg = if trailing_comments.is_empty() {
                arg
            } else {
                match &arg {
                    Expression::Literal(_) | Expression::Boolean(_) | Expression::Null(_) => {
                        Expression::Annotated(Box::new(Annotated {
                            this: arg,
                            trailing_comments,
                        }))
                    }
                    _ => arg,
                }
            };

            args.push(arg);

            if !self.match_token(TokenType::Comma) {
                break;
            }
            // Skip consecutive commas (Snowflake allows skipping optional named args)
            // e.g., ROUND(SCALE => 1, EXPR => 2.25, , ROUNDING_MODE => 'HALF_TO_EVEN')
            while self.check(TokenType::Comma) {
                self.advance();
            }
        }

        // ClickHouse: SETTINGS key=value, ... at end of function args before RParen
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) && self.check(TokenType::Settings)
            && self.current + 2 < self.tokens.len()
            && (self.tokens[self.current + 1].token_type == TokenType::Var
                || self.tokens[self.current + 1].token_type == TokenType::Identifier)
            && self.tokens[self.current + 2].token_type == TokenType::Eq
        {
            self.advance(); // consume SETTINGS
            loop {
                let _key = if self.is_identifier_token() || self.is_safe_keyword_as_identifier() {
                    self.advance().text
                } else {
                    break;
                };
                if self.match_token(TokenType::Eq) {
                    let _value = self.parse_primary()?;
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
        }

        Ok(args)
    }

    /// Parse optional FILTER clause
    fn parse_filter_clause(&mut self) -> Result<Option<Expression>> {
        if self.match_token(TokenType::Filter) {
            self.expect(TokenType::LParen)?;
            // WHERE is optional (DuckDB allows FILTER(condition) without WHERE)
            self.match_token(TokenType::Where);
            let filter_expr = self.parse_expression()?;
            self.expect(TokenType::RParen)?;
            Ok(Some(filter_expr))
        } else {
            Ok(None)
        }
    }

    /// Parse STRUCT arguments with optional AS aliases: STRUCT(x, y AS name, ...)
    fn parse_struct_args(&mut self) -> Result<Vec<Expression>> {
        let mut args = Vec::new();

        loop {
            let expr = self.parse_expression()?;

            // Check for AS alias
            if self.match_token(TokenType::As) {
                let alias = self.expect_identifier_or_keyword()?;
                args.push(Expression::Alias(Box::new(Alias {
                    this: expr,
                    alias: Identifier::new(alias),
                    column_aliases: Vec::new(),
                    pre_alias_comments: Vec::new(),
                    trailing_comments: Vec::new(),
                    inferred_type: None,
                })));
            } else {
                args.push(expr);
            }

            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        Ok(args)
    }

    /// Maybe parse OVER clause for window functions or WITHIN GROUP for ordered-set aggregates
    fn maybe_parse_over(&mut self, expr: Expression) -> Result<Expression> {
        let expr = self.maybe_parse_subscript(expr)?;

        // For Oracle: Check for interval span after expression (e.g., (expr) DAY(9) TO SECOND(3))
        // https://docs.oracle.com/en/database/oracle/oracle-database/26/sqlrf/Interval-Expressions.html
        let expr = if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::Oracle)
        ) {
            self.try_parse_oracle_interval_span(expr)?
        } else {
            expr
        };

        // Check for WITHIN GROUP (for ordered-set aggregate functions like LISTAGG, PERCENTILE_CONT)
        let expr = if self.check(TokenType::Within) && self.check_next(TokenType::Group) {
            self.advance(); // consume WITHIN
            self.advance(); // consume GROUP
            self.expect(TokenType::LParen)?;
            self.expect(TokenType::Order)?;
            self.expect(TokenType::By)?;
            let order_by = self.parse_order_by_list()?;
            self.expect(TokenType::RParen)?;
            Expression::WithinGroup(Box::new(WithinGroup {
                this: expr,
                order_by,
            }))
        } else {
            expr
        };

        // Check for FILTER clause (can follow WITHIN GROUP or standalone aggregate)
        // SQL:2003 syntax: aggregate_function(...) FILTER (WHERE condition)
        let expr = if self.match_token(TokenType::Filter) {
            self.expect(TokenType::LParen)?;
            // WHERE is required in standard SQL FILTER clause
            self.expect(TokenType::Where)?;
            let filter_expr = self.parse_expression()?;
            self.expect(TokenType::RParen)?;
            Expression::Filter(Box::new(Filter {
                this: Box::new(expr),
                expression: Box::new(filter_expr),
            }))
        } else {
            expr
        };

        // ClickHouse: IGNORE NULLS / RESPECT NULLS modifier after function call (before OVER)
        // This handles cases like: func(args) IGNORE NULLS OVER w
        // and parametric aggregates: func(params)(args) IGNORE NULLS
        let expr = if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) && (self.match_keywords(&[TokenType::Ignore, TokenType::Nulls])
            || self.match_keywords(&[TokenType::Respect, TokenType::Nulls]))
        {
            // Consume the modifier — we don't need to store it for transpilation
            expr
        } else {
            expr
        };

        // Check for KEEP clause (Oracle: aggregate KEEP (DENSE_RANK FIRST|LAST ORDER BY ...))
        // Only if KEEP is followed by LPAREN - otherwise KEEP is used as an alias
        let keep = if self.check(TokenType::Keep) && self.check_next(TokenType::LParen) {
            self.advance(); // consume KEEP
            Some(self.parse_keep_clause()?)
        } else {
            None
        };

        // Check for OVER clause (can follow KEEP, FILTER, WITHIN GROUP, or standalone aggregate)
        if self.match_token(TokenType::Over) {
            let over = self.parse_over_clause()?;
            Ok(Expression::WindowFunction(Box::new(WindowFunction {
                this: expr,
                over,
                keep,
                inferred_type: None,
            })))
        } else if keep.is_some() {
            // KEEP without OVER - still a window-like construct
            // Create a WindowFunction with empty Over
            Ok(Expression::WindowFunction(Box::new(WindowFunction {
                this: expr,
                over: Over {
                    window_name: None,
                    partition_by: Vec::new(),
                    order_by: Vec::new(),
                    frame: None,
                    alias: None,
                },
                keep,
                inferred_type: None,
            })))
        } else {
            Ok(expr)
        }
    }

    /// ClickHouse: parse parameterized aggregate functions like func(params)(args)
    fn maybe_parse_clickhouse_parameterized_agg(&mut self, expr: Expression) -> Result<Expression> {
        if !matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) {
            return Ok(expr);
        }
        if !self.check(TokenType::LParen) {
            return Ok(expr);
        }

        let (name, quoted, params) = match expr {
            Expression::Function(func) => (func.name, func.quoted, func.args),
            Expression::AggregateFunction(agg) => {
                if agg.distinct
                    || agg.filter.is_some()
                    || !agg.order_by.is_empty()
                    || agg.limit.is_some()
                    || agg.ignore_nulls.is_some()
                {
                    return Ok(Expression::AggregateFunction(agg));
                }
                (agg.name, false, agg.args)
            }
            _ => return Ok(expr),
        };

        self.advance(); // consume (
                        // Handle DISTINCT in second arg list: func(params)(DISTINCT args)
        let distinct = self.match_token(TokenType::Distinct);
        let expressions = if self.check(TokenType::RParen) {
            Vec::new()
        } else {
            self.parse_function_arguments()?
        };
        self.expect(TokenType::RParen)?;

        let ident = Identifier {
            name,
            quoted,
            trailing_comments: Vec::new(),
            span: None,
        };

        // If DISTINCT was used, wrap the result to indicate it
        // For now, we just include it in the CombinedParameterizedAgg
        let _ = distinct; // DISTINCT is consumed but not separately tracked in this AST node
        Ok(Expression::CombinedParameterizedAgg(Box::new(
            CombinedParameterizedAgg {
                this: Box::new(Expression::Identifier(ident)),
                params,
                expressions,
            },
        )))
    }

    /// Parse Oracle KEEP clause: KEEP (DENSE_RANK FIRST|LAST ORDER BY ...)
    fn parse_keep_clause(&mut self) -> Result<Keep> {
        self.expect(TokenType::LParen)?;

        // Expect DENSE_RANK
        if !self.match_identifier("DENSE_RANK") {
            return Err(self.parse_error("Expected DENSE_RANK in KEEP clause"));
        }

        // Expect FIRST or LAST
        let first = if self.match_token(TokenType::First) {
            true
        } else if self.match_token(TokenType::Last) {
            false
        } else {
            return Err(self.parse_error("Expected FIRST or LAST in KEEP clause"));
        };

        // Expect ORDER BY
        self.expect(TokenType::Order)?;
        self.expect(TokenType::By)?;

        let order_by = self.parse_order_by_list()?;

        self.expect(TokenType::RParen)?;

        Ok(Keep { first, order_by })
    }

    /// Parse a JSON path operand - just the immediate literal/identifier without any subscript processing
    /// This is used for JSON arrow operators (->, ->>) to get proper left-to-right associativity
    fn parse_json_path_operand(&mut self) -> Result<Expression> {
        // Negative number literal (e.g., -1)
        if self.check(TokenType::Dash) {
            let dash_pos = self.current;
            self.advance(); // consume the dash
            if self.check(TokenType::Number) {
                let token = self.advance();
                return Ok(Expression::Neg(Box::new(UnaryOp {
                    this: Expression::Literal(Literal::Number(token.text)),
                    inferred_type: None,
                })));
            }
            // Not a negative number, backtrack
            self.current = dash_pos;
        }

        // Number literal
        if self.check(TokenType::Number) {
            let token = self.advance();
            // Check for numeric literal suffix encoded as "number::TYPE" by tokenizer
            if let Some(sep_pos) = token.text.find("::") {
                let num_part = &token.text[..sep_pos];
                let type_name = &token.text[sep_pos + 2..];
                let num_expr = Expression::Literal(Literal::Number(num_part.to_string()));
                let data_type = match type_name {
                    "BIGINT" => crate::expressions::DataType::BigInt { length: None },
                    "SMALLINT" => crate::expressions::DataType::SmallInt { length: None },
                    "TINYINT" => crate::expressions::DataType::TinyInt { length: None },
                    "DOUBLE" => crate::expressions::DataType::Double {
                        precision: None,
                        scale: None,
                    },
                    "FLOAT" => crate::expressions::DataType::Float {
                        precision: None,
                        scale: None,
                        real_spelling: false,
                    },
                    "DECIMAL" => crate::expressions::DataType::Decimal {
                        precision: None,
                        scale: None,
                    },
                    _ => crate::expressions::DataType::Custom {
                        name: type_name.to_string(),
                    },
                };
                return Ok(Expression::TryCast(Box::new(crate::expressions::Cast {
                    this: num_expr,
                    to: data_type,
                    trailing_comments: Vec::new(),
                    double_colon_syntax: false,
                    format: None,
                    default: None,
                    inferred_type: None,
                })));
            }
            return Ok(Expression::Literal(Literal::Number(token.text)));
        }

        // String literal
        if self.check(TokenType::String) {
            let token = self.advance();
            return Ok(Expression::Literal(Literal::String(token.text)));
        }

        // Parenthesized expression (for complex paths)
        if self.match_token(TokenType::LParen) {
            let expr = self.parse_expression()?;
            self.expect(TokenType::RParen)?;
            return Ok(Expression::Paren(Box::new(Paren {
                this: expr,
                trailing_comments: Vec::new(),
            })));
        }

        // Array literal: ['$.family', '$.species']
        // Used in DuckDB for multi-path JSON extraction
        if self.match_token(TokenType::LBracket) {
            // Empty array: []
            if self.match_token(TokenType::RBracket) {
                return Ok(Expression::ArrayFunc(Box::new(ArrayConstructor {
                    expressions: Vec::new(),
                    bracket_notation: true,
                    use_list_keyword: false,
                })));
            }

            // Parse array elements
            let mut expressions = vec![self.parse_expression()?];
            while self.match_token(TokenType::Comma) {
                if self.check(TokenType::RBracket) {
                    break;
                }
                expressions.push(self.parse_expression()?);
            }
            self.expect(TokenType::RBracket)?;

            return Ok(Expression::ArrayFunc(Box::new(ArrayConstructor {
                expressions,
                bracket_notation: true,
                use_list_keyword: false,
            })));
        }

        // Identifier (possibly qualified like table.column)
        if self.is_identifier_token() {
            let first_ident = self.expect_identifier_with_quoted()?;

            // Check for qualified name: identifier.identifier
            if self.match_token(TokenType::Dot) {
                if self.is_identifier_token() || self.is_safe_keyword_as_identifier() {
                    let second_ident = if self.is_identifier_token() {
                        self.expect_identifier_with_quoted()?
                    } else {
                        let token = self.advance();
                        Identifier::new(token.text)
                    };
                    return Ok(Expression::Column(Column {
                        name: second_ident,
                        table: Some(first_ident),
                        join_mark: false,
                        trailing_comments: Vec::new(),
                        span: None,
                        inferred_type: None,
                    }));
                }
            }

            return Ok(Expression::Column(Column {
                name: first_ident,
                table: None,
                join_mark: false,
                trailing_comments: Vec::new(),
                span: None,
                inferred_type: None,
            }));
        }

        // Keywords as identifiers (possibly qualified)
        if self.is_safe_keyword_as_identifier() {
            let token = self.advance();
            let first_ident = Identifier::new(token.text);

            // Check for qualified name: identifier.identifier
            if self.match_token(TokenType::Dot) {
                if self.is_identifier_token() || self.is_safe_keyword_as_identifier() {
                    let second_ident = if self.is_identifier_token() {
                        self.expect_identifier_with_quoted()?
                    } else {
                        let token = self.advance();
                        Identifier::new(token.text)
                    };
                    return Ok(Expression::Column(Column {
                        name: second_ident,
                        table: Some(first_ident),
                        join_mark: false,
                        trailing_comments: Vec::new(),
                        span: None,
                        inferred_type: None,
                    }));
                }
            }

            return Ok(Expression::Column(Column {
                name: first_ident,
                table: None,
                join_mark: false,
                trailing_comments: Vec::new(),
                span: None,
                inferred_type: None,
            }));
        }

        Err(self.parse_error(format!(
            "Unexpected token in JSON path: {:?}",
            self.peek().token_type
        )))
    }

    /// Maybe parse subscript access (array[index], struct.field)
    fn maybe_parse_subscript(&mut self, mut expr: Expression) -> Result<Expression> {
        loop {
            if self.match_token(TokenType::LBracket) {
                // Check if expr is an array/list constructor keyword (ARRAY[...] or LIST[...])
                let array_constructor_type = match &expr {
                    Expression::Column(col) if col.table.is_none() => {
                        let upper = col.name.name.to_uppercase();
                        if upper == "ARRAY" || upper == "LIST" {
                            Some(upper)
                        } else {
                            None
                        }
                    }
                    Expression::Identifier(id) => {
                        let upper = id.name.to_uppercase();
                        if upper == "ARRAY" || upper == "LIST" {
                            Some(upper)
                        } else {
                            None
                        }
                    }
                    _ => None,
                };

                if let Some(constructor_type) = array_constructor_type {
                    // Parse ARRAY[expr, expr, ...] or LIST[expr, expr, ...]
                    // bracket_notation=false means we have the ARRAY/LIST keyword prefix
                    let use_list_keyword = constructor_type == "LIST";
                    if self.check(TokenType::RBracket) {
                        // Empty array: ARRAY[]
                        self.advance();
                        expr = Expression::ArrayFunc(Box::new(ArrayConstructor {
                            expressions: Vec::new(),
                            bracket_notation: false, // Has ARRAY/LIST keyword
                            use_list_keyword,
                        }));
                    } else {
                        let expressions = self.parse_expression_list()?;
                        self.expect(TokenType::RBracket)?;
                        expr = Expression::ArrayFunc(Box::new(ArrayConstructor {
                            expressions,
                            bracket_notation: false, // Has ARRAY/LIST keyword
                            use_list_keyword,
                        }));
                    }
                    continue;
                }

                // Special case: MAP[...] constructor syntax
                // Check if expr is a MAP identifier
                // ClickHouse: map[key] is always subscript access, not a MAP constructor
                let is_map_constructor = !matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) && match &expr {
                    Expression::Column(col) => {
                        col.name.name.to_uppercase() == "MAP" && col.table.is_none()
                    }
                    Expression::Identifier(id) => id.name.to_uppercase() == "MAP",
                    _ => false,
                };

                if is_map_constructor {
                    let is_materialize = matches!(
                        self.config.dialect,
                        Some(crate::dialects::DialectType::Materialize)
                    );

                    // Materialize: MAP[] empty map or MAP['a' => 1, ...] with fat arrow
                    if is_materialize {
                        if self.check(TokenType::RBracket) {
                            // Empty map: MAP[]
                            self.advance();
                            expr = Expression::ToMap(Box::new(ToMap {
                                this: Box::new(Expression::Struct(Box::new(Struct {
                                    fields: Vec::new(),
                                }))),
                            }));
                            continue;
                        }

                        // Parse MAP['a' => 1, 'b' => 2, ...] with fat arrow entries
                        // Store entries as PropertyEQ expressions (key => value)
                        let mut entries = Vec::new();
                        loop {
                            let key = self.parse_expression()?;
                            self.expect(TokenType::FArrow)?;
                            let value = self.parse_expression()?;
                            // Store as PropertyEQ which will be output as key => value
                            entries.push((
                                None,
                                Expression::PropertyEQ(Box::new(BinaryOp::new(key, value))),
                            ));

                            if !self.match_token(TokenType::Comma) {
                                break;
                            }
                        }
                        self.expect(TokenType::RBracket)?;

                        expr = Expression::ToMap(Box::new(ToMap {
                            this: Box::new(Expression::Struct(Box::new(Struct {
                                fields: entries,
                            }))),
                        }));
                        continue;
                    }

                    // DuckDB/BigQuery: MAP[keys, values] syntax
                    let keys = self.parse_expression()?;
                    self.expect(TokenType::Comma)?;
                    let values = self.parse_expression()?;
                    self.expect(TokenType::RBracket)?;
                    expr = Expression::Function(Box::new(Function {
                        name: "MAP".to_string(),
                        args: vec![keys, values],
                        distinct: false,
                        trailing_comments: Vec::new(),
                        use_bracket_syntax: true,
                        no_parens: false,
                        quoted: false,
                        span: None,
                        inferred_type: None,
                    }));
                    continue;
                }

                // Check for slice syntax: [start:end:step]
                // Handle [:...] case where start is omitted
                if self.check(TokenType::Colon) {
                    self.advance(); // consume first :
                                    // Parse end - use parse_slice_element to avoid : being interpreted as parameter
                    let end = self.parse_slice_element()?;
                    // Check for step (second colon)
                    let step = if self.match_token(TokenType::Colon) {
                        self.parse_slice_element()?
                    } else {
                        None
                    };
                    self.expect(TokenType::RBracket)?;
                    if step.is_some() {
                        // Three-part slice with step: Subscript with Slice index
                        let slice = Expression::Slice(Box::new(Slice {
                            this: None, // start is omitted
                            expression: end.map(Box::new),
                            step: step.map(Box::new),
                        }));
                        expr = Expression::Subscript(Box::new(Subscript {
                            this: expr,
                            index: slice,
                        }));
                    } else {
                        expr = Expression::ArraySlice(Box::new(ArraySlice {
                            this: expr,
                            start: None,
                            end,
                        }));
                    }
                } else {
                    let start = self.parse_slice_element()?;
                    // Check if this is a slice
                    if self.match_token(TokenType::Colon) {
                        let end = self.parse_slice_element()?;
                        // Check for step (second colon)
                        let step = if self.match_token(TokenType::Colon) {
                            self.parse_slice_element()?
                        } else {
                            None
                        };
                        self.expect(TokenType::RBracket)?;
                        if step.is_some() {
                            // Three-part slice with step: Subscript with Slice index
                            let slice = Expression::Slice(Box::new(Slice {
                                this: start.map(Box::new),
                                expression: end.map(Box::new),
                                step: step.map(Box::new),
                            }));
                            expr = Expression::Subscript(Box::new(Subscript {
                                this: expr,
                                index: slice,
                            }));
                        } else {
                            expr = Expression::ArraySlice(Box::new(ArraySlice {
                                this: expr,
                                start,
                                end,
                            }));
                        }
                    } else {
                        self.expect(TokenType::RBracket)?;
                        // Simple subscript access - start must be Some
                        let index =
                            start.unwrap_or_else(|| Expression::Null(crate::expressions::Null));
                        expr = Expression::Subscript(Box::new(Subscript { this: expr, index }));
                    }
                }
            } else if self.match_token(TokenType::DotColon) {
                let data_type = self.parse_data_type()?;
                expr = Expression::JSONCast(Box::new(JSONCast {
                    this: Box::new(expr),
                    to: data_type,
                }));
            } else if self.match_token(TokenType::Dot) {
                // Handle chained dot access (a.b.c.d)
                if self.match_token(TokenType::Star) {
                    // expr.* - struct field expansion with potential modifiers (EXCEPT, REPLACE, etc.)
                    let table_name = match &expr {
                        Expression::Column(col) => {
                            if let Some(ref table) = col.table {
                                Some(Identifier::new(format!("{}.{}", table.name, col.name.name)))
                            } else {
                                Some(col.name.clone())
                            }
                        }
                        Expression::Dot(d) => {
                            fn dot_to_name_inner(expr: &Expression) -> String {
                                match expr {
                                    Expression::Column(col) => {
                                        if let Some(ref table) = col.table {
                                            format!("{}.{}", table.name, col.name.name)
                                        } else {
                                            col.name.name.clone()
                                        }
                                    }
                                    Expression::Dot(d) => {
                                        format!("{}.{}", dot_to_name_inner(&d.this), d.field.name)
                                    }
                                    _ => String::new(),
                                }
                            }
                            Some(Identifier::new(dot_to_name_inner(&Expression::Dot(
                                d.clone(),
                            ))))
                        }
                        _ => None,
                    };
                    if table_name.is_some() {
                        let star = self.parse_star_modifiers(table_name)?;
                        expr = Expression::Star(star);
                        // ClickHouse: a.* APPLY(func) EXCEPT(col) REPLACE(expr AS col) in any order
                        if matches!(
                            self.config.dialect,
                            Some(crate::dialects::DialectType::ClickHouse)
                        ) {
                            loop {
                                if self.check(TokenType::Apply) {
                                    self.advance();
                                    let apply_expr = if self.match_token(TokenType::LParen) {
                                        let e = self.parse_expression()?;
                                        self.expect(TokenType::RParen)?;
                                        e
                                    } else {
                                        self.parse_expression()?
                                    };
                                    expr = Expression::Apply(Box::new(crate::expressions::Apply {
                                        this: Box::new(expr),
                                        expression: Box::new(apply_expr),
                                    }));
                                } else if self.check(TokenType::Except)
                                    || self.check(TokenType::Exclude)
                                {
                                    self.advance();
                                    self.match_identifier("STRICT");
                                    if self.match_token(TokenType::LParen) {
                                        loop {
                                            if self.check(TokenType::RParen) {
                                                break;
                                            }
                                            let _ = self.parse_expression()?;
                                            if !self.match_token(TokenType::Comma) {
                                                break;
                                            }
                                        }
                                        self.expect(TokenType::RParen)?;
                                    } else if self.is_identifier_token()
                                        || self.is_safe_keyword_as_identifier()
                                    {
                                        let _ = self.parse_expression()?;
                                    }
                                } else if self.check(TokenType::Replace) {
                                    self.advance();
                                    self.match_identifier("STRICT");
                                    if self.match_token(TokenType::LParen) {
                                        loop {
                                            if self.check(TokenType::RParen) {
                                                break;
                                            }
                                            let _ = self.parse_expression()?;
                                            if self.match_token(TokenType::As) {
                                                if self.is_identifier_token()
                                                    || self.is_safe_keyword_as_identifier()
                                                {
                                                    self.advance();
                                                }
                                            }
                                            if !self.match_token(TokenType::Comma) {
                                                break;
                                            }
                                        }
                                        self.expect(TokenType::RParen)?;
                                    } else {
                                        let _ = self.parse_expression()?;
                                        if self.match_token(TokenType::As) {
                                            if self.is_identifier_token()
                                                || self.is_safe_keyword_as_identifier()
                                            {
                                                self.advance();
                                            }
                                        }
                                    }
                                } else {
                                    break;
                                }
                            }
                        }
                    } else {
                        // For complex expressions (like CAST, function calls), use Dot with * as field
                        expr = Expression::Dot(Box::new(DotAccess {
                            this: expr,
                            field: Identifier::new("*"),
                        }));
                    }
                } else if self.check(TokenType::Identifier)
                    || self.check(TokenType::Var)
                    || self.check(TokenType::QuotedIdentifier)
                    || self.check_keyword()
                {
                    let is_quoted = self.check(TokenType::QuotedIdentifier);
                    let field_name = self.advance().text;
                    // Check if this is a method call (field followed by parentheses)
                    if self.check(TokenType::LParen) && !is_quoted {
                        // This is a method call like a.b.C() or x.EXTRACT()
                        self.advance(); // consume (
                        let args = if self.check(TokenType::RParen) {
                            Vec::new()
                        } else {
                            self.parse_expression_list()?
                        };
                        self.expect(TokenType::RParen)?;
                        // Create a method call expression (DotAccess with function call)
                        expr = Expression::MethodCall(Box::new(MethodCall {
                            this: expr,
                            method: Identifier::new(field_name),
                            args,
                        }));
                    } else {
                        let mut ident = Identifier::new(field_name);
                        if is_quoted {
                            ident.quoted = true;
                        }
                        expr = Expression::Dot(Box::new(DotAccess {
                            this: expr,
                            field: ident,
                        }));
                    }
                } else if self.check(TokenType::Number) {
                    // Handle numeric field access like a.0 or x.1
                    let field_name = self.advance().text;
                    expr = Expression::Dot(Box::new(DotAccess {
                        this: expr,
                        field: Identifier::new(field_name),
                    }));
                } else if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) && self.check(TokenType::Caret)
                {
                    // ClickHouse: json.^path — the ^ prefix means "get all nested subcolumns"
                    self.advance(); // consume ^
                                    // What follows should be an identifier path
                    let mut field_name = "^".to_string();
                    if self.check(TokenType::Identifier)
                        || self.check(TokenType::Var)
                        || self.check_keyword()
                    {
                        field_name.push_str(&self.advance().text);
                    }
                    expr = Expression::Dot(Box::new(DotAccess {
                        this: expr,
                        field: Identifier::new(field_name),
                    }));
                } else if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) && self.check(TokenType::Colon)
                {
                    // ClickHouse: json.path.:Type — the : prefix means type cast on JSON path
                    self.advance(); // consume :
                                    // Consume the type name
                    let mut type_name = ":".to_string();
                    if self.check(TokenType::Identifier)
                        || self.check(TokenType::Var)
                        || self.check_keyword()
                    {
                        type_name.push_str(&self.advance().text);
                    }
                    expr = Expression::Dot(Box::new(DotAccess {
                        this: expr,
                        field: Identifier::new(type_name),
                    }));
                } else if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) && self.check(TokenType::Dash)
                    && self
                        .peek_nth(1)
                        .is_some_and(|t| t.token_type == TokenType::Number)
                {
                    // ClickHouse: tuple.-1 — negative tuple index
                    self.advance(); // consume -
                    let num = self.advance().text;
                    expr = Expression::Dot(Box::new(DotAccess {
                        this: expr,
                        field: Identifier::new(format!("-{}", num)),
                    }));
                } else {
                    return Err(self.parse_error("Expected field name after dot"));
                }
            } else if self.match_token(TokenType::Collate) {
                // Parse COLLATE 'collation_name' or COLLATE "collation_name" or COLLATE collation_name
                let (collation, quoted, double_quoted) = if self.check(TokenType::String) {
                    // Single-quoted string: COLLATE 'de_DE'
                    (self.advance().text, true, false)
                } else if self.check(TokenType::QuotedIdentifier) {
                    // Double-quoted identifier: COLLATE "de_DE"
                    (self.advance().text, false, true)
                } else {
                    // Unquoted identifier: COLLATE de_DE
                    (self.expect_identifier_or_keyword()?, false, false)
                };
                expr = Expression::Collation(Box::new(CollationExpr {
                    this: expr,
                    collation,
                    quoted,
                    double_quoted,
                }));
            } else if self.check(TokenType::DColon)
                || self.check(TokenType::DColonDollar)
                || self.check(TokenType::DColonPercent)
                || self.check(TokenType::DColonQMark)
            {
                // For SingleStore, :: variants are JSON path extraction
                // For other dialects, :: is cast syntax (PostgreSQL-style)
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::SingleStore)
                ) {
                    // SingleStore JSON path extraction: expr::key, expr::$key, expr::%key, expr::?key
                    if self.match_token(TokenType::DColon) {
                        // ::key -> JSON_EXTRACT_JSON(expr, 'key')
                        let path_key =
                            if self.check(TokenType::Identifier) || self.check(TokenType::Var) {
                                self.advance().text
                            } else if self.check(TokenType::Number) {
                                self.advance().text
                            } else if self.check(TokenType::QuotedIdentifier) {
                                self.advance().text
                            } else {
                                return Err(self.parse_error(
                                    "Expected identifier or number after :: in JSON path",
                                ));
                            };
                        expr = Expression::Function(Box::new(Function::new(
                            "JSON_EXTRACT_JSON".to_string(),
                            vec![expr, Expression::string(&path_key)],
                        )));
                    } else if self.match_token(TokenType::DColonDollar) {
                        // ::$key -> JSON_EXTRACT_STRING(expr, 'key')
                        let path_key =
                            if self.check(TokenType::Identifier) || self.check(TokenType::Var) {
                                self.advance().text
                            } else if self.check(TokenType::Number) {
                                self.advance().text
                            } else {
                                return Err(self.parse_error(
                                    "Expected identifier or number after ::$ in JSON path",
                                ));
                            };
                        expr = Expression::Function(Box::new(Function::new(
                            "JSON_EXTRACT_STRING".to_string(),
                            vec![expr, Expression::string(&path_key)],
                        )));
                    } else if self.match_token(TokenType::DColonPercent) {
                        // ::%key -> JSON_EXTRACT_DOUBLE(expr, 'key')
                        let path_key =
                            if self.check(TokenType::Identifier) || self.check(TokenType::Var) {
                                self.advance().text
                            } else if self.check(TokenType::Number) {
                                self.advance().text
                            } else {
                                return Err(self.parse_error(
                                    "Expected identifier or number after ::% in JSON path",
                                ));
                            };
                        expr = Expression::Function(Box::new(Function::new(
                            "JSON_EXTRACT_DOUBLE".to_string(),
                            vec![expr, Expression::string(&path_key)],
                        )));
                    } else if self.match_token(TokenType::DColonQMark) {
                        // ::?key -> SingleStoreJsonPathQMark function (for JSON_MATCH_ANY patterns)
                        let path_key =
                            if self.check(TokenType::Identifier) || self.check(TokenType::Var) {
                                self.advance().text
                            } else if self.check(TokenType::Number) {
                                self.advance().text
                            } else {
                                return Err(self.parse_error(
                                    "Expected identifier or number after ::? in JSON path",
                                ));
                            };
                        // Use a special function name that SingleStore generator will recognize
                        expr = Expression::Function(Box::new(Function::new(
                            "__SS_JSON_PATH_QMARK__".to_string(),
                            vec![expr, Expression::string(&path_key)],
                        )));
                    }
                } else {
                    // PostgreSQL :: cast operator: expr::type
                    self.advance(); // consume DColon
                                    // Use parse_data_type_for_cast to avoid consuming subscripts as array dimensions
                    let data_type = self.parse_data_type_for_cast()?;
                    expr = Expression::Cast(Box::new(Cast {
                        this: expr,
                        to: data_type,
                        trailing_comments: Vec::new(),
                        double_colon_syntax: true,
                        format: None,
                        default: None,
                        inferred_type: None,
                    }));
                }
            } else if self.match_token(TokenType::ColonGt) {
                // SingleStore :> cast operator: expr :> type
                let data_type = self.parse_data_type_for_cast()?;
                expr = Expression::Cast(Box::new(Cast {
                    this: expr,
                    to: data_type,
                    trailing_comments: Vec::new(),
                    double_colon_syntax: false, // Use :> syntax in generator
                    format: None,
                    default: None,
                    inferred_type: None,
                }));
            } else if self.match_token(TokenType::NColonGt) {
                // SingleStore !:> try cast operator: expr !:> type
                let data_type = self.parse_data_type_for_cast()?;
                expr = Expression::TryCast(Box::new(Cast {
                    this: expr,
                    to: data_type,
                    trailing_comments: Vec::new(),
                    double_colon_syntax: false,
                    format: None,
                    default: None,
                    inferred_type: None,
                }));
            } else if self.match_token(TokenType::QDColon) {
                // Databricks ?:: try cast operator: expr?::type
                let data_type = self.parse_data_type_for_cast()?;
                expr = Expression::TryCast(Box::new(Cast {
                    this: expr,
                    to: data_type,
                    trailing_comments: Vec::new(),
                    double_colon_syntax: true, // Uses :: style syntax
                    format: None,
                    default: None,
                    inferred_type: None,
                }));
            } else if self.check(TokenType::Arrow)
                && !matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                )
            {
                self.advance(); // consume ->
                                // JSON extract operator: expr -> path (PostgreSQL, MySQL, DuckDB)
                                // Use parse_json_path_operand to get only the immediate operand for proper left-to-right associativity
                let path = self.parse_json_path_operand()?;
                expr = Expression::JsonExtract(Box::new(JsonExtractFunc {
                    this: expr,
                    path,
                    returning: None,
                    arrow_syntax: true,
                    hash_arrow_syntax: false,
                    wrapper_option: None,
                    quotes_option: None,
                    on_scalar_string: false,
                    on_error: None,
                }));
            } else if self.match_token(TokenType::DArrow) {
                // JSON extract text operator: expr ->> path (PostgreSQL, MySQL, DuckDB)
                // Use parse_json_path_operand to get only the immediate operand for proper left-to-right associativity
                let path = self.parse_json_path_operand()?;
                expr = Expression::JsonExtractScalar(Box::new(JsonExtractFunc {
                    this: expr,
                    path,
                    returning: None,
                    arrow_syntax: true,
                    hash_arrow_syntax: false,
                    wrapper_option: None,
                    quotes_option: None,
                    on_scalar_string: false,
                    on_error: None,
                }));
            } else if self.match_token(TokenType::HashArrow) {
                // JSONB path extract: expr #> path (PostgreSQL)
                // Use parse_json_path_operand to get only the immediate operand for proper left-to-right associativity
                let path = self.parse_json_path_operand()?;
                expr = Expression::JsonExtractPath(Box::new(JsonPathFunc {
                    this: expr,
                    paths: vec![path],
                }));
            } else if self.match_token(TokenType::DHashArrow) {
                // JSONB path extract text: expr #>> path (PostgreSQL)
                // For now, use JsonExtractScalar since the result is text
                // Use parse_json_path_operand to get only the immediate operand for proper left-to-right associativity
                let path = self.parse_json_path_operand()?;
                expr = Expression::JsonExtractScalar(Box::new(JsonExtractFunc {
                    this: expr,
                    path,
                    returning: None,
                    arrow_syntax: false,     // This is #>> not ->>
                    hash_arrow_syntax: true, // Mark as #>> operator
                    wrapper_option: None,
                    quotes_option: None,
                    on_scalar_string: false,
                    on_error: None,
                }));
            } else if self.check_join_marker() {
                // Oracle/Redshift-style outer join marker: column (+)
                // Only applies to Column expressions
                if let Expression::Column(col) = &mut expr {
                    self.advance(); // consume (
                    self.advance(); // consume +
                    self.advance(); // consume )
                    col.join_mark = true;
                    // Don't continue - join marker is terminal (no more postfix ops after it)
                    break;
                }
                // If not a Column, just break - the marker is invalid in this context
                else {
                    break;
                }
            } else {
                break;
            }
        }
        Ok(expr)
    }

    /// Check if the next tokens are the Oracle-style join marker (+)
    fn check_join_marker(&self) -> bool {
        self.check(TokenType::LParen)
            && self
                .peek_nth(1)
                .map_or(false, |t| t.token_type == TokenType::Plus)
            && self
                .peek_nth(2)
                .map_or(false, |t| t.token_type == TokenType::RParen)
    }

    /// Parse OVER clause
    fn parse_over_clause(&mut self) -> Result<Over> {
        // Handle OVER window_name (without parentheses)
        if !self.check(TokenType::LParen) {
            // OVER window_name - just a named window reference
            let window_name = self.expect_identifier_or_keyword()?;
            return Ok(Over {
                window_name: Some(Identifier::new(window_name)),
                partition_by: Vec::new(),
                order_by: Vec::new(),
                frame: None,
                alias: None,
            });
        }

        self.expect(TokenType::LParen)?;

        // Check for named window reference at start of OVER clause
        // e.g., OVER (w ORDER BY y) - w is a window name that can be extended
        let window_name = if (self.check(TokenType::Identifier)
            || self.check(TokenType::Var)
            || self.check_keyword())
            && !self.check(TokenType::Partition)
            && !self.check(TokenType::Order)
            && !self.check(TokenType::Rows)
            && !self.check(TokenType::Range)
            && !self.check(TokenType::Groups)
            && !self.check(TokenType::Distribute)
            && !self.check(TokenType::Sort)
        {
            // Look ahead to see if next token indicates this is a window name
            let pos = self.current;
            let name = self.advance().text;
            // If next token is a keyword that can follow a window name, this is a named reference
            if self.check(TokenType::Order)
                || self.check(TokenType::Partition)
                || self.check(TokenType::Rows)
                || self.check(TokenType::Range)
                || self.check(TokenType::Groups)
                || self.check(TokenType::RParen)
                || self.check(TokenType::Distribute)
                || self.check(TokenType::Sort)
            {
                Some(Identifier::new(name))
            } else {
                // Not a named window, restore position
                self.current = pos;
                None
            }
        } else {
            None
        };

        // Parse PARTITION BY or DISTRIBUTE BY (Hive uses DISTRIBUTE BY in window specs)
        let partition_by = if self.match_keywords(&[TokenType::Partition, TokenType::By]) {
            self.parse_expression_list()?
        } else if self.match_keywords(&[TokenType::Distribute, TokenType::By]) {
            // Hive: DISTRIBUTE BY is equivalent to PARTITION BY in window specs
            self.parse_expression_list()?
        } else {
            Vec::new()
        };

        // Parse ORDER BY or SORT BY (Hive uses SORT BY in window specs)
        let order_by = if self.match_keywords(&[TokenType::Order, TokenType::By])
            || self.match_keywords(&[TokenType::Sort, TokenType::By])
        {
            let mut exprs = Vec::new();
            loop {
                let expr = self.parse_expression()?;
                let (desc, explicit_asc) = if self.match_token(TokenType::Desc) {
                    (true, false)
                } else if self.match_token(TokenType::Asc) {
                    (false, true)
                } else {
                    (false, false)
                };
                // ClickHouse/SQL: COLLATE 'collation' in window ORDER BY
                if self.match_token(TokenType::Collate) {
                    // Consume collation name (string or identifier)
                    if self.check(TokenType::String) {
                        self.advance();
                    } else if self.check(TokenType::QuotedIdentifier) {
                        self.advance();
                    } else {
                        let _ = self.expect_identifier_or_keyword();
                    }
                }
                let nulls_first = if self.match_token(TokenType::Nulls) {
                    if self.match_token(TokenType::First) {
                        Some(true)
                    } else if self.match_token(TokenType::Last) {
                        Some(false)
                    } else {
                        return Err(self.parse_error("Expected FIRST or LAST after NULLS"));
                    }
                } else {
                    None
                };
                // ClickHouse: WITH FILL in window ORDER BY
                let with_fill = if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) && self.check(TokenType::With)
                    && self.current + 1 < self.tokens.len()
                    && self.tokens[self.current + 1]
                        .text
                        .eq_ignore_ascii_case("FILL")
                {
                    self.advance(); // consume WITH
                    self.advance(); // consume FILL
                    let from_ = if self.match_token(TokenType::From) {
                        Some(Box::new(self.parse_or()?))
                    } else {
                        None
                    };
                    let to = if self.match_text_seq(&["TO"]) {
                        Some(Box::new(self.parse_or()?))
                    } else {
                        None
                    };
                    let step = if self.match_text_seq(&["STEP"]) {
                        Some(Box::new(self.parse_or()?))
                    } else {
                        None
                    };
                    let staleness = if self.match_text_seq(&["STALENESS"]) {
                        Some(Box::new(self.parse_or()?))
                    } else {
                        None
                    };
                    let interpolate = if self.match_text_seq(&["INTERPOLATE"]) {
                        if self.match_token(TokenType::LParen) {
                            let items = self.parse_expression_list()?;
                            self.expect(TokenType::RParen)?;
                            if items.len() == 1 {
                                Some(Box::new(items.into_iter().next().unwrap()))
                            } else {
                                Some(Box::new(Expression::Tuple(Box::new(
                                    crate::expressions::Tuple { expressions: items },
                                ))))
                            }
                        } else {
                            None
                        }
                    } else {
                        None
                    };
                    Some(Box::new(WithFill {
                        from_,
                        to,
                        step,
                        staleness,
                        interpolate,
                    }))
                } else {
                    None
                };
                exprs.push(Ordered {
                    this: expr,
                    desc,
                    nulls_first,
                    explicit_asc,
                    with_fill,
                });
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            exprs
        } else {
            Vec::new()
        };

        // Parse window frame
        let frame = self.parse_window_frame()?;

        self.expect(TokenType::RParen)?;

        Ok(Over {
            window_name,
            partition_by,
            order_by,
            frame,
            alias: None,
        })
    }

    /// Parse window frame specification (ROWS/RANGE/GROUPS BETWEEN ...)
    fn parse_window_frame(&mut self) -> Result<Option<WindowFrame>> {
        let (kind, kind_text) = if self.match_token(TokenType::Rows) {
            (
                WindowFrameKind::Rows,
                self.tokens[self.current - 1].text.clone(),
            )
        } else if self.match_token(TokenType::Range) {
            (
                WindowFrameKind::Range,
                self.tokens[self.current - 1].text.clone(),
            )
        } else if self.match_token(TokenType::Groups) {
            (
                WindowFrameKind::Groups,
                self.tokens[self.current - 1].text.clone(),
            )
        } else {
            return Ok(None);
        };

        // Parse BETWEEN or single bound
        let (start, start_side_text, end, end_side_text) = if self.match_token(TokenType::Between) {
            let (start, st) = self.parse_window_frame_bound()?;
            self.expect(TokenType::And)?;
            let (end, et) = self.parse_window_frame_bound()?;
            (start, st, Some(end), et)
        } else {
            let (start, st) = self.parse_window_frame_bound()?;
            (start, st, None, None)
        };

        // Parse optional EXCLUDE clause
        let exclude = if self.match_token(TokenType::Exclude) {
            if self.match_token(TokenType::Current) {
                self.expect(TokenType::Row)?;
                Some(WindowFrameExclude::CurrentRow)
            } else if self.match_token(TokenType::Group) {
                Some(WindowFrameExclude::Group)
            } else if self.match_token(TokenType::Ties) {
                Some(WindowFrameExclude::Ties)
            } else if self.match_token(TokenType::No) {
                self.expect(TokenType::Others)?;
                Some(WindowFrameExclude::NoOthers)
            } else {
                return Err(self
                    .parse_error("Expected CURRENT ROW, GROUP, TIES, or NO OTHERS after EXCLUDE"));
            }
        } else {
            None
        };

        Ok(Some(WindowFrame {
            kind,
            start,
            end,
            exclude,
            kind_text: Some(kind_text),
            start_side_text,
            end_side_text,
        }))
    }

    /// Parse a window frame bound, returning the bound and the original text of the side keyword
    fn parse_window_frame_bound(&mut self) -> Result<(WindowFrameBound, Option<String>)> {
        if self.match_token(TokenType::Current) {
            self.expect(TokenType::Row)?;
            Ok((WindowFrameBound::CurrentRow, None))
        } else if self.match_token(TokenType::Unbounded) {
            if self.match_token(TokenType::Preceding) {
                let text = self.tokens[self.current - 1].text.clone();
                Ok((WindowFrameBound::UnboundedPreceding, Some(text)))
            } else if self.match_token(TokenType::Following) {
                let text = self.tokens[self.current - 1].text.clone();
                Ok((WindowFrameBound::UnboundedFollowing, Some(text)))
            } else {
                Err(self.parse_error("Expected PRECEDING or FOLLOWING after UNBOUNDED"))
            }
        } else if self.match_token(TokenType::Preceding) {
            let text = self.tokens[self.current - 1].text.clone();
            // PRECEDING [value] (inverted syntax for some dialects)
            // If no value follows (e.g., just "PRECEDING" or "PRECEDING)"), use BarePreceding
            if self.check(TokenType::RParen) || self.check(TokenType::Comma) {
                Ok((WindowFrameBound::BarePreceding, Some(text)))
            } else {
                let expr = self.parse_primary()?;
                Ok((WindowFrameBound::Preceding(Box::new(expr)), Some(text)))
            }
        } else if self.match_token(TokenType::Following) {
            let text = self.tokens[self.current - 1].text.clone();
            // FOLLOWING [value] (inverted syntax for some dialects)
            // If no value follows (e.g., just "FOLLOWING" or "FOLLOWING)"), use BareFollowing
            if self.check(TokenType::RParen) || self.check(TokenType::Comma) {
                Ok((WindowFrameBound::BareFollowing, Some(text)))
            } else {
                let expr = self.parse_primary()?;
                Ok((WindowFrameBound::Following(Box::new(expr)), Some(text)))
            }
        } else {
            // <expr> PRECEDING | FOLLOWING (standard syntax)
            // Use parse_addition to handle expressions like 1 + 1 PRECEDING
            let expr = self.parse_addition()?;
            if self.match_token(TokenType::Preceding) {
                let text = self.tokens[self.current - 1].text.clone();
                Ok((WindowFrameBound::Preceding(Box::new(expr)), Some(text)))
            } else if self.match_token(TokenType::Following) {
                let text = self.tokens[self.current - 1].text.clone();
                Ok((WindowFrameBound::Following(Box::new(expr)), Some(text)))
            } else {
                // Bare numeric bounds without PRECEDING/FOLLOWING
                // (e.g., RANGE BETWEEN 1 AND 3)
                Ok((WindowFrameBound::Value(Box::new(expr)), None))
            }
        }
    }

    /// Try to parse INTERVAL expression. Returns None if INTERVAL should be treated as identifier.
    fn try_parse_interval(&mut self) -> Result<Option<Expression>> {
        self.try_parse_interval_internal(true)
    }

    /// Internal interval parsing that optionally matches the INTERVAL keyword.
    /// When match_interval is false, it parses a chained interval value-unit pair
    /// without requiring the INTERVAL keyword.
    fn try_parse_interval_internal(&mut self, match_interval: bool) -> Result<Option<Expression>> {
        let start_pos = self.current;

        // Consume the INTERVAL keyword if required
        if match_interval {
            if !self.check(TokenType::Interval) {
                return Ok(None);
            }
            self.expect(TokenType::Interval)?;

            // Check if next token is an operator - if so, INTERVAL is used as identifier
            if self.check(TokenType::Eq)
                || self.check(TokenType::Neq)
                || self.check(TokenType::Lt)
                || self.check(TokenType::Gt)
                || self.check(TokenType::Lte)
                || self.check(TokenType::Gte)
                || self.check(TokenType::And)
                || self.check(TokenType::Or)
                || self.check(TokenType::Is)
                || self.check(TokenType::In)
                || self.check(TokenType::Like)
                || self.check(TokenType::ILike)
                || self.check(TokenType::Between)
                || self.check(TokenType::Then)
                || self.check(TokenType::Else)
                || self.check(TokenType::When)
                || self.check(TokenType::End)
                || self.check(TokenType::Comma)
                || self.check(TokenType::RParen)
                || self.check(TokenType::DColon)
            {
                // INTERVAL is used as identifier
                self.current = start_pos;
                return Ok(None);
            }
        }

        // Parse the value after INTERVAL
        // IMPORTANT: For string literals, don't use parse_primary() because it calls
        // maybe_parse_subscript() which would consume postfix operators like ::TYPE.
        // Those should be applied to the full INTERVAL expression, not just the value inside.
        // e.g., INTERVAL '1 hour'::VARCHAR should be CAST(INTERVAL '1 hour' AS VARCHAR)
        //       not INTERVAL CAST('1 hour' AS VARCHAR)
        // For non-string values, use parse_addition() to handle expressions like
        // INTERVAL 2 * 2 MONTH or INTERVAL DAYOFMONTH(dt) - 1 DAY (MySQL syntax)
        // This matches Python sqlglot's _parse_term() behavior which handles +, -, *, /, %
        let value = if self.check(TokenType::String) {
            let token = self.advance();
            Some(Expression::Literal(Literal::String(token.text)))
        } else if !self.is_at_end() && !self.is_statement_terminator() {
            Some(self.parse_addition()?)
        } else {
            None
        };

        // Check if we should treat INTERVAL as an identifier instead
        // This happens when:
        // - No value was parsed, OR
        // - Value is an unqualified, unquoted column reference AND
        //   what follows is NOT a valid interval unit
        if let Some(ref val) = value {
            if let Expression::Column(col) = val {
                // Column without table qualifier
                if col.table.is_none() {
                    // Check if identifier is quoted
                    let is_quoted = col.name.quoted;
                    if !is_quoted {
                        // Check if next token is a valid interval unit
                        if !self.is_valid_interval_unit() && !self.check(TokenType::As) {
                            // Backtrack - INTERVAL is used as identifier
                            self.current = start_pos;
                            return Ok(None);
                        }
                    }
                }
            } else if let Expression::Identifier(id) = val {
                // Bare identifier without table qualifier
                let is_quoted = id.quoted;
                if !is_quoted {
                    // Check if next token is a valid interval unit
                    if !self.is_valid_interval_unit() && !self.check(TokenType::As) {
                        // Backtrack - INTERVAL is used as identifier
                        self.current = start_pos;
                        return Ok(None);
                    }
                }
            }
        } else if self.is_at_end() || self.is_statement_terminator() {
            // No value, and at end/terminator - INTERVAL is an identifier
            self.current = start_pos;
            return Ok(None);
        }

        // Now parse the optional unit
        let mut unit = self.try_parse_interval_unit()?;

        // Split compound interval strings like '1 day' into value '1' and unit DAY
        // This matches Python sqlglot's INTERVAL_STRING_RE behavior
        // Only apply in generic mode -- dialects like PostgreSQL preserve compound strings
        let is_generic = self.config.dialect.is_none()
            || matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::Generic)
            );
        let value = if unit.is_none() && is_generic {
            if let Some(Expression::Literal(Literal::String(ref s))) = value {
                let trimmed = s.trim();
                // Match pattern: optional negative sign, digits (optional decimal), space(s), alpha unit
                let mut split_pos = None;
                let mut found_space = false;
                let bytes = trimmed.as_bytes();
                let mut i = 0;
                // Skip optional negative sign
                if i < bytes.len() && bytes[i] == b'-' {
                    i += 1;
                }
                // Expect digits
                let digit_start = i;
                while i < bytes.len() && bytes[i].is_ascii_digit() {
                    i += 1;
                }
                if i > digit_start {
                    // Optional decimal part
                    if i < bytes.len() && bytes[i] == b'.' {
                        i += 1;
                        while i < bytes.len() && bytes[i].is_ascii_digit() {
                            i += 1;
                        }
                    }
                    // Expect whitespace
                    let space_start = i;
                    while i < bytes.len() && bytes[i].is_ascii_whitespace() {
                        i += 1;
                    }
                    if i > space_start {
                        found_space = true;
                        split_pos = Some(i);
                    }
                }
                if found_space {
                    if let Some(pos) = split_pos {
                        let unit_text = &trimmed[pos..];
                        // Verify it's all alpha
                        if !unit_text.is_empty()
                            && unit_text.chars().all(|c| c.is_ascii_alphabetic())
                        {
                            let num_part = trimmed[..pos].trim_end().to_string();
                            let unit_upper = unit_text.to_uppercase();
                            // Try to parse as interval unit
                            if let Some(parsed_unit) =
                                Self::parse_interval_unit_from_string(&unit_upper)
                            {
                                // Check if the original text had an 'S' suffix (plural)
                                let is_plural = unit_text.to_uppercase().ends_with('S');
                                unit = Some(IntervalUnitSpec::Simple {
                                    unit: parsed_unit,
                                    use_plural: is_plural,
                                });
                                Some(Expression::Literal(Literal::String(num_part)))
                            } else {
                                value
                            }
                        } else {
                            value
                        }
                    } else {
                        value
                    }
                } else {
                    value
                }
            } else {
                value
            }
        } else {
            value
        };

        // Convert number literals to string literals in intervals (canonical form).
        // Most dialects support INTERVAL '5' DAY, so we normalize to this form
        // for easier transpilation. This matches Python sqlglot's behavior in
        // _parse_interval_span: "if this and this.is_number: this = exp.Literal.string(this.to_py())"
        let value = match value {
            Some(Expression::Literal(Literal::Number(n))) if unit.is_some() => {
                Some(Expression::Literal(Literal::String(n)))
            }
            other => other,
        };

        let interval = Expression::Interval(Box::new(Interval { this: value, unit }));

        // Support for chained multi-unit interval syntax (Spark/Hive):
        // INTERVAL '5' HOURS '30' MINUTES -> INTERVAL '5' HOURS + INTERVAL '30' MINUTES
        // This is done by optionally matching a PLUS sign, and if followed by
        // another string or number (without INTERVAL keyword), recursively parsing
        // and creating an Add expression.
        let before_plus = self.current;
        let has_plus = self.match_token(TokenType::Plus);

        // Check if followed by a STRING or NUMBER (potential chained interval)
        if self.check(TokenType::String) || self.check(TokenType::Number) {
            // Recursively parse the chained interval without the INTERVAL keyword
            if let Some(next_interval) = self.try_parse_interval_internal(false)? {
                return Ok(Some(Expression::Add(Box::new(BinaryOp::new(
                    interval,
                    next_interval,
                )))));
            }
        }

        // If we consumed a PLUS but didn't find a chained interval, backtrack
        if has_plus {
            self.current = before_plus;
        }

        Ok(Some(interval))
    }

    /// Check if current token is a valid interval unit
    fn is_valid_interval_unit(&self) -> bool {
        if self.is_at_end() {
            return false;
        }
        let text = self.peek().text.to_uppercase();
        matches!(
            text.as_str(),
            "YEAR"
                | "YEARS"
                | "MONTH"
                | "MONTHS"
                | "DAY"
                | "DAYS"
                | "HOUR"
                | "HOURS"
                | "MINUTE"
                | "MINUTES"
                | "SECOND"
                | "SECONDS"
                | "MILLISECOND"
                | "MILLISECONDS"
                | "MICROSECOND"
                | "MICROSECONDS"
                | "NANOSECOND"
                | "NANOSECONDS"
                | "WEEK"
                | "WEEKS"
                | "QUARTER"
                | "QUARTERS"
        )
    }

    /// Check if current token terminates a statement/expression context
    fn is_statement_terminator(&self) -> bool {
        if self.is_at_end() {
            return true;
        }
        matches!(
            self.peek().token_type,
            TokenType::Semicolon
                | TokenType::RParen
                | TokenType::RBracket
                | TokenType::Comma
                | TokenType::From
                | TokenType::Where
                | TokenType::GroupBy
                | TokenType::Having
                | TokenType::OrderBy
                | TokenType::Limit
                | TokenType::Union
                | TokenType::Intersect
                | TokenType::Except
                | TokenType::End
                | TokenType::Then
                | TokenType::Else
                | TokenType::When
        )
    }

    /// Try to parse interval unit - returns None if no unit present
    fn try_parse_interval_unit(&mut self) -> Result<Option<IntervalUnitSpec>> {
        // First, check if there's a function (like CURRENT_DATE, CAST(...))
        if self.is_function_start() {
            let func = self.parse_primary()?;
            return Ok(Some(IntervalUnitSpec::Expr(Box::new(func))));
        }

        // Try to parse a simple unit or span
        if let Some((unit, use_plural)) = self.try_parse_simple_interval_unit()? {
            // Check for "TO" to make it a span (e.g., YEAR TO MONTH)
            // Use lookahead to avoid consuming TO when it's part of WITH FILL
            if self.check_keyword_text("TO") {
                let saved = self.current;
                self.advance(); // consume TO
                if let Some((end_unit, _)) = self.try_parse_simple_interval_unit()? {
                    return Ok(Some(IntervalUnitSpec::Span(IntervalSpan {
                        this: unit,
                        expression: end_unit,
                    })));
                } else {
                    // Not followed by a valid interval unit — backtrack
                    self.current = saved;
                }
            }
            return Ok(Some(IntervalUnitSpec::Simple { unit, use_plural }));
        }

        // No unit found
        Ok(None)
    }

    /// Parse an interval unit from a string (used for splitting compound interval strings)
    fn parse_interval_unit_from_string(s: &str) -> Option<IntervalUnit> {
        // Strip trailing 'S' for plural forms
        let base = if s.ends_with('S') && s.len() > 1 {
            &s[..s.len() - 1]
        } else {
            s
        };
        match base {
            "YEAR" => Some(IntervalUnit::Year),
            "MONTH" => Some(IntervalUnit::Month),
            "DAY" => Some(IntervalUnit::Day),
            "HOUR" => Some(IntervalUnit::Hour),
            "MINUTE" => Some(IntervalUnit::Minute),
            "SECOND" => Some(IntervalUnit::Second),
            "MILLISECOND" => Some(IntervalUnit::Millisecond),
            "MICROSECOND" => Some(IntervalUnit::Microsecond),
            "QUARTER" => Some(IntervalUnit::Quarter),
            "WEEK" => Some(IntervalUnit::Week),
            _ => None,
        }
    }

    /// Try to parse a simple interval unit (YEAR, MONTH, etc.) - returns (unit, is_plural)
    fn try_parse_simple_interval_unit(&mut self) -> Result<Option<(IntervalUnit, bool)>> {
        if self.is_at_end() {
            return Ok(None);
        }

        let text_upper = self.peek().text.to_uppercase();
        let result = match text_upper.as_str() {
            "YEAR" => Some((IntervalUnit::Year, false)),
            "YEARS" => Some((IntervalUnit::Year, true)),
            "MONTH" => Some((IntervalUnit::Month, false)),
            "MONTHS" => Some((IntervalUnit::Month, true)),
            "DAY" => Some((IntervalUnit::Day, false)),
            "DAYS" => Some((IntervalUnit::Day, true)),
            "HOUR" => Some((IntervalUnit::Hour, false)),
            "HOURS" => Some((IntervalUnit::Hour, true)),
            "MINUTE" => Some((IntervalUnit::Minute, false)),
            "MINUTES" => Some((IntervalUnit::Minute, true)),
            "SECOND" => Some((IntervalUnit::Second, false)),
            "SECONDS" => Some((IntervalUnit::Second, true)),
            "MILLISECOND" => Some((IntervalUnit::Millisecond, false)),
            "MILLISECONDS" => Some((IntervalUnit::Millisecond, true)),
            "MICROSECOND" => Some((IntervalUnit::Microsecond, false)),
            "MICROSECONDS" => Some((IntervalUnit::Microsecond, true)),
            "NANOSECOND" => Some((IntervalUnit::Nanosecond, false)),
            "NANOSECONDS" => Some((IntervalUnit::Nanosecond, true)),
            "QUARTER" => Some((IntervalUnit::Quarter, false)),
            "QUARTERS" => Some((IntervalUnit::Quarter, true)),
            "WEEK" => Some((IntervalUnit::Week, false)),
            "WEEKS" => Some((IntervalUnit::Week, true)),
            _ => None,
        };

        if result.is_some() {
            self.advance(); // consume the unit token
        }

        Ok(result)
    }

    /// Check if current position starts a function call or no-paren function
    fn is_function_start(&self) -> bool {
        if self.is_at_end() {
            return false;
        }
        let token_type = self.peek().token_type;

        // Check NO_PAREN_FUNCTIONS configuration map
        if NO_PAREN_FUNCTIONS.contains(&token_type) {
            if !matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) || token_type != TokenType::CurrentTimestamp
            {
                return true;
            }
        }

        // Cast functions are always functions
        if matches!(
            token_type,
            TokenType::Cast | TokenType::TryCast | TokenType::SafeCast
        ) {
            return true;
        }

        // Check NO_PAREN_FUNCTION_NAMES for string-based lookup
        // (handles cases where functions are tokenized as Var/Identifier)
        let text_upper = self.peek().text.to_uppercase();
        if crate::function_registry::is_no_paren_function_name_upper(text_upper.as_str()) {
            if !matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) || text_upper.as_str() != "CURRENT_TIMESTAMP"
            {
                return true;
            }
        }

        // Identifier followed by left paren (function call)
        if self.is_identifier_token() && self.check_next(TokenType::LParen) {
            return true;
        }

        false
    }

    /// Try to parse Oracle interval span after an expression.
    /// Syntax: (expr) DAY[(precision)] TO SECOND[(fractional_precision)]
    /// This is used in Oracle for interval expressions like:
    /// (SYSTIMESTAMP - order_date) DAY(9) TO SECOND(3)
    fn try_parse_oracle_interval_span(&mut self, expr: Expression) -> Result<Expression> {
        let start_pos = self.current;

        // Check if current token is an interval unit keyword (DAY, HOUR, MINUTE, SECOND, YEAR, MONTH)
        let start_unit_name = if !self.is_at_end() {
            let text = self.peek().text.to_uppercase();
            if matches!(
                text.as_str(),
                "DAY" | "HOUR" | "MINUTE" | "SECOND" | "YEAR" | "MONTH"
            ) {
                Some(text)
            } else {
                None
            }
        } else {
            None
        };

        if start_unit_name.is_none() {
            return Ok(expr);
        }

        let start_unit_name = start_unit_name.unwrap();
        self.advance(); // consume the unit keyword

        // Parse optional precision: DAY(9) or just DAY
        let start_unit = if self.match_token(TokenType::LParen) {
            // Parse precision
            let precision = self.parse_expression()?;
            self.expect(TokenType::RParen)?;
            // Create a function-like expression for the unit with precision
            Expression::Anonymous(Box::new(Anonymous {
                this: Box::new(Expression::Identifier(Identifier {
                    name: start_unit_name.clone(),
                    quoted: false,
                    trailing_comments: Vec::new(),
                    span: None,
                })),
                expressions: vec![precision],
            }))
        } else {
            // Simple unit without precision
            Expression::Var(Box::new(Var {
                this: start_unit_name,
            }))
        };

        // Check for TO keyword
        if !self.match_keyword("TO") {
            // Not an interval span, backtrack
            self.current = start_pos;
            return Ok(expr);
        }

        // Parse end unit
        let end_unit_name = if !self.is_at_end() {
            let text = self.peek().text.to_uppercase();
            if matches!(
                text.as_str(),
                "DAY" | "HOUR" | "MINUTE" | "SECOND" | "YEAR" | "MONTH"
            ) {
                Some(text)
            } else {
                None
            }
        } else {
            None
        };

        let end_unit_name = match end_unit_name {
            Some(name) => name,
            None => {
                // No valid end unit, backtrack
                self.current = start_pos;
                return Ok(expr);
            }
        };

        self.advance(); // consume the end unit keyword

        // Parse optional precision for end unit: SECOND(3) or just SECOND
        let end_unit = if self.match_token(TokenType::LParen) {
            // Parse fractional precision
            let precision = self.parse_expression()?;
            self.expect(TokenType::RParen)?;
            // Create a function-like expression for the unit with precision
            Expression::Anonymous(Box::new(Anonymous {
                this: Box::new(Expression::Identifier(Identifier {
                    name: end_unit_name.clone(),
                    quoted: false,
                    trailing_comments: Vec::new(),
                    span: None,
                })),
                expressions: vec![precision],
            }))
        } else {
            // Simple unit without precision
            Expression::Var(Box::new(Var {
                this: end_unit_name,
            }))
        };

        // Create an Interval expression with ExprSpan unit
        Ok(Expression::Interval(Box::new(Interval {
            this: Some(expr),
            unit: Some(IntervalUnitSpec::ExprSpan(IntervalSpanExpr {
                this: Box::new(start_unit),
                expression: Box::new(end_unit),
            })),
        })))
    }

    /// Check if the current position starts a typed column list (for table function aliases)
    /// like: (col1 type1, col2 type2)
    /// This peeks ahead to see if the first column name is followed by a type token,
    /// rather than a comma or closing paren (which would indicate simple column aliases).
    /// Used for PostgreSQL functions like JSON_TO_RECORDSET that have typed column definitions.
    fn check_typed_column_list(&self) -> bool {
        // We're positioned after '(' - check pattern: identifier type
        // If we see identifier followed by something that's not ',' or ')', it's typed
        if self.is_at_end() {
            return false;
        }

        // Check if current is an identifier (column name)
        let has_identifier = self.check(TokenType::Identifier)
            || self.check(TokenType::QuotedIdentifier)
            || self.check(TokenType::Var);

        if !has_identifier {
            return false;
        }

        // Look at next token (after the identifier)
        let next_pos = self.current + 1;
        if next_pos >= self.tokens.len() {
            return false;
        }

        let next_token = &self.tokens[next_pos];

        // If next token is comma or rparen, it's simple column aliases
        if next_token.token_type == TokenType::Comma || next_token.token_type == TokenType::RParen {
            return false;
        }

        // If next token could be a type name (identifier, var, or type keyword), it's typed columns
        // Check for type tokens or identifiers that could be type names
        TYPE_TOKENS.contains(&next_token.token_type)
            || next_token.token_type == TokenType::Identifier
            || next_token.token_type == TokenType::Var
    }

    /// Check if current token is a no-paren function
    fn is_no_paren_function(&self) -> bool {
        if self.is_at_end() {
            return false;
        }
        let token_type = self.peek().token_type;
        if NO_PAREN_FUNCTIONS.contains(&token_type) {
            if !matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) || token_type != TokenType::CurrentTimestamp
            {
                return true;
            }
        }
        let text_upper = self.peek().text.to_uppercase();
        if crate::function_registry::is_no_paren_function_name_upper(text_upper.as_str()) {
            if !matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) || text_upper.as_str() != "CURRENT_TIMESTAMP"
            {
                return true;
            }
        }
        false
    }

    /// Match a keyword by text (case-insensitive)
    fn match_keyword(&mut self, keyword: &str) -> bool {
        if self.is_at_end() {
            return false;
        }
        if self.peek().text.to_uppercase() == keyword {
            self.advance();
            true
        } else {
            false
        }
    }

    /// Match a sequence of keywords by text (case-insensitive)
    fn match_text_seq(&mut self, keywords: &[&str]) -> bool {
        for (i, &kw) in keywords.iter().enumerate() {
            if self.current + i >= self.tokens.len() {
                return false;
            }
            if self.tokens[self.current + i].text.to_uppercase() != kw {
                return false;
            }
        }
        self.current += keywords.len();
        true
    }

    /// Check (without consuming) if the next tokens match a sequence of keywords by text (case-insensitive)
    fn check_text_seq(&self, keywords: &[&str]) -> bool {
        for (i, &kw) in keywords.iter().enumerate() {
            if self.current + i >= self.tokens.len() {
                return false;
            }
            if self.tokens[self.current + i].text.to_uppercase() != kw {
                return false;
            }
        }
        true
    }

    /// Match any of the given texts (case-insensitive)
    fn match_texts(&mut self, texts: &[&str]) -> bool {
        if self.is_at_end() {
            return false;
        }
        let current_text = self.peek().text.to_uppercase();
        for text in texts {
            if current_text == text.to_uppercase() {
                self.advance();
                return true;
            }
        }
        false
    }

    /// Parse CASE expression
    fn parse_case(&mut self) -> Result<Expression> {
        self.expect(TokenType::Case)?;
        // Capture trailing comments from the CASE keyword (e.g., CASE /* test */ WHEN ...)
        let case_comments = self.previous_trailing_comments();

        // Check for simple CASE (CASE expr WHEN ...)
        let operand = if !self.check(TokenType::When) {
            Some(self.parse_expression()?)
        } else {
            None
        };

        let mut whens = Vec::new();
        while self.match_token(TokenType::When) {
            let condition = self.parse_expression()?;
            self.expect(TokenType::Then)?;
            let mut result = self.parse_expression()?;
            // ClickHouse: CASE WHEN x THEN 1 as alias WHEN y THEN alias / 2 END
            // Aliases can appear in CASE THEN expressions
            if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && self.match_token(TokenType::As)
            {
                let alias = self.expect_identifier_or_keyword()?;
                result = Expression::Alias(Box::new(Alias {
                    this: result,
                    alias: Identifier::new(alias),
                    column_aliases: Vec::new(),
                    pre_alias_comments: Vec::new(),
                    trailing_comments: Vec::new(),
                    inferred_type: None,
                }));
            }
            whens.push((condition, result));
        }

        let else_ = if self.match_token(TokenType::Else) {
            Some(self.parse_expression()?)
        } else {
            None
        };

        self.expect(TokenType::End)?;

        Ok(Expression::Case(Box::new(Case {
            operand,
            whens,
            else_,
            comments: case_comments,
            inferred_type: None,
        })))
    }

    /// Parse CAST expression
    fn parse_cast(&mut self) -> Result<Expression> {
        self.expect(TokenType::Cast)?;
        self.expect(TokenType::LParen)?;
        // Use parse_or() instead of parse_expression() to avoid consuming AS
        // as an alias (e.g. CAST((1, 2) AS Tuple(a Int8, b Int16)))
        // Python sqlglot uses _parse_disjunction() here, which is equivalent.
        let expr = self.parse_or()?;

        // ClickHouse: ternary operator inside CAST: CAST(cond ? true_val : false_val AS Type)
        let expr = if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) && self.match_token(TokenType::Parameter)
        {
            if self.check(TokenType::Colon) {
                return Err(
                    self.parse_error("Expected true expression after ? in ClickHouse ternary")
                );
            }
            let true_value = self.parse_or()?;
            let false_value = if self.match_token(TokenType::Colon) {
                self.parse_or()?
            } else {
                Expression::Null(Null)
            };
            Expression::IfFunc(Box::new(IfFunc {
                original_name: None,
                condition: expr,
                true_value,
                false_value: Some(false_value),
                inferred_type: None,
            }))
        } else {
            expr
        };

        // ClickHouse: implicit alias in CAST: cast('1234' lhs AS UInt32) or cast('1234' lhs, 'UInt32')
        let expr = self.try_clickhouse_implicit_alias(expr);

        // ClickHouse: CAST(expr, 'type_string') or CAST(expr, expression) syntax with comma instead of AS
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) && self.match_token(TokenType::Comma)
        {
            // Parse as expression to handle concat and other operations: CAST(x, 'Str' || 'ing')
            let type_expr = self.parse_expression()?;
            // ClickHouse: alias on type expr: cast('1234' lhs, 'UInt32' rhs) or cast('1234', 'UInt32' AS rhs)
            let type_expr = self.try_clickhouse_func_arg_alias(type_expr);
            self.expect(TokenType::RParen)?;
            let _trailing_comments = self.previous_trailing_comments();
            return Ok(Expression::CastToStrType(Box::new(CastToStrType {
                this: Box::new(expr),
                to: Some(Box::new(type_expr)),
            })));
        }

        self.expect(TokenType::As)?;

        // ClickHouse: CAST(expr AS alias AS Type) — inner alias before type
        // If the next token is an identifier followed by AS, treat it as an alias
        let expr = if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) && (self.is_identifier_token() || self.is_safe_keyword_as_identifier())
            && self
                .peek_nth(1)
                .map_or(false, |t| t.token_type == TokenType::As)
        {
            let alias = self.expect_identifier_or_keyword_with_quoted()?;
            self.expect(TokenType::As)?;
            Expression::Alias(Box::new(Alias::new(expr, alias)))
        } else if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) && (self.is_identifier_token() || self.is_safe_keyword_as_identifier())
            && self
                .peek_nth(1)
                .map_or(false, |t| t.token_type == TokenType::Comma)
        {
            // ClickHouse: CAST(expr AS alias, type_string) — alias before comma syntax
            let alias = self.expect_identifier_or_keyword_with_quoted()?;
            let expr = Expression::Alias(Box::new(Alias::new(expr, alias)));
            self.expect(TokenType::Comma)?;
            let type_expr = self.parse_expression()?;
            let type_expr = self.try_clickhouse_func_arg_alias(type_expr);
            self.expect(TokenType::RParen)?;
            let _trailing_comments = self.previous_trailing_comments();
            return Ok(Expression::CastToStrType(Box::new(CastToStrType {
                this: Box::new(expr),
                to: Some(Box::new(type_expr)),
            })));
        } else {
            expr
        };

        // Teradata: CAST(x AS FORMAT 'fmt') (no explicit type)
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::Teradata)
        ) && self.match_token(TokenType::Format)
        {
            let format = Some(Box::new(self.parse_expression()?));
            self.expect(TokenType::RParen)?;
            let trailing_comments = self.previous_trailing_comments();
            return Ok(Expression::Cast(Box::new(Cast {
                this: expr,
                to: DataType::Unknown,
                trailing_comments,
                double_colon_syntax: false,
                format,
                default: None,
                inferred_type: None,
            })));
        }

        let data_type = self.parse_data_type()?;

        // Parse optional DEFAULT ... ON CONVERSION ERROR (Oracle)
        // CAST(x AS type DEFAULT val ON CONVERSION ERROR)
        let default = if self.match_token(TokenType::Default) {
            let default_val = self.parse_primary()?;
            // Expect "ON CONVERSION ERROR"
            if !self.match_text_seq(&["ON", "CONVERSION", "ERROR"]) {
                return Err(self.parse_error("Expected ON CONVERSION ERROR"));
            }
            Some(Box::new(default_val))
        } else {
            None
        };

        // Parse optional FORMAT clause for BigQuery: CAST(x AS STRING FORMAT 'format_string')
        // Or for Oracle with comma: CAST(x AS DATE DEFAULT NULL ON CONVERSION ERROR, 'format')
        let format = if self.match_token(TokenType::Format) {
            Some(Box::new(self.parse_expression()?))
        } else if self.match_token(TokenType::Comma) {
            // Oracle date format: CAST(x AS DATE, 'format')
            Some(Box::new(self.parse_expression()?))
        } else {
            None
        };

        self.expect(TokenType::RParen)?;
        let trailing_comments = self.previous_trailing_comments();

        Ok(Expression::Cast(Box::new(Cast {
            this: expr,
            to: data_type,
            trailing_comments,
            double_colon_syntax: false,
            format,
            default,
            inferred_type: None,
        })))
    }

    /// Parse TRY_CAST expression
    fn parse_try_cast(&mut self) -> Result<Expression> {
        self.expect(TokenType::TryCast)?;
        self.expect(TokenType::LParen)?;
        let expr = self.parse_or()?;
        self.expect(TokenType::As)?;
        let data_type = self.parse_data_type()?;

        // Parse optional FORMAT clause
        let format = if self.match_token(TokenType::Format) {
            Some(Box::new(self.parse_expression()?))
        } else {
            None
        };

        self.expect(TokenType::RParen)?;
        let trailing_comments = self.previous_trailing_comments();

        Ok(Expression::TryCast(Box::new(Cast {
            this: expr,
            to: data_type,
            trailing_comments,
            double_colon_syntax: false,
            format,
            default: None,
            inferred_type: None,
        })))
    }

    /// Parse SAFE_CAST expression (BigQuery)
    fn parse_safe_cast(&mut self) -> Result<Expression> {
        self.expect(TokenType::SafeCast)?;
        self.expect(TokenType::LParen)?;
        let expr = self.parse_or()?;
        self.expect(TokenType::As)?;
        let data_type = self.parse_data_type()?;

        // Parse optional FORMAT clause
        let format = if self.match_token(TokenType::Format) {
            Some(Box::new(self.parse_expression()?))
        } else {
            None
        };

        self.expect(TokenType::RParen)?;
        let trailing_comments = self.previous_trailing_comments();

        Ok(Expression::SafeCast(Box::new(Cast {
            this: expr,
            to: data_type,
            trailing_comments,
            double_colon_syntax: false,
            format,
            default: None,
            inferred_type: None,
        })))
    }

    /// Parse a data type
    fn parse_data_type(&mut self) -> Result<DataType> {
        // Handle special token types that represent data type keywords
        // Teradata tokenizes ST_GEOMETRY as TokenType::Geometry
        if self.check(TokenType::Geometry) {
            let _token = self.advance();
            let (subtype, srid) = self.parse_spatial_type_args()?;
            return Ok(DataType::Geometry { subtype, srid });
        }
        // Data types can be keywords (DATE, TIMESTAMP, etc.) or identifiers
        let mut raw_name = self.expect_identifier_or_keyword()?;
        // Allow dotted custom types like SYSUDTLIB.INT
        while self.match_token(TokenType::Dot) {
            let part = self.expect_identifier_or_keyword()?;
            raw_name.push('.');
            raw_name.push_str(&part);
        }
        let mut name = raw_name.to_uppercase();

        // SQL standard: NATIONAL CHAR/CHARACTER → NCHAR
        if name == "NATIONAL" {
            let next_upper = if !self.is_at_end() {
                self.peek().text.to_uppercase()
            } else {
                String::new()
            };
            if next_upper == "CHAR" || next_upper == "CHARACTER" {
                self.advance(); // consume CHAR/CHARACTER
                name = "NCHAR".to_string();
                // NATIONAL CHARACTER VARYING → NVARCHAR equivalent
                if next_upper == "CHARACTER" && self.check_identifier("VARYING") {
                    self.advance(); // consume VARYING
                    let length = if self.match_token(TokenType::LParen) {
                        if self.check(TokenType::RParen) {
                            self.advance();
                            None
                        } else {
                            let n = self.expect_number()? as u32;
                            self.expect(TokenType::RParen)?;
                            Some(n)
                        }
                    } else {
                        None
                    };
                    return Ok(DataType::VarChar {
                        length,
                        parenthesized_length: false,
                    });
                }
            }
        }

        let base_type = match name.as_str() {
            "INT" | "INTEGER" => {
                // MySQL allows INT(N) for display width; ClickHouse allows INT()
                let length = if self.match_token(TokenType::LParen) {
                    if self.check(TokenType::RParen) {
                        self.advance();
                        None
                    } else {
                        let n = self.expect_number()? as u32;
                        self.expect(TokenType::RParen)?;
                        Some(n)
                    }
                } else {
                    None
                };
                let integer_spelling = name == "INTEGER";
                Ok(DataType::Int {
                    length,
                    integer_spelling,
                })
            }
            "BIGINT" => {
                // MySQL allows BIGINT(N) for display width; ClickHouse allows BIGINT()
                let length = if self.match_token(TokenType::LParen) {
                    if self.check(TokenType::RParen) {
                        self.advance();
                        None
                    } else {
                        let n = self.expect_number()? as u32;
                        self.expect(TokenType::RParen)?;
                        Some(n)
                    }
                } else {
                    None
                };
                Ok(DataType::BigInt { length })
            }
            "SMALLINT" => {
                let length = if self.match_token(TokenType::LParen) {
                    if self.check(TokenType::RParen) {
                        self.advance();
                        None
                    } else {
                        let n = self.expect_number()? as u32;
                        self.expect(TokenType::RParen)?;
                        Some(n)
                    }
                } else {
                    None
                };
                Ok(DataType::SmallInt { length })
            }
            "TINYINT" => {
                let length = if self.match_token(TokenType::LParen) {
                    if self.check(TokenType::RParen) {
                        self.advance();
                        None
                    } else {
                        let n = self.expect_number()? as u32;
                        self.expect(TokenType::RParen)?;
                        Some(n)
                    }
                } else {
                    None
                };
                Ok(DataType::TinyInt { length })
            }
            "FLOAT" | "REAL" => {
                let real_spelling = name == "REAL";
                // MySQL allows FLOAT(precision) or FLOAT(precision, scale)
                let (precision, scale) = if self.match_token(TokenType::LParen) {
                    let p = self.expect_number()? as u32;
                    let s = if self.match_token(TokenType::Comma) {
                        Some(self.expect_number()? as u32)
                    } else {
                        None
                    };
                    self.expect(TokenType::RParen)?;
                    (Some(p), s)
                } else {
                    (None, None)
                };
                Ok(DataType::Float {
                    precision,
                    scale,
                    real_spelling,
                })
            }
            "BINARY_FLOAT" => {
                // Oracle's BINARY_FLOAT -> DataType::Float
                Ok(DataType::Float {
                    precision: None,
                    scale: None,
                    real_spelling: false,
                })
            }
            "BINARY_DOUBLE" => {
                // Oracle's BINARY_DOUBLE -> DataType::Double
                Ok(DataType::Double {
                    precision: None,
                    scale: None,
                })
            }
            "DOUBLE" => {
                // Handle DOUBLE PRECISION (PostgreSQL standard SQL)
                let _ = self.match_identifier("PRECISION");
                // MySQL allows DOUBLE(precision, scale)
                let (precision, scale) = if self.match_token(TokenType::LParen) {
                    let p = self.expect_number()? as u32;
                    let s = if self.match_token(TokenType::Comma) {
                        Some(self.expect_number()? as u32)
                    } else {
                        None
                    };
                    self.expect(TokenType::RParen)?;
                    (Some(p), s)
                } else {
                    (None, None)
                };
                Ok(DataType::Double { precision, scale })
            }
            "DECIMAL" | "NUMERIC" => {
                let (precision, scale) = if self.match_token(TokenType::LParen) {
                    let p = self.expect_number()? as u32;
                    let s = if self.match_token(TokenType::Comma) {
                        Some(self.expect_number()? as u32)
                    } else {
                        None
                    };
                    self.expect(TokenType::RParen)?;
                    (Some(p), s)
                } else {
                    (None, None)
                };
                Ok(DataType::Decimal { precision, scale })
            }
            "BOOLEAN" | "BOOL" => Ok(DataType::Boolean),
            "CHAR" | "CHARACTER" | "NCHAR" => {
                let is_nchar = name == "NCHAR";
                // SQL standard: CHARACTER LARGE OBJECT → CLOB/TEXT
                if self.match_identifier("LARGE") && self.match_identifier("OBJECT") {
                    return Ok(DataType::Text);
                }
                // Check for VARYING to convert to VARCHAR (SQL standard: CHAR VARYING, CHARACTER VARYING)
                if self.match_identifier("VARYING") {
                    let length = if self.match_token(TokenType::LParen) {
                        if self.check(TokenType::RParen) {
                            self.advance();
                            None
                        } else {
                            let n = self.expect_number()? as u32;
                            self.expect(TokenType::RParen)?;
                            Some(n)
                        }
                    } else {
                        None
                    };
                    Ok(DataType::VarChar {
                        length,
                        parenthesized_length: false,
                    })
                } else {
                    let length = if self.match_token(TokenType::LParen) {
                        // Allow empty parens like NCHAR() - treat as no length specified
                        if self.check(TokenType::RParen) {
                            self.advance(); // consume RParen
                            None
                        } else {
                            let n = self.expect_number()? as u32;
                            self.expect(TokenType::RParen)?;
                            Some(n)
                        }
                    } else {
                        None
                    };
                    // CHAR CHARACTER SET charset (MySQL CAST context, no length)
                    // When length is specified (e.g., CHAR(4) CHARACTER SET LATIN),
                    // CHARACTER SET is a column attribute handled at the column def level
                    if length.is_none()
                        && self.match_identifier("CHARACTER")
                        && self.match_token(TokenType::Set)
                    {
                        let charset = self.expect_identifier_or_keyword()?;
                        return Ok(DataType::CharacterSet { name: charset });
                    }
                    // Preserve NCHAR as Custom DataType so target dialects can map it properly
                    // (Oracle keeps NCHAR, TSQL keeps NCHAR, others map to CHAR)
                    if is_nchar {
                        let name = if let Some(len) = length {
                            format!("NCHAR({})", len)
                        } else {
                            "NCHAR".to_string()
                        };
                        return Ok(DataType::Custom { name });
                    }
                    Ok(DataType::Char { length })
                }
            }
            "VARCHAR" | "NVARCHAR" => {
                let is_nvarchar = name == "NVARCHAR";
                if self.match_token(TokenType::LParen) {
                    // Allow empty parens like NVARCHAR() - treat as no length specified
                    if self.check(TokenType::RParen) {
                        self.advance(); // consume RParen
                        if is_nvarchar {
                            return Ok(DataType::Custom {
                                name: "NVARCHAR".to_string(),
                            });
                        }
                        Ok(DataType::VarChar {
                            length: None,
                            parenthesized_length: false,
                        })
                    } else if self.check_identifier("MAX") {
                        // TSQL: VARCHAR(MAX) / NVARCHAR(MAX)
                        self.advance(); // consume MAX
                        self.expect(TokenType::RParen)?;
                        let type_name = if is_nvarchar {
                            "NVARCHAR(MAX)"
                        } else {
                            "VARCHAR(MAX)"
                        };
                        Ok(DataType::Custom {
                            name: type_name.to_string(),
                        })
                    } else {
                        // Hive allows VARCHAR((50)) - extra parentheses around the length
                        let parenthesized_length = self.match_token(TokenType::LParen);
                        let n = self.expect_number()? as u32;
                        if parenthesized_length {
                            self.expect(TokenType::RParen)?;
                        }
                        self.expect(TokenType::RParen)?;
                        // Preserve NVARCHAR as Custom DataType so target dialects can map properly
                        if is_nvarchar {
                            return Ok(DataType::Custom {
                                name: format!("NVARCHAR({})", n),
                            });
                        }
                        Ok(DataType::VarChar {
                            length: Some(n),
                            parenthesized_length,
                        })
                    }
                } else {
                    if is_nvarchar {
                        return Ok(DataType::Custom {
                            name: "NVARCHAR".to_string(),
                        });
                    }
                    Ok(DataType::VarChar {
                        length: None,
                        parenthesized_length: false,
                    })
                }
            }
            "TEXT" | "NTEXT" => {
                // TEXT(n) - optional length parameter
                if self.match_token(TokenType::LParen) {
                    let n = self.expect_number()? as u32;
                    self.expect(TokenType::RParen)?;
                    Ok(DataType::TextWithLength { length: n })
                } else {
                    Ok(DataType::Text)
                }
            }
            "STRING" => {
                // BigQuery STRING(n) - parameterized string with max length
                let length = if self.match_token(TokenType::LParen) {
                    let n = self.expect_number()? as u32;
                    self.expect(TokenType::RParen)?;
                    Some(n)
                } else {
                    None
                };
                Ok(DataType::String { length })
            }
            "DATE" => Ok(DataType::Date),
            "TIME" => {
                // ClickHouse: Time('timezone') is a custom type with string arg
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) && self.check(TokenType::LParen)
                    && self.current + 1 < self.tokens.len()
                    && self.tokens[self.current + 1].token_type == TokenType::String
                {
                    self.advance(); // consume LParen
                    let args = self.parse_custom_type_args_balanced()?;
                    self.expect(TokenType::RParen)?;
                    return Ok(DataType::Custom {
                        name: format!("Time({})", args),
                    });
                }
                let precision = if self.match_token(TokenType::LParen) {
                    if self.check(TokenType::RParen) {
                        self.advance();
                        None
                    } else {
                        let p = self.expect_number()? as u32;
                        self.expect(TokenType::RParen)?;
                        Some(p)
                    }
                } else {
                    None
                };
                // Handle TIME WITH/WITHOUT TIME ZONE
                let timezone = if self.match_token(TokenType::With) {
                    self.match_keyword("TIME");
                    self.match_keyword("ZONE");
                    true
                } else if self.match_keyword("WITHOUT") {
                    self.match_keyword("TIME");
                    self.match_keyword("ZONE");
                    false
                } else {
                    false
                };
                Ok(DataType::Time {
                    precision,
                    timezone,
                })
            }
            "TIMETZ" => {
                let precision = if self.match_token(TokenType::LParen) {
                    let p = self.expect_number()? as u32;
                    self.expect(TokenType::RParen)?;
                    Some(p)
                } else {
                    None
                };
                Ok(DataType::Time {
                    precision,
                    timezone: true,
                })
            }
            "TIMESTAMP" => {
                // Parse optional precision: TIMESTAMP(p)
                let precision = if self.match_token(TokenType::LParen) {
                    let p = self.expect_number()? as u32;
                    self.expect(TokenType::RParen)?;
                    Some(p)
                } else {
                    None
                };
                // Parse optional WITH/WITHOUT TIME ZONE or WITH LOCAL TIME ZONE
                // Note: TIME is a keyword (TokenType::Time) and LOCAL is a keyword (TokenType::Local)
                if self.match_token(TokenType::With) {
                    // Check for LOCAL TIME ZONE (Exasol) vs TIME ZONE
                    // LOCAL is tokenized as TokenType::Local, not as Identifier
                    if self.match_token(TokenType::Local) {
                        self.match_keyword("TIME");
                        self.match_keyword("ZONE");
                        // TIMESTAMP WITH LOCAL TIME ZONE - return as custom type for Exasol handling
                        Ok(DataType::Custom {
                            name: "TIMESTAMPLTZ".to_string(),
                        })
                    } else {
                        self.match_keyword("TIME");
                        self.match_keyword("ZONE");
                        Ok(DataType::Timestamp {
                            precision,
                            timezone: true,
                        })
                    }
                } else if self.match_keyword("WITHOUT") {
                    self.match_keyword("TIME");
                    self.match_keyword("ZONE");
                    Ok(DataType::Timestamp {
                        precision,
                        timezone: false,
                    })
                } else {
                    Ok(DataType::Timestamp {
                        precision,
                        timezone: false,
                    })
                }
            }
            "TIMESTAMPTZ" => {
                let precision = if self.match_token(TokenType::LParen) {
                    let p = self.expect_number()? as u32;
                    self.expect(TokenType::RParen)?;
                    Some(p)
                } else {
                    None
                };
                Ok(DataType::Timestamp {
                    precision,
                    timezone: true,
                })
            }
            "TIMESTAMPLTZ" | "TIMESTAMP_LTZ" => {
                let precision = if self.match_token(TokenType::LParen) {
                    let p = self.expect_number()? as u32;
                    self.expect(TokenType::RParen)?;
                    Some(p)
                } else {
                    None
                };
                let name = if let Some(p) = precision {
                    format!("TIMESTAMPLTZ({})", p)
                } else {
                    "TIMESTAMPLTZ".to_string()
                };
                Ok(DataType::Custom { name })
            }
            "INTERVAL" => {
                // Parse optional unit (DAYS, DAY, HOUR, etc.)
                // Don't consume GENERATED, AS, NOT, NULL, etc. which are column constraints
                let unit = if (self.check(TokenType::Identifier)
                    || self.check(TokenType::Var)
                    || self.check_keyword())
                    && !self.check(TokenType::Generated)
                    && !self.check(TokenType::As)
                    && !self.check(TokenType::Not)
                    && !self.check(TokenType::Null)
                    && !self.check(TokenType::Default)
                    && !self.check(TokenType::PrimaryKey)
                    && !self.check(TokenType::Unique)
                    && !self.check(TokenType::Check)
                    && !self.check(TokenType::Constraint)
                    && !self.check(TokenType::References)
                    && !self.check(TokenType::Collate)
                    && !self.check(TokenType::Comment)
                    && !self.check(TokenType::RParen)
                    && !self.check(TokenType::Comma)
                {
                    Some(self.advance().text.to_uppercase())
                } else {
                    None
                };
                // Parse optional TO unit for range intervals like DAY TO HOUR
                let to = if self.match_token(TokenType::To) {
                    if self.check(TokenType::Identifier)
                        || self.check(TokenType::Var)
                        || self.check_keyword()
                    {
                        Some(self.advance().text.to_uppercase())
                    } else {
                        None
                    }
                } else {
                    None
                };
                Ok(DataType::Interval { unit, to })
            }
            "JSON" => {
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) && self.match_token(TokenType::LParen)
                {
                    // ClickHouse: JSON(subcolumn_specs) e.g. JSON(a String, b UInt32) or JSON(max_dynamic_paths=8)
                    let args = self.parse_custom_type_args_balanced()?;
                    self.expect(TokenType::RParen)?;
                    Ok(DataType::Custom {
                        name: format!("JSON({})", args),
                    })
                } else {
                    Ok(DataType::Json)
                }
            }
            "JSONB" => Ok(DataType::JsonB),
            "UUID" => Ok(DataType::Uuid),
            "BLOB" => Ok(DataType::Blob),
            "BYTEA" => Ok(DataType::VarBinary { length: None }),
            "BIT" => {
                let length = if self.match_token(TokenType::LParen) {
                    let n = self.expect_number()? as u32;
                    self.expect(TokenType::RParen)?;
                    Some(n)
                } else {
                    None
                };
                Ok(DataType::Bit { length })
            }
            "VARBIT" | "BIT VARYING" => {
                let length = if self.match_token(TokenType::LParen) {
                    let n = self.expect_number()? as u32;
                    self.expect(TokenType::RParen)?;
                    Some(n)
                } else {
                    None
                };
                Ok(DataType::VarBit { length })
            }
            "BINARY" => {
                // SQL standard: BINARY LARGE OBJECT → BLOB
                if self.match_identifier("LARGE") && self.match_identifier("OBJECT") {
                    return Ok(DataType::Blob);
                }
                // Handle BINARY VARYING (SQL standard for VARBINARY)
                if self.match_identifier("VARYING") {
                    let length = if self.match_token(TokenType::LParen) {
                        let len = self.expect_number()? as u32;
                        self.expect(TokenType::RParen)?;
                        Some(len)
                    } else {
                        None
                    };
                    Ok(DataType::VarBinary { length })
                } else {
                    let length = if self.match_token(TokenType::LParen) {
                        let len = self.expect_number()? as u32;
                        self.expect(TokenType::RParen)?;
                        Some(len)
                    } else {
                        None
                    };
                    Ok(DataType::Binary { length })
                }
            }
            "VARBINARY" => {
                let length = if self.match_token(TokenType::LParen) {
                    let len = self.expect_number()? as u32;
                    self.expect(TokenType::RParen)?;
                    Some(len)
                } else {
                    None
                };
                Ok(DataType::VarBinary { length })
            }
            // Generic types with angle bracket or parentheses syntax: ARRAY<T>, ARRAY(T), MAP<K,V>, MAP(K,V)
            "ARRAY" => {
                if self.match_token(TokenType::Lt) {
                    // ARRAY<element_type> - angle bracket style
                    let element_type = self.parse_data_type()?;
                    self.expect_gt()?;
                    Ok(DataType::Array {
                        element_type: Box::new(element_type),
                        dimension: None,
                    })
                } else if self.match_token(TokenType::LParen) {
                    // ARRAY(element_type) - Snowflake parentheses style
                    let element_type = self.parse_data_type()?;
                    self.expect(TokenType::RParen)?;
                    Ok(DataType::Array {
                        element_type: Box::new(element_type),
                        dimension: None,
                    })
                } else {
                    // Just ARRAY without type parameter
                    Ok(DataType::Custom {
                        name: "ARRAY".to_string(),
                    })
                }
            }
            "MAP" => {
                if self.match_token(TokenType::Lt) {
                    // MAP<key_type, value_type> - angle bracket style
                    let key_type = self.parse_data_type()?;
                    self.expect(TokenType::Comma)?;
                    let value_type = self.parse_data_type()?;
                    self.expect_gt()?;
                    Ok(DataType::Map {
                        key_type: Box::new(key_type),
                        value_type: Box::new(value_type),
                    })
                } else if self.match_token(TokenType::LBracket) {
                    // Materialize: MAP[TEXT => INT] type syntax
                    let key_type = self.parse_data_type()?;
                    self.expect(TokenType::FArrow)?;
                    let value_type = self.parse_data_type()?;
                    self.expect(TokenType::RBracket)?;
                    Ok(DataType::Map {
                        key_type: Box::new(key_type),
                        value_type: Box::new(value_type),
                    })
                } else if self.match_token(TokenType::LParen) {
                    // MAP(key_type, value_type) - Snowflake parentheses style
                    let key_type = self.parse_data_type()?;
                    self.expect(TokenType::Comma)?;
                    let value_type = self.parse_data_type()?;
                    self.expect(TokenType::RParen)?;
                    Ok(DataType::Map {
                        key_type: Box::new(key_type),
                        value_type: Box::new(value_type),
                    })
                } else {
                    // Just MAP without type parameters
                    Ok(DataType::Custom {
                        name: "MAP".to_string(),
                    })
                }
            }
            // VECTOR(type, dimension) - Snowflake vector type
            // VECTOR(dimension, element_type_alias) or VECTOR(dimension) - SingleStore vector type
            "VECTOR" => {
                if self.match_token(TokenType::LParen) {
                    if self.check(TokenType::Number) {
                        // SingleStore format: VECTOR(dimension) or VECTOR(dimension, type_alias)
                        let dimension = self.expect_number()? as u32;
                        let element_type = if self.match_token(TokenType::Comma) {
                            // Parse the type alias (I8, I16, I32, I64, F32, F64)
                            let type_alias = self.expect_identifier_or_keyword()?;
                            let mapped_type = match type_alias.to_uppercase().as_str() {
                                "I8" => DataType::TinyInt { length: None },
                                "I16" => DataType::SmallInt { length: None },
                                "I32" => DataType::Int {
                                    length: None,
                                    integer_spelling: false,
                                },
                                "I64" => DataType::BigInt { length: None },
                                "F32" => DataType::Float {
                                    precision: None,
                                    scale: None,
                                    real_spelling: false,
                                },
                                "F64" => DataType::Double {
                                    precision: None,
                                    scale: None,
                                },
                                _ => DataType::Custom {
                                    name: type_alias.to_string(),
                                },
                            };
                            Some(Box::new(mapped_type))
                        } else {
                            // Just dimension, no type
                            None
                        };
                        self.expect(TokenType::RParen)?;
                        Ok(DataType::Vector {
                            element_type,
                            dimension: Some(dimension),
                        })
                    } else {
                        // Snowflake format: VECTOR(type, dimension)
                        let element_type = self.parse_data_type()?;
                        self.expect(TokenType::Comma)?;
                        let dimension = self.expect_number()? as u32;
                        self.expect(TokenType::RParen)?;
                        Ok(DataType::Vector {
                            element_type: Some(Box::new(element_type)),
                            dimension: Some(dimension),
                        })
                    }
                } else {
                    Ok(DataType::Custom {
                        name: "VECTOR".to_string(),
                    })
                }
            }
            // OBJECT(field1 type1, field2 type2, ...) - Snowflake structured object type
            "OBJECT" => {
                if self.match_token(TokenType::LParen) {
                    // ClickHouse: Object('json') — string literal argument
                    if matches!(
                        self.config.dialect,
                        Some(crate::dialects::DialectType::ClickHouse)
                    ) && self.check(TokenType::String)
                    {
                        let arg = self.advance().text;
                        self.expect(TokenType::RParen)?;
                        return Ok(DataType::Custom {
                            name: format!("Object('{}')", arg),
                        });
                    }
                    let mut fields = Vec::new();
                    if !self.check(TokenType::RParen) {
                        loop {
                            let field_name = self.expect_identifier_or_keyword()?;
                            let field_type = self.parse_data_type()?;
                            // Optional NOT NULL constraint
                            let not_null = if self.match_keyword("NOT") {
                                // Consume NULL if present
                                self.match_keyword("NULL");
                                true
                            } else {
                                false
                            };
                            fields.push((field_name, field_type, not_null));
                            if !self.match_token(TokenType::Comma) {
                                break;
                            }
                        }
                    }
                    self.expect(TokenType::RParen)?;
                    // Check for RENAME FIELDS or ADD FIELDS modifier
                    let modifier = if self.match_keyword("RENAME") {
                        if self.match_keyword("FIELDS") {
                            Some("RENAME FIELDS".to_string())
                        } else {
                            Some("RENAME".to_string())
                        }
                    } else if self.match_keyword("ADD") {
                        if self.match_keyword("FIELDS") {
                            Some("ADD FIELDS".to_string())
                        } else {
                            Some("ADD".to_string())
                        }
                    } else {
                        None
                    };
                    Ok(DataType::Object { fields, modifier })
                } else {
                    Ok(DataType::Custom {
                        name: "OBJECT".to_string(),
                    })
                }
            }
            "STRUCT" => {
                if self.match_token(TokenType::Lt) {
                    // STRUCT<field1 type1, field2 type2, ...> - BigQuery angle-bracket syntax
                    let fields = self.parse_struct_type_fields(false)?;
                    self.expect_gt()?;
                    Ok(DataType::Struct {
                        fields,
                        nested: false,
                    })
                } else if self.match_token(TokenType::LParen) {
                    // STRUCT(field1 type1, field2 type2, ...) - DuckDB parenthesized syntax
                    let fields = self.parse_struct_type_fields(true)?;
                    self.expect(TokenType::RParen)?;
                    Ok(DataType::Struct {
                        fields,
                        nested: true,
                    })
                } else {
                    // Just STRUCT without type parameters
                    Ok(DataType::Custom {
                        name: "STRUCT".to_string(),
                    })
                }
            }
            "ROW" => {
                // ROW(field1 type1, field2 type2, ...) - same as STRUCT with parens
                if self.match_token(TokenType::LParen) {
                    let fields = self.parse_struct_type_fields(true)?;
                    self.expect(TokenType::RParen)?;
                    Ok(DataType::Struct {
                        fields,
                        nested: true,
                    })
                } else {
                    Ok(DataType::Custom {
                        name: "ROW".to_string(),
                    })
                }
            }
            "RECORD" => {
                // RECORD(field1 type1, field2 type2, ...) - SingleStore record type (like ROW/STRUCT)
                if self.match_token(TokenType::LParen) {
                    let fields = self.parse_struct_type_fields(true)?;
                    self.expect(TokenType::RParen)?;
                    // Use Struct with nested=true, generator will output RECORD for SingleStore
                    Ok(DataType::Struct {
                        fields,
                        nested: true,
                    })
                } else {
                    Ok(DataType::Custom {
                        name: "RECORD".to_string(),
                    })
                }
            }
            "ENUM" => {
                // ENUM('RED', 'GREEN', 'BLUE') - DuckDB enum type
                // ClickHouse: Enum('hello' = 1, 'world' = 2)
                // ClickHouse also allows NULL in enum: Enum('a', 'b', NULL)
                if self.match_token(TokenType::LParen) {
                    let mut values = Vec::new();
                    let mut assignments = Vec::new();
                    if !self.check(TokenType::RParen) {
                        loop {
                            let val = if matches!(
                                self.config.dialect,
                                Some(crate::dialects::DialectType::ClickHouse)
                            ) && self.check(TokenType::Null)
                            {
                                self.advance();
                                "NULL".to_string()
                            } else {
                                self.expect_string()?
                            };
                            values.push(val);
                            // ClickHouse: optional = value assignment (including negative numbers)
                            if self.match_token(TokenType::Eq) {
                                let negative = self.match_token(TokenType::Dash);
                                let num_token = self.advance();
                                let val = if negative {
                                    format!("-{}", num_token.text)
                                } else {
                                    num_token.text.clone()
                                };
                                assignments.push(Some(val));
                            } else {
                                assignments.push(None);
                            }
                            if !self.match_token(TokenType::Comma) {
                                break;
                            }
                        }
                    }
                    self.expect(TokenType::RParen)?;
                    Ok(DataType::Enum {
                        values,
                        assignments,
                    })
                } else {
                    Ok(DataType::Custom {
                        name: "ENUM".to_string(),
                    })
                }
            }
            "SET" => {
                // MySQL SET('a', 'b', 'c') type
                if self.match_token(TokenType::LParen) {
                    let mut values = Vec::new();
                    if !self.check(TokenType::RParen) {
                        loop {
                            let val = self.expect_string()?;
                            values.push(val);
                            if !self.match_token(TokenType::Comma) {
                                break;
                            }
                        }
                    }
                    self.expect(TokenType::RParen)?;
                    Ok(DataType::Set { values })
                } else {
                    Ok(DataType::Custom {
                        name: "SET".to_string(),
                    })
                }
            }
            "UNION" if self.check(TokenType::LParen) => {
                // UNION(num INT, str TEXT) - DuckDB union type (only when followed by paren)
                self.advance(); // consume LParen
                let struct_fields = self.parse_struct_type_fields(true)?;
                self.expect(TokenType::RParen)?;
                // Convert StructField to (String, DataType) for Union
                let fields: Vec<(String, DataType)> = struct_fields
                    .into_iter()
                    .map(|f| (f.name, f.data_type))
                    .collect();
                Ok(DataType::Union { fields })
            }
            // Spatial types
            "GEOMETRY" => {
                let (subtype, srid) = self.parse_spatial_type_args()?;
                Ok(DataType::Geometry { subtype, srid })
            }
            "GEOGRAPHY" => {
                let (subtype, srid) = self.parse_spatial_type_args()?;
                Ok(DataType::Geography { subtype, srid })
            }
            // MySQL spatial subtypes without wrapper
            "POINT" | "LINESTRING" | "POLYGON" | "MULTIPOINT" | "MULTILINESTRING"
            | "MULTIPOLYGON" | "GEOMETRYCOLLECTION" => {
                // Check for optional SRID clause (MySQL syntax)
                let srid = if self.match_identifier("SRID") {
                    Some(self.expect_number()? as u32)
                } else {
                    None
                };
                Ok(DataType::Geometry {
                    subtype: Some(name),
                    srid,
                })
            }
            // BigQuery ANY TYPE - templated parameter type for UDFs
            "ANY" => {
                if self.match_token(TokenType::Type) {
                    Ok(DataType::Custom {
                        name: "ANY TYPE".to_string(),
                    })
                } else {
                    Ok(DataType::Custom {
                        name: "ANY".to_string(),
                    })
                }
            }
            // LONG VARCHAR (Exasol) - same as TEXT
            "LONG" => {
                if self.match_identifier("VARCHAR") {
                    Ok(DataType::Text)
                } else {
                    Ok(DataType::Custom {
                        name: "LONG".to_string(),
                    })
                }
            }
            // MySQL SIGNED [INTEGER] / UNSIGNED [INTEGER] in CAST context
            // CAST(x AS SIGNED INTEGER) -> CAST(x AS SIGNED)
            "SIGNED" | "UNSIGNED" => {
                // Consume optional INTEGER keyword after SIGNED/UNSIGNED
                if self.check_identifier("INTEGER")
                    || self.check_keyword_text("INTEGER")
                    || self.check_keyword_text("INT")
                {
                    self.advance();
                }
                Ok(DataType::Custom { name })
            }
            // ClickHouse Nullable(T) wrapper type
            "NULLABLE" => {
                self.expect(TokenType::LParen)?;
                let inner = self.parse_data_type()?;
                self.expect(TokenType::RParen)?;
                Ok(DataType::Nullable {
                    inner: Box::new(inner),
                })
            }
            _ => {
                // Handle custom types with optional parenthesized precision/args
                // e.g., DATETIME2(2), DATETIMEOFFSET(7), NVARCHAR2(100)
                // Use uppercase name for known SQL custom types, but preserve original case
                // for user-defined type names (e.g., UserDefinedTableType)
                let is_known = convert_name_is_known_custom(&name);
                let custom_name = if is_known {
                    name.clone()
                } else {
                    raw_name.clone()
                };
                if self.match_token(TokenType::LParen) {
                    if matches!(
                        self.config.dialect,
                        Some(crate::dialects::DialectType::ClickHouse)
                    ) {
                        let args = self.parse_custom_type_args_balanced()?;
                        self.expect(TokenType::RParen)?;
                        Ok(DataType::Custom {
                            name: format!("{}({})", custom_name, args),
                        })
                    } else {
                        let mut args = Vec::new();
                        let mut after_comma = true; // treat first token as start of new arg
                        loop {
                            if self.check(TokenType::RParen) {
                                break;
                            }
                            let token = self.advance();
                            // If the previous token was space-separated (not comma-separated),
                            // append to the last arg. E.g., VARCHAR2(2328 CHAR) -> "2328 CHAR"
                            if !after_comma && !args.is_empty() {
                                if let Some(last) = args.last_mut() {
                                    *last = format!("{} {}", last, token.text);
                                }
                            } else {
                                args.push(token.text.clone());
                            }
                            after_comma = self.match_token(TokenType::Comma);
                        }
                        self.expect(TokenType::RParen)?;
                        // Include args in the name: DATETIME2(2), VARCHAR2(2328 CHAR)
                        Ok(DataType::Custom {
                            name: format!("{}({})", custom_name, args.join(", ")),
                        })
                    }
                } else {
                    Ok(DataType::Custom { name: custom_name })
                }
            }
        }?;

        // UNSIGNED/SIGNED modifiers for integer types (MySQL) are handled
        // by the column definition parser which sets col.unsigned = true.
        // Do NOT consume them here; the column parser needs to see them.
        let mut result_type = base_type;

        // Materialize: handle postfix LIST syntax (INT LIST, INT LIST LIST LIST)
        let is_materialize = matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::Materialize)
        );
        if is_materialize {
            while self.check_identifier("LIST") || self.check(TokenType::List) {
                self.advance(); // consume LIST
                result_type = DataType::List {
                    element_type: Box::new(result_type),
                };
            }
        }

        // PostgreSQL array syntax: TYPE[], TYPE[N], TYPE[N][M], etc.
        let result_type = self.maybe_parse_array_dimensions(result_type)?;

        // ClickHouse: mark string-like standard types as non-nullable by converting to Custom
        // This prevents the generator from wrapping them in Nullable() during identity transforms.
        // Types parsed from other dialects remain standard and will get Nullable wrapping when
        // transpiling to ClickHouse.
        if matches!(self.config.dialect, Some(crate::dialects::DialectType::ClickHouse)) {
            return Ok(Self::clickhouse_mark_non_nullable(result_type));
        }

        Ok(result_type)
    }

    /// Convert standard types to Custom equivalents for ClickHouse to prevent Nullable wrapping.
    /// This mirrors Python sqlglot's behavior of marking ClickHouse-parsed types as non-nullable.
    fn clickhouse_mark_non_nullable(dt: DataType) -> DataType {
        match dt {
            DataType::Text => DataType::Custom { name: "String".to_string() },
            DataType::VarChar { .. } => DataType::Custom { name: "String".to_string() },
            DataType::Char { .. } => DataType::Custom { name: "String".to_string() },
            DataType::String { .. } => DataType::Custom { name: "String".to_string() },
            _ => dt,
        }
    }

    /// Parse a data type for cast syntax (::TYPE)
    /// For dialects that support fixed-size arrays (like DuckDB), brackets like [3] are
    /// parsed as array dimensions (e.g., x::INT[3] means cast to INT[3] array type).
    /// For other dialects (like Snowflake), brackets are subscript operations
    /// (e.g., x::VARIANT[0] means cast to VARIANT, then subscript with [0]).
    fn parse_data_type_for_cast(&mut self) -> Result<DataType> {
        // Check if dialect supports array type suffixes (e.g., INT[], VARCHAR[3])
        // PostgreSQL: INT[], TEXT[] (no fixed size)
        // DuckDB: INT[3] (fixed size arrays)
        let supports_array_type_suffix = matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::DuckDB)
                | Some(crate::dialects::DialectType::PostgreSQL)
                | Some(crate::dialects::DialectType::Redshift)
        );

        // Check if it's a quoted identifier (e.g., "udt") — preserve case and quoting
        let is_quoted = self.check(TokenType::QuotedIdentifier);
        let raw_name = self.expect_identifier_or_keyword()?;
        if is_quoted {
            // Check if the quoted name matches a known type — if so, normalize it
            let known_type = self.convert_name_to_type(&raw_name);
            if let Ok(ref dt) = known_type {
                if !matches!(dt, DataType::Custom { .. }) {
                    return known_type;
                }
            }
            // Truly custom type — preserve original case with quotes
            return Ok(DataType::Custom {
                name: format!("\"{}\"", raw_name),
            });
        }
        let name = raw_name.to_uppercase();

        // Handle parametric types like ARRAY<T>, MAP<K,V>
        let base_type = match name.as_str() {
            "ARRAY" => {
                if self.match_token(TokenType::Lt) {
                    let element_type = self.parse_data_type()?;
                    self.expect_gt()?;
                    DataType::Array {
                        element_type: Box::new(element_type),
                        dimension: None,
                    }
                } else if self.match_token(TokenType::LParen) {
                    // ClickHouse: Array(Type) syntax with parentheses
                    let element_type = self.parse_data_type_for_cast()?;
                    self.expect(TokenType::RParen)?;
                    DataType::Array {
                        element_type: Box::new(element_type),
                        dimension: None,
                    }
                } else {
                    DataType::Custom { name }
                }
            }
            "MAP" => {
                if self.match_token(TokenType::Lt) {
                    let key_type = self.parse_data_type()?;
                    self.expect(TokenType::Comma)?;
                    let value_type = self.parse_data_type()?;
                    self.expect_gt()?;
                    DataType::Map {
                        key_type: Box::new(key_type),
                        value_type: Box::new(value_type),
                    }
                } else if self.match_token(TokenType::LParen) {
                    // Snowflake: MAP(key_type, value_type) syntax
                    let key_type = self.parse_data_type_for_cast()?;
                    self.expect(TokenType::Comma)?;
                    let value_type = self.parse_data_type_for_cast()?;
                    self.expect(TokenType::RParen)?;
                    DataType::Map {
                        key_type: Box::new(key_type),
                        value_type: Box::new(value_type),
                    }
                } else if self.match_token(TokenType::LBracket) {
                    // Materialize: MAP[TEXT => INT] type syntax
                    let key_type = self.parse_data_type_for_cast()?;
                    self.expect(TokenType::FArrow)?;
                    let value_type = self.parse_data_type_for_cast()?;
                    self.expect(TokenType::RBracket)?;
                    DataType::Map {
                        key_type: Box::new(key_type),
                        value_type: Box::new(value_type),
                    }
                } else {
                    DataType::Custom { name }
                }
            }
            "STRUCT" => {
                if self.match_token(TokenType::Lt) {
                    let fields = self.parse_struct_type_fields(false)?;
                    self.expect_gt()?;
                    DataType::Struct {
                        fields,
                        nested: false,
                    }
                } else if self.match_token(TokenType::LParen) {
                    let fields = self.parse_struct_type_fields(true)?;
                    self.expect(TokenType::RParen)?;
                    DataType::Struct {
                        fields,
                        nested: true,
                    }
                } else {
                    DataType::Custom { name }
                }
            }
            "ROW" => {
                if self.match_token(TokenType::LParen) {
                    let fields = self.parse_struct_type_fields(true)?;
                    self.expect(TokenType::RParen)?;
                    DataType::Struct {
                        fields,
                        nested: true,
                    }
                } else {
                    DataType::Custom { name }
                }
            }
            "RECORD" => {
                // SingleStore RECORD type (like ROW/STRUCT)
                if self.match_token(TokenType::LParen) {
                    let fields = self.parse_struct_type_fields(true)?;
                    self.expect(TokenType::RParen)?;
                    DataType::Struct {
                        fields,
                        nested: true,
                    }
                } else {
                    DataType::Custom { name }
                }
            }
            // Multi-word types that need special handling in cast context
            "DOUBLE" => {
                // Handle DOUBLE PRECISION
                let _ = self.match_identifier("PRECISION");
                // ClickHouse/SQL: DOUBLE(precision) or DOUBLE(precision, scale)
                let (precision, scale) = if self.match_token(TokenType::LParen) {
                    let p = Some(self.expect_number()? as u32);
                    let s = if self.match_token(TokenType::Comma) {
                        Some(self.expect_number()? as u32)
                    } else {
                        None
                    };
                    self.expect(TokenType::RParen)?;
                    (p, s)
                } else {
                    (None, None)
                };
                DataType::Double { precision, scale }
            }
            "CHARACTER" | "CHAR" | "NCHAR" => {
                // Handle CHARACTER VARYING / CHAR VARYING
                if self.match_identifier("VARYING") {
                    let length = if self.match_token(TokenType::LParen) {
                        let len = Some(self.expect_number()? as u32);
                        self.expect(TokenType::RParen)?;
                        len
                    } else {
                        None
                    };
                    DataType::VarChar {
                        length,
                        parenthesized_length: false,
                    }
                } else {
                    let length = if self.match_token(TokenType::LParen) {
                        let len = Some(self.expect_number()? as u32);
                        self.expect(TokenType::RParen)?;
                        len
                    } else {
                        None
                    };
                    // CHAR CHARACTER SET charset (MySQL CAST context, no length)
                    if length.is_none()
                        && self.match_identifier("CHARACTER")
                        && self.match_token(TokenType::Set)
                    {
                        let charset = self.expect_identifier_or_keyword()?;
                        return Ok(DataType::CharacterSet { name: charset });
                    }
                    DataType::Char { length }
                }
            }
            "TIME" => {
                // Handle TIME(precision) WITH/WITHOUT TIME ZONE
                let precision = if self.match_token(TokenType::LParen) {
                    let p = Some(self.expect_number()? as u32);
                    self.expect(TokenType::RParen)?;
                    p
                } else {
                    None
                };
                let timezone = if self.match_token(TokenType::With) {
                    self.match_keyword("TIME");
                    self.match_keyword("ZONE");
                    true
                } else if self.match_keyword("WITHOUT") {
                    self.match_keyword("TIME");
                    self.match_keyword("ZONE");
                    false
                } else {
                    false
                };
                DataType::Time {
                    precision,
                    timezone,
                }
            }
            "TIMETZ" => {
                let precision = if self.match_token(TokenType::LParen) {
                    let p = Some(self.expect_number()? as u32);
                    self.expect(TokenType::RParen)?;
                    p
                } else {
                    None
                };
                DataType::Time {
                    precision,
                    timezone: true,
                }
            }
            "TIMESTAMP" => {
                // Handle TIMESTAMP(precision) WITH/WITHOUT TIME ZONE or WITH LOCAL TIME ZONE
                let precision = if self.match_token(TokenType::LParen) {
                    let p = Some(self.expect_number()? as u32);
                    self.expect(TokenType::RParen)?;
                    p
                } else {
                    None
                };
                // Note: TIME is a keyword (TokenType::Time), so use match_keyword instead of match_identifier
                if self.match_token(TokenType::With) {
                    // Check for LOCAL TIME ZONE vs TIME ZONE
                    if self.match_token(TokenType::Local) {
                        self.match_keyword("TIME");
                        self.match_keyword("ZONE");
                        // TIMESTAMP WITH LOCAL TIME ZONE -> TIMESTAMPLTZ
                        DataType::Custom {
                            name: "TIMESTAMPLTZ".to_string(),
                        }
                    } else {
                        self.match_keyword("TIME");
                        self.match_keyword("ZONE");
                        DataType::Timestamp {
                            precision,
                            timezone: true,
                        }
                    }
                } else if self.match_keyword("WITHOUT") {
                    self.match_keyword("TIME");
                    self.match_keyword("ZONE");
                    DataType::Timestamp {
                        precision,
                        timezone: false,
                    }
                } else {
                    DataType::Timestamp {
                        precision,
                        timezone: false,
                    }
                }
            }
            "TIMESTAMPTZ" => {
                let precision = if self.match_token(TokenType::LParen) {
                    let p = self.expect_number()? as u32;
                    self.expect(TokenType::RParen)?;
                    Some(p)
                } else {
                    None
                };
                DataType::Timestamp {
                    precision,
                    timezone: true,
                }
            }
            "TIMESTAMPLTZ" | "TIMESTAMP_LTZ" => {
                let precision = if self.match_token(TokenType::LParen) {
                    let p = self.expect_number()? as u32;
                    self.expect(TokenType::RParen)?;
                    Some(p)
                } else {
                    None
                };
                let dt_name = if let Some(p) = precision {
                    format!("TIMESTAMPLTZ({})", p)
                } else {
                    "TIMESTAMPLTZ".to_string()
                };
                DataType::Custom { name: dt_name }
            }
            "INTERVAL" => {
                // Parse optional unit (DAY, HOUR, etc.) after INTERVAL in cast context
                let unit = if (self.check(TokenType::Identifier)
                    || self.check(TokenType::Var)
                    || self.check_keyword())
                    && !self.check(TokenType::RParen)
                    && !self.check(TokenType::Comma)
                    && !self.check(TokenType::As)
                    && !self.check(TokenType::Not)
                    && !self.check(TokenType::Null)
                {
                    Some(self.advance().text.to_uppercase())
                } else {
                    None
                };
                // Parse optional TO unit for range intervals like DAY TO HOUR
                let to = if self.match_token(TokenType::To) {
                    if self.check(TokenType::Identifier)
                        || self.check(TokenType::Var)
                        || self.check_keyword()
                    {
                        Some(self.advance().text.to_uppercase())
                    } else {
                        None
                    }
                } else {
                    None
                };
                DataType::Interval { unit, to }
            }
            // VARCHAR/NVARCHAR with optional (N) or (MAX) parameter
            "VARCHAR" | "NVARCHAR" => {
                let is_nvarchar = name == "NVARCHAR";
                if self.match_token(TokenType::LParen) {
                    if self.check(TokenType::RParen) {
                        self.advance();
                        DataType::VarChar {
                            length: None,
                            parenthesized_length: false,
                        }
                    } else if self.check_identifier("MAX") {
                        self.advance();
                        self.expect(TokenType::RParen)?;
                        let type_name = if is_nvarchar {
                            "NVARCHAR(MAX)"
                        } else {
                            "VARCHAR(MAX)"
                        };
                        DataType::Custom {
                            name: type_name.to_string(),
                        }
                    } else {
                        let n = self.expect_number()? as u32;
                        self.expect(TokenType::RParen)?;
                        DataType::VarChar {
                            length: Some(n),
                            parenthesized_length: false,
                        }
                    }
                } else {
                    DataType::VarChar {
                        length: None,
                        parenthesized_length: false,
                    }
                }
            }
            // VARBINARY with optional (N) or (MAX) parameter
            "VARBINARY" => {
                if self.match_token(TokenType::LParen) {
                    if self.check(TokenType::RParen) {
                        self.advance();
                        DataType::VarBinary { length: None }
                    } else if self.check_identifier("MAX") {
                        self.advance();
                        self.expect(TokenType::RParen)?;
                        DataType::Custom {
                            name: "VARBINARY(MAX)".to_string(),
                        }
                    } else {
                        let n = self.expect_number()? as u32;
                        self.expect(TokenType::RParen)?;
                        DataType::VarBinary { length: Some(n) }
                    }
                } else {
                    DataType::VarBinary { length: None }
                }
            }
            // DECIMAL/NUMERIC with optional (precision, scale)
            "DECIMAL" | "NUMERIC" | "NUMBER" => {
                if self.match_token(TokenType::LParen) {
                    let precision = Some(self.expect_number()? as u32);
                    let scale = if self.match_token(TokenType::Comma) {
                        Some(self.expect_number()? as u32)
                    } else {
                        None
                    };
                    self.expect(TokenType::RParen)?;
                    DataType::Decimal { precision, scale }
                } else {
                    DataType::Decimal {
                        precision: None,
                        scale: None,
                    }
                }
            }
            // INT/INTEGER/BIGINT/SMALLINT/TINYINT with optional (N) display width
            "INT" | "INTEGER" => {
                let length = if self.match_token(TokenType::LParen) {
                    let n = Some(self.expect_number()? as u32);
                    self.expect(TokenType::RParen)?;
                    n
                } else {
                    None
                };
                DataType::Int {
                    length,
                    integer_spelling: name == "INTEGER",
                }
            }
            "BIGINT" => {
                let length = if self.match_token(TokenType::LParen) {
                    let n = Some(self.expect_number()? as u32);
                    self.expect(TokenType::RParen)?;
                    n
                } else {
                    None
                };
                DataType::BigInt { length }
            }
            "SMALLINT" => {
                let length = if self.match_token(TokenType::LParen) {
                    let n = Some(self.expect_number()? as u32);
                    self.expect(TokenType::RParen)?;
                    n
                } else {
                    None
                };
                DataType::SmallInt { length }
            }
            "TINYINT" => {
                let length = if self.match_token(TokenType::LParen) {
                    let n = Some(self.expect_number()? as u32);
                    self.expect(TokenType::RParen)?;
                    n
                } else {
                    None
                };
                DataType::TinyInt { length }
            }
            // FLOAT with optional (precision)
            "FLOAT" | "REAL" | "BINARY_FLOAT" => {
                let (precision, scale) = if self.match_token(TokenType::LParen) {
                    let n = Some(self.expect_number()? as u32);
                    let s = if self.match_token(TokenType::Comma) {
                        Some(self.expect_number()? as u32)
                    } else {
                        None
                    };
                    self.expect(TokenType::RParen)?;
                    (n, s)
                } else {
                    (None, None)
                };
                DataType::Float {
                    precision,
                    scale,
                    real_spelling: name == "REAL",
                }
            }
            "BINARY_DOUBLE" => DataType::Double {
                precision: None,
                scale: None,
            },
            // BINARY with optional (length)
            "BINARY" => {
                let length = if self.match_token(TokenType::LParen) {
                    let n = Some(self.expect_number()? as u32);
                    self.expect(TokenType::RParen)?;
                    n
                } else {
                    None
                };
                DataType::Binary { length }
            }
            // MySQL SIGNED [INTEGER] / UNSIGNED [INTEGER] in CAST context
            // CAST(x AS SIGNED INTEGER) -> CAST(x AS SIGNED)
            // CAST(x AS UNSIGNED INTEGER) -> CAST(x AS UNSIGNED)
            "SIGNED" | "UNSIGNED" => {
                // Consume optional INTEGER keyword after SIGNED/UNSIGNED
                if self.check_identifier("INTEGER")
                    || self.check_keyword_text("INTEGER")
                    || self.check_keyword_text("INT")
                {
                    self.advance();
                }
                DataType::Custom { name }
            }
            // ClickHouse Nullable(T) wrapper type
            "NULLABLE" => {
                self.expect(TokenType::LParen)?;
                let inner = self.parse_data_type_for_cast()?;
                self.expect(TokenType::RParen)?;
                DataType::Nullable {
                    inner: Box::new(inner),
                }
            }
            // For simple types, use convert_name_to_type to get proper DataType variants
            // This ensures VARCHAR becomes DataType::VarChar, not DataType::Custom
            // For user-defined types in generic mode, preserve original case from raw_name
            _ => {
                let base = self.convert_name_to_type(&name)?;
                // ClickHouse: consume parenthesized args for custom types like DateTime('UTC'),
                // LowCardinality(String), Variant(String, UInt64), JSON(max_dynamic_paths=8)
                if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) && self.check(TokenType::LParen)
                    && (matches!(
                        base,
                        DataType::Custom { .. } | DataType::Json | DataType::JsonB
                    ))
                {
                    self.advance(); // consume (
                    let args = self.parse_custom_type_args_balanced()?;
                    self.expect(TokenType::RParen)?;
                    let base_name = match &base {
                        DataType::Json => "JSON".to_string(),
                        DataType::JsonB => "JSONB".to_string(),
                        DataType::Custom { name } => name.clone(),
                        _ => unreachable!(),
                    };
                    DataType::Custom {
                        name: format!("{}({})", base_name, args),
                    }
                } else if matches!(base, DataType::Custom { .. }) && self.check(TokenType::Dot) {
                    // Handle schema-qualified user-defined types (e.g., app.status_enum)
                    // by consuming dot-separated identifiers like Python sqlglot's
                    // _parse_user_defined_type()
                    // Use raw_name to preserve original case for schema-qualified types
                    let mut type_name = raw_name.to_string();
                    while self.match_token(TokenType::Dot) {
                        let tok = self.advance();
                        type_name = format!("{}.{}", type_name, tok.text);
                    }
                    DataType::Custom { name: type_name }
                } else if matches!(base, DataType::Custom { .. }) && self.config.dialect.is_none() {
                    // Preserve original case for user-defined types in generic mode
                    DataType::Custom {
                        name: raw_name.to_string(),
                    }
                } else {
                    base
                }
            }
        };

        // Materialize: handle postfix LIST syntax (INT LIST, INT LIST LIST LIST)
        let is_materialize = matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::Materialize)
        );
        let mut result_type = base_type;
        if is_materialize {
            while self.check_identifier("LIST") || self.check(TokenType::List) {
                self.advance(); // consume LIST
                result_type = DataType::List {
                    element_type: Box::new(result_type),
                };
            }
        }

        // For dialects that support array type suffixes (DuckDB, PostgreSQL, Redshift),
        // parse array dimensions. For other dialects, brackets after a cast are subscript operations.
        if supports_array_type_suffix {
            self.maybe_parse_array_dimensions(result_type)
        } else {
            Ok(result_type)
        }
    }

    /// Parse custom type arguments with balanced parentheses, preserving nested types
    fn parse_custom_type_args_balanced(&mut self) -> Result<String> {
        let mut depth = 0usize;
        let mut out = String::new();
        let mut prev_wordish = false;

        while !self.is_at_end() {
            if self.check(TokenType::RParen) && depth == 0 {
                break;
            }

            let token = self.advance();
            match token.token_type {
                TokenType::LParen => {
                    out.push('(');
                    depth += 1;
                    prev_wordish = false;
                }
                TokenType::RParen => {
                    if depth == 0 {
                        break;
                    }
                    depth -= 1;
                    out.push(')');
                    prev_wordish = true;
                }
                TokenType::Comma => {
                    out.push_str(", ");
                    prev_wordish = false;
                }
                TokenType::Eq => {
                    out.push_str(" = ");
                    prev_wordish = false;
                }
                TokenType::Plus => {
                    out.push_str(" + ");
                    prev_wordish = false;
                }
                TokenType::Dash => {
                    out.push('-');
                    prev_wordish = false;
                }
                TokenType::Dot => {
                    out.push('.');
                    prev_wordish = false;
                }
                TokenType::String | TokenType::DollarString => {
                    if prev_wordish {
                        out.push(' ');
                    }
                    let escaped = token.text.replace('\'', "''");
                    out.push('\'');
                    out.push_str(&escaped);
                    out.push('\'');
                    prev_wordish = true;
                }
                TokenType::Number | TokenType::Parameter => {
                    if prev_wordish {
                        out.push(' ');
                    }
                    out.push_str(&token.text);
                    prev_wordish = true;
                }
                TokenType::QuotedIdentifier => {
                    if prev_wordish {
                        out.push(' ');
                    }
                    out.push('"');
                    out.push_str(&token.text);
                    out.push('"');
                    prev_wordish = true;
                }
                _ => {
                    if prev_wordish {
                        out.push(' ');
                    }
                    out.push_str(&token.text);
                    prev_wordish = true;
                }
            }
        }

        Ok(out)
    }

    /// Try to parse a data type optionally - returns None if no valid type found
    /// Used for JSON_TABLE column definitions where type may or may not be present
    fn parse_data_type_optional(&mut self) -> Result<Option<DataType>> {
        // Check if current token looks like a type name
        if !self.check(TokenType::Identifier)
            && !self.check(TokenType::Var)
            && !self.check_keyword()
        {
            return Ok(None);
        }

        // Don't try to parse PATH as a type
        if self.check_identifier("PATH") {
            return Ok(None);
        }

        // ClickHouse: ALIAS, EPHEMERAL, MATERIALIZED are column modifiers, not types
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) && (self.check_identifier("ALIAS")
            || self.check_identifier("EPHEMERAL")
            || self.check(TokenType::Materialized))
        {
            return Ok(None);
        }

        let saved_pos = self.current;
        match self.parse_data_type() {
            Ok(dt) => Ok(Some(dt)),
            Err(_) => {
                self.current = saved_pos;
                Ok(None)
            }
        }
    }

    /// Convert a DataType to a string representation for JSONColumnDef.kind
    fn data_type_to_string(&self, dt: &DataType) -> String {
        match dt {
            DataType::Int {
                length: Some(n),
                integer_spelling: true,
            } => format!("INTEGER({})", n),
            DataType::Int {
                length: Some(n), ..
            } => format!("INT({})", n),
            DataType::Int {
                length: None,
                integer_spelling: true,
            } => "INTEGER".to_string(),
            DataType::Int { length: None, .. } => "INT".to_string(),
            DataType::BigInt { length: Some(n) } => format!("BIGINT({})", n),
            DataType::BigInt { length: None } => "BIGINT".to_string(),
            DataType::SmallInt { length: Some(n) } => format!("SMALLINT({})", n),
            DataType::SmallInt { length: None } => "SMALLINT".to_string(),
            DataType::TinyInt { length: Some(n) } => format!("TINYINT({})", n),
            DataType::TinyInt { length: None } => "TINYINT".to_string(),
            DataType::Float {
                precision: Some(p),
                scale: Some(s),
                ..
            } => format!("FLOAT({}, {})", p, s),
            DataType::Float {
                precision: Some(p),
                scale: None,
                ..
            } => format!("FLOAT({})", p),
            DataType::Float {
                precision: None, ..
            } => "FLOAT".to_string(),
            DataType::Double {
                precision: Some(p),
                scale: Some(s),
            } => format!("DOUBLE({}, {})", p, s),
            DataType::Double {
                precision: Some(p),
                scale: None,
            } => format!("DOUBLE({})", p),
            DataType::Double {
                precision: None, ..
            } => "DOUBLE".to_string(),
            DataType::Decimal {
                precision: Some(p),
                scale: Some(s),
            } => format!("DECIMAL({}, {})", p, s),
            DataType::Decimal {
                precision: Some(p),
                scale: None,
            } => format!("DECIMAL({})", p),
            DataType::Decimal {
                precision: None, ..
            } => "DECIMAL".to_string(),
            DataType::VarChar {
                length: Some(n), ..
            } => format!("VARCHAR({})", n),
            DataType::VarChar { length: None, .. } => "VARCHAR".to_string(),
            DataType::Char { length: Some(n) } => format!("CHAR({})", n),
            DataType::Char { length: None } => "CHAR".to_string(),
            DataType::Text => "TEXT".to_string(),
            DataType::Boolean => "BOOLEAN".to_string(),
            DataType::Date => "DATE".to_string(),
            DataType::Time {
                precision: Some(p), ..
            } => format!("TIME({})", p),
            DataType::Time {
                precision: None, ..
            } => "TIME".to_string(),
            DataType::Timestamp {
                precision: Some(p),
                timezone: true,
            } => format!("TIMESTAMPTZ({})", p),
            DataType::Timestamp {
                precision: Some(p),
                timezone: false,
            } => format!("TIMESTAMP({})", p),
            DataType::Timestamp {
                precision: None,
                timezone: true,
            } => "TIMESTAMPTZ".to_string(),
            DataType::Timestamp {
                precision: None,
                timezone: false,
            } => "TIMESTAMP".to_string(),
            DataType::Json => "JSON".to_string(),
            DataType::JsonB => "JSONB".to_string(),
            DataType::Binary { length: Some(n) } => format!("BINARY({})", n),
            DataType::Binary { length: None } => "BINARY".to_string(),
            DataType::VarBinary { length: Some(n) } => format!("VARBINARY({})", n),
            DataType::VarBinary { length: None } => "VARBINARY".to_string(),
            DataType::String { length: Some(n) } => format!("STRING({})", n),
            DataType::String { length: None } => "STRING".to_string(),
            DataType::Array { element_type, .. } => {
                format!("ARRAY({})", self.data_type_to_string(element_type))
            }
            DataType::Nullable { inner } => {
                format!("Nullable({})", self.data_type_to_string(inner))
            }
            DataType::Custom { name } => name.clone(),
            _ => format!("{:?}", dt),
        }
    }

    /// Parse optional array dimensions after a type: [], [N], [N][M], ARRAY, ARRAY[N], etc.
    fn maybe_parse_array_dimensions(&mut self, base_type: DataType) -> Result<DataType> {
        let mut current_type = base_type;

        // Handle PostgreSQL ARRAY keyword suffix: type ARRAY or type ARRAY[3]
        if self.check_identifier("ARRAY") {
            self.advance(); // consume ARRAY
                            // Check for optional dimension: ARRAY[N]
            let dimension = if self.match_token(TokenType::LBracket) {
                let dim = if self.check(TokenType::Number) {
                    let n = self.expect_number()? as u32;
                    Some(n)
                } else {
                    None
                };
                self.expect(TokenType::RBracket)?;
                dim
            } else {
                None
            };
            current_type = DataType::Array {
                element_type: Box::new(current_type),
                dimension,
            };
        }

        // Handle bracket-based array dimensions: TYPE[], TYPE[N], TYPE[][N], etc.
        while self.match_token(TokenType::LBracket) {
            // Check for optional dimension: [N] or just []
            let dimension = if self.check(TokenType::Number) {
                let n = self.expect_number()? as u32;
                Some(n)
            } else {
                None
            };
            self.expect(TokenType::RBracket)?;

            current_type = DataType::Array {
                element_type: Box::new(current_type),
                dimension,
            };
        }

        Ok(current_type)
    }

    /// Parse spatial type arguments like GEOMETRY(Point, 4326) or GEOGRAPHY
    fn parse_spatial_type_args(&mut self) -> Result<(Option<String>, Option<u32>)> {
        if self.match_token(TokenType::LParen) {
            // First arg can be a subtype name (POINT, LINESTRING, etc.) or a numeric dimension
            if self.check(TokenType::Number) {
                // Numeric argument (e.g., ST_GEOMETRY(1) in Teradata)
                let n = self.expect_number()? as u32;
                self.expect(TokenType::RParen)?;
                return Ok((None, Some(n)));
            }
            // Parse subtype
            let subtype = Some(self.expect_identifier()?.to_uppercase());

            // Parse optional SRID
            let srid = if self.match_token(TokenType::Comma) {
                Some(self.expect_number()? as u32)
            } else {
                None
            };

            self.expect(TokenType::RParen)?;
            Ok((subtype, srid))
        } else {
            Ok((None, None))
        }
    }

    /// Parse struct/row/union type fields: name TYPE, name TYPE, ...
    /// `paren_style` indicates whether we're parsing parenthesized syntax (terminates at RParen)
    /// or angle-bracket syntax (terminates at Gt/GtGt).
    fn parse_struct_type_fields(&mut self, paren_style: bool) -> Result<Vec<StructField>> {
        let mut fields = Vec::new();
        // Check for empty field list
        if (paren_style && self.check(TokenType::RParen))
            || (!paren_style && (self.check(TokenType::Gt) || self.check(TokenType::GtGt)))
        {
            return Ok(fields);
        }
        loop {
            // Parse field name or just type (for anonymous struct fields)
            // Track whether it was a quoted identifier to preserve quoting
            let is_quoted = self.check(TokenType::QuotedIdentifier);
            let first = self.expect_identifier_or_keyword()?;
            let first_upper = first.to_uppercase();

            // Check if this is a parametric type (ARRAY<T>, MAP<K,V>, STRUCT<...>, STRUCT(...))
            let is_parametric_type = (first_upper == "ARRAY"
                || first_upper == "MAP"
                || first_upper == "STRUCT"
                || first_upper == "ROW")
                && (self.check(TokenType::Lt) || self.check(TokenType::LParen));

            let (field_name, field_type) = if is_parametric_type {
                // This is a parametric type as an anonymous field
                let field_type = self.parse_data_type_from_name(&first_upper)?;
                (String::new(), field_type)
            } else if self.check(TokenType::Comma)
                || self.match_identifier("OPTIONS")  // Check for OPTIONS (but don't consume yet)
                || (paren_style && self.check(TokenType::RParen))
                || (!paren_style && (self.check(TokenType::Gt) || self.check(TokenType::GtGt)))
            {
                // Check if we just matched OPTIONS - if so, retreat
                if self.previous().text.to_uppercase() == "OPTIONS" {
                    self.current -= 1;
                }
                // Anonymous field: just a type name
                let field_type = self.convert_name_to_type(&first)?;
                (String::new(), field_type)
            } else if self.is_identifier_token()
                || self.is_safe_keyword_as_identifier()
                || self.check(TokenType::Lt)
                || self.check(TokenType::LParen)
                || self.check(TokenType::Colon)
            {
                // Named field: fieldname TYPE (or fieldname: TYPE for Hive)
                // Consume optional colon separator (Hive-style: `STRUCT<field_name: TYPE>`)
                self.match_token(TokenType::Colon);
                let field_type = self.parse_data_type()?;
                // Preserve quoting for field names
                let field_name = if is_quoted {
                    format!("\"{}\"", first)
                } else {
                    first
                };
                (field_name, field_type)
            } else {
                // Just a type name
                let field_type = self.convert_name_to_type(&first)?;
                (String::new(), field_type)
            };

            // Spark/Databricks: Check for COMMENT clause on struct field
            let comment = if self.match_token(TokenType::Comment) {
                Some(self.expect_string()?)
            } else {
                None
            };

            // BigQuery: Check for OPTIONS clause on struct field
            let options = if self.match_identifier("OPTIONS") {
                self.parse_options_list()?
            } else {
                Vec::new()
            };

            fields.push(StructField::with_options_and_comment(
                field_name, field_type, options, comment,
            ));

            if !self.match_token(TokenType::Comma) {
                break;
            }
        }
        Ok(fields)
    }

    /// Parse a data type given a name that was already consumed
    /// This is used for standalone type expressions like ARRAY<T>
    fn parse_data_type_from_name(&mut self, name: &str) -> Result<DataType> {
        match name {
            "ARRAY" => {
                if self.match_token(TokenType::Lt) {
                    let element_type = self.parse_data_type()?;
                    self.expect_gt()?;
                    Ok(DataType::Array {
                        element_type: Box::new(element_type),
                        dimension: None,
                    })
                } else {
                    Ok(DataType::Custom {
                        name: "ARRAY".to_string(),
                    })
                }
            }
            "MAP" => {
                if self.match_token(TokenType::Lt) {
                    let key_type = self.parse_data_type()?;
                    self.expect(TokenType::Comma)?;
                    let value_type = self.parse_data_type()?;
                    self.expect_gt()?;
                    Ok(DataType::Map {
                        key_type: Box::new(key_type),
                        value_type: Box::new(value_type),
                    })
                } else {
                    Ok(DataType::Custom {
                        name: "MAP".to_string(),
                    })
                }
            }
            "STRUCT" => {
                if self.match_token(TokenType::Lt) {
                    let fields = self.parse_struct_type_fields(false)?;
                    self.expect_gt()?;
                    Ok(DataType::Struct {
                        fields,
                        nested: false,
                    })
                } else if self.match_token(TokenType::LParen) {
                    let fields = self.parse_struct_type_fields(true)?;
                    self.expect(TokenType::RParen)?;
                    Ok(DataType::Struct {
                        fields,
                        nested: true,
                    })
                } else {
                    Ok(DataType::Custom {
                        name: "STRUCT".to_string(),
                    })
                }
            }
            "ROW" => {
                if self.match_token(TokenType::LParen) {
                    let fields = self.parse_struct_type_fields(true)?;
                    self.expect(TokenType::RParen)?;
                    Ok(DataType::Struct {
                        fields,
                        nested: true,
                    })
                } else {
                    Ok(DataType::Custom {
                        name: "ROW".to_string(),
                    })
                }
            }
            _ => Ok(DataType::Custom {
                name: name.to_string(),
            }),
        }
    }

    /// Convert a type name string to a DataType
    /// Used for anonymous struct fields where we have just a type name
    fn convert_name_to_type(&self, name: &str) -> Result<DataType> {
        let upper = name.to_uppercase();
        Ok(match upper.as_str() {
            "INT" => DataType::Int {
                length: None,
                integer_spelling: false,
            },
            "INTEGER" => DataType::Int {
                length: None,
                integer_spelling: true,
            },
            "BIGINT" => DataType::BigInt { length: None },
            "SMALLINT" => DataType::SmallInt { length: None },
            "TINYINT" => DataType::TinyInt { length: None },
            "FLOAT" | "BINARY_FLOAT" => DataType::Float {
                precision: None,
                scale: None,
                real_spelling: false,
            },
            "REAL" => DataType::Float {
                precision: None,
                scale: None,
                real_spelling: true,
            },
            "DOUBLE" | "BINARY_DOUBLE" => DataType::Double {
                precision: None,
                scale: None,
            },
            "DECIMAL" | "NUMERIC" => DataType::Decimal {
                precision: None,
                scale: None,
            },
            "BOOLEAN" | "BOOL" => DataType::Boolean,
            "CHAR" | "CHARACTER" | "NCHAR" => DataType::Char { length: None },
            "VARCHAR" | "NVARCHAR" => DataType::VarChar {
                length: None,
                parenthesized_length: false,
            },
            "TEXT" | "STRING" | "NTEXT" => DataType::Text,
            "DATE" => DataType::Date,
            "TIME" => DataType::Time {
                precision: None,
                timezone: false,
            },
            "TIMETZ" => DataType::Time {
                precision: None,
                timezone: true,
            },
            "TIMESTAMP" => DataType::Timestamp {
                precision: None,
                timezone: false,
            },
            "INTERVAL" => DataType::Interval {
                unit: None,
                to: None,
            },
            "JSON" => DataType::Json,
            "JSONB" => DataType::JsonB,
            "UUID" => DataType::Uuid,
            "BLOB" => DataType::Blob,
            "BYTEA" => DataType::VarBinary { length: None },
            "BINARY" => DataType::Binary { length: None },
            "VARBINARY" => DataType::VarBinary { length: None },
            "BIT" => DataType::Bit { length: None },
            "VARBIT" => DataType::VarBit { length: None },
            _ => DataType::Custom {
                name: name.to_string(),
            },
        })
    }

    /// Parse star modifiers: EXCLUDE/EXCEPT, REPLACE, RENAME
    /// Syntax varies by dialect:
    /// - DuckDB: * EXCLUDE (col1, col2)
    /// - BigQuery: * EXCEPT (col1, col2), * REPLACE (expr AS col)
    /// - Snowflake: * EXCLUDE col, * RENAME (old AS new)
    fn parse_star_modifiers(&mut self, table: Option<Identifier>) -> Result<Star> {
        self.parse_star_modifiers_with_comments(table, Vec::new())
    }

    /// Parse star modifiers with explicit trailing comments from the star token
    fn parse_star_modifiers_with_comments(
        &mut self,
        table: Option<Identifier>,
        star_trailing_comments: Vec<String>,
    ) -> Result<Star> {
        let mut except = None;
        let mut replace = None;
        let mut rename = None;

        // Parse EXCLUDE / EXCEPT clause
        if self.match_token(TokenType::Exclude) || self.match_token(TokenType::Except) {
            // ClickHouse: EXCEPT STRICT col1, col2 (STRICT is optional modifier)
            let _ = self.match_text_seq(&["STRICT"]);
            let mut columns = Vec::new();
            if self.match_token(TokenType::LParen) {
                // EXCLUDE (col1, col2) or EXCEPT (A.COL_1, B.COL_2)
                loop {
                    // ClickHouse: allow string literals in EXCEPT ('col_regex')
                    // and keywords like 'key', 'index' as column names
                    let col = if self.check(TokenType::String) {
                        self.advance().text
                    } else if self.is_safe_keyword_as_identifier() {
                        self.advance().text
                    } else {
                        self.expect_identifier()?
                    };
                    // Handle qualified column names like A.COL_1
                    if self.match_token(TokenType::Dot) {
                        let subcol = if self.is_safe_keyword_as_identifier() {
                            self.advance().text
                        } else {
                            self.expect_identifier()?
                        };
                        columns.push(Identifier::new(format!("{}.{}", col, subcol)));
                    } else {
                        columns.push(Identifier::new(col));
                    }
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
                self.expect(TokenType::RParen)?;
            } else {
                // EXCLUDE col (single column, Snowflake) or EXCEPT col1, col2 (ClickHouse)
                // or EXCEPT 'regex' (ClickHouse)
                loop {
                    let col = if self.check(TokenType::String) {
                        self.advance().text
                    } else if self.is_safe_keyword_as_identifier() {
                        self.advance().text
                    } else {
                        self.expect_identifier()?
                    };
                    columns.push(Identifier::new(col));
                    // ClickHouse allows comma-separated columns without parens: EXCEPT col1, col2
                    // But only if the next token after comma looks like a column name
                    if !matches!(
                        self.config.dialect,
                        Some(crate::dialects::DialectType::ClickHouse)
                    ) || !self.check(TokenType::Comma)
                        || !matches!(
                            self.peek_nth(1).map(|t| t.token_type),
                            Some(TokenType::Identifier)
                                | Some(TokenType::QuotedIdentifier)
                                | Some(TokenType::Var)
                                | Some(TokenType::String)
                        )
                    {
                        break;
                    }
                    self.advance(); // consume comma
                }
            }
            except = Some(columns);
        }

        // Parse REPLACE clause
        if self.match_token(TokenType::Replace) {
            // ClickHouse: REPLACE STRICT is optional modifier
            let _ = self.match_text_seq(&["STRICT"]);
            let mut replacements = Vec::new();
            if self.match_token(TokenType::LParen) {
                loop {
                    let expr = self.parse_expression()?;
                    self.expect(TokenType::As)?;
                    let alias = self.expect_identifier_or_keyword()?;
                    replacements.push(Alias::new(expr, Identifier::new(alias)));
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
                self.expect(TokenType::RParen)?;
            } else if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) {
                // ClickHouse: REPLACE [STRICT] expr AS name (single entry without parens)
                // Multiple entries require parens: REPLACE(expr1 AS name1, expr2 AS name2)
                let expr = self.parse_expression()?;
                self.expect(TokenType::As)?;
                let alias = self.expect_identifier_or_keyword()?;
                replacements.push(Alias::new(expr, Identifier::new(alias)));
            } else {
                return Err(self.parse_error("Expected LParen after REPLACE"));
            }
            replace = Some(replacements);
        }

        // Parse RENAME clause (Snowflake)
        if self.match_token(TokenType::Rename) {
            let mut renames = Vec::new();
            if self.match_token(TokenType::LParen) {
                loop {
                    let old_name = self.expect_identifier()?;
                    self.expect(TokenType::As)?;
                    let new_name = self.expect_identifier()?;
                    renames.push((Identifier::new(old_name), Identifier::new(new_name)));
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
                self.expect(TokenType::RParen)?;
            } else {
                // Single rename without parens
                let old_name = self.expect_identifier()?;
                self.expect(TokenType::As)?;
                let new_name = self.expect_identifier()?;
                renames.push((Identifier::new(old_name), Identifier::new(new_name)));
            }
            rename = Some(renames);
        }

        Ok(Star {
            table,
            except,
            replace,
            rename,
            trailing_comments: star_trailing_comments,
            span: None,
        })
    }

    // === Helper methods ===

    /// Check if at end of tokens
    fn is_at_end(&self) -> bool {
        self.current >= self.tokens.len()
    }

    /// Check if current token is a query modifier keyword or end of input.
    /// Used after GROUP BY ALL/DISTINCT to decide whether to parse expression lists.
    fn is_at_query_modifier_or_end(&self) -> bool {
        if self.is_at_end() {
            return true;
        }
        matches!(
            self.peek().token_type,
            TokenType::Having
                | TokenType::Qualify
                | TokenType::Window
                | TokenType::Order
                | TokenType::Limit
                | TokenType::Fetch
                | TokenType::Offset
                | TokenType::For
                | TokenType::Lock
                | TokenType::Union
                | TokenType::Except
                | TokenType::Intersect
                | TokenType::RParen
                | TokenType::Semicolon
                | TokenType::Where
        )
    }

    /// Create a parse error with position from the current token
    fn parse_error(&self, message: impl Into<String>) -> Error {
        let span = self.peek().span;
        Error::parse(message, span.line, span.column, span.start, span.end)
    }

    /// Peek at current token
    /// Returns reference to current token, or last token if at end
    fn peek(&self) -> &Token {
        if self.current >= self.tokens.len() {
            // Return last token as fallback when at end
            // In practice, callers should check is_at_end() before calling peek()
            // but this prevents panic
            self.tokens.last().expect("Token list should not be empty")
        } else {
            &self.tokens[self.current]
        }
    }

    /// Look ahead by n positions (0 = current token)
    fn peek_nth(&self, n: usize) -> Option<&Token> {
        let idx = self.current + n;
        if idx < self.tokens.len() {
            Some(&self.tokens[idx])
        } else {
            None
        }
    }

    /// Advance to next token
    fn advance(&mut self) -> Token {
        if self.current >= self.tokens.len() {
            // Return last token as fallback if we're past the end
            // In practice, callers should check is_at_end() before calling advance()
            return self
                .tokens
                .last()
                .cloned()
                .expect("Token list should not be empty");
        }
        let token = self.tokens[self.current].clone();
        self.current += 1;
        token
    }

    /// Get the previous token (last consumed)
    fn previous(&self) -> &Token {
        &self.tokens[self.current - 1]
    }

    /// Get trailing comments from the previous token
    fn previous_trailing_comments(&self) -> Vec<String> {
        if self.current > 0 {
            self.tokens[self.current - 1].trailing_comments.clone()
        } else {
            Vec::new()
        }
    }

    /// Get the token type of the previous token (the one before current).
    fn previous_token_type(&self) -> Option<TokenType> {
        if self.current > 0 {
            Some(self.tokens[self.current - 1].token_type.clone())
        } else {
            None
        }
    }

    /// Wrap a query expression in a Subquery node.
    /// Only wraps if the expression is a query statement (Select, Union, etc.),
    /// not for simple expressions like column references.
    fn maybe_wrap_in_subquery(&self, inner: Expression) -> Expression {
        if matches!(
            &inner,
            Expression::Select(_)
                | Expression::Union(_)
                | Expression::Intersect(_)
                | Expression::Except(_)
        ) {
            Expression::Subquery(Box::new(Subquery {
                this: inner,
                alias: None,
                column_aliases: Vec::new(),
                order_by: None,
                limit: None,
                offset: None,
                distribute_by: None,
                sort_by: None,
                cluster_by: None,
                lateral: false,
                modifiers_inside: false,
                trailing_comments: Vec::new(),
                inferred_type: None,
            }))
        } else {
            inner
        }
    }

    /// Clear trailing_comments from the rightmost leaf of an expression tree.
    /// Used by parse_and/parse_or to avoid comment duplication: when the same comment
    /// is captured both in an expression's trailing_comments (during parse_primary) and
    /// in a BinaryOp's operator_comments (during parse_and/parse_or), we clear the
    /// expression's copy since the operator_comments position (after AND/OR) is correct.
    fn clear_rightmost_trailing_comments(expr: &mut Expression) {
        match expr {
            Expression::Column(col) => col.trailing_comments.clear(),
            Expression::And(op) | Expression::Or(op) => {
                Self::clear_rightmost_trailing_comments(&mut op.right);
            }
            Expression::Not(op) => {
                Self::clear_rightmost_trailing_comments(&mut op.this);
            }
            // For comparison ops, the rightmost is the right operand
            Expression::Eq(op)
            | Expression::Neq(op)
            | Expression::Lt(op)
            | Expression::Lte(op)
            | Expression::Gt(op)
            | Expression::Gte(op)
            | Expression::Add(op)
            | Expression::Sub(op)
            | Expression::Mul(op)
            | Expression::Div(op) => {
                Self::clear_rightmost_trailing_comments(&mut op.right);
            }
            // For other expressions, trailing_comments might be stored differently
            // We don't need to handle all variants, just the common ones that appear
            // as operands in AND/OR expressions
            _ => {}
        }
    }

    /// Get leading comments from the current token (comments that appeared before it)
    fn current_leading_comments(&self) -> Vec<String> {
        if !self.is_at_end() {
            self.tokens[self.current].comments.clone()
        } else {
            Vec::new()
        }
    }

    /// Convert a slice of tokens to SQL string with proper quoting for strings
    fn tokens_to_sql(&self, start: usize, end: usize) -> String {
        let mut result = String::new();
        let mut prev_line: Option<usize> = None;
        let mut prev_end_offset: Option<usize> = None;

        for t in &self.tokens[start..end] {
            // Check if we moved to a new line (preserve original line structure)
            let is_new_line = prev_line.is_some() && t.span.line > prev_line.unwrap();

            // Use byte offsets to determine original spacing between tokens.
            // This preserves the exact spacing from the source (e.g., TRANSFORM( vs OPTIONS ())
            if is_new_line {
                result.push('\n');
                // Preserve original indentation
                // span.column is the column AFTER the last character (1-based),
                // so start column = span.column - text.chars().count()
                let text_len = t.text.chars().count();
                let start_col = t.span.column.saturating_sub(text_len);
                // For string tokens, add 2 for the quotes that were stripped
                let start_col = if t.token_type == TokenType::String {
                    start_col.saturating_sub(2)
                } else {
                    start_col
                };
                let indent = if start_col > 1 { start_col - 1 } else { 0 };
                for _ in 0..indent {
                    result.push(' ');
                }
            } else if !result.is_empty() {
                // Same line: use byte offsets to detect if there was whitespace
                let had_space = prev_end_offset.map_or(false, |prev_end| t.span.start > prev_end);
                if had_space {
                    result.push(' ');
                }
            }

            if t.token_type == TokenType::String {
                // Re-add quotes around string literals
                result.push('\'');
                result.push_str(&t.text.replace('\'', "''"));
                result.push('\'');
            } else {
                result.push_str(&t.text);
            }

            prev_line = Some(t.span.line);
            prev_end_offset = Some(t.span.end);
        }
        result
    }

    /// Convert tokens to SQL for CREATE STAGE, normalizing FILE_FORMAT clause
    /// Transforms FILE_FORMAT='value' to FILE_FORMAT=(FORMAT_NAME='value')
    /// and FILE_FORMAT=schema.format to FILE_FORMAT=(FORMAT_NAME=schema.format)
    fn tokens_to_sql_stage_format(&self, start: usize, end: usize) -> String {
        let mut result = String::new();
        let mut prev_token_type: Option<TokenType> = None;
        let mut i = start;

        while i < end {
            let t = &self.tokens[i];

            // Check for FILE_FORMAT= pattern that needs normalization
            // FILE_FORMAT must be followed by = and then NOT by (
            if (t.token_type == TokenType::Var || t.token_type == TokenType::Identifier)
                && t.text.to_uppercase() == "FILE_FORMAT"
                && i + 1 < end
                && self.tokens[i + 1].token_type == TokenType::Eq
                && (i + 2 >= end || self.tokens[i + 2].token_type != TokenType::LParen)
            {
                // Need to normalize: FILE_FORMAT=value -> FILE_FORMAT=(FORMAT_NAME=value)
                if !result.is_empty() && prev_token_type != Some(TokenType::LParen) {
                    result.push(' ');
                }
                result.push_str("FILE_FORMAT=(FORMAT_NAME=");

                // Skip FILE_FORMAT and =
                i += 2;

                // Collect the value (string literal or qualified identifier like schema.format)
                while i < end {
                    let val = &self.tokens[i];
                    if val.token_type == TokenType::String {
                        // String literal: 'format1'
                        result.push('\'');
                        result.push_str(&val.text.replace('\'', "''"));
                        result.push('\'');
                        i += 1;
                        break;
                    } else if val.token_type == TokenType::Var
                        || val.token_type == TokenType::Identifier
                    {
                        // Identifier: schema1 or format1
                        result.push_str(&val.text);
                        i += 1;
                        // Check for dot (qualified name)
                        if i < end && self.tokens[i].token_type == TokenType::Dot {
                            result.push('.');
                            i += 1;
                            // Expect identifier after dot
                            if i < end {
                                result.push_str(&self.tokens[i].text);
                                i += 1;
                            }
                        }
                        break;
                    } else {
                        break;
                    }
                }
                result.push(')');
                prev_token_type = Some(TokenType::RParen);
                continue;
            }

            // Normal token handling (same as tokens_to_sql)
            let needs_space = !result.is_empty()
                && prev_token_type != Some(TokenType::LParen)
                && prev_token_type != Some(TokenType::Eq)
                && prev_token_type != Some(TokenType::Dot)
                && t.token_type != TokenType::Comma
                && t.token_type != TokenType::RParen
                && t.token_type != TokenType::LParen
                && t.token_type != TokenType::Eq
                && t.token_type != TokenType::Dot;

            if needs_space {
                result.push(' ');
            }

            if t.token_type == TokenType::String {
                result.push('\'');
                result.push_str(&t.text.replace('\'', "''"));
                result.push('\'');
            } else {
                result.push_str(&t.text);
            }

            prev_token_type = Some(t.token_type);
            i += 1;
        }
        result
    }

    /// Like tokens_to_sql but also uppercases keyword tokens and adds space after commas
    fn tokens_to_sql_uppercased(&self, start: usize, end: usize) -> String {
        let mut result = String::new();
        let mut prev_token_type: Option<TokenType> = None;
        let mut prev_token_text: Option<String> = None;

        for t in &self.tokens[start..end] {
            // Smart spacing: no space before comma, ), . or after (, .
            // Add space before ( only when preceded by a structural keyword or identifier
            // (e.g., "PRIMARY KEY (Id)", "CLUSTERED (EmpID)")
            // but NOT after data type keywords (e.g., "VARCHAR(100)", "INT(11)")
            let is_lparen_after_keyword = t.token_type == TokenType::LParen
                && prev_token_type.map_or(false, |p: TokenType| {
                    // Only add space for structural SQL keywords, not data type keywords
                    match p {
                        TokenType::PrimaryKey | TokenType::ForeignKey | TokenType::Unique
                        | TokenType::Check | TokenType::Index | TokenType::Key
                        | TokenType::Constraint | TokenType::References
                        | TokenType::Not | TokenType::Null
                        | TokenType::Default | TokenType::Values | TokenType::In
                        | TokenType::Exists | TokenType::Select | TokenType::From
                        | TokenType::Where | TokenType::Having | TokenType::Using
                        | TokenType::On | TokenType::Set | TokenType::Into
                        | TokenType::Table | TokenType::View | TokenType::Create
                        | TokenType::Insert | TokenType::Update | TokenType::Delete
                        | TokenType::Join | TokenType::Left | TokenType::Right
                        | TokenType::Inner | TokenType::Outer | TokenType::Full
                        | TokenType::Cross | TokenType::Case | TokenType::When
                        | TokenType::Then | TokenType::Else | TokenType::End
                        | TokenType::If | TokenType::Partition | TokenType::Over
                        | TokenType::Between | TokenType::Like | TokenType::Replace
                        | TokenType::Grant | TokenType::Revoke
                        => true,
                        _ => false,
                    }
                })
                // For Var/Identifier tokens, add space before ( only for structural tokens
                // (CLUSTERED, NONCLUSTERED, INDEX) but not data types (VARCHAR, INT, etc.)
                || (t.token_type == TokenType::LParen
                    && prev_token_text.as_ref().map_or(false, |text| {
                        let upper = text.to_uppercase();
                        matches!(upper.as_str(),
                            "CLUSTERED" | "NONCLUSTERED" | "HASH" | "RANGE"
                            | "INCLUDE" | "FILLFACTOR" | "PAD_INDEX"
                        )
                    }));
            let needs_space = !result.is_empty()
                && prev_token_type != Some(TokenType::LParen)
                && prev_token_type != Some(TokenType::Dot)
                && t.token_type != TokenType::Comma
                && t.token_type != TokenType::RParen
                && t.token_type != TokenType::Dot
                && (t.token_type != TokenType::LParen || is_lparen_after_keyword);

            // Add space after comma
            if prev_token_type == Some(TokenType::Comma) {
                result.push(' ');
            } else if needs_space {
                result.push(' ');
            }

            if t.token_type == TokenType::String {
                // Re-add quotes around string literals
                result.push('\'');
                result.push_str(&t.text.replace('\'', "''"));
                result.push('\'');
            } else if t.token_type.is_keyword() {
                // Uppercase keyword tokens
                result.push_str(&t.text.to_uppercase());
            } else {
                // For non-keyword tokens, preserve original text
                result.push_str(&t.text);
            }

            prev_token_type = Some(t.token_type);
            prev_token_text = Some(t.text.clone());
        }
        result
    }

    /// Check if current token matches type
    fn check(&self, token_type: TokenType) -> bool {
        if self.is_at_end() {
            false
        } else {
            self.peek().token_type == token_type
        }
    }

    /// Check if current token is a keyword
    fn check_keyword(&self) -> bool {
        if self.is_at_end() {
            false
        } else {
            self.peek().token_type.is_keyword()
        }
    }

    /// Check if current UNPIVOT token starts an UNPIVOT clause (vs being an alias).
    /// UNPIVOT clause starts with: UNPIVOT(, UNPIVOT INCLUDE, or UNPIVOT EXCLUDE
    fn is_unpivot_clause_start(&self) -> bool {
        if !self.check(TokenType::Unpivot) {
            return false;
        }
        let next_idx = self.current + 1;
        if next_idx >= self.tokens.len() {
            return false;
        }
        let next = &self.tokens[next_idx];
        if next.token_type == TokenType::LParen {
            return true;
        }
        // UNPIVOT INCLUDE NULLS (...) or UNPIVOT EXCLUDE NULLS (...)
        let next_text = next.text.to_uppercase();
        next_text == "INCLUDE" || next_text == "EXCLUDE"
    }

    /// Check if current token text matches (case-insensitive), does not advance
    fn check_keyword_text(&self, keyword: &str) -> bool {
        if self.is_at_end() {
            false
        } else {
            self.peek().text.to_uppercase() == keyword.to_uppercase()
        }
    }

    /// Check if current token is FROM keyword
    fn check_from_keyword(&self) -> bool {
        self.check(TokenType::From)
    }

    /// Check if next token matches type
    fn check_next(&self, token_type: TokenType) -> bool {
        if self.current + 1 >= self.tokens.len() {
            false
        } else {
            self.tokens[self.current + 1].token_type == token_type
        }
    }

    /// Check if next token is an identifier with specific name (case-insensitive)
    fn check_next_identifier(&self, name: &str) -> bool {
        if self.current + 1 >= self.tokens.len() {
            false
        } else {
            let token = &self.tokens[self.current + 1];
            (token.token_type == TokenType::Var || token.token_type == TokenType::Identifier)
                && token.text.to_uppercase() == name.to_uppercase()
        }
    }

    /// Match an identifier with specific text (case insensitive)
    /// Checks for Identifier, Var, and QuotedIdentifier tokens
    fn match_identifier(&mut self, text: &str) -> bool {
        if (self.check(TokenType::Identifier)
            || self.check(TokenType::Var)
            || self.check(TokenType::QuotedIdentifier))
            && self.peek().text.to_uppercase() == text.to_uppercase()
        {
            self.advance();
            true
        } else {
            false
        }
    }

    /// Check if current token is an identifier with specific text (case insensitive)
    /// Does NOT advance the parser
    fn check_identifier(&self, text: &str) -> bool {
        if self.is_at_end() {
            return false;
        }
        (self.check(TokenType::Identifier)
            || self.check(TokenType::Var)
            || self.check(TokenType::QuotedIdentifier))
            && self.peek().text.to_uppercase() == text.to_uppercase()
    }

    /// Check if current token is a "safe" keyword that can be used as an identifier.
    /// Check if the current Percent token is a PERCENT modifier (not a modulo operator).
    /// "PERCENT" spelled out is always a modifier. "%" is a modifier when followed by
    /// a clause boundary (OFFSET, end of input, semicolon, RParen, comma, etc.)
    fn is_percent_modifier(&self) -> bool {
        if self.is_at_end() {
            return false;
        }
        let text = self.peek().text.to_uppercase();
        if text == "PERCENT" {
            return true;
        }
        // "%" symbol — only treat as PERCENT modifier if followed by a boundary
        if text == "%" {
            let next_idx = self.current + 1;
            if next_idx >= self.tokens.len() {
                return true; // at end — it's PERCENT
            }
            let next_type = self.tokens[next_idx].token_type;
            return matches!(
                next_type,
                TokenType::Offset
                    | TokenType::Semicolon
                    | TokenType::RParen
                    | TokenType::From
                    | TokenType::Where
                    | TokenType::GroupBy
                    | TokenType::OrderBy
                    | TokenType::Having
                    | TokenType::Union
                    | TokenType::Intersect
                    | TokenType::Except
                    | TokenType::Comma
                    | TokenType::With // WITH TIES
            ) || next_idx >= self.tokens.len();
        }
        false
    }

    /// Structural keywords like FROM, WHERE, JOIN, SELECT are NOT safe.
    /// Non-structural keywords like FILTER, UPDATE, END, VALUES can be used as identifiers.
    fn is_safe_keyword_as_identifier(&self) -> bool {
        if self.is_at_end() {
            return false;
        }
        let token_type = self.peek().token_type;
        // Structural keywords that should NOT be used as identifiers
        let is_structural = matches!(
            token_type,
            TokenType::From
                | TokenType::Where
                | TokenType::Select
                | TokenType::Insert
                | TokenType::Delete
                | TokenType::Create
                | TokenType::Drop
                | TokenType::Alter
                | TokenType::Join
                | TokenType::Inner
                | TokenType::Cross
                | TokenType::On
                | TokenType::GroupBy
                | TokenType::OrderBy
                | TokenType::Having
                | TokenType::With
                | TokenType::Union
                | TokenType::Intersect
                | TokenType::Except
                | TokenType::Qualify
                | TokenType::Into
                | TokenType::Set
                | TokenType::Using
                | TokenType::Lateral
                | TokenType::Natural
        );
        // ClickHouse allows many SQL keywords as identifiers (table names, column aliases, etc.)
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) {
            let is_ch_structural = matches!(
                token_type,
                TokenType::From
                    | TokenType::Where
                    | TokenType::Select
                    | TokenType::Create
                    | TokenType::Drop
                    | TokenType::Alter
                    | TokenType::On
                    | TokenType::GroupBy
                    | TokenType::OrderBy
                    | TokenType::Having
                    | TokenType::With
                    | TokenType::Union
                    | TokenType::Intersect
                    | TokenType::Except
                    | TokenType::Into
                    | TokenType::Using
                    | TokenType::Lateral
                    | TokenType::Natural
            );
            // Also allow certain operator tokens and non-keyword tokens as identifiers
            if matches!(token_type, TokenType::RLike | TokenType::Values) {
                return true;
            }
            return self.peek().token_type.is_keyword() && !is_ch_structural;
        }
        // If it's a keyword but NOT structural, it's safe to use as identifier
        self.peek().token_type.is_keyword() && !is_structural
    }

    /// Check if a token at current position is the last meaningful token in an expression context.
    /// This is used to detect when a keyword like IS or KEEP should be treated as an alias
    /// instead of an operator keyword.
    fn is_last_expression_token(&self, _token_type: TokenType) -> bool {
        // Check if the token after the current one is end-of-input or a clause boundary
        let next_idx = self.current + 1;
        if next_idx >= self.tokens.len() {
            return true; // at end of input
        }
        let next_type = self.tokens[next_idx].token_type;
        // Clause boundaries that indicate the current token is the last in the expression
        matches!(
            next_type,
            TokenType::From
                | TokenType::Where
                | TokenType::GroupBy
                | TokenType::OrderBy
                | TokenType::Having
                | TokenType::Limit
                | TokenType::Union
                | TokenType::Intersect
                | TokenType::Except
                | TokenType::Semicolon
                | TokenType::RParen
                | TokenType::Comma
        )
    }

    /// Check if current token is a type keyword (for lambda type annotations)
    fn is_type_keyword(&self) -> bool {
        if self.is_at_end() {
            return false;
        }
        let token = self.peek();
        // Check for common type keywords that might appear in lambda annotations
        // Use text comparison to avoid depending on specific TokenType variants
        let text_upper = token.text.to_uppercase();
        matches!(
            text_upper.as_str(),
            "INT"
                | "INTEGER"
                | "BIGINT"
                | "SMALLINT"
                | "TINYINT"
                | "DOUBLE"
                | "FLOAT"
                | "DECIMAL"
                | "NUMERIC"
                | "REAL"
                | "VARCHAR"
                | "CHAR"
                | "TEXT"
                | "STRING"
                | "NVARCHAR"
                | "NCHAR"
                | "BOOLEAN"
                | "BOOL"
                | "DATE"
                | "TIME"
                | "TIMESTAMP"
                | "DATETIME"
                | "INTERVAL"
                | "BINARY"
                | "VARBINARY"
                | "BLOB"
                | "ARRAY"
                | "MAP"
                | "STRUCT"
                | "OBJECT"
                | "VARIANT"
                | "JSON"
                | "NUMBER"
                | "VARCHAR2"
        )
    }

    /// Check if current token is a command keyword that can safely be used as an implicit alias.
    /// This is a narrow set of command-like keywords (GET, PUT, COPY, SHOW, etc.) that are
    /// unlikely to conflict with SQL clause keywords when used as implicit aliases.
    fn is_command_keyword_as_alias(&self) -> bool {
        if self.is_at_end() {
            return false;
        }
        let token_type = self.peek().token_type;
        // FORMAT is a query modifier in ClickHouse, so don't treat it as an alias there
        if matches!(token_type, TokenType::Format) {
            return !matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            );
        }
        // Base keywords that can be aliases in all dialects
        if matches!(
            token_type,
            TokenType::Get
                | TokenType::Put
                | TokenType::Copy
                | TokenType::Show
                | TokenType::Rename
                | TokenType::Enum
                | TokenType::Sample
                | TokenType::Collate
                | TokenType::Add
        ) {
            return true;
        }
        // Spark/Hive allow LIMIT and OFFSET as aliases (without quoting)
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::Spark) | Some(crate::dialects::DialectType::Hive)
        ) && matches!(token_type, TokenType::Limit | TokenType::Offset)
        {
            return true;
        }
        false
    }

    /// Check if current token is a keyword that can be used as a table alias.
    /// This is more permissive than is_safe_keyword_as_identifier - it allows
    /// LEFT, RIGHT, OUTER, FULL which are JOIN keywords but can also be aliases.
    fn can_be_alias_keyword(&self) -> bool {
        if self.is_at_end() {
            return false;
        }
        let token_type = self.peek().token_type;
        // Keywords that can be used as aliases (similar to is_safe_keyword but more permissive)
        matches!(
            token_type,
            TokenType::Left
                | TokenType::Right
                | TokenType::Outer
                | TokenType::Full
                | TokenType::Only
                | TokenType::Next
                | TokenType::All
                | TokenType::If
        ) || self.is_safe_keyword_as_identifier()
    }

    /// Match and consume a token type
    fn match_token(&mut self, token_type: TokenType) -> bool {
        if self.check(token_type) {
            self.advance();
            true
        } else {
            false
        }
    }

    /// Match a sequence of keywords
    fn match_keywords(&mut self, keywords: &[TokenType]) -> bool {
        // Check if all keywords match
        for (i, &kw) in keywords.iter().enumerate() {
            if self.current + i >= self.tokens.len() {
                return false;
            }
            if self.tokens[self.current + i].token_type != kw {
                return false;
            }
        }

        // Consume all matched keywords
        self.current += keywords.len();
        true
    }

    /// Expect a specific token type
    fn expect(&mut self, token_type: TokenType) -> Result<Token> {
        if self.check(token_type) {
            Ok(self.advance())
        } else {
            let got = if self.is_at_end() {
                "end of input".to_string()
            } else {
                format!("{:?}", self.peek().token_type)
            };
            let got_text = if self.is_at_end() {
                "".to_string()
            } else {
                self.peek().text.clone()
            };
            let start = self.current.saturating_sub(3);
            let end = (self.current + 4).min(self.tokens.len());
            let context = self.tokens_to_sql(start, end).replace('\n', " ");
            Err(self.parse_error(format!(
                "Expected {:?}, got {} ('{}') near [{}]",
                token_type, got, got_text, context
            )))
        }
    }

    /// Expect a `>` token, handling the case where `>>` was tokenized as GtGt
    /// This is needed for parsing nested generic types like `ARRAY<ARRAY<INT>>`
    fn expect_gt(&mut self) -> Result<Token> {
        if self.check(TokenType::Gt) {
            Ok(self.advance())
        } else if self.check(TokenType::GtGt) {
            // Split >> into two > tokens
            // Replace the GtGt with Gt and return a synthetic Gt token
            let token = self.peek().clone();
            self.tokens[self.current] = Token {
                token_type: TokenType::Gt,
                text: ">".to_string(),
                span: Span {
                    start: token.span.start + 1,
                    end: token.span.end,
                    line: token.span.line,
                    column: token.span.column + 1,
                },
                comments: Vec::new(),
                trailing_comments: Vec::new(),
            };
            Ok(Token {
                token_type: TokenType::Gt,
                text: ">".to_string(),
                span: Span {
                    start: token.span.start,
                    end: token.span.start + 1,
                    line: token.span.line,
                    column: token.span.column,
                },
                comments: token.comments,
                trailing_comments: Vec::new(),
            })
        } else {
            Err(self.parse_error(format!(
                "Expected Gt, got {:?}",
                if self.is_at_end() {
                    "end of input".to_string()
                } else {
                    format!("{:?}", self.peek().token_type)
                }
            )))
        }
    }

    /// Expect a string literal and return its value
    fn expect_string(&mut self) -> Result<String> {
        if self.check(TokenType::String) || self.check(TokenType::DollarString) {
            Ok(self.advance().text)
        } else {
            Err(self.parse_error(format!(
                "Expected string, got {:?}",
                if self.is_at_end() {
                    "end of input".to_string()
                } else {
                    format!("{:?}", self.peek().token_type)
                }
            )))
        }
    }

    /// Check if the current token is any kind of identifier (regular, quoted, or var)
    fn is_identifier_token(&self) -> bool {
        self.check(TokenType::Var)
            || self.check(TokenType::Identifier)
            || self.check(TokenType::QuotedIdentifier)
    }

    /// Check if current token is a stage reference (starts with @)
    /// This handles both DAt token and Var tokens that start with @
    fn is_stage_reference(&self) -> bool {
        self.check(TokenType::DAt)
            || (self.check(TokenType::Var) && self.peek().text.starts_with('@'))
    }

    /// Check if the current token could be a MySQL numeric-starting identifier (e.g., 00f, 1d)
    /// This checks that the Number token is followed by a connected Var/Identifier token
    fn is_mysql_numeric_identifier(&self) -> bool {
        if !self.check(TokenType::Number)
            || !matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::MySQL)
            )
        {
            return false;
        }
        // Check if the next token is connected (no space) and is a var/identifier
        if self.current + 1 < self.tokens.len() {
            let curr = &self.tokens[self.current];
            let next = &self.tokens[self.current + 1];
            // Tokens are connected if they are immediately adjacent (no whitespace between)
            // span.end is exclusive, so if curr.end == next.start, they are adjacent
            let connected = curr.span.end == next.span.start;
            connected
                && (next.token_type == TokenType::Var || next.token_type == TokenType::Identifier)
        } else {
            false
        }
    }

    /// Parse a MySQL numeric-starting identifier (e.g., 00f, 1d)
    /// Merges the number token with connected identifier tokens
    fn parse_mysql_numeric_identifier(&mut self) -> Identifier {
        let num_token = self.advance();
        let mut name = num_token.text.clone();
        // Merge with connected identifier/var tokens
        while !self.is_at_end()
            && self.is_connected()
            && (self.check(TokenType::Var) || self.check(TokenType::Identifier))
        {
            let tok = self.advance();
            name.push_str(&tok.text);
        }
        Identifier {
            name,
            // sqlglot treats this as an identifier token and re-emits it quoted.
            quoted: true,
            trailing_comments: Vec::new(),
            span: None,
        }
    }

    /// Check if an uppercase string starting with '_' is a MySQL charset introducer
    fn is_mysql_charset_introducer(text: &str) -> bool {
        matches!(
            text,
            "_ARMSCII8"
                | "_ASCII"
                | "_BIG5"
                | "_BINARY"
                | "_CP1250"
                | "_CP1251"
                | "_CP1256"
                | "_CP1257"
                | "_CP850"
                | "_CP852"
                | "_CP866"
                | "_CP932"
                | "_DEC8"
                | "_EUCJPMS"
                | "_EUCKR"
                | "_GB18030"
                | "_GB2312"
                | "_GBK"
                | "_GEOSTD8"
                | "_GREEK"
                | "_HEBREW"
                | "_HP8"
                | "_KEYBCS2"
                | "_KOI8R"
                | "_KOI8U"
                | "_LATIN1"
                | "_LATIN2"
                | "_LATIN5"
                | "_LATIN7"
                | "_MACCE"
                | "_MACROMAN"
                | "_SJIS"
                | "_SWE7"
                | "_TIS620"
                | "_UCS2"
                | "_UJIS"
                | "_UTF8"
                | "_UTF16"
                | "_UTF16LE"
                | "_UTF32"
                | "_UTF8MB3"
                | "_UTF8MB4"
        )
    }

    /// Check if the current token can be used as an identifier (includes keywords)
    fn is_identifier_or_keyword_token(&self) -> bool {
        self.is_identifier_token() || self.check_keyword()
    }

    /// Expect an identifier and return an Identifier struct with quoted flag
    fn expect_identifier_with_quoted(&mut self) -> Result<Identifier> {
        if self.is_mysql_numeric_identifier() {
            return Ok(self.parse_mysql_numeric_identifier());
        }
        if self.is_identifier_token() {
            let token = self.advance();
            let quoted = token.token_type == TokenType::QuotedIdentifier;
            Ok(Identifier {
                name: token.text,
                quoted,
                trailing_comments: Vec::new(),
                span: None,
            })
        } else if self.check(TokenType::LBrace)
            && matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            )
        {
            if let Some(param_expr) = self.parse_clickhouse_braced_parameter()? {
                if let Expression::Parameter(param) = &param_expr {
                    let name = format!(
                        "{{{}: {}}}",
                        param.name.as_deref().unwrap_or(""),
                        param.expression.as_deref().unwrap_or("")
                    );
                    return Ok(Identifier {
                        name,
                        quoted: false,
                        trailing_comments: Vec::new(),
                        span: None,
                    });
                }
            }
            Err(self.parse_error("Expected identifier, got LBrace"))
        } else {
            Err(self.parse_error(format!(
                "Expected identifier, got {:?}",
                if self.is_at_end() {
                    "end of input".to_string()
                } else {
                    format!("{:?}", self.peek().token_type)
                }
            )))
        }
    }

    /// Expect an identifier or keyword (for column names, field names, etc.)
    fn expect_identifier_or_keyword_with_quoted(&mut self) -> Result<Identifier> {
        // MySQL numeric-starting identifiers (e.g., 00f, 1d)
        if self.is_mysql_numeric_identifier() {
            return Ok(self.parse_mysql_numeric_identifier());
        }
        // Also accept ? (Parameter) as an identifier placeholder
        // For positional parameters like $23, the token text is "23" (without $)
        if self.check(TokenType::Parameter) {
            let token = self.advance();
            // If the text is a number, it's a positional parameter like $1, $2, $23
            // Construct $N as the identifier name
            let name = if token.text.chars().all(|c| c.is_ascii_digit()) && !token.text.is_empty() {
                format!("${}", token.text)
            } else {
                // Plain ? placeholder or other parameter
                "?".to_string()
            };
            return Ok(Identifier {
                name,
                quoted: false,
                trailing_comments: Vec::new(),
                span: None,
            });
        }
        if self.is_identifier_or_keyword_token() {
            let token = self.advance();
            let quoted = token.token_type == TokenType::QuotedIdentifier;
            Ok(Identifier {
                name: token.text,
                quoted,
                trailing_comments: Vec::new(),
                span: None,
            })
        } else if self.check(TokenType::LBrace)
            && matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            )
        {
            // ClickHouse query parameter: {name:Type}
            if let Some(param_expr) = self.parse_clickhouse_braced_parameter()? {
                // Extract the parameter name to use as the identifier
                if let Expression::Parameter(param) = &param_expr {
                    let name = format!(
                        "{{{}: {}}}",
                        param.name.as_deref().unwrap_or(""),
                        param.expression.as_deref().unwrap_or("")
                    );
                    return Ok(Identifier {
                        name,
                        quoted: false,
                        trailing_comments: Vec::new(),
                        span: None,
                    });
                }
            }
            Err(self.parse_error("Expected identifier, got LBrace"))
        } else {
            Err(self.parse_error(format!(
                "Expected identifier, got {:?}",
                if self.is_at_end() {
                    "end of input".to_string()
                } else {
                    format!("{:?}", self.peek().token_type)
                }
            )))
        }
    }

    /// Expect an identifier
    fn expect_identifier(&mut self) -> Result<String> {
        if self.is_identifier_token() {
            Ok(self.advance().text)
        } else if self.check(TokenType::LBrace)
            && matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            )
        {
            if let Some(param_expr) = self.parse_clickhouse_braced_parameter()? {
                if let Expression::Parameter(param) = &param_expr {
                    return Ok(format!(
                        "{{{}: {}}}",
                        param.name.as_deref().unwrap_or(""),
                        param.expression.as_deref().unwrap_or("")
                    ));
                }
            }
            Err(self.parse_error("Expected identifier, got LBrace"))
        } else {
            Err(self.parse_error(format!(
                "Expected identifier, got {:?}",
                if self.is_at_end() {
                    "end of input".to_string()
                } else {
                    format!("{:?}", self.peek().token_type)
                }
            )))
        }
    }

    /// Expect an identifier or keyword (for aliases, column names, etc.)
    fn expect_identifier_or_keyword(&mut self) -> Result<String> {
        if self.is_identifier_or_keyword_token() {
            Ok(self.advance().text)
        } else if self.check(TokenType::LBrace)
            && matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            )
        {
            if let Some(param_expr) = self.parse_clickhouse_braced_parameter()? {
                if let Expression::Parameter(param) = &param_expr {
                    return Ok(format!(
                        "{{{}: {}}}",
                        param.name.as_deref().unwrap_or(""),
                        param.expression.as_deref().unwrap_or("")
                    ));
                }
            }
            Err(self.parse_error("Expected identifier, got LBrace"))
        } else {
            Err(self.parse_error(format!(
                "Expected identifier, got {:?}",
                if self.is_at_end() {
                    "end of input".to_string()
                } else {
                    format!("{:?}", self.peek().token_type)
                }
            )))
        }
    }

    /// Expect an identifier or safe keyword (for CTE names, column names in CREATE TABLE, etc.)
    /// This is more permissive than expect_identifier but excludes structural keywords
    fn expect_identifier_or_safe_keyword(&mut self) -> Result<String> {
        if self.is_identifier_token() || self.is_safe_keyword_as_identifier() {
            Ok(self.advance().text)
        } else if self.check(TokenType::LBrace)
            && matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            )
        {
            if let Some(param_expr) = self.parse_clickhouse_braced_parameter()? {
                if let Expression::Parameter(param) = &param_expr {
                    return Ok(format!(
                        "{{{}: {}}}",
                        param.name.as_deref().unwrap_or(""),
                        param.expression.as_deref().unwrap_or("")
                    ));
                }
            }
            Err(self.parse_error("Expected identifier, got LBrace"))
        } else {
            Err(self.parse_error(format!(
                "Expected identifier, got {:?}",
                if self.is_at_end() {
                    "end of input".to_string()
                } else {
                    format!("{:?}", self.peek().token_type)
                }
            )))
        }
    }

    /// Expect an identifier or safe keyword, preserving quoted flag
    fn expect_identifier_or_safe_keyword_with_quoted(&mut self) -> Result<Identifier> {
        if self.is_mysql_numeric_identifier() {
            return Ok(self.parse_mysql_numeric_identifier());
        }
        if self.is_identifier_token() || self.is_safe_keyword_as_identifier() {
            let token = self.advance();
            let quoted = token.token_type == TokenType::QuotedIdentifier;
            Ok(Identifier {
                name: token.text,
                quoted,
                trailing_comments: Vec::new(),
                span: None,
            })
        } else {
            Err(self.parse_error(format!(
                "Expected identifier, got {:?}",
                if self.is_at_end() {
                    "end of input".to_string()
                } else {
                    format!("{:?}", self.peek().token_type)
                }
            )))
        }
    }

    fn expect_identifier_or_alias_keyword_with_quoted(&mut self) -> Result<Identifier> {
        // ClickHouse: any keyword can be used as a table alias after explicit AS
        let ch_keyword = matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) && self.peek().token_type.is_keyword();
        if self.is_identifier_token()
            || self.can_be_alias_keyword()
            || self.is_safe_keyword_as_identifier()
            || ch_keyword
        {
            let token = self.advance();
            let quoted = token.token_type == TokenType::QuotedIdentifier;
            Ok(Identifier {
                name: token.text,
                quoted,
                trailing_comments: Vec::new(),
                span: None,
            })
        } else if self.check(TokenType::String)
            && matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::DuckDB)
            )
        {
            // DuckDB allows string literals as identifiers (e.g., WITH 'x' AS (...))
            let token = self.advance();
            Ok(Identifier {
                name: token.text,
                quoted: true,
                trailing_comments: Vec::new(),
                span: None,
            })
        } else {
            Err(self.parse_error(format!(
                "Expected identifier, got {:?}",
                if self.is_at_end() {
                    "end of input".to_string()
                } else {
                    format!("{:?}", self.peek().token_type)
                }
            )))
        }
    }

    /// Expect a number
    fn expect_number(&mut self) -> Result<i64> {
        let negative = self.match_token(TokenType::Dash);
        if self.check(TokenType::Number) {
            let text = self.advance().text;
            let val = text
                .parse::<i64>()
                .map_err(|_| self.parse_error(format!("Invalid number: {}", text)))?;
            Ok(if negative { -val } else { val })
        } else {
            Err(self.parse_error("Expected number"))
        }
    }

    /// Parse a comma-separated list of expressions.
    /// Supports named arguments with => or := syntax.
    fn parse_expression_list_with_capacity(
        &mut self,
        capacity_hint: usize,
    ) -> Result<Vec<Expression>> {
        let mut expressions = Vec::with_capacity(capacity_hint);

        loop {
            // Check if this is a named argument: identifier => value or identifier := value
            // Also check for safe keywords (like TYPE, FORMAT, etc.) that can be used as named arg names
            let expr = if self.is_identifier_token() || self.is_safe_keyword_as_identifier() {
                let start_pos = self.current;
                let name = self.expect_identifier_or_keyword_with_quoted()?;

                if self.match_token(TokenType::FArrow) {
                    // name => value
                    let value = self.parse_expression()?;
                    Expression::NamedArgument(Box::new(NamedArgument {
                        name,
                        value,
                        separator: NamedArgSeparator::DArrow,
                    }))
                } else if self.match_token(TokenType::ColonEq) {
                    // name := value
                    let value = self.parse_expression()?;
                    Expression::NamedArgument(Box::new(NamedArgument {
                        name,
                        value,
                        separator: NamedArgSeparator::ColonEq,
                    }))
                } else {
                    // Not a named argument, backtrack and parse as regular expression
                    self.current = start_pos;
                    self.parse_expression()?
                }
            } else {
                self.parse_expression()?
            };

            // Check for AS alias on this expression (Spark/Hive: IF(cond, val AS name, ...))
            let expr = if self.check(TokenType::As) {
                let as_pos = self.current;
                self.advance(); // consume AS
                                // Check if what follows looks like an alias name
                if self.is_identifier_token()
                    || self.is_safe_keyword_as_identifier()
                    || (matches!(
                        self.config.dialect,
                        Some(crate::dialects::DialectType::ClickHouse)
                    ) && self.peek().token_type.is_keyword())
                {
                    let alias = self.expect_identifier_or_keyword_with_quoted()?;
                    let alias_expr = Expression::Alias(Box::new(Alias {
                        this: expr,
                        alias,
                        column_aliases: Vec::new(),
                        pre_alias_comments: Vec::new(),
                        trailing_comments: Vec::new(),
                        inferred_type: None,
                    }));
                    // ClickHouse: if followed by an operator, the alias is part of a bigger expression
                    // e.g., blockSize() AS bs < 1000 means (blockSize() AS bs) < 1000
                    if matches!(
                        self.config.dialect,
                        Some(crate::dialects::DialectType::ClickHouse)
                    ) && matches!(
                        self.peek().token_type,
                        TokenType::Lt
                            | TokenType::Gt
                            | TokenType::Lte
                            | TokenType::Gte
                            | TokenType::Eq
                            | TokenType::Neq
                            | TokenType::Plus
                            | TokenType::Dash
                            | TokenType::Star
                            | TokenType::Slash
                            | TokenType::Percent
                            | TokenType::And
                            | TokenType::Or
                            | TokenType::Like
                            | TokenType::Not
                            | TokenType::In
                            | TokenType::Is
                            | TokenType::Between
                    ) {
                        // Parse the operator and right-hand side
                        let op_token = self.advance();
                        let right = self.parse_expression()?;
                        match op_token.token_type {
                            TokenType::Lt => {
                                Expression::Lt(Box::new(BinaryOp::new(alias_expr, right)))
                            }
                            TokenType::Gt => {
                                Expression::Gt(Box::new(BinaryOp::new(alias_expr, right)))
                            }
                            TokenType::Lte => {
                                Expression::Lte(Box::new(BinaryOp::new(alias_expr, right)))
                            }
                            TokenType::Gte => {
                                Expression::Gte(Box::new(BinaryOp::new(alias_expr, right)))
                            }
                            TokenType::Eq => {
                                Expression::Eq(Box::new(BinaryOp::new(alias_expr, right)))
                            }
                            TokenType::Neq => {
                                Expression::Neq(Box::new(BinaryOp::new(alias_expr, right)))
                            }
                            TokenType::Plus => {
                                Expression::Add(Box::new(BinaryOp::new(alias_expr, right)))
                            }
                            TokenType::Dash => {
                                Expression::Sub(Box::new(BinaryOp::new(alias_expr, right)))
                            }
                            TokenType::Star => {
                                Expression::Mul(Box::new(BinaryOp::new(alias_expr, right)))
                            }
                            TokenType::Slash => {
                                Expression::Div(Box::new(BinaryOp::new(alias_expr, right)))
                            }
                            TokenType::Percent => {
                                Expression::Mod(Box::new(BinaryOp::new(alias_expr, right)))
                            }
                            TokenType::And => {
                                Expression::And(Box::new(BinaryOp::new(alias_expr, right)))
                            }
                            TokenType::Or => {
                                Expression::Or(Box::new(BinaryOp::new(alias_expr, right)))
                            }
                            _ => alias_expr, // fallback, shouldn't happen
                        }
                    } else {
                        alias_expr
                    }
                } else {
                    // Not an alias name, backtrack
                    self.current = as_pos;
                    expr
                }
            } else {
                expr
            };

            // Check for trailing comments on this expression
            // Only wrap in Annotated for expression types that don't have their own trailing_comments field
            let trailing_comments = self.previous_trailing_comments();
            let expr = if trailing_comments.is_empty() {
                expr
            } else {
                // Only annotate Literals and other types that don't capture trailing comments
                match &expr {
                    Expression::Literal(_) | Expression::Boolean(_) | Expression::Null(_) => {
                        Expression::Annotated(Box::new(Annotated {
                            this: expr,
                            trailing_comments,
                        }))
                    }
                    // For expressions that already capture trailing_comments, don't double-wrap
                    _ => expr,
                }
            };
            expressions.push(expr);

            if !self.match_token(TokenType::Comma) {
                break;
            }
            // ClickHouse: allow trailing comma before RParen in expression lists
            if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && self.check(TokenType::RParen)
            {
                break;
            }
        }

        Ok(expressions)
    }

    /// Parse a comma-separated list of expressions.
    /// Supports named arguments with => or := syntax.
    fn parse_expression_list(&mut self) -> Result<Vec<Expression>> {
        self.parse_expression_list_with_capacity(0)
    }

    /// Estimate top-level expression count until the next unmatched `)`.
    ///
    /// This is used for pre-allocating comma-separated lists like `IN (...)`
    /// to reduce `Vec` growth churn on very large lists.
    fn estimate_expression_list_capacity_until_rparen(&self) -> usize {
        if self.current >= self.tokens.len() || self.check(TokenType::RParen) {
            return 0;
        }

        let mut idx = self.current;
        let mut paren_depth = 0usize;
        let mut bracket_depth = 0usize;
        let mut brace_depth = 0usize;
        let mut commas = 0usize;
        let mut has_any_token = false;

        while idx < self.tokens.len() {
            let token_type = self.tokens[idx].token_type;
            match token_type {
                TokenType::LParen => paren_depth += 1,
                TokenType::RParen => {
                    if paren_depth == 0 && bracket_depth == 0 && brace_depth == 0 {
                        break;
                    }
                    paren_depth = paren_depth.saturating_sub(1);
                }
                TokenType::LBracket => bracket_depth += 1,
                TokenType::RBracket => bracket_depth = bracket_depth.saturating_sub(1),
                TokenType::LBrace => brace_depth += 1,
                TokenType::RBrace => brace_depth = brace_depth.saturating_sub(1),
                TokenType::Comma if paren_depth == 0 && bracket_depth == 0 && brace_depth == 0 => {
                    commas += 1;
                }
                _ => {}
            }
            has_any_token = true;
            idx += 1;
        }

        if has_any_token {
            commas + 1
        } else {
            0
        }
    }

    /// Parse function arguments with lambda support (for TRANSFORM and similar functions).
    /// Handles Snowflake typed lambda syntax: `a int -> a + 1`
    fn parse_function_args_with_lambda(&mut self) -> Result<Vec<Expression>> {
        let mut expressions = Vec::new();

        loop {
            // Try to detect typed lambda: identifier type -> body
            let expr = if self.is_identifier_token() || self.is_safe_keyword_as_identifier() {
                let saved_pos = self.current;
                let ident_token = self.advance();
                let ident_name = ident_token.text.clone();

                // Check for arrow (simple lambda: a -> body)
                if self.match_token(TokenType::Arrow) {
                    let body = self.parse_expression()?;
                    Expression::Lambda(Box::new(LambdaExpr {
                        parameters: vec![Identifier::new(ident_name)],
                        body,
                        colon: false,
                        parameter_types: Vec::new(),
                    }))
                }
                // Check for type annotation followed by arrow: a int -> body
                else if !self.is_at_end()
                    && self.is_type_keyword()
                    && !self.check(TokenType::FArrow)
                    && !self.check(TokenType::ColonEq)
                {
                    let type_annotation = self.parse_data_type()?;
                    if self.match_token(TokenType::Arrow) {
                        let body = self.parse_expression()?;
                        Expression::Lambda(Box::new(LambdaExpr {
                            parameters: vec![Identifier::new(ident_name)],
                            body,
                            colon: false,
                            parameter_types: vec![Some(type_annotation)],
                        }))
                    } else {
                        self.current = saved_pos;
                        self.parse_expression()?
                    }
                } else {
                    // Not a lambda, backtrack and parse as regular expression
                    self.current = saved_pos;
                    self.parse_expression()?
                }
            } else {
                self.parse_expression()?
            };

            expressions.push(expr);
            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        Ok(expressions)
    }

    /// Parse a comma-separated list of expressions for VALUES tuples
    /// This variant supports AS aliases on each element (Hive syntax): VALUES (1 AS a, 2 AS b, 3)
    fn parse_values_expression_list(&mut self) -> Result<Vec<Expression>> {
        let mut expressions = Vec::new();

        loop {
            // Handle DEFAULT keyword in VALUES - output as unquoted Var (like Python sqlglot's exp.var("DEFAULT"))
            let expr = if self.match_token(TokenType::Default) {
                Expression::Var(Box::new(crate::expressions::Var {
                    this: "DEFAULT".to_string(),
                }))
            } else {
                self.parse_expression()?
            };

            // Capture trailing comments on the expression (e.g., `1 /* c4 */`)
            let trailing_comments = self.previous_trailing_comments();
            let expr = if !trailing_comments.is_empty() {
                match &expr {
                    Expression::Literal(_) | Expression::Boolean(_) | Expression::Null(_) => {
                        Expression::Annotated(Box::new(crate::expressions::Annotated {
                            this: expr,
                            trailing_comments,
                        }))
                    }
                    _ => expr,
                }
            } else {
                expr
            };

            // Check for AS alias on this value element (Hive syntax)
            let expr_with_alias = if self.match_token(TokenType::As) {
                let alias = self.expect_identifier_or_keyword_with_quoted()?;
                Expression::Alias(Box::new(Alias::new(expr, alias)))
            } else {
                expr
            };

            expressions.push(expr_with_alias);

            if !self.match_token(TokenType::Comma) {
                break;
            }
            // ClickHouse: trailing comma in VALUES, e.g., (1, 2, 3,)
            if self.check(TokenType::RParen) {
                break;
            }
        }

        Ok(expressions)
    }

    /// Parse a comma-separated list of identifiers
    fn parse_identifier_list(&mut self) -> Result<Vec<Identifier>> {
        let mut identifiers = Vec::new();

        loop {
            // Allow keywords as identifiers in identifier lists (e.g., CTE column aliases)
            // Check if it's a quoted identifier before consuming
            let quoted = self.check(TokenType::QuotedIdentifier);
            let mut name = self.expect_identifier_or_safe_keyword()?;
            // ClickHouse: handle dotted names in identifier lists (e.g., INSERT INTO t (n.a, n.b))
            // Use keyword_with_quoted to allow any keyword after dot (e.g., replace.from)
            if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) {
                while self.match_token(TokenType::Dot) {
                    let sub_id = self.expect_identifier_or_keyword_with_quoted()?;
                    name = format!("{}.{}", name, sub_id.name);
                }
            }
            let trailing_comments = self.previous_trailing_comments();
            identifiers.push(Identifier {
                name,
                quoted,
                trailing_comments,
                span: None,
            });

            if !self.match_token(TokenType::Comma) {
                break;
            }
            // ClickHouse: allow trailing comma before RParen in identifier lists
            if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && self.check(TokenType::RParen)
            {
                break;
            }
        }

        Ok(identifiers)
    }

    /// Parse a comma-separated list of column references for USING clause
    /// Supports qualified names like table.col but extracts only the column part
    fn parse_using_column_list(&mut self) -> Result<Vec<Identifier>> {
        let mut identifiers = Vec::new();

        loop {
            // ClickHouse: USING * — wildcard in USING clause
            if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && self.match_token(TokenType::Star)
            {
                identifiers.push(Identifier::new("*".to_string()));
                if !self.match_token(TokenType::Comma) {
                    break;
                }
                continue;
            }
            // Check if it's a quoted identifier before consuming
            let quoted = self.check(TokenType::QuotedIdentifier);
            let mut name = self.expect_identifier_or_safe_keyword()?;
            let mut final_quoted = quoted;

            // Handle qualified names: table.column or schema.table.column
            // Keep only the final column name
            while self.match_token(TokenType::Dot) {
                final_quoted = self.check(TokenType::QuotedIdentifier);
                name = self.expect_identifier_or_safe_keyword()?;
            }

            // ClickHouse: USING (col AS alias) — consume optional AS alias
            if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && self.match_token(TokenType::As)
            {
                // Use the alias name instead
                final_quoted = self.check(TokenType::QuotedIdentifier);
                name = self.expect_identifier_or_safe_keyword()?;
            }

            let trailing_comments = self.previous_trailing_comments();
            identifiers.push(Identifier {
                name,
                quoted: final_quoted,
                trailing_comments,
                span: None,
            });

            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        Ok(identifiers)
    }

    /// Parse a comma-separated list of identifiers for index columns.
    /// Supports MySQL prefix lengths: col(16) and sort order: col DESC
    fn parse_index_identifier_list(&mut self) -> Result<Vec<Identifier>> {
        let mut identifiers = Vec::new();

        loop {
            let quoted = self.check(TokenType::QuotedIdentifier);
            let name = self.expect_identifier_or_safe_keyword()?;
            let trailing_comments = self.previous_trailing_comments();

            // Check for prefix length: col(16)
            let mut display_name = name.clone();
            if self.match_token(TokenType::LParen) {
                if self.check(TokenType::Number) {
                    let len = self.advance().text;
                    display_name = format!("{}({})", name, len);
                }
                self.expect(TokenType::RParen)?;
            }

            // Check for DESC/ASC sort order
            if self.match_token(TokenType::Desc) {
                display_name = format!("{} DESC", display_name);
            } else if self.match_token(TokenType::Asc) {
                display_name = format!("{} ASC", display_name);
            }

            identifiers.push(Identifier {
                name: display_name,
                quoted,
                trailing_comments,
                span: None,
            });

            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        Ok(identifiers)
    }
    // =============================================================================
    // Auto-generated Missing Parser Methods
    // Total: 296 methods
    // =============================================================================

    /// parse_add_column - Implemented from Python _parse_add_column
    /// Calls: parse_column, parse_column_def_with_exists
    #[allow(unused_variables, unused_mut)]
    pub fn parse_add_column(&mut self) -> Result<Option<Expression>> {
        if self.match_texts(&["FIRST", "AFTER"]) {
            // Matched one of: FIRST, AFTER
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_alias - Parses alias for an expression
    /// This method parses just the alias part (AS name or just name)
    /// Python: _parse_alias
    pub fn parse_alias(&mut self) -> Result<Option<Expression>> {
        // Check for AS keyword (explicit alias)
        let _explicit = self.match_token(TokenType::Alias);

        // Parse the alias identifier
        if let Some(alias_expr) = self.parse_id_var()? {
            let alias_ident = match alias_expr {
                Expression::Identifier(id) => id,
                _ => return Ok(None),
            };
            // Return just the alias identifier wrapped in an expression
            return Ok(Some(Expression::Identifier(alias_ident)));
        }

        Ok(None)
    }

    /// parse_alias_with_expr - Wraps an expression with an alias if present
    pub fn parse_alias_with_expr(
        &mut self,
        this: Option<Expression>,
    ) -> Result<Option<Expression>> {
        if this.is_none() {
            return Ok(None);
        }
        let expr = this.unwrap();

        // Check for AS keyword (explicit alias)
        // Accept both TokenType::Alias and TokenType::As
        let has_as = self.match_token(TokenType::Alias) || self.match_token(TokenType::As);

        // Check for column aliases: (col1, col2)
        if has_as && self.match_token(TokenType::LParen) {
            let mut column_aliases = Vec::new();
            loop {
                if let Some(col_expr) = self.parse_id_var()? {
                    if let Expression::Identifier(id) = col_expr {
                        column_aliases.push(id);
                    }
                } else {
                    break;
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            self.match_token(TokenType::RParen);

            if !column_aliases.is_empty() {
                return Ok(Some(Expression::Alias(Box::new(Alias {
                    this: expr,
                    alias: Identifier::new(String::new()), // Empty alias when only column aliases
                    column_aliases,
                    pre_alias_comments: Vec::new(),
                    trailing_comments: Vec::new(),
                    inferred_type: None,
                }))));
            }
        }

        // Parse the alias identifier
        if let Some(alias_expr) = self.parse_id_var()? {
            let alias_ident = match alias_expr {
                Expression::Identifier(id) => id,
                _ => return Ok(Some(expr)),
            };
            return Ok(Some(Expression::Alias(Box::new(Alias {
                this: expr,
                alias: alias_ident,
                column_aliases: Vec::new(),
                pre_alias_comments: Vec::new(),
                trailing_comments: Vec::new(),
                inferred_type: None,
            }))));
        }

        Ok(Some(expr))
    }

    /// parse_alter_diststyle - Implemented from Python _parse_alter_diststyle
    #[allow(unused_variables, unused_mut)]
    /// parse_alter_diststyle - Parses ALTER TABLE DISTSTYLE clause (Redshift)
    /// Python: parser.py:7797-7802
    pub fn parse_alter_diststyle(&mut self) -> Result<Option<Expression>> {
        // Check for ALL, EVEN, AUTO
        if self.match_texts(&["ALL", "EVEN", "AUTO"]) {
            let style = self.previous().text.to_uppercase();
            return Ok(Some(Expression::DistStyleProperty(Box::new(
                DistStyleProperty {
                    this: Box::new(Expression::Identifier(Identifier::new(style))),
                },
            ))));
        }

        // KEY DISTKEY column
        if self.match_text_seq(&["KEY", "DISTKEY"]) {
            if let Some(column) = self.parse_column()? {
                return Ok(Some(Expression::DistStyleProperty(Box::new(
                    DistStyleProperty {
                        this: Box::new(column),
                    },
                ))));
            }
        }

        Ok(None)
    }

    /// parse_alter_session - Parses ALTER SESSION SET/UNSET statements
    /// Python: parser.py:7879-7889
    pub fn parse_alter_session(&mut self) -> Result<Option<Expression>> {
        // ALTER SESSION SET var = value, ...
        if self.match_token(TokenType::Set) {
            let mut expressions = Vec::new();
            loop {
                if let Some(item) = self.parse_set_item_assignment()? {
                    expressions.push(item);
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            return Ok(Some(Expression::AlterSession(Box::new(AlterSession {
                expressions,
                unset: None,
            }))));
        }

        // ALTER SESSION UNSET var, ...
        if self.match_text_seq(&["UNSET"]) {
            let mut expressions = Vec::new();
            loop {
                if let Some(var) = self.parse_id_var()? {
                    // For UNSET, we just use the identifier directly
                    expressions.push(var);
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            return Ok(Some(Expression::AlterSession(Box::new(AlterSession {
                expressions,
                unset: Some(Box::new(Expression::Boolean(BooleanLiteral {
                    value: true,
                }))),
            }))));
        }

        Ok(None)
    }

    /// parse_alter_sortkey - Parses ALTER TABLE SORTKEY clause (Redshift)
    /// Python: parser.py:7804-7816
    pub fn parse_alter_sortkey(&mut self) -> Result<Option<Expression>> {
        self.parse_alter_sortkey_impl(None)
    }

    /// Implementation of parse_alter_sortkey with compound option
    pub fn parse_alter_sortkey_impl(
        &mut self,
        compound: Option<bool>,
    ) -> Result<Option<Expression>> {
        // For compound sortkey, match SORTKEY keyword
        if compound == Some(true) {
            self.match_text_seq(&["SORTKEY"]);
        }

        // Check for (column_list) syntax
        if self.check(TokenType::LParen) {
            let wrapped = self.parse_wrapped_id_vars()?;
            // Extract expressions from Tuple
            let expressions = if let Some(Expression::Tuple(t)) = wrapped {
                t.expressions
            } else {
                Vec::new()
            };
            return Ok(Some(Expression::AlterSortKey(Box::new(AlterSortKey {
                this: None,
                expressions,
                compound: compound
                    .map(|c| Box::new(Expression::Boolean(BooleanLiteral { value: c }))),
            }))));
        }

        // Check for AUTO or NONE
        if self.match_texts(&["AUTO", "NONE"]) {
            let style = self.previous().text.to_uppercase();
            return Ok(Some(Expression::AlterSortKey(Box::new(AlterSortKey {
                this: Some(Box::new(Expression::Identifier(Identifier::new(style)))),
                expressions: Vec::new(),
                compound: compound
                    .map(|c| Box::new(Expression::Boolean(BooleanLiteral { value: c }))),
            }))));
        }

        Ok(None)
    }

    /// parse_alter_table_add - Parses ALTER TABLE ADD clause
    /// Python: parser.py:7715-7751
    pub fn parse_alter_table_add(&mut self) -> Result<Option<Expression>> {
        // Check for ADD keyword (optional in some contexts)
        self.match_text_seq(&["ADD"]);

        // Check for INDEX/KEY with optional FULLTEXT/SPATIAL prefix (MySQL)
        // Syntax: ADD [FULLTEXT|SPATIAL] {INDEX|KEY} [name] (columns) [USING {BTREE|HASH}]
        let kind = if self.match_identifier("FULLTEXT") {
            Some("FULLTEXT".to_string())
        } else if self.match_identifier("SPATIAL") {
            Some("SPATIAL".to_string())
        } else {
            None
        };

        if self.check(TokenType::Index) || self.check(TokenType::Key) || kind.is_some() {
            // Consume INDEX or KEY keyword, track which was used
            let use_key_keyword = if self.match_token(TokenType::Key) {
                true
            } else {
                self.match_token(TokenType::Index);
                false
            };

            // Optional index name (before the columns)
            let name = if !self.check(TokenType::LParen) && !self.check(TokenType::Using) {
                Some(self.expect_identifier_with_quoted()?)
            } else {
                None
            };

            // Parse columns (with optional prefix length and DESC)
            self.expect(TokenType::LParen)?;
            let columns = self.parse_index_identifier_list()?;
            self.expect(TokenType::RParen)?;

            // Parse optional USING BTREE|HASH
            let modifiers = self.parse_constraint_modifiers();

            return Ok(Some(Expression::AlterTable(Box::new(AlterTable {
                name: TableRef::new(""),
                actions: vec![AlterTableAction::AddConstraint(TableConstraint::Index {
                    name,
                    columns,
                    kind,
                    modifiers,
                    use_key_keyword,
                    expression: None,
                    index_type: None,
                    granularity: None,
                })],
                if_exists: false,
                algorithm: None,
                lock: None,
                with_check: None,
                partition: None,
                on_cluster: None,
            }))));
        }

        // Check for constraint keywords (PRIMARY KEY, FOREIGN KEY, UNIQUE, CHECK, CONSTRAINT)
        if self.check(TokenType::PrimaryKey)
            || self.check(TokenType::ForeignKey)
            || self.check(TokenType::Unique)
            || self.check(TokenType::Check)
            || self.check(TokenType::Constraint)
        {
            // Parse a single constraint and return it wrapped in Constraint
            if let Some(constraint) = self.parse_constraint()? {
                return Ok(Some(Expression::Constraint(Box::new(Constraint {
                    this: Box::new(constraint),
                    expressions: Vec::new(),
                }))));
            }
        }

        // Check for COLUMNS keyword (batch column addition)
        if self.match_text_seq(&["COLUMNS"]) {
            // Parse schema or column definitions
            if let Some(schema) = self.parse_schema()? {
                return Ok(Some(schema));
            }
        }

        // Check for IF NOT EXISTS PARTITION (must check before parse_add_column)
        let exists = self.match_keywords(&[TokenType::If, TokenType::Not, TokenType::Exists]);
        if self.match_token(TokenType::Partition) {
            // Parse PARTITION(key = value, ...)
            self.expect(TokenType::LParen)?;
            let mut partition_exprs = Vec::new();
            loop {
                if let Some(expr) = self.parse_conjunction()? {
                    partition_exprs.push(expr);
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            self.expect(TokenType::RParen)?;

            let partition = Expression::Partition(Box::new(crate::expressions::Partition {
                expressions: partition_exprs,
                subpartition: false,
            }));

            let location = if self.match_text_seq(&["LOCATION"]) {
                self.parse_property()?
            } else {
                None
            };
            return Ok(Some(Expression::AddPartition(Box::new(AddPartition {
                this: Box::new(partition),
                exists,
                location: location.map(Box::new),
            }))));
        }

        // Try to parse column definition (after checking for PARTITION)
        if let Some(column) = self.parse_add_column()? {
            return Ok(Some(column));
        }

        Ok(None)
    }

    /// parse_alter_table_alter - Parses ALTER TABLE ALTER COLUMN clause
    /// Python: parser.py:7753-7795
    pub fn parse_alter_table_alter(&mut self) -> Result<Option<Expression>> {
        // Match optional COLUMN keyword
        self.match_token(TokenType::Column);

        // Parse the column name - required for ALTER COLUMN
        let column = match self.parse_field()? {
            Some(c) => c,
            None => return Ok(None),
        };

        // DROP DEFAULT
        if self.match_keywords(&[TokenType::Drop, TokenType::Default]) {
            return Ok(Some(Expression::AlterColumn(Box::new(AlterColumn {
                this: Box::new(column),
                dtype: None,
                collate: None,
                using: None,
                default: None,
                drop: Some(Box::new(Expression::Boolean(BooleanLiteral {
                    value: true,
                }))),
                allow_null: None,
                comment: None,
                visible: None,
                rename_to: None,
            }))));
        }

        // SET DEFAULT expr
        if self.match_keywords(&[TokenType::Set, TokenType::Default]) {
            let default_val = self.parse_disjunction()?;
            return Ok(Some(Expression::AlterColumn(Box::new(AlterColumn {
                this: Box::new(column),
                dtype: None,
                collate: None,
                using: None,
                default: default_val.map(Box::new),
                drop: None,
                allow_null: None,
                comment: None,
                visible: None,
                rename_to: None,
            }))));
        }

        // COMMENT 'string'
        if self.match_token(TokenType::Comment) {
            let comment_val = self.parse_string()?;
            return Ok(Some(Expression::AlterColumn(Box::new(AlterColumn {
                this: Box::new(column),
                dtype: None,
                collate: None,
                using: None,
                default: None,
                drop: None,
                allow_null: None,
                comment: comment_val.map(Box::new),
                visible: None,
                rename_to: None,
            }))));
        }

        // DROP NOT NULL
        if self.match_text_seq(&["DROP", "NOT", "NULL"]) {
            return Ok(Some(Expression::AlterColumn(Box::new(AlterColumn {
                this: Box::new(column),
                dtype: None,
                collate: None,
                using: None,
                default: None,
                drop: Some(Box::new(Expression::Boolean(BooleanLiteral {
                    value: true,
                }))),
                allow_null: Some(Box::new(Expression::Boolean(BooleanLiteral {
                    value: true,
                }))),
                comment: None,
                visible: None,
                rename_to: None,
            }))));
        }

        // SET NOT NULL
        if self.match_text_seq(&["SET", "NOT", "NULL"]) {
            return Ok(Some(Expression::AlterColumn(Box::new(AlterColumn {
                this: Box::new(column),
                dtype: None,
                collate: None,
                using: None,
                default: None,
                drop: None,
                allow_null: Some(Box::new(Expression::Boolean(BooleanLiteral {
                    value: false,
                }))),
                comment: None,
                visible: None,
                rename_to: None,
            }))));
        }

        // SET VISIBLE
        if self.match_text_seq(&["SET", "VISIBLE"]) {
            return Ok(Some(Expression::AlterColumn(Box::new(AlterColumn {
                this: Box::new(column),
                dtype: None,
                collate: None,
                using: None,
                default: None,
                drop: None,
                allow_null: None,
                comment: None,
                visible: Some(Box::new(Expression::Identifier(Identifier::new(
                    "VISIBLE".to_string(),
                )))),
                rename_to: None,
            }))));
        }

        // SET INVISIBLE
        if self.match_text_seq(&["SET", "INVISIBLE"]) {
            return Ok(Some(Expression::AlterColumn(Box::new(AlterColumn {
                this: Box::new(column),
                dtype: None,
                collate: None,
                using: None,
                default: None,
                drop: None,
                allow_null: None,
                comment: None,
                visible: Some(Box::new(Expression::Identifier(Identifier::new(
                    "INVISIBLE".to_string(),
                )))),
                rename_to: None,
            }))));
        }

        // [SET DATA] TYPE type [COLLATE collation] [USING expr]
        self.match_text_seq(&["SET", "DATA"]);
        self.match_text_seq(&["TYPE"]);

        let dtype = self.parse_types()?;
        let collate = if self.match_token(TokenType::Collate) {
            self.parse_term()?
        } else {
            None
        };
        let using = if self.match_token(TokenType::Using) {
            self.parse_disjunction()?
        } else {
            None
        };

        Ok(Some(Expression::AlterColumn(Box::new(AlterColumn {
            this: Box::new(column),
            dtype: dtype.map(Box::new),
            collate: collate.map(Box::new),
            using: using.map(Box::new),
            default: None,
            drop: None,
            allow_null: None,
            comment: None,
            visible: None,
            rename_to: None,
        }))))
    }

    /// Parse ALTER TABLE DROP action
    /// Note: Main ALTER TABLE DROP logic is implemented inline in parse_alter_table
    /// This method provides a separate entry point for the same functionality
    pub fn parse_alter_table_drop(&mut self) -> Result<Option<Expression>> {
        // Check for IF EXISTS before PARTITION
        let exists = self.match_keywords(&[TokenType::If, TokenType::Exists]);

        // Check if this is DROP PARTITION
        if self.check(TokenType::Partition) {
            return self.parse_drop_partition_with_exists(exists);
        }

        // Check for DROP FOREIGN KEY (Oracle/MySQL)
        if self.match_keywords(&[TokenType::ForeignKey, TokenType::Key]) {
            let name = self.expect_identifier_with_quoted()?;
            return Ok(Some(Expression::AlterTable(Box::new(AlterTable {
                name: TableRef::new(""),
                actions: vec![AlterTableAction::DropForeignKey { name }],
                if_exists: false,
                algorithm: None,
                lock: None,
                with_check: None,
                partition: None,
                on_cluster: None,
            }))));
        }

        // Check for DROP COLUMNS (col1, col2, ...) syntax (Spark/Databricks)
        if self.check_identifier("COLUMNS") && self.check_next(TokenType::LParen) {
            self.advance(); // consume COLUMNS
            self.expect(TokenType::LParen)?;
            let mut columns = Vec::new();
            loop {
                if let Some(col) = self.parse_identifier()? {
                    columns.push(col);
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            self.expect(TokenType::RParen)?;
            if columns.is_empty() {
                return Ok(None);
            } else if columns.len() == 1 {
                return Ok(Some(columns.remove(0)));
            } else {
                return Ok(Some(Expression::Tuple(Box::new(Tuple {
                    expressions: columns,
                }))));
            }
        }

        // Otherwise, parse as DROP COLUMN(s)
        let mut columns = Vec::new();

        // Parse first column
        if let Some(col) = self.parse_drop_column()? {
            columns.push(col);
        }

        // Parse additional columns (comma-separated)
        while self.match_token(TokenType::Comma) {
            // Match optional DROP keyword before next column
            self.match_token(TokenType::Drop);
            if let Some(col) = self.parse_drop_column()? {
                columns.push(col);
            }
        }

        if columns.is_empty() {
            Ok(None)
        } else if columns.len() == 1 {
            Ok(Some(columns.remove(0)))
        } else {
            // Multiple columns - wrap in a Tuple
            Ok(Some(Expression::Tuple(Box::new(Tuple {
                expressions: columns,
            }))))
        }
    }

    /// parse_alter_table_rename - Parses ALTER TABLE RENAME clause
    /// Python: parser.py:7828-7841
    pub fn parse_alter_table_rename(&mut self) -> Result<Option<Expression>> {
        // RENAME COLUMN old_name TO new_name
        if self.match_token(TokenType::Column) {
            let exists = self.match_keywords(&[TokenType::If, TokenType::Exists]);
            let old_column = match self.parse_column()? {
                Some(c) => c,
                None => return Ok(None),
            };

            if !self.match_text_seq(&["TO"]) {
                return Ok(None);
            }

            let new_column = self.parse_column()?;

            return Ok(Some(Expression::RenameColumn(Box::new(RenameColumn {
                this: Box::new(old_column),
                to: new_column.map(Box::new),
                exists,
            }))));
        }

        // RENAME TO new_table_name
        if self.match_text_seq(&["TO"]) {
            // Return the table expression directly - the caller will handle it as a rename target
            let new_table = self.parse_table()?;
            return Ok(new_table);
        }

        // SQLite allows: RENAME old_name TO new_name (without COLUMN keyword)
        // Try to parse as column rename if followed by identifier and TO
        if self.is_identifier_token() || self.is_safe_keyword_as_identifier() {
            let old_column = match self.parse_column()? {
                Some(c) => c,
                None => return Ok(None),
            };

            if self.match_text_seq(&["TO"]) {
                let new_column = self.parse_column()?;
                return Ok(Some(Expression::RenameColumn(Box::new(RenameColumn {
                    this: Box::new(old_column),
                    to: new_column.map(Box::new),
                    exists: false,
                }))));
            } else {
                // Not TO after identifier - put it back and return error
                return Err(self.parse_error("Expected COLUMN or TO after RENAME"));
            }
        }

        Ok(None)
    }

    /// parse_alter_table_set - Parses ALTER TABLE SET clause
    /// Python: parser.py:7843-7877
    pub fn parse_alter_table_set(&mut self) -> Result<Option<Expression>> {
        let mut alter_set = AlterSet {
            expressions: Vec::new(),
            option: None,
            tablespace: None,
            access_method: None,
            file_format: None,
            copy_options: None,
            tag: None,
            location: None,
            serde: None,
        };

        // SET AUTHORIZATION [ROLE] user
        if self.match_token(TokenType::Authorization) {
            let mut auth_text = "AUTHORIZATION ".to_string();
            if self.match_texts(&["ROLE"]) {
                auth_text.push_str("ROLE ");
            }
            let user = self.expect_identifier()?;
            auth_text.push_str(&user);
            alter_set.option = Some(Box::new(Expression::Identifier(Identifier::new(auth_text))));
            return Ok(Some(Expression::AlterSet(Box::new(alter_set))));
        }

        // SET PROPERTIES prop = value, ...
        if self.match_text_seq(&["PROPERTIES"]) {
            let mut assignments = Vec::new();
            loop {
                // Parse property name (could be identifier or string literal)
                let key = if self.check(TokenType::String) {
                    self.parse_string()?.unwrap_or(Expression::Null(Null))
                } else {
                    let name = self.expect_identifier()?;
                    Expression::Identifier(Identifier::new(name))
                };
                self.expect(TokenType::Eq)?;
                // Parse value (could be DEFAULT or an expression)
                let value = if self.match_token(TokenType::Default) {
                    Expression::Identifier(Identifier::new("DEFAULT".to_string()))
                } else {
                    self.parse_expression()?
                };
                assignments.push(Expression::Eq(Box::new(BinaryOp {
                    left: key,
                    right: value,
                    left_comments: Vec::new(),
                    operator_comments: Vec::new(),
                    trailing_comments: Vec::new(),
                    inferred_type: None,
                })));
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            alter_set.expressions = assignments;
            return Ok(Some(Expression::AlterSet(Box::new(alter_set))));
        }

        // SET (properties) or SET TABLE PROPERTIES (properties)
        if self.check(TokenType::LParen) || self.match_text_seq(&["TABLE", "PROPERTIES"]) {
            let assignments = self.parse_wrapped_csv_assignments()?;
            alter_set.expressions = assignments;
            return Ok(Some(Expression::AlterSet(Box::new(alter_set))));
        }

        // SET FILESTREAM_ON = value
        if self.match_text_seq(&["FILESTREAM_ON"]) {
            if let Some(assignment) = self.parse_assignment()? {
                alter_set.expressions = vec![assignment];
            }
            return Ok(Some(Expression::AlterSet(Box::new(alter_set))));
        }

        // SET LOGGED or SET UNLOGGED
        if self.match_texts(&["LOGGED", "UNLOGGED"]) {
            let option = self.previous().text.to_uppercase();
            alter_set.option = Some(Box::new(Expression::Identifier(Identifier::new(option))));
            return Ok(Some(Expression::AlterSet(Box::new(alter_set))));
        }

        // SET WITHOUT CLUSTER or SET WITHOUT OIDS
        if self.match_text_seq(&["WITHOUT"]) {
            if self.match_texts(&["CLUSTER", "OIDS"]) {
                let option = format!("WITHOUT {}", self.previous().text.to_uppercase());
                alter_set.option = Some(Box::new(Expression::Identifier(Identifier::new(option))));
                return Ok(Some(Expression::AlterSet(Box::new(alter_set))));
            }
        }

        // SET LOCATION path
        if self.match_text_seq(&["LOCATION"]) {
            let loc = self.parse_field()?;
            alter_set.location = loc.map(Box::new);
            return Ok(Some(Expression::AlterSet(Box::new(alter_set))));
        }

        // SET ACCESS METHOD method
        if self.match_text_seq(&["ACCESS", "METHOD"]) {
            let method = self.parse_field()?;
            alter_set.access_method = method.map(Box::new);
            return Ok(Some(Expression::AlterSet(Box::new(alter_set))));
        }

        // SET TABLESPACE name
        if self.match_text_seq(&["TABLESPACE"]) {
            let tablespace = self.parse_field()?;
            alter_set.tablespace = tablespace.map(Box::new);
            return Ok(Some(Expression::AlterSet(Box::new(alter_set))));
        }

        // SET FILE FORMAT format or SET FILEFORMAT format
        if self.match_text_seq(&["FILE", "FORMAT"]) || self.match_text_seq(&["FILEFORMAT"]) {
            let format = self.parse_field()?;
            alter_set.file_format = format.map(Box::new);
            return Ok(Some(Expression::AlterSet(Box::new(alter_set))));
        }

        // SET STAGE_FILE_FORMAT = (options)
        if self.match_text_seq(&["STAGE_FILE_FORMAT"]) {
            let options = self.parse_wrapped_options()?;
            alter_set.file_format = options.map(Box::new);
            return Ok(Some(Expression::AlterSet(Box::new(alter_set))));
        }

        // SET STAGE_COPY_OPTIONS = (options)
        if self.match_text_seq(&["STAGE_COPY_OPTIONS"]) {
            let options = self.parse_wrapped_options()?;
            alter_set.copy_options = options.map(Box::new);
            return Ok(Some(Expression::AlterSet(Box::new(alter_set))));
        }

        // SET TAG or SET TAGS
        if self.match_text_seq(&["TAG"]) || self.match_text_seq(&["TAGS"]) {
            let mut tags = Vec::new();
            loop {
                if let Some(assignment) = self.parse_assignment()? {
                    tags.push(assignment);
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            if !tags.is_empty() {
                alter_set.tag = Some(Box::new(Expression::Tuple(Box::new(Tuple {
                    expressions: tags,
                }))));
            }
            return Ok(Some(Expression::AlterSet(Box::new(alter_set))));
        }

        // SET SERDE 'class' [WITH SERDEPROPERTIES (...)]
        if self.match_text_seq(&["SERDE"]) {
            let serde = self.parse_field()?;
            alter_set.serde = serde.map(Box::new);

            // Parse optional properties
            let properties = self.parse_wrapped()?;
            if let Some(props) = properties {
                alter_set.expressions = vec![props];
            }
            return Ok(Some(Expression::AlterSet(Box::new(alter_set))));
        }

        Ok(None)
    }

    /// Helper to parse wrapped CSV of assignments
    fn parse_wrapped_csv_assignments(&mut self) -> Result<Vec<Expression>> {
        if !self.match_token(TokenType::LParen) {
            return Ok(Vec::new());
        }
        let mut assignments = Vec::new();
        loop {
            if let Some(assignment) = self.parse_assignment()? {
                assignments.push(assignment);
            }
            if !self.match_token(TokenType::Comma) {
                break;
            }
        }
        self.expect(TokenType::RParen)?;
        Ok(assignments)
    }

    /// parse_analyze - Implemented from Python _parse_analyze
    /// Calls: parse_table_parts, parse_number, parse_table
    #[allow(unused_variables, unused_mut)]
    /// parse_analyze - Parses ANALYZE statement
    /// Python: parser.py:7937-7999
    pub fn parse_analyze(&mut self) -> Result<Option<Expression>> {
        // If no more tokens, return empty Analyze
        if self.is_at_end() {
            return Ok(Some(Expression::Analyze(Box::new(Analyze {
                kind: None,
                this: None,
                options: Vec::new(),
                mode: None,
                partition: None,
                expression: None,
                properties: Vec::new(),
                columns: Vec::new(),
            }))));
        }

        // Parse options (VERBOSE, SKIP_LOCKED, etc.)
        // StarRocks uses FULL and SAMPLE as options
        let mut options = Vec::new();
        let analyze_styles = [
            "VERBOSE",
            "SKIP_LOCKED",
            "BUFFER_USAGE_LIMIT",
            "FULL",
            "SAMPLE",
        ];
        while self.match_texts(&analyze_styles) {
            let style = self.previous().text.to_uppercase();
            if style == "BUFFER_USAGE_LIMIT" {
                // Parse number after BUFFER_USAGE_LIMIT
                if let Some(num) = self.parse_number()? {
                    options.push(Expression::Identifier(Identifier::new(format!(
                        "BUFFER_USAGE_LIMIT {}",
                        if let Expression::Literal(Literal::Number(n)) = &num {
                            n.clone()
                        } else {
                            String::new()
                        }
                    ))));
                }
            } else {
                options.push(Expression::Identifier(Identifier::new(style)));
            }
        }

        let mut this: Option<Expression> = None;
        let mut kind: Option<String> = None;
        let mut inner_expression: Option<Expression> = None;

        // Parse TABLE or INDEX
        if self.match_token(TokenType::Table) {
            kind = Some("TABLE".to_string());
            this = self.parse_table_parts()?;
        } else if self.match_token(TokenType::Index) {
            kind = Some("INDEX".to_string());
            this = self.parse_table_parts()?;
        } else if self.match_text_seq(&["TABLES"]) {
            kind = Some("TABLES".to_string());
            if self.match_token(TokenType::From) || self.match_token(TokenType::In) {
                let dir = self.previous().text.to_uppercase();
                kind = Some(format!("TABLES {}", dir));
                // Parse database name as identifier
                let db_name = self.expect_identifier()?;
                this = Some(Expression::Identifier(Identifier::new(db_name)));
            }
        } else if self.match_text_seq(&["DATABASE"]) {
            kind = Some("DATABASE".to_string());
            this = self.parse_table_parts()?;
        } else if self.match_text_seq(&["CLUSTER"]) {
            kind = Some("CLUSTER".to_string());
            this = self.parse_table_parts()?;
        } else if self.match_texts(&["LOCAL", "NO_WRITE_TO_BINLOG"]) {
            // MySQL: ANALYZE LOCAL TABLE tbl / ANALYZE NO_WRITE_TO_BINLOG TABLE tbl
            let opt_text = self.previous().text.to_uppercase();
            options.push(Expression::Identifier(Identifier::new(opt_text)));
            if self.match_token(TokenType::Table) {
                kind = Some("TABLE".to_string());
            }
            this = self.parse_table_parts()?;
        } else if self.match_text_seq(&["COMPUTE"]) {
            // Check ANALYZE_EXPRESSION_PARSERS keywords before fallback to parse_table_parts
            // Python: elif self._match_texts(self.ANALYZE_EXPRESSION_PARSERS)
            inner_expression = self.parse_analyze_statistics()?;
        } else if self.match_text_seq(&["DELETE"]) {
            inner_expression = self.parse_analyze_delete()?;
        } else if self.match_text_seq(&["VALIDATE"]) {
            inner_expression = self.parse_analyze_validate()?;
        } else if self.match_text_seq(&["LIST"]) {
            inner_expression = self.parse_analyze_list()?;
        } else if self.match_text_seq(&["DROP"]) {
            inner_expression = self.parse_analyze_histogram()?;
        } else if self.match_text_seq(&["UPDATE"]) {
            inner_expression = self.parse_analyze_histogram()?;
        } else if self.match_texts(&["ALL", "PREDICATE"]) {
            inner_expression = self.parse_analyze_columns()?;
        } else {
            // Try to parse table directly (empty kind - https://prestodb.io/docs/current/sql/analyze.html)
            this = self.parse_table_parts()?;
        }

        // Parse optional column list: ANALYZE tbl(col1, col2) (PostgreSQL)
        let columns = if this.is_some() && self.match_token(TokenType::LParen) {
            let mut cols = Vec::new();
            loop {
                cols.push(self.expect_identifier_or_keyword()?);
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            self.expect(TokenType::RParen)?;
            cols
        } else {
            Vec::new()
        };

        // Parse optional PARTITION
        let partition = self.parse_partition()?;

        // Parse optional WITH SYNC/ASYNC MODE or WITH (prop=val, ...) for Presto
        let mut mode = None;
        let mut properties = Vec::new();

        if self.match_text_seq(&["WITH", "SYNC", "MODE"]) {
            mode = Some(Box::new(Expression::Identifier(Identifier::new(
                "WITH SYNC MODE".to_string(),
            ))));
        } else if self.match_text_seq(&["WITH", "ASYNC", "MODE"]) {
            mode = Some(Box::new(Expression::Identifier(Identifier::new(
                "WITH ASYNC MODE".to_string(),
            ))));
        } else if self.match_text_seq(&["WITH"]) {
            // Presto syntax: ANALYZE tbl WITH (prop1=val1, prop2=val2)
            if self.match_token(TokenType::LParen) {
                loop {
                    // Parse key=value pairs
                    let key = self.parse_id_var()?;
                    if key.is_none() {
                        break;
                    }

                    // Expect = sign
                    if self.match_token(TokenType::Eq) {
                        // Parse the value
                        let value = self.parse_primary()?;
                        if let Some(k) = key {
                            properties.push(Expression::Property(Box::new(Property {
                                this: Box::new(k),
                                value: Some(Box::new(value)),
                            })));
                        }
                    } else if let Some(k) = key {
                        // Key without value
                        properties.push(Expression::Property(Box::new(Property {
                            this: Box::new(k),
                            value: None,
                        })));
                    }

                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
                self.expect(TokenType::RParen)?;
            }
        }

        // Parse optional inner expressions (COMPUTE, DELETE, etc.)
        // Only if inner_expression wasn't already set (for cases like ANALYZE TABLE tbl VALIDATE...)
        if inner_expression.is_none() {
            if self.match_text_seq(&["COMPUTE"]) {
                inner_expression = self.parse_analyze_statistics()?;
            } else if self.match_text_seq(&["DELETE"]) {
                inner_expression = self.parse_analyze_delete()?;
            } else if self.match_text_seq(&["VALIDATE"]) {
                inner_expression = self.parse_analyze_validate()?;
            } else if self.match_text_seq(&["LIST"]) {
                inner_expression = self.parse_analyze_list()?;
            } else if self.match_text_seq(&["DROP"]) {
                inner_expression = self.parse_analyze_histogram()?;
            } else if self.match_text_seq(&["UPDATE"]) {
                inner_expression = self.parse_analyze_histogram()?;
            } else if self.match_texts(&["ALL", "PREDICATE"]) {
                // Redshift: ANALYZE TBL ALL COLUMNS / ANALYZE TBL PREDICATE COLUMNS
                inner_expression = self.parse_analyze_columns()?;
            }
        }

        // Parse optional properties (if not already parsed from WITH clause)
        // StarRocks syntax: ANALYZE TABLE TBL PROPERTIES ('prop1'=val1, 'prop2'=val2)
        if properties.is_empty() && self.match_text_seq(&["PROPERTIES"]) {
            if self.match_token(TokenType::LParen) {
                loop {
                    // Parse key (can be a string literal or identifier)
                    let key = if self.check(TokenType::String) {
                        self.advance();
                        let key_str = self.previous().text.clone();
                        Expression::Literal(Literal::String(key_str))
                    } else {
                        self.parse_id_var()?
                            .unwrap_or(Expression::Identifier(Identifier::new(String::new())))
                    };

                    // Expect = sign
                    if self.match_token(TokenType::Eq) {
                        // Parse the value
                        let value = self.parse_primary()?;
                        properties.push(Expression::Property(Box::new(Property {
                            this: Box::new(key),
                            value: Some(Box::new(value)),
                        })));
                    } else {
                        // Key without value
                        properties.push(Expression::Property(Box::new(Property {
                            this: Box::new(key),
                            value: None,
                        })));
                    }

                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
                self.expect(TokenType::RParen)?;
            }
        }

        Ok(Some(Expression::Analyze(Box::new(Analyze {
            kind,
            this: this.map(Box::new),
            options,
            mode,
            partition: partition.map(Box::new),
            expression: inner_expression.map(Box::new),
            properties,
            columns,
        }))))
    }

    /// parse_analyze_columns - Parses ANALYZE ... COLUMNS
    /// Python: parser.py:8055-8059
    /// Note: AnalyzeColumns not in expressions.rs, using Identifier instead
    pub fn parse_analyze_columns(&mut self) -> Result<Option<Expression>> {
        let prev_text = self.previous().text.to_uppercase();
        if self.match_text_seq(&["COLUMNS"]) {
            return Ok(Some(Expression::Identifier(Identifier::new(format!(
                "{} COLUMNS",
                prev_text
            )))));
        }
        Ok(None)
    }

    /// parse_analyze_delete - Parses ANALYZE DELETE STATISTICS
    /// Python: parser.py:8061-8065
    pub fn parse_analyze_delete(&mut self) -> Result<Option<Expression>> {
        let kind = if self.match_text_seq(&["SYSTEM"]) {
            Some("SYSTEM".to_string())
        } else {
            None
        };

        if self.match_text_seq(&["STATISTICS"]) {
            return Ok(Some(Expression::AnalyzeDelete(Box::new(AnalyzeDelete {
                kind,
            }))));
        }

        Ok(None)
    }

    /// parse_analyze_histogram - Parses ANALYZE ... HISTOGRAM ON
    /// Python: parser.py:8073-8108
    pub fn parse_analyze_histogram(&mut self) -> Result<Option<Expression>> {
        let action = self.previous().text.to_uppercase(); // DROP or UPDATE
        let mut expressions = Vec::new();
        let mut update_options: Option<Box<Expression>> = None;
        let mut expression: Option<Box<Expression>> = None;

        if !self.match_text_seq(&["HISTOGRAM", "ON"]) {
            return Ok(None);
        }

        // Parse column references
        loop {
            if let Some(col) = self.parse_column_reference()? {
                expressions.push(col);
            } else {
                break;
            }
            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        // Parse USING DATA 'json_data' (MySQL) - must check before WITH
        if self.match_text_seq(&["USING", "DATA"]) {
            if self.check(TokenType::String) {
                let tok = self.advance();
                expression = Some(Box::new(Expression::Identifier(Identifier::new(format!(
                    "USING DATA '{}'",
                    tok.text
                )))));
            } else {
                expression = Some(Box::new(Expression::Identifier(Identifier::new(
                    "USING DATA".to_string(),
                ))));
            }
        }

        // Parse WITH options - can have two WITH clauses:
        // 1. WITH SYNC/ASYNC MODE (optional)
        // 2. WITH n BUCKETS (optional)
        // StarRocks syntax: WITH SYNC MODE WITH 5 BUCKETS
        let mut mode_str: Option<String> = None;
        let mut buckets_str: Option<String> = None;

        if self.match_token(TokenType::With) {
            if self.match_texts(&["SYNC", "ASYNC"]) {
                let mode = self.previous().text.to_uppercase();
                if self.match_text_seq(&["MODE"]) {
                    mode_str = Some(format!("WITH {} MODE", mode));
                }
                // Check for second WITH clause for buckets
                if self.match_token(TokenType::With) {
                    if let Some(num) = self.parse_number()? {
                        if self.match_text_seq(&["BUCKETS"]) {
                            let num_str = if let Expression::Literal(Literal::Number(n)) = &num {
                                n.clone()
                            } else {
                                String::new()
                            };
                            buckets_str = Some(format!("WITH {} BUCKETS", num_str));
                        }
                    }
                }
            } else if let Some(num) = self.parse_number()? {
                if self.match_text_seq(&["BUCKETS"]) {
                    let num_str = if let Expression::Literal(Literal::Number(n)) = &num {
                        n.clone()
                    } else {
                        String::new()
                    };
                    buckets_str = Some(format!("WITH {} BUCKETS", num_str));
                }
            }
        }

        // Combine mode and buckets into expression
        match (mode_str, buckets_str) {
            (Some(m), Some(b)) => {
                expression = Some(Box::new(Expression::Identifier(Identifier::new(format!(
                    "{} {}",
                    m, b
                )))));
            }
            (Some(m), None) => {
                expression = Some(Box::new(Expression::Identifier(Identifier::new(m))));
            }
            (None, Some(b)) => {
                expression = Some(Box::new(Expression::Identifier(Identifier::new(b))));
            }
            (None, None) => {}
        }

        // Parse AUTO UPDATE or MANUAL UPDATE (MySQL 8.0.27+)
        if self.match_texts(&["MANUAL", "AUTO"]) {
            let mode = self.previous().text.to_uppercase();
            if self.check(TokenType::Update) {
                update_options = Some(Box::new(Expression::Identifier(Identifier::new(mode))));
                self.advance(); // consume UPDATE
            }
        }

        Ok(Some(Expression::AnalyzeHistogram(Box::new(
            AnalyzeHistogram {
                this: Box::new(Expression::Identifier(Identifier::new(action))),
                expressions,
                expression,
                update_options,
            },
        ))))
    }

    /// parse_analyze_list - Parses ANALYZE LIST CHAINED ROWS
    /// Python: parser.py:8067-8070
    pub fn parse_analyze_list(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["CHAINED", "ROWS"]) {
            let expression = self.parse_into()?.map(Box::new);
            return Ok(Some(Expression::AnalyzeListChainedRows(Box::new(
                AnalyzeListChainedRows { expression },
            ))));
        }
        Ok(None)
    }

    /// parse_analyze_statistics - Parses ANALYZE ... STATISTICS
    /// Python: parser.py:8002-8031
    pub fn parse_analyze_statistics(&mut self) -> Result<Option<Expression>> {
        let kind = self.previous().text.to_uppercase();
        let option = if self.match_text_seq(&["DELTA"]) {
            Some(Box::new(Expression::Identifier(Identifier::new(
                "DELTA".to_string(),
            ))))
        } else {
            None
        };

        // Expect STATISTICS keyword
        if !self.match_text_seq(&["STATISTICS"]) {
            return Ok(None);
        }

        let mut this: Option<Box<Expression>> = None;
        let mut expressions = Vec::new();

        if self.match_text_seq(&["NOSCAN"]) {
            this = Some(Box::new(Expression::Identifier(Identifier::new(
                "NOSCAN".to_string(),
            ))));
        } else if self.match_token(TokenType::For) {
            if self.match_text_seq(&["ALL", "COLUMNS"]) {
                this = Some(Box::new(Expression::Identifier(Identifier::new(
                    "FOR ALL COLUMNS".to_string(),
                ))));
            } else if self.match_text_seq(&["COLUMNS"]) {
                this = Some(Box::new(Expression::Identifier(Identifier::new(
                    "FOR COLUMNS".to_string(),
                ))));
                // Parse column list
                loop {
                    if let Some(col) = self.parse_column_reference()? {
                        expressions.push(col);
                    } else {
                        break;
                    }
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
            }
        } else if self.match_text_seq(&["SAMPLE"]) {
            // Parse SAMPLE number [PERCENT]
            if let Some(sample) = self.parse_number()? {
                let sample_kind = if self.match_token(TokenType::Percent) {
                    Some("PERCENT".to_string())
                } else {
                    None
                };
                expressions.push(Expression::AnalyzeSample(Box::new(AnalyzeSample {
                    kind: sample_kind.unwrap_or_default(),
                    sample: Some(Box::new(sample)),
                })));
            }
        }

        Ok(Some(Expression::AnalyzeStatistics(Box::new(
            AnalyzeStatistics {
                kind,
                option,
                this,
                expressions,
            },
        ))))
    }

    /// parse_analyze_validate - Parses ANALYZE VALIDATE
    /// Python: parser.py:8034-8053
    pub fn parse_analyze_validate(&mut self) -> Result<Option<Expression>> {
        let mut kind = String::new();
        let mut this: Option<Box<Expression>> = None;
        let mut expression: Option<Box<Expression>> = None;

        if self.match_text_seq(&["REF", "UPDATE"]) {
            kind = "REF".to_string();
            this = Some(Box::new(Expression::Identifier(Identifier::new(
                "UPDATE".to_string(),
            ))));
            if self.match_text_seq(&["SET", "DANGLING", "TO", "NULL"]) {
                this = Some(Box::new(Expression::Identifier(Identifier::new(
                    "UPDATE SET DANGLING TO NULL".to_string(),
                ))));
            }
        } else if self.match_text_seq(&["STRUCTURE"]) {
            kind = "STRUCTURE".to_string();
            if self.match_text_seq(&["CASCADE", "FAST"]) {
                this = Some(Box::new(Expression::Identifier(Identifier::new(
                    "CASCADE FAST".to_string(),
                ))));
            } else if self.match_text_seq(&["CASCADE", "COMPLETE"]) {
                if self.match_texts(&["ONLINE", "OFFLINE"]) {
                    let mode = self.previous().text.to_uppercase();
                    this = Some(Box::new(Expression::Identifier(Identifier::new(format!(
                        "CASCADE COMPLETE {}",
                        mode
                    )))));
                    expression = self.parse_into()?.map(Box::new);
                }
            }
        }

        if kind.is_empty() {
            return Ok(None);
        }

        Ok(Some(Expression::AnalyzeValidate(Box::new(
            AnalyzeValidate {
                kind,
                this,
                expression,
            },
        ))))
    }

    /// parse_attach_detach - Parses ATTACH/DETACH statements (DuckDB)
    /// Python: DuckDB._parse_attach_detach
    pub fn parse_attach_detach(&mut self, is_attach: bool) -> Result<Expression> {
        // ATTACH [DATABASE] [IF NOT EXISTS] 'path' [AS alias] [(options)]
        // DETACH [DATABASE] [IF EXISTS] name
        // DATABASE can be tokenized as TokenType::Database (keyword), not just Var
        let _ = self.match_identifier("DATABASE") || self.match_token(TokenType::Database);

        let exists = if is_attach {
            self.match_text_seq(&["IF", "NOT", "EXISTS"])
        } else {
            self.match_text_seq(&["IF", "EXISTS"])
        };

        // Parse the expression (can be a path string, identifier, or expression like 'foo' || '.foo2'
        // or NOT EXISTS(subquery) for conditional attach)
        let this_expr = self.parse_expression()?;

        // Check for AS alias
        let this = if self.match_token(TokenType::As) {
            let alias = self.expect_identifier_or_keyword_with_quoted()?;
            Expression::Alias(Box::new(Alias {
                this: this_expr,
                alias,
                column_aliases: Vec::new(),
                pre_alias_comments: Vec::new(),
                trailing_comments: Vec::new(),
                inferred_type: None,
            }))
        } else {
            this_expr
        };

        if is_attach {
            // Parse optional (options)
            let expressions = if self.match_token(TokenType::LParen) {
                let mut opts = Vec::new();
                loop {
                    // Parse option: KEY [VALUE]
                    let key_name = self.advance().text.to_uppercase();
                    let key = Expression::Identifier(Identifier::new(key_name));
                    let value = if !self.check(TokenType::Comma) && !self.check(TokenType::RParen) {
                        // The value can be an identifier, string, boolean, etc.
                        let val_token = self.advance();
                        let val_expr = if val_token.token_type == TokenType::String {
                            Expression::Literal(Literal::String(val_token.text.clone()))
                        } else if val_token.token_type == TokenType::True {
                            Expression::Boolean(BooleanLiteral { value: true })
                        } else if val_token.token_type == TokenType::False {
                            Expression::Boolean(BooleanLiteral { value: false })
                        } else {
                            Expression::Identifier(Identifier::new(val_token.text.clone()))
                        };
                        Some(Box::new(val_expr))
                    } else {
                        None
                    };
                    opts.push(Expression::AttachOption(Box::new(AttachOption {
                        this: Box::new(key),
                        expression: value,
                    })));
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
                self.expect(TokenType::RParen)?;
                opts
            } else {
                Vec::new()
            };

            Ok(Expression::Attach(Box::new(Attach {
                this: Box::new(this),
                exists,
                expressions,
            })))
        } else {
            Ok(Expression::Detach(Box::new(Detach {
                this: Box::new(this),
                exists,
            })))
        }
    }

    /// parse_install - Parses INSTALL statement (DuckDB)
    /// Python: DuckDB._parse_install
    pub fn parse_install(&mut self, force: bool) -> Result<Expression> {
        // INSTALL extension [FROM source]
        let name = self.expect_identifier_or_keyword()?;
        let this = Expression::Identifier(Identifier::new(name));

        let from_ = if self.match_token(TokenType::From) {
            // FROM can be followed by a string or identifier
            Some(Box::new(self.parse_primary()?))
        } else {
            None
        };

        Ok(Expression::Install(Box::new(Install {
            this: Box::new(this),
            from_,
            force: if force {
                Some(Box::new(Expression::Boolean(BooleanLiteral {
                    value: true,
                })))
            } else {
                None
            },
        })))
    }

    /// parse_force_statement - Parses FORCE INSTALL/CHECKPOINT (DuckDB)
    /// Python: DuckDB._parse_force
    pub fn parse_force_statement(&mut self) -> Result<Expression> {
        if self.match_identifier("INSTALL") {
            return self.parse_install(true);
        }
        // FORCE CHECKPOINT or other: fallback to command
        self.parse_as_command()?
            .ok_or_else(|| self.parse_error("Failed to parse FORCE statement"))
    }

    /// parse_summarize_statement - Parses SUMMARIZE statement (DuckDB)
    /// Python: DuckDB parser for SUMMARIZE
    pub fn parse_summarize_statement(&mut self) -> Result<Expression> {
        // SUMMARIZE [TABLE] expression
        let is_table = self.match_token(TokenType::Table);

        // Try to parse a SELECT statement, string, or table reference
        let this = if self.check(TokenType::Select) || self.check(TokenType::With) {
            self.parse_select()?
        } else if self.check(TokenType::String) {
            self.parse_primary()?
        } else {
            // Parse as table name
            self.parse_table_parts()?
                .unwrap_or(Expression::Identifier(Identifier::new(String::new())))
        };

        Ok(Expression::Summarize(Box::new(Summarize {
            this: Box::new(this),
            table: if is_table {
                Some(Box::new(Expression::Boolean(BooleanLiteral {
                    value: true,
                })))
            } else {
                None
            },
        })))
    }

    /// parse_deallocate_prepare - Parses DEALLOCATE PREPARE <name>
    /// Presto/Trino syntax for deallocating prepared statements
    pub fn parse_deallocate_prepare(&mut self) -> Result<Expression> {
        self.advance(); // consume DEALLOCATE

        // Check for PREPARE keyword
        if self.match_identifier("PREPARE") {
            // Parse the statement name
            let name = if !self.is_at_end() && !self.check(TokenType::Semicolon) {
                self.advance().text.clone()
            } else {
                String::new()
            };

            // Build the command text
            let command_text = if name.is_empty() {
                "DEALLOCATE PREPARE".to_string()
            } else {
                format!("DEALLOCATE PREPARE {}", name)
            };

            Ok(Expression::Command(Box::new(Command {
                this: command_text,
            })))
        } else {
            // Just DEALLOCATE without PREPARE - consume rest as command
            let mut parts = vec!["DEALLOCATE".to_string()];
            while !self.is_at_end() && !self.check(TokenType::Semicolon) {
                let token = self.advance();
                parts.push(token.text.clone());
            }
            Ok(Expression::Command(Box::new(Command {
                this: parts.join(" "),
            })))
        }
    }

    /// parse_as_command - Creates Command expression
    #[allow(unused_variables, unused_mut)]
    /// parse_as_command - Parses remaining tokens as a raw command
    /// Python: _parse_as_command
    /// Used as fallback when specific parsing fails
    pub fn parse_as_command(&mut self) -> Result<Option<Expression>> {
        // Get the starting token text
        let start_text = if self.current > 0 {
            self.tokens
                .get(self.current - 1)
                .map(|t| t.text.clone())
                .unwrap_or_default()
        } else {
            String::new()
        };

        // Consume all remaining tokens, storing both text and type
        let mut tokens_info: Vec<(String, TokenType)> = Vec::new();
        while !self.is_at_end() {
            let token = self.advance();
            tokens_info.push((token.text.clone(), token.token_type.clone()));
        }

        // Join tokens intelligently, avoiding spaces around punctuation
        let mut expression = String::new();
        for (i, (text, token_type)) in tokens_info.iter().enumerate() {
            if i > 0 {
                // Check if we should add a space before this token
                let prev_type = &tokens_info[i - 1].1;
                let needs_space = !Self::is_punctuation_token(prev_type)
                    && !Self::is_punctuation_token(token_type);
                if needs_space {
                    expression.push(' ');
                }
            }
            expression.push_str(text);
        }

        Ok(Some(Expression::Command(Box::new(Command {
            this: if expression.is_empty() {
                start_text
            } else {
                format!("{} {}", start_text, expression)
            },
        }))))
    }

    /// Helper to determine if a token type is punctuation that shouldn't have spaces around it
    fn is_punctuation_token(token_type: &TokenType) -> bool {
        matches!(
            token_type,
            TokenType::Dot | TokenType::Colon | TokenType::DColon
        )
    }

    /// Fallback to Command expression from a saved position.
    /// Extracts verbatim SQL text from source if available, consuming tokens until semicolon/EOF.
    fn fallback_to_command(&mut self, start_pos: usize) -> Result<Expression> {
        let start_span = self.tokens[start_pos].span.start;
        // Consume until semicolon or end
        while !self.is_at_end() && !self.check(TokenType::Semicolon) {
            self.advance();
        }
        let command_text = if let Some(ref source) = self.source {
            let end_span = if self.current > 0 {
                self.tokens[self.current - 1].span.end
            } else {
                start_span
            };
            source[start_span..end_span].trim().to_string()
        } else {
            // Fallback: join token texts
            let mut parts = Vec::new();
            for i in start_pos..self.current {
                if self.tokens[i].token_type == TokenType::String {
                    parts.push(format!("'{}'", self.tokens[i].text.replace('\'', "''")));
                } else {
                    parts.push(self.tokens[i].text.clone());
                }
            }
            parts.join(" ")
        };
        Ok(Expression::Command(Box::new(Command {
            this: command_text,
        })))
    }

    /// parse_assignment - Parses assignment expressions (variable := value)
    /// Python: _parse_assignment
    pub fn parse_assignment(&mut self) -> Result<Option<Expression>> {
        // First parse a disjunction (left side of potential assignment)
        let mut this = self.parse_disjunction()?;

        // Handle := assignment operator
        while self.match_token(TokenType::ColonEq) {
            if let Some(left) = this {
                let right = self.parse_assignment()?;
                if let Some(right_expr) = right {
                    this = Some(Expression::PropertyEQ(Box::new(BinaryOp {
                        left,
                        right: right_expr,
                        left_comments: Vec::new(),
                        operator_comments: Vec::new(),
                        trailing_comments: Vec::new(),
                        inferred_type: None,
                    })));
                } else {
                    this = Some(left);
                    break;
                }
            } else {
                break;
            }
        }

        // ClickHouse ternary operator: condition ? true_value : false_value
        // Parsed as: If(this=condition, true=true_value, false=false_value)
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) {
            if let Some(condition) = this {
                if self.match_token(TokenType::Parameter) {
                    if self.check(TokenType::Colon) {
                        return Err(self.parse_error(
                            "Expected true expression after ? in ClickHouse ternary",
                        ));
                    }
                    let true_value = self.parse_assignment()?.ok_or_else(|| {
                        self.parse_error("Expected true expression after ? in ClickHouse ternary")
                    })?;
                    let false_value = if self.match_token(TokenType::Colon) {
                        self.parse_assignment()?.unwrap_or(Expression::Null(Null))
                    } else {
                        Expression::Null(Null)
                    };
                    return Ok(Some(Expression::IfFunc(Box::new(IfFunc {
                        original_name: None,
                        condition,
                        true_value,
                        false_value: Some(false_value),
                        inferred_type: None,
                    }))));
                }
                this = Some(condition);
            }
        }

        Ok(this)
    }

    /// parse_auto_increment - Implemented from Python _parse_auto_increment
    /// Calls: parse_bitwise
    #[allow(unused_variables, unused_mut)]
    pub fn parse_auto_increment(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["START"]) {
            return Ok(Some(Expression::GeneratedAsIdentityColumnConstraint(
                Box::new(GeneratedAsIdentityColumnConstraint {
                    this: None,
                    expression: None,
                    on_null: None,
                    start: None,
                    increment: None,
                    minvalue: None,
                    maxvalue: None,
                    cycle: None,
                    order: None,
                }),
            )));
        }
        if self.match_text_seq(&["INCREMENT"]) {
            // Matched: INCREMENT
            return Ok(None);
        }
        if self.match_text_seq(&["ORDER"]) {
            // Matched: ORDER
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_auto_property - Implemented from Python _parse_auto_property
    #[allow(unused_variables, unused_mut)]
    pub fn parse_auto_property(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["REFRESH"]) {
            // Matched: REFRESH
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_between - Implemented from Python _parse_between
    #[allow(unused_variables, unused_mut)]
    pub fn parse_between(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["SYMMETRIC"]) {
            // Matched: SYMMETRIC
            return Ok(None);
        }
        if self.match_text_seq(&["ASYMMETRIC"]) {
            // Matched: ASYMMETRIC
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_bitwise - Parses bitwise OR/XOR/AND expressions
    /// Python: _parse_bitwise
    /// Delegates to the existing parse_bitwise_or in the operator precedence chain
    pub fn parse_bitwise(&mut self) -> Result<Option<Expression>> {
        let start = self.current;
        match self.parse_bitwise_or() {
            Ok(expr) => Ok(Some(expr)),
            Err(_err) if self.current == start => Ok(None),
            Err(err) => Err(err),
        }
    }

    /// parse_blockcompression - Implemented from Python _parse_blockcompression
    #[allow(unused_variables, unused_mut)]
    pub fn parse_blockcompression(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["ALWAYS"]) {
            return Ok(Some(Expression::BlockCompressionProperty(Box::new(
                BlockCompressionProperty {
                    autotemp: None,
                    always: None,
                    default: None,
                    manual: None,
                    never: None,
                },
            ))));
        }
        if self.match_text_seq(&["MANUAL"]) {
            // Matched: MANUAL
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_boolean - Parse boolean literal (TRUE/FALSE)
    /// Python: if self._match(TokenType.TRUE): return exp.Boolean(this=True)
    pub fn parse_boolean(&mut self) -> Result<Option<Expression>> {
        if self.match_token(TokenType::True) {
            return Ok(Some(Expression::Boolean(BooleanLiteral { value: true })));
        }
        if self.match_token(TokenType::False) {
            return Ok(Some(Expression::Boolean(BooleanLiteral { value: false })));
        }
        Ok(None)
    }

    /// parse_bracket - Ported from Python _parse_bracket
    /// Parses bracket expressions: array[index], array literal [1,2,3], or struct {key: value}
    #[allow(unused_variables, unused_mut)]
    pub fn parse_bracket(&mut self) -> Result<Option<Expression>> {
        self.parse_bracket_with_expr(None)
    }

    /// parse_bracket_with_expr - Parses bracket with optional left-side expression
    fn parse_bracket_with_expr(&mut self, this: Option<Expression>) -> Result<Option<Expression>> {
        // Check for [ or {
        let is_bracket = self.match_token(TokenType::LBracket);
        let is_brace = if !is_bracket {
            self.match_token(TokenType::LBrace)
        } else {
            false
        };

        if !is_bracket && !is_brace {
            return Ok(this);
        }

        // Parse comma-separated expressions inside brackets
        let mut expressions: Vec<Expression> = Vec::new();

        if is_bracket && !self.check(TokenType::RBracket) {
            // Check for slice syntax at the start: [:...] or [:-...]
            // This needs to be detected before parse_bracket_key_value which calls parse_primary
            // and parse_primary would consume : as a parameter prefix
            let first_expr = if self.check(TokenType::Colon) {
                // This is slice syntax like [:] or [:-1] or [::step]
                // Parse it using slice parser with no 'this'
                if let Some(slice) = self.parse_slice()? {
                    slice
                } else {
                    self.parse_expression()?
                }
            } else if let Ok(Some(expr)) = self.parse_bracket_key_value() {
                expr
            } else {
                // Parse regular expression and check for slice
                let expr = self.parse_expression()?;
                // Check if followed by colon (slice syntax like [start:end])
                if self.check(TokenType::Colon) {
                    if let Some(slice) = self.parse_slice_with_this(Some(expr))? {
                        slice
                    } else {
                        return Err(self.parse_error("Failed to parse slice"));
                    }
                } else {
                    expr
                }
            };

            // Check for comprehension syntax: [expr FOR var IN iterator [IF condition]]
            if self.match_token(TokenType::For) {
                // Parse loop variable - typically a simple identifier like 'x'
                let loop_var = self.parse_primary()?;

                // Parse optional position (second variable after comma)
                let position = if self.match_token(TokenType::Comma) {
                    Some(self.parse_primary()?)
                } else {
                    None
                };

                // Expect IN keyword
                if !self.match_token(TokenType::In) {
                    return Err(self.parse_error("Expected IN in comprehension"));
                }

                // Parse iterator expression
                let iterator = self.parse_expression()?;

                // Parse optional condition after IF
                let condition = if self.match_token(TokenType::If) {
                    Some(self.parse_expression()?)
                } else {
                    None
                };

                // Expect closing bracket
                self.expect(TokenType::RBracket)?;

                // Return Comprehension wrapped in an expression
                return Ok(Some(Expression::Comprehension(Box::new(Comprehension {
                    this: Box::new(first_expr),
                    expression: Box::new(loop_var),
                    position: position.map(Box::new),
                    iterator: Some(Box::new(iterator)),
                    condition: condition.map(Box::new),
                }))));
            }

            expressions.push(first_expr);

            // Continue parsing remaining expressions
            while self.match_token(TokenType::Comma) {
                if let Ok(Some(expr)) = self.parse_bracket_key_value() {
                    expressions.push(expr);
                } else {
                    match self.parse_expression() {
                        Ok(expr) => expressions.push(expr),
                        Err(_) => break,
                    }
                }
            }
        } else if is_brace && !self.check(TokenType::RBrace) {
            loop {
                if let Ok(Some(expr)) = self.parse_bracket_key_value() {
                    expressions.push(expr);
                } else {
                    match self.parse_expression() {
                        Ok(expr) => expressions.push(expr),
                        Err(_) => break,
                    }
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
        }

        // Expect closing bracket
        if is_bracket {
            self.expect(TokenType::RBracket)?;
        } else if is_brace {
            self.expect(TokenType::RBrace)?;
        }

        // Build the result
        if is_brace {
            // Struct literal: {key: value, ...}
            // Convert expressions to (Option<name>, expr) pairs
            let fields: Vec<(Option<String>, Expression)> =
                expressions.into_iter().map(|e| (None, e)).collect();
            Ok(Some(Expression::Struct(Box::new(Struct { fields }))))
        } else if let Some(base_expr) = this {
            // Subscript access: base[index]
            if expressions.len() == 1 {
                Ok(Some(Expression::Subscript(Box::new(Subscript {
                    this: base_expr,
                    index: expressions.remove(0),
                }))))
            } else {
                // Multiple indices - create nested subscripts or array
                let mut result = base_expr;
                for expr in expressions {
                    result = Expression::Subscript(Box::new(Subscript {
                        this: result,
                        index: expr,
                    }));
                }
                Ok(Some(result))
            }
        } else {
            // Array literal: [1, 2, 3]
            Ok(Some(Expression::Array(Box::new(Array { expressions }))))
        }
    }

    /// parse_bracket_key_value - Ported from Python _parse_bracket_key_value
    /// Parses key-value pairs in brackets: key: value or key => value
    #[allow(unused_variables, unused_mut)]
    pub fn parse_bracket_key_value(&mut self) -> Result<Option<Expression>> {
        let saved_pos = self.current;

        // Try to parse as key: value or key => value
        if let Ok(key) = self.parse_primary() {
            // Check for : or =>
            if self.match_token(TokenType::Colon) || self.match_text_seq(&["=>"]) {
                match self.parse_expression() {
                    Ok(value) => {
                        // Return as NamedArgument for key-value pair
                        // Extract the name from the key (identifier or string literal)
                        let name = match &key {
                            Expression::Identifier(id) => id.clone(),
                            Expression::Literal(crate::expressions::Literal::String(s)) => {
                                Identifier::new(s.clone())
                            }
                            _ => Identifier::new("".to_string()),
                        };
                        return Ok(Some(Expression::NamedArgument(Box::new(NamedArgument {
                            name,
                            value,
                            separator: NamedArgSeparator::DArrow, // Using DArrow for colon-style key: value
                        }))));
                    }
                    Err(_) => {
                        self.current = saved_pos;
                        return Ok(None);
                    }
                }
            }
            self.current = saved_pos;
        }

        Ok(None)
    }

    /// parse_ceil_floor - Implemented from Python _parse_ceil_floor
    /// Calls: parse_lambda, parse_var
    #[allow(unused_variables, unused_mut)]
    pub fn parse_ceil_floor(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["TO"]) {
            // Matched: TO
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_changes - Implemented from Python _parse_changes
    /// Parses: CHANGES(INFORMATION => var) AT|BEFORE(...) END(...)
    pub fn parse_changes(&mut self) -> Result<Option<Expression>> {
        // Match: CHANGES(INFORMATION =>
        if !self.match_text_seq(&["CHANGES", "(", "INFORMATION", "=>"]) {
            return Ok(None);
        }

        // Parse information (any token as var)
        let information = self.parse_var()?.map(Box::new);

        // Match closing paren
        self.match_token(TokenType::RParen);

        // Parse at_before (Snowflake AT/BEFORE clause)
        let at_before = self.parse_historical_data()?.map(Box::new);

        // Parse end (optional second historical data clause)
        let end = self.parse_historical_data()?.map(Box::new);

        Ok(Some(Expression::Changes(Box::new(Changes {
            information,
            at_before,
            end,
        }))))
    }

    /// parse_char - Parses CHAR/CHR function with optional USING charset
    /// Python: CHAR(args...) [USING charset]
    /// MySQL: CHAR(n1, n2, ... USING charset)
    pub fn parse_char(&mut self) -> Result<Option<Expression>> {
        // Parse expressions inside CHAR()
        let mut args = Vec::new();
        loop {
            let expr = self.parse_expression()?;
            args.push(expr);
            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        // Check for USING charset
        let charset = if self.match_token(TokenType::Using) {
            self.parse_var()?.map(|v| {
                if let Expression::Identifier(id) = v {
                    id.name
                } else {
                    String::new()
                }
            })
        } else {
            None
        };

        if args.is_empty() {
            return Ok(None);
        }

        // If there's a charset or multiple args, use CharFunc (MySQL-style)
        // Otherwise use simple Chr for single-arg CHR function
        if charset.is_some() || args.len() > 1 {
            Ok(Some(Expression::CharFunc(Box::new(
                crate::expressions::CharFunc {
                    args,
                    charset,
                    name: None, // defaults to CHAR
                },
            ))))
        } else {
            Ok(Some(Expression::Chr(Box::new(UnaryFunc::new(
                args.into_iter().next().unwrap(),
            )))))
        }
    }

    /// parse_character_set - Ported from Python _parse_character_set
    #[allow(unused_variables, unused_mut)]
    /// parse_character_set - Parses CHARACTER SET property
    /// Example: CHARACTER SET = utf8 or CHARACTER SET utf8mb4
    pub fn parse_character_set(&mut self) -> Result<Option<Expression>> {
        // Optional = sign
        self.match_token(TokenType::Eq);

        // Parse the charset name (variable or string)
        let charset = self.parse_var_or_string()?;
        if charset.is_none() {
            return Ok(None);
        }

        Ok(Some(Expression::CharacterSetProperty(Box::new(
            CharacterSetProperty {
                this: Box::new(charset.unwrap()),
                default: None,
            },
        ))))
    }

    /// parse_checksum - Implemented from Python _parse_checksum
    #[allow(unused_variables, unused_mut)]
    pub fn parse_checksum(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["OFF"]) {
            return Ok(Some(Expression::ChecksumProperty(Box::new(
                ChecksumProperty {
                    on: None,
                    default: None,
                },
            ))));
        }
        Ok(None)
    }

    /// parse_cluster - CLUSTER BY clause for Hive/Spark-style queries
    /// Parses a list of ordered expressions (columns with optional ASC/DESC)
    #[allow(unused_variables, unused_mut)]
    pub fn parse_cluster(&mut self) -> Result<Option<Expression>> {
        let mut expressions: Vec<Ordered> = Vec::new();

        loop {
            // Parse an ordered expression (column with optional direction)
            if let Some(ordered) = self.parse_ordered_item()? {
                expressions.push(ordered);
            } else {
                break;
            }

            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        if expressions.is_empty() {
            return Ok(None);
        }

        Ok(Some(Expression::ClusterBy(Box::new(ClusterBy {
            expressions,
        }))))
    }

    /// parse_clustered_by - Implemented from Python _parse_clustered_by
    #[allow(unused_variables, unused_mut)]
    pub fn parse_clustered_by(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["BY"]) {
            return Ok(Some(Expression::ClusteredByProperty(Box::new(
                ClusteredByProperty {
                    expressions: Vec::new(),
                    sorted_by: None,
                    buckets: None,
                },
            ))));
        }
        if self.match_text_seq(&["SORTED", "BY"]) {
            // Matched: SORTED BY
            return Ok(None);
        }
        Ok(None)
    }

    /// Parse Snowflake colon JSON path extraction: data:field or data:field.subfield
    /// Python: def _parse_colon_as_variant_extract(self, this)
    pub fn parse_colon_as_variant_extract(
        &mut self,
        this: Expression,
    ) -> Result<Option<Expression>> {
        // Build a JSON path from colon-separated identifiers
        // Track whether each segment was quoted (needs bracket notation for spaces/special chars)
        let mut json_path: Vec<(String, bool)> = Vec::new();

        while self.match_token(TokenType::Colon) {
            // Parse the path segment (field name)
            if let Some(field) = self.parse_identifier()? {
                if let Expression::Identifier(ident) = field {
                    json_path.push((
                        ident.name.clone(),
                        ident.quoted || ident.name.contains(' ') || ident.name.contains('\''),
                    ));
                }
            }

            // Check for dot-separated sub-paths
            while self.match_token(TokenType::Dot) {
                if let Some(subfield) = self.parse_identifier()? {
                    if let Expression::Identifier(ident) = subfield {
                        json_path.push((
                            ident.name.clone(),
                            ident.quoted || ident.name.contains(' ') || ident.name.contains('\''),
                        ));
                    }
                }
            }
        }

        if json_path.is_empty() {
            return Ok(Some(this));
        }

        // Build the JSON path expression string
        // Use bracket notation for segments with spaces/special chars: a["b c"]
        // Use dot notation for simple segments: a.b.c
        let mut path_str = String::new();
        for (i, (segment, needs_bracket)) in json_path.iter().enumerate() {
            if *needs_bracket {
                // Bracket notation: ["key with spaces"]
                path_str.push('[');
                path_str.push('"');
                path_str.push_str(segment);
                path_str.push('"');
                path_str.push(']');
            } else {
                if i > 0 {
                    path_str.push('.');
                }
                path_str.push_str(segment);
            }
        }

        Ok(Some(Expression::JSONExtract(Box::new(JSONExtract {
            this: Box::new(this),
            expression: Box::new(Expression::Literal(Literal::String(path_str))),
            only_json_types: None,
            expressions: Vec::new(),
            variant_extract: Some(Box::new(Expression::Boolean(BooleanLiteral {
                value: true,
            }))),
            json_query: None,
            option: None,
            quote: None,
            on_condition: None,
            requires_json: None,
        }))))
    }

    /// parse_column - Parse column expression
    /// Python: this = self._parse_column_reference(); return self._parse_column_ops(this)
    pub fn parse_column(&mut self) -> Result<Option<Expression>> {
        // Parse column reference (field name that becomes a Column expression)
        let column_ref = self.parse_column_reference()?;
        if column_ref.is_some() {
            // Apply column ops (bracket subscript, property access with dots, casts)
            return self.parse_column_ops_with_expr(column_ref);
        }
        // Try parsing bracket directly if no column reference
        self.parse_bracket()
    }

    /// parse_column_constraint - Ported from Python _parse_column_constraint
    /// Parses column-level constraints like NOT NULL, PRIMARY KEY, UNIQUE, DEFAULT, CHECK, etc.
    #[allow(unused_variables, unused_mut)]
    pub fn parse_column_constraint(&mut self) -> Result<Option<Expression>> {
        // Check for optional CONSTRAINT keyword and name
        let constraint_name = if self.match_token(TokenType::Constraint) {
            self.parse_id_var()?.and_then(|e| {
                if let Expression::Identifier(id) = e {
                    Some(id)
                } else {
                    None
                }
            })
        } else {
            None
        };

        // NOT NULL
        if self.match_text_seq(&["NOT", "NULL"]) {
            return Ok(Some(Expression::NotNullColumnConstraint(Box::new(
                NotNullColumnConstraint { allow_null: None },
            ))));
        }

        // NOT FOR REPLICATION (SQL Server) - must be before NULL check
        if self.match_text_seq(&["NOT", "FOR", "REPLICATION"]) {
            return Ok(Some(Expression::Property(Box::new(
                crate::expressions::Property {
                    this: Box::new(Expression::Identifier(Identifier::new(
                        "NOT FOR REPLICATION".to_string(),
                    ))),
                    value: None,
                },
            ))));
        }

        // NULL
        if self.match_text_seq(&["NULL"]) {
            return Ok(Some(Expression::NotNullColumnConstraint(Box::new(
                NotNullColumnConstraint {
                    allow_null: Some(Box::new(Expression::Boolean(BooleanLiteral {
                        value: true,
                    }))),
                },
            ))));
        }

        // PRIMARY KEY
        if self.match_text_seq(&["PRIMARY", "KEY"]) {
            return Ok(Some(Expression::PrimaryKeyColumnConstraint(Box::new(
                PrimaryKeyColumnConstraint {
                    desc: None,
                    options: Vec::new(),
                },
            ))));
        }

        // UNIQUE
        if self.match_text_seq(&["UNIQUE"]) {
            // Check for optional KEY/INDEX
            let _ = self.match_texts(&["KEY", "INDEX"]);
            // Check for NULLS NOT DISTINCT (PostgreSQL 15+ feature)
            let nulls = if self.match_text_seq(&["NULLS", "NOT", "DISTINCT"]) {
                Some(Box::new(Expression::Boolean(BooleanLiteral {
                    value: true,
                })))
            } else {
                None
            };
            return Ok(Some(Expression::UniqueColumnConstraint(Box::new(
                UniqueColumnConstraint {
                    this: None,
                    index_type: None,
                    on_conflict: None,
                    nulls,
                    options: Vec::new(),
                },
            ))));
        }

        // DEFAULT
        if self.match_text_seq(&["DEFAULT"]) {
            let default_value = self.parse_select_or_expression()?;
            if let Some(val) = default_value {
                return Ok(Some(Expression::DefaultColumnConstraint(Box::new(
                    DefaultColumnConstraint {
                        this: Box::new(val),
                    },
                ))));
            }
            return Ok(None);
        }

        // CHECK
        if self.match_text_seq(&["CHECK"]) {
            if self.match_token(TokenType::LParen) {
                let expr = self.parse_select_or_expression()?;
                self.match_token(TokenType::RParen);
                if let Some(check_expr) = expr {
                    return Ok(Some(Expression::CheckColumnConstraint(Box::new(
                        CheckColumnConstraint {
                            this: Box::new(check_expr),
                            enforced: None,
                        },
                    ))));
                }
            }
            return Ok(None);
        }

        // REFERENCES (foreign key)
        if self.match_text_seq(&["REFERENCES"]) {
            let table = self.parse_table_parts()?;
            let columns = if self.match_token(TokenType::LParen) {
                let mut cols = Vec::new();
                loop {
                    if let Some(col) = self.parse_id_var()? {
                        cols.push(col);
                    }
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
                self.match_token(TokenType::RParen);
                cols
            } else {
                Vec::new()
            };

            return Ok(Some(Expression::ForeignKey(Box::new(ForeignKey {
                expressions: columns,
                reference: table.map(Box::new),
                delete: None,
                update: None,
                options: Vec::new(),
            }))));
        }

        // AUTO_INCREMENT / AUTOINCREMENT / IDENTITY
        if self.match_texts(&["AUTO_INCREMENT", "AUTOINCREMENT", "IDENTITY"]) {
            // Check for IDENTITY(start, increment) or IDENTITY START x INCREMENT y syntax
            let mut start = None;
            let mut increment = None;

            if self.match_token(TokenType::LParen) {
                // Parse (start, increment)
                start = self.parse_bitwise()?;
                if self.match_token(TokenType::Comma) {
                    increment = self.parse_bitwise()?;
                }
                self.expect(TokenType::RParen)?;
            } else if self.match_text_seq(&["START"]) {
                // Parse START x INCREMENT y
                start = self.parse_bitwise()?;
                if self.match_text_seq(&["INCREMENT"]) {
                    increment = self.parse_bitwise()?;
                }
            }

            if start.is_some() || increment.is_some() {
                return Ok(Some(Expression::GeneratedAsIdentityColumnConstraint(
                    Box::new(GeneratedAsIdentityColumnConstraint {
                        this: Some(Box::new(Expression::Boolean(BooleanLiteral {
                            value: false,
                        }))),
                        expression: None,
                        on_null: None,
                        start: start.map(Box::new),
                        increment: increment.map(Box::new),
                        minvalue: None,
                        maxvalue: None,
                        cycle: None,
                        order: None,
                    }),
                )));
            }
            return Ok(Some(Expression::AutoIncrementColumnConstraint(
                AutoIncrementColumnConstraint,
            )));
        }

        // COMMENT 'text' - CommentColumnConstraint is a unit struct, use a different expression
        if self.match_text_seq(&["COMMENT"]) {
            if let Some(comment) = self.parse_string()? {
                // Use CommentColumnConstraint unit struct
                return Ok(Some(Expression::CommentColumnConstraint(
                    CommentColumnConstraint,
                )));
            }
            return Ok(None);
        }

        // COLLATE collation_name - use CollateProperty instead
        if self.match_text_seq(&["COLLATE"]) {
            if let Some(collation) = self.parse_id_var()? {
                return Ok(Some(Expression::CollateProperty(Box::new(
                    CollateProperty {
                        this: Box::new(collation),
                        default: None,
                    },
                ))));
            }
            return Ok(None);
        }

        // ClickHouse dictionary column attributes: HIERARCHICAL, IS_OBJECT_ID, INJECTIVE
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) {
            if self.match_texts(&["HIERARCHICAL", "IS_OBJECT_ID", "INJECTIVE"]) {
                let attr_name = self.previous().text.to_uppercase();
                return Ok(Some(Expression::Property(Box::new(
                    crate::expressions::Property {
                        this: Box::new(Expression::Identifier(Identifier::new(attr_name))),
                        value: None,
                    },
                ))));
            }
            // ClickHouse EXPRESSION expr and ALIAS expr (dictionary column attributes)
            if self.match_texts(&["EXPRESSION"]) {
                let expr = self.parse_expression()?;
                return Ok(Some(Expression::DefaultColumnConstraint(Box::new(
                    DefaultColumnConstraint {
                        this: Box::new(expr),
                    },
                ))));
            }
        }

        // GENERATED ... AS IDENTITY
        if self.match_text_seq(&["GENERATED"]) {
            let always = self.match_text_seq(&["ALWAYS"]);
            if !always {
                self.match_text_seq(&["BY", "DEFAULT"]);
            }
            let on_null = self.match_text_seq(&["ON", "NULL"]);
            if self.match_text_seq(&["AS", "IDENTITY"]) {
                return Ok(Some(Expression::GeneratedAsIdentityColumnConstraint(
                    Box::new(GeneratedAsIdentityColumnConstraint {
                        this: None,
                        expression: None,
                        on_null: if on_null {
                            Some(Box::new(Expression::Boolean(BooleanLiteral {
                                value: true,
                            })))
                        } else {
                            None
                        },
                        start: None,
                        increment: None,
                        minvalue: None,
                        maxvalue: None,
                        cycle: None,
                        order: None,
                    }),
                )));
            }
            return Ok(None);
        }

        // PATH 'xpath' - for XMLTABLE/JSON_TABLE columns
        if self.match_text_seq(&["PATH"]) {
            if let Some(path_expr) = self.parse_string()? {
                return Ok(Some(Expression::PathColumnConstraint(Box::new(
                    PathColumnConstraint {
                        this: Box::new(path_expr),
                    },
                ))));
            }
            return Ok(None);
        }

        // Return the constraint name if we matched CONSTRAINT but no actual constraint
        if let Some(name) = constraint_name {
            return Ok(Some(Expression::Identifier(name)));
        }

        Ok(None)
    }

    /// parse_column_def_with_exists - Ported from Python _parse_column_def_with_exists
    /// Parses a column definition with optional IF [NOT] EXISTS clause
    #[allow(unused_variables, unused_mut)]
    pub fn parse_column_def_with_exists(&mut self) -> Result<Option<Expression>> {
        let start = self.current;

        // Optionally match COLUMN keyword
        let _ = self.match_text_seq(&["COLUMN"]);

        // Check for IF NOT EXISTS
        let not_exists = self.match_text_seq(&["IF", "NOT", "EXISTS"]);
        let exists = if !not_exists {
            self.match_text_seq(&["IF", "EXISTS"])
        } else {
            false
        };

        // Parse the field definition
        let expression = self.parse_field_def()?;

        if expression.is_none() {
            self.current = start;
            return Ok(None);
        }

        // If it's a ColumnDef, we're good
        if let Some(Expression::ColumnDef(ref _col_def)) = expression {
            // The exists flag would be set on the ColumnDef, but our struct doesn't have that field
            // Just return the expression as-is
            return Ok(expression);
        }

        // Not a ColumnDef, backtrack
        self.current = start;
        Ok(None)
    }

    /// parse_column_ops - Parses column operations (stub for compatibility)
    pub fn parse_column_ops(&mut self) -> Result<Option<Expression>> {
        self.parse_column_ops_with_expr(None)
    }

    /// parse_column_ops_with_expr - Parses column operations (dot access, brackets, casts)
    /// Python: _parse_column_ops(this)
    pub fn parse_column_ops_with_expr(
        &mut self,
        this: Option<Expression>,
    ) -> Result<Option<Expression>> {
        // First apply any bracket subscripts
        let mut result = if let Some(expr) = this {
            if self.match_token(TokenType::LBracket) {
                let index = self.parse_disjunction()?;
                self.match_token(TokenType::RBracket);
                if let Some(idx) = index {
                    Some(Expression::Subscript(Box::new(Subscript {
                        this: expr,
                        index: idx,
                    })))
                } else {
                    Some(expr)
                }
            } else {
                Some(expr)
            }
        } else {
            None
        };

        // Handle DOT for qualified column names: table.column or schema.table.column
        while self.match_token(TokenType::Dot) {
            if result.is_none() {
                break;
            }
            // Handle .* (qualified star) with modifiers
            if self.match_token(TokenType::Star) {
                // Determine table name from the expression
                let table_name = match &result {
                    Some(Expression::Column(col)) if col.table.is_none() => Some(col.name.clone()),
                    Some(Expression::Dot(dot)) => {
                        // For deep qualified names like schema.table.*, use the whole expression name
                        fn dot_to_name(expr: &Expression) -> String {
                            match expr {
                                Expression::Column(col) => {
                                    if let Some(ref table) = col.table {
                                        format!("{}.{}", table.name, col.name.name)
                                    } else {
                                        col.name.name.clone()
                                    }
                                }
                                Expression::Dot(d) => {
                                    format!("{}.{}", dot_to_name(&d.this), d.field.name)
                                }
                                _ => String::new(),
                            }
                        }
                        Some(Identifier::new(dot_to_name(&Expression::Dot(dot.clone()))))
                    }
                    _ => None,
                };
                let star = self.parse_star_modifiers(table_name)?;
                result = Some(Expression::Star(star));
                break;
            }
            // Parse the field identifier - use is_identifier_or_keyword_token to allow keywords
            // like "schema" as field names in dot access
            // ClickHouse: also allow numeric tuple index access like expr.1, expr.2
            if self.is_identifier_or_keyword_token()
                || self.check(TokenType::QuotedIdentifier)
                || (matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) && self.check(TokenType::Number))
            {
                let token = self.advance();
                let field_ident = Identifier {
                    name: token.text,
                    quoted: token.token_type == TokenType::QuotedIdentifier,
                    trailing_comments: Vec::new(),
                    span: None,
                };
                result = Some(Expression::Dot(Box::new(DotAccess {
                    this: result.take().unwrap(),
                    field: field_ident,
                })));
            } else {
                break;
            }
        }

        // Handle EXCLAMATION for Snowflake model attribute syntax: model!PREDICT(...)
        if self.match_token(TokenType::Exclamation) {
            if let Some(expr) = result.take() {
                // Parse the attribute/function after the exclamation mark
                // This can be either a simple identifier (model!admin) or a function call (model!PREDICT(1))
                let attr = self.parse_unary()?;
                result = Some(Expression::ModelAttribute(Box::new(ModelAttribute {
                    this: Box::new(expr),
                    expression: Box::new(attr),
                })));
            }
        }

        // Handle DCOLON for casts (PostgreSQL syntax: column::type)
        if self.match_token(TokenType::DColon) {
            if let Some(type_expr) = self.parse_types()? {
                if let Some(expr) = result {
                    // Extract DataType from the expression
                    let data_type = match type_expr {
                        Expression::DataType(dt) => dt,
                        _ => {
                            result = Some(expr);
                            return Ok(result);
                        }
                    };
                    result = Some(Expression::Cast(Box::new(Cast {
                        this: expr,
                        to: data_type,
                        trailing_comments: Vec::new(),
                        double_colon_syntax: true,
                        format: None,
                        default: None,
                        inferred_type: None,
                    })));
                }
            }
        }

        // Teradata: (FORMAT '...') phrase after a column/expression
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::Teradata)
        ) && self.check(TokenType::LParen)
            && self.check_next(TokenType::Format)
        {
            self.advance(); // consume (
            self.advance(); // consume FORMAT
            let format = self.expect_string()?;
            self.expect(TokenType::RParen)?;
            if let Some(expr) = result.take() {
                result = Some(Expression::FormatPhrase(Box::new(FormatPhrase {
                    this: Box::new(expr),
                    format,
                })));
            }
        }

        Ok(result)
    }

    /// parse_column_reference - Parse column reference (field -> Column)
    /// Python: this = self._parse_field(); if isinstance(this, exp.Identifier): return exp.Column(this=this)
    pub fn parse_column_reference(&mut self) -> Result<Option<Expression>> {
        // Parse the field (identifier or literal)
        if let Some(field) = self.parse_field()? {
            // If it's an identifier, wrap it in a Column expression
            match &field {
                Expression::Identifier(id) => {
                    return Ok(Some(Expression::Column(Column {
                        name: id.clone(),
                        table: None,
                        join_mark: false,
                        trailing_comments: Vec::new(),
                        span: None,
                        inferred_type: None,
                    })));
                }
                // If it's already something else (like a literal), return as-is
                _ => return Ok(Some(field)),
            }
        }
        Ok(None)
    }

    /// parse_command - Parses a generic SQL command
    /// Python: _parse_command
    /// Used for commands that we don't have specific parsing for
    pub fn parse_command(&mut self) -> Result<Option<Expression>> {
        // Get the command keyword from the previous token
        let command_text = self.previous().text.to_uppercase();

        // Collect remaining tokens as the command expression (until statement end)
        // Use (text, token_type) tuples for smart spacing with join_command_tokens
        let mut tokens: Vec<(String, TokenType)> = vec![(command_text, TokenType::Var)];
        while !self.is_at_end() && !self.check(TokenType::Semicolon) {
            let token = self.advance();
            // Preserve quotes for quoted identifiers and strings
            let text = if token.token_type == TokenType::QuotedIdentifier {
                // Re-add the identifier quote characters
                // Use backticks as default; this handles MySQL backtick-quoted identifiers
                // and double-quoted identifiers for other dialects
                let quote_char = if self.config.dialect == Some(crate::dialects::DialectType::MySQL)
                    || self.config.dialect == Some(crate::dialects::DialectType::SingleStore)
                    || self.config.dialect == Some(crate::dialects::DialectType::Doris)
                    || self.config.dialect == Some(crate::dialects::DialectType::StarRocks)
                {
                    '`'
                } else {
                    '"'
                };
                format!("{}{}{}", quote_char, token.text, quote_char)
            } else if token.token_type == TokenType::String {
                format!("'{}'", token.text)
            } else {
                token.text.clone()
            };
            tokens.push((text, token.token_type));
        }

        Ok(Some(Expression::Command(Box::new(Command {
            this: self.join_command_tokens(tokens),
        }))))
    }

    /// parse_commit_or_rollback - Implemented from Python _parse_commit_or_rollback
    #[allow(unused_variables, unused_mut)]
    pub fn parse_commit_or_rollback(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["TO"]) {
            return Ok(Some(Expression::Rollback(Box::new(Rollback {
                savepoint: None,
                this: None,
            }))));
        }
        if self.match_text_seq(&["SAVEPOINT"]) {
            // Matched: SAVEPOINT
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_composite_key_property - Implemented from Python _parse_composite_key_property
    #[allow(unused_variables, unused_mut)]
    pub fn parse_composite_key_property(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["KEY"]) {
            // Matched: KEY
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_comprehension - Implemented from Python _parse_comprehension
    /// Parses list comprehension: expr FOR var [, position] IN iterator [IF condition]
    pub fn parse_comprehension(&mut self, this: Option<Expression>) -> Result<Option<Expression>> {
        let start_index = self.current;

        // Parse expression (column)
        let expression = self.parse_column()?;

        // Parse optional position (if comma follows)
        let position = if self.match_token(TokenType::Comma) {
            self.parse_column()?.map(Box::new)
        } else {
            None
        };

        // Must have IN keyword
        if !self.match_token(TokenType::In) {
            // Backtrack
            self.current = start_index.saturating_sub(1);
            return Ok(None);
        }

        // Parse iterator
        let iterator = self.parse_column()?.map(Box::new);

        // Parse optional condition (IF followed by expression)
        let condition = if self.match_text_seq(&["IF"]) {
            self.parse_disjunction()?.map(Box::new)
        } else {
            None
        };

        // Build the comprehension expression
        match (this, expression) {
            (Some(t), Some(e)) => Ok(Some(Expression::Comprehension(Box::new(Comprehension {
                this: Box::new(t),
                expression: Box::new(e),
                position,
                iterator,
                condition,
            })))),
            _ => Ok(None),
        }
    }

    /// parse_compress - Parses COMPRESS column constraint (Teradata)
    /// Python: _parse_compress
    /// Format: COMPRESS or COMPRESS (value1, value2, ...)
    pub fn parse_compress(&mut self) -> Result<Option<Expression>> {
        // Check if it's a parenthesized list of values
        if self.check(TokenType::LParen) {
            // Parse wrapped CSV of bitwise expressions
            self.advance(); // consume LParen
            let mut expressions = Vec::new();
            loop {
                if let Some(expr) = self.parse_bitwise()? {
                    expressions.push(expr);
                } else {
                    break;
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            self.expect(TokenType::RParen)?;

            // Wrap in a Tuple if multiple values
            let this = if expressions.len() == 1 {
                Some(Box::new(expressions.into_iter().next().unwrap()))
            } else if expressions.is_empty() {
                None
            } else {
                Some(Box::new(Expression::Tuple(Box::new(Tuple { expressions }))))
            };

            Ok(Some(Expression::CompressColumnConstraint(Box::new(
                CompressColumnConstraint { this },
            ))))
        } else {
            // Single value or no value
            let this = self.parse_bitwise()?.map(Box::new);
            Ok(Some(Expression::CompressColumnConstraint(Box::new(
                CompressColumnConstraint { this },
            ))))
        }
    }

    /// parse_conjunction - Parses AND expressions
    /// Python: _parse_conjunction
    /// Delegates to the existing parse_and in the operator precedence chain
    pub fn parse_conjunction(&mut self) -> Result<Option<Expression>> {
        match self.parse_and() {
            Ok(expr) => Ok(Some(expr)),
            Err(_) => Ok(None),
        }
    }

    /// parse_connect_with_prior - Parses expression in CONNECT BY context with PRIOR support
    /// Python: _parse_connect_with_prior
    /// This method temporarily treats PRIOR as a prefix operator while parsing the expression
    pub fn parse_connect_with_prior(&mut self) -> Result<Option<Expression>> {
        // parse_connect_expression already handles PRIOR as a prefix operator
        let connect = self.parse_connect_expression()?;
        Ok(Some(connect))
    }

    /// parse_constraint - Parses named or unnamed constraint
    /// Python: _parse_constraint
    pub fn parse_constraint(&mut self) -> Result<Option<Expression>> {
        // Check for CONSTRAINT keyword (named constraint)
        if !self.match_token(TokenType::Constraint) {
            // Try to parse an unnamed constraint
            return self.parse_unnamed_constraint();
        }

        // Parse the constraint name
        let name = self.parse_id_var()?;
        if name.is_none() {
            return Ok(None);
        }

        // Parse the constraint expressions (PRIMARY KEY, UNIQUE, FOREIGN KEY, CHECK, etc.)
        let expressions = self.parse_unnamed_constraints()?;

        Ok(Some(Expression::Constraint(Box::new(Constraint {
            this: Box::new(name.unwrap()),
            expressions,
        }))))
    }

    /// parse_unnamed_constraints - Parses multiple unnamed constraints
    /// Python: _parse_unnamed_constraints
    pub fn parse_unnamed_constraints(&mut self) -> Result<Vec<Expression>> {
        let mut constraints = Vec::new();

        loop {
            if let Some(constraint) = self.parse_unnamed_constraint()? {
                constraints.push(constraint);
            } else {
                break;
            }
        }

        Ok(constraints)
    }

    /// parse_unnamed_constraint - Parses a single unnamed constraint
    /// Python: _parse_unnamed_constraint
    pub fn parse_unnamed_constraint(&mut self) -> Result<Option<Expression>> {
        // Try PRIMARY KEY
        if self.match_text_seq(&["PRIMARY", "KEY"]) {
            // ClickHouse: PRIMARY KEY expr (without parens) in schema = table-level PK expression
            if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && !self.check(TokenType::LParen)
            {
                let expr = self.parse_expression()?;
                return Ok(Some(Expression::Raw(Raw {
                    sql: format!("PRIMARY KEY {}", expr),
                })));
            }
            return self.parse_primary_key();
        }

        // Try UNIQUE
        if self.match_texts(&["UNIQUE"]) {
            return self.parse_unique();
        }

        // Try FOREIGN KEY
        if self.match_text_seq(&["FOREIGN", "KEY"]) {
            return self.parse_foreign_key();
        }

        // Try CHECK
        if self.match_texts(&["CHECK"]) {
            let expr = self.parse_wrapped()?;
            if let Some(check_expr) = expr {
                return Ok(Some(Expression::CheckColumnConstraint(Box::new(
                    CheckColumnConstraint {
                        this: Box::new(check_expr),
                        enforced: None,
                    },
                ))));
            }
        }

        // Try NOT NULL
        if self.match_text_seq(&["NOT", "NULL"]) {
            return Ok(Some(Expression::NotNullColumnConstraint(Box::new(
                NotNullColumnConstraint {
                    allow_null: None, // NOT NULL means allow_null is not set
                },
            ))));
        }

        // Try NULL (allow null)
        if self.match_texts(&["NULL"]) {
            return Ok(Some(Expression::NotNullColumnConstraint(Box::new(
                NotNullColumnConstraint {
                    allow_null: Some(Box::new(Expression::Boolean(BooleanLiteral {
                        value: true,
                    }))),
                },
            ))));
        }

        // Try DEFAULT
        if self.match_token(TokenType::Default) {
            let default_value = self.parse_bitwise()?;
            if let Some(val) = default_value {
                return Ok(Some(Expression::DefaultColumnConstraint(Box::new(
                    DefaultColumnConstraint {
                        this: Box::new(val),
                    },
                ))));
            }
        }

        // Try REFERENCES (inline foreign key)
        if self.match_texts(&["REFERENCES"]) {
            return self.parse_references();
        }

        // ClickHouse: INDEX name expr TYPE type_name [GRANULARITY n]
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) && self.match_token(TokenType::Index)
        {
            let name = self.expect_identifier_or_keyword_with_quoted()?;
            // Use parse_conjunction to handle comparisons like c0 < (SELECT _table)
            let expression = self.parse_conjunction()?.ok_or_else(|| {
                self.parse_error("Expected expression in ClickHouse INDEX definition")
            })?;
            let index_type = if self.match_token(TokenType::Type) {
                if let Some(func) = self.parse_function()? {
                    Some(Box::new(func))
                } else if !self.is_at_end() {
                    let type_name = self.advance().text.clone();
                    if self.check(TokenType::LParen) {
                        self.advance();
                        let mut args = Vec::new();
                        if !self.check(TokenType::RParen) {
                            args.push(self.parse_expression()?);
                            while self.match_token(TokenType::Comma) {
                                args.push(self.parse_expression()?);
                            }
                        }
                        self.expect(TokenType::RParen)?;
                        Some(Box::new(Expression::Function(Box::new(Function::new(
                            type_name, args,
                        )))))
                    } else {
                        Some(Box::new(Expression::Identifier(Identifier::new(type_name))))
                    }
                } else {
                    None
                }
            } else {
                None
            };
            let _granularity = if self.match_identifier("GRANULARITY") {
                let _ = self.parse_expression()?;
                true
            } else {
                false
            };
            // Return as a raw SQL expression preserving the INDEX definition
            let mut sql = format!("INDEX {} ", name.name);
            if let Some(ref idx_type) = index_type {
                sql.push_str(&format!("{} TYPE {} ", expression, idx_type));
            }
            return Ok(Some(Expression::Raw(Raw {
                sql: sql.trim().to_string(),
            })));
        }

        // ClickHouse: PROJECTION name (SELECT ...) or PROJECTION name INDEX expr TYPE type_name
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) && self.check_identifier("PROJECTION")
        {
            self.advance(); // consume PROJECTION
            let name = self.expect_identifier_or_keyword_with_quoted()?;
            // Parse the projection body - either (SELECT ...) or INDEX expr TYPE type_name
            if self.match_token(TokenType::LParen) {
                let mut depth = 1i32;
                let start = self.current;
                while !self.is_at_end() && depth > 0 {
                    if self.check(TokenType::LParen) {
                        depth += 1;
                    }
                    if self.check(TokenType::RParen) {
                        depth -= 1;
                        if depth == 0 {
                            break;
                        }
                    }
                    self.advance();
                }
                let body_sql = self.tokens_to_sql(start, self.current);
                self.expect(TokenType::RParen)?;
                return Ok(Some(Expression::Raw(Raw {
                    sql: format!("PROJECTION {} ({})", name.name, body_sql),
                })));
            }
            // PROJECTION name INDEX expr TYPE type_name
            if self.match_token(TokenType::Index) {
                let expr = self.parse_bitwise()?.ok_or_else(|| {
                    self.parse_error(
                        "Expected expression in ClickHouse PROJECTION INDEX definition",
                    )
                })?;
                let type_str = if self.match_token(TokenType::Type) {
                    if !self.is_at_end() {
                        let t = self.advance().text.clone();
                        format!(" TYPE {}", t)
                    } else {
                        String::new()
                    }
                } else {
                    String::new()
                };
                return Ok(Some(Expression::Raw(Raw {
                    sql: format!("PROJECTION {} INDEX {}{}", name.name, expr, type_str),
                })));
            }
            return Ok(Some(Expression::Raw(Raw {
                sql: format!("PROJECTION {}", name.name),
            })));
        }

        Ok(None)
    }

    /// parse_contains_property - Implemented from Python _parse_contains_property
    #[allow(unused_variables, unused_mut)]
    pub fn parse_contains_property(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["SQL"]) {
            // Matched: SQL
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_convert - Ported from Python _parse_convert
    /// Parses CONVERT function: CONVERT(expr USING charset) or CONVERT(expr, type)
    #[allow(unused_variables, unused_mut)]
    pub fn parse_convert(&mut self) -> Result<Option<Expression>> {
        // Parse the expression to convert
        let this = match self.parse_bitwise() {
            Ok(Some(expr)) => expr,
            Ok(None) => return Ok(None),
            Err(e) => return Err(e),
        };

        // Check for USING charset (CONVERT(x USING utf8))
        if self.match_token(TokenType::Using) {
            let _ = self.parse_var(); // charset
                                      // Return as Cast with charset
            return Ok(Some(Expression::Cast(Box::new(Cast {
                this,
                to: DataType::Char { length: None },
                trailing_comments: Vec::new(),
                double_colon_syntax: false,
                format: None,
                default: None,
                inferred_type: None,
            }))));
        }

        // Check for comma then type (CONVERT(x, INT))
        if self.match_token(TokenType::Comma) {
            let data_type = self.parse_data_type()?;
            return Ok(Some(Expression::Cast(Box::new(Cast {
                this,
                to: data_type,
                trailing_comments: Vec::new(),
                double_colon_syntax: false,
                format: None,
                default: None,
                inferred_type: None,
            }))));
        }

        // No type specified, return as-is wrapped in Cast
        Ok(Some(Expression::Cast(Box::new(Cast {
            this,
            to: DataType::Char { length: None },
            trailing_comments: Vec::new(),
            double_colon_syntax: false,
            format: None,
            default: None,
            inferred_type: None,
        }))))
    }

    /// parse_copy_parameters - Implemented from Python _parse_copy_parameters
    /// parse_copy_parameters - Parses COPY statement parameters
    /// Returns a tuple of CopyParameter expressions
    pub fn parse_copy_parameters(&mut self) -> Result<Option<Expression>> {
        let mut options = Vec::new();

        while !self.is_at_end() && !self.check(TokenType::RParen) {
            // Parse option name as var
            let option = self.parse_var()?;
            if option.is_none() {
                break;
            }

            let option_name = match &option {
                Some(Expression::Var(v)) => v.this.to_uppercase(),
                Some(Expression::Identifier(id)) => id.name.to_uppercase(),
                _ => String::new(),
            };

            // Options and values may be separated by whitespace, "=" or "AS"
            self.match_token(TokenType::Eq);
            self.match_token(TokenType::Alias);

            // Parse value based on option type
            let (expression, expressions) = if (option_name == "FILE_FORMAT"
                || option_name == "FORMAT_OPTIONS")
                && self.check(TokenType::LParen)
            {
                // Parse wrapped options for FILE_FORMAT
                let wrapped = self.parse_wrapped_options()?;
                let exprs = match wrapped {
                    Some(Expression::Tuple(t)) => t.expressions,
                    Some(e) => vec![e],
                    None => Vec::new(),
                };
                (None, exprs)
            } else if option_name == "FILE_FORMAT" {
                // T-SQL external file format case
                let field = self.parse_field()?;
                (field, Vec::new())
            } else if option_name == "FORMAT"
                && self.previous().token_type == TokenType::Alias
                && self.match_texts(&["AVRO", "JSON"])
            {
                // FORMAT AS AVRO/JSON
                let format_type = self.previous().text.to_uppercase();
                let field = self.parse_field()?;
                (
                    Some(Expression::Var(Box::new(Var {
                        this: format!("FORMAT AS {}", format_type),
                    }))),
                    field.map_or(Vec::new(), |f| vec![f]),
                )
            } else {
                // Parse unquoted field or bracket
                let expr = self
                    .parse_unquoted_field()?
                    .or_else(|| self.parse_bracket().ok().flatten());
                (expr, Vec::new())
            };

            options.push(Expression::CopyParameter(Box::new(CopyParameter {
                name: option_name,
                value: expression,
                values: expressions,
                eq: true,
            })));

            // Optional comma separator (dialect-specific)
            self.match_token(TokenType::Comma);
        }

        if options.is_empty() {
            Ok(None)
        } else {
            Ok(Some(Expression::Tuple(Box::new(Tuple {
                expressions: options,
            }))))
        }
    }

    /// parse_copy_property - Implemented from Python _parse_copy_property
    #[allow(unused_variables, unused_mut)]
    pub fn parse_copy_property(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["GRANTS"]) {
            // Matched: GRANTS
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_create_like - Implemented from Python _parse_create_like
    /// Calls: parse_id_var
    #[allow(unused_variables, unused_mut)]
    pub fn parse_create_like(&mut self) -> Result<Option<Expression>> {
        if self.match_texts(&["INCLUDING", "EXCLUDING"]) {
            // Matched one of: INCLUDING, EXCLUDING
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_credentials - Implemented from Python _parse_credentials
    #[allow(unused_variables, unused_mut)]
    pub fn parse_credentials(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["STORAGE_INTEGRATION", "="]) {
            return Ok(Some(Expression::Credentials(Box::new(Credentials {
                credentials: Vec::new(),
                encryption: None,
                storage: None,
            }))));
        }
        if self.match_text_seq(&["CREDENTIALS"]) {
            // Matched: CREDENTIALS
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_csv - Parses comma-separated expressions
    /// Python: _parse_csv
    /// In Python this takes a parse_method callback, but in Rust we use parse_expression_list
    pub fn parse_csv(&mut self) -> Result<Option<Expression>> {
        let expressions = self.parse_expression_list()?;
        if expressions.is_empty() {
            return Ok(None);
        }
        Ok(Some(Expression::Tuple(Box::new(Tuple { expressions }))))
    }

    /// parse_cte - Implemented from Python _parse_cte
    /// Calls: parse_wrapped_id_vars
    #[allow(unused_variables, unused_mut)]
    pub fn parse_cte(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["USING", "KEY"]) {
            return Ok(Some(Expression::Values(Box::new(Values {
                expressions: Vec::new(),
                alias: None,
                column_aliases: Vec::new(),
            }))));
        }
        if self.match_text_seq(&["NOT", "MATERIALIZED"]) {
            // Matched: NOT MATERIALIZED
            return Ok(None);
        }
        if self.match_text_seq(&["MATERIALIZED"]) {
            // Matched: MATERIALIZED
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_cube_or_rollup - Ported from Python _parse_cube_or_rollup
    /// Parses CUBE(...) or ROLLUP(...) expressions in GROUP BY
    #[allow(unused_variables, unused_mut)]
    pub fn parse_cube_or_rollup(&mut self) -> Result<Option<Expression>> {
        // Check for CUBE or ROLLUP keyword
        let is_cube = self.match_texts(&["CUBE"]);
        let is_rollup = if !is_cube {
            self.match_texts(&["ROLLUP"])
        } else {
            false
        };

        if !is_cube && !is_rollup {
            return Ok(None);
        }

        // Parse wrapped expressions
        self.expect(TokenType::LParen)?;
        let mut expressions = Vec::new();
        if !self.check(TokenType::RParen) {
            loop {
                match self.parse_bitwise() {
                    Ok(Some(expr)) => expressions.push(expr),
                    Ok(None) => break,
                    Err(e) => return Err(e),
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
        }
        self.expect(TokenType::RParen)?;

        if is_cube {
            Ok(Some(Expression::Cube(Box::new(Cube { expressions }))))
        } else {
            Ok(Some(Expression::Rollup(Box::new(Rollup { expressions }))))
        }
    }

    /// parse_data_deletion_property - Implemented from Python _parse_data_deletion_property
    /// Calls: parse_column, parse_retention_period
    #[allow(unused_variables, unused_mut)]
    pub fn parse_data_deletion_property(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["ON"]) {
            // Matched: ON
            return Ok(None);
        }
        if self.match_text_seq(&["OFF"]) {
            // Matched: OFF
            return Ok(None);
        }
        if self.match_text_seq(&["FILTER_COLUMN", "="]) {
            // Matched: FILTER_COLUMN =
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_datablocksize - Implemented from Python _parse_datablocksize
    /// Calls: parse_number
    #[allow(unused_variables, unused_mut)]
    pub fn parse_datablocksize(&mut self) -> Result<Option<Expression>> {
        if self.match_texts(&["BYTES", "KBYTES", "KILOBYTES"]) {
            // Matched one of: BYTES, KBYTES, KILOBYTES
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_dcolon - Delegates to parse_types
    #[allow(unused_variables, unused_mut)]
    pub fn parse_dcolon(&mut self) -> Result<Option<Expression>> {
        self.parse_types()
    }

    /// parse_ddl_select - Ported from Python _parse_ddl_select
    /// Parses a SELECT statement in DDL context (CREATE TABLE AS SELECT, INSERT INTO ... SELECT)
    #[allow(unused_variables, unused_mut)]
    pub fn parse_ddl_select(&mut self) -> Result<Option<Expression>> {
        // Parse a nested SELECT statement
        let select = self.parse_select_query()?;

        if select.is_none() {
            return Ok(None);
        }

        // Apply set operations (UNION, INTERSECT, EXCEPT)
        let with_set_ops = self.parse_set_operations_with_expr(select)?;

        // Return the result (query modifiers would be applied by parse_select_query already)
        Ok(with_set_ops)
    }

    /// parse_for_in - BigQuery procedural FOR...IN...DO loop
    /// Python: BigQuery._parse_for_in
    /// Format: FOR variable IN (query) DO statement(s) END FOR
    /// Example: FOR record IN (SELECT * FROM t) DO SELECT record.col
    pub fn parse_for_in(&mut self) -> Result<Expression> {
        // Parse: variable IN (query)
        // This is handled by parse_range which produces an In expression
        let this = self
            .parse_range()?
            .ok_or_else(|| self.parse_error("Expected expression after FOR"))?;

        // Match DO keyword
        self.match_text_seq(&["DO"]);

        // Parse the body statement
        let expression = self.parse_statement()?;

        Ok(Expression::ForIn(Box::new(ForIn {
            this: Box::new(this),
            expression: Box::new(expression),
        })))
    }

    /// parse_declare - Parses DECLARE statement
    /// Python: _parse_declare
    /// Format: DECLARE var1 type [DEFAULT expr], var2 type [DEFAULT expr], ...
    pub fn parse_declare(&mut self) -> Result<Option<Expression>> {
        // Try to parse comma-separated declare items
        let mut expressions = Vec::new();

        // BigQuery multi-variable DECLARE: DECLARE X, Y, Z INT64 [DEFAULT expr]
        // Detect by looking ahead: if we see identifier, comma, identifier pattern
        // before a data type keyword, collect all names then parse type once.
        let saved = self.current;
        let mut multi_names: Vec<Expression> = Vec::new();
        if let Some(first_var) = self.parse_id_var()? {
            // Check if next is a comma (BigQuery multi-var syntax)
            if self.check(TokenType::Comma) && !self.check_identifier("CURSOR") {
                // Speculatively collect comma-separated identifiers
                multi_names.push(first_var);
                while self.match_token(TokenType::Comma) {
                    if let Some(next_var) = self.parse_id_var()? {
                        multi_names.push(next_var);
                    } else {
                        break;
                    }
                }
                // Now check if we're at a data type (not comma, not @, not semicolon)
                // If so, this is BigQuery multi-var syntax
                if multi_names.len() > 1 && !self.is_at_end() && !self.check(TokenType::Semicolon) {
                    let data_type = self.parse_data_type()?;
                    let kind_str = self.data_type_to_sql(&data_type);
                    let default = if self.match_token(TokenType::Default)
                        || self.match_token(TokenType::Eq)
                    {
                        Some(Box::new(self.parse_expression()?))
                    } else {
                        None
                    };
                    let first_name = multi_names.remove(0);
                    expressions.push(Expression::DeclareItem(Box::new(DeclareItem {
                        this: Box::new(first_name),
                        kind: Some(kind_str),
                        default,
                        has_as: false,
                        additional_names: multi_names,
                    })));
                    return Ok(Some(Expression::Declare(Box::new(Declare { expressions }))));
                }
            }
        }
        // Reset and parse normally
        self.current = saved;

        loop {
            if let Some(item) = self.parse_declareitem()? {
                expressions.push(item);
            } else {
                break;
            }
            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        // If we successfully parsed at least one item, return the Declare
        if !expressions.is_empty() {
            return Ok(Some(Expression::Declare(Box::new(Declare { expressions }))));
        }

        Ok(None)
    }

    /// parse_declareitem - Parse a DECLARE item (variable declaration)
    /// TSQL format: @var AS type [= expr] or @var type [= expr]
    /// Also handles: DECLARE name CURSOR FOR SELECT ...
    /// Also handles: DECLARE @var TABLE (col_defs)
    #[allow(unused_variables, unused_mut)]
    pub fn parse_declareitem(&mut self) -> Result<Option<Expression>> {
        // Consume optional VAR or VARIABLE keyword (Spark/Databricks)
        if self.check_identifier("VAR") || self.check_identifier("VARIABLE") {
            self.advance();
        }

        // Parse the variable name (starts with @ or is a cursor name)
        let var = if let Some(v) = self.parse_id_var()? {
            v
        } else {
            return Ok(None);
        };

        // Check for CURSOR FOR syntax: DECLARE name CURSOR FOR SELECT ...
        if self.check_identifier("CURSOR") {
            self.advance(); // consume CURSOR
                            // Parse optional cursor options before FOR (e.g., SCROLL, INSENSITIVE, etc.)
                            // For now just look for FOR
            if self.match_token(TokenType::For) {
                // Capture the remaining tokens as the cursor query using tokens_to_sql for proper spacing
                let start = self.current;
                while !self.is_at_end() && !self.check(TokenType::Semicolon) {
                    self.advance();
                }
                let query_str = self.tokens_to_sql_uppercased(start, self.current);
                let kind_str = format!("CURSOR FOR {}", query_str);
                return Ok(Some(Expression::DeclareItem(Box::new(DeclareItem {
                    this: Box::new(var),
                    kind: Some(kind_str),
                    default: None,
                    has_as: false,
                    additional_names: Vec::new(),
                }))));
            } else {
                return Ok(Some(Expression::DeclareItem(Box::new(DeclareItem {
                    this: Box::new(var),
                    kind: Some("CURSOR".to_string()),
                    default: None,
                    has_as: false,
                    additional_names: Vec::new(),
                }))));
            }
        }

        // Parse optional AS keyword
        let has_as = self.match_token(TokenType::As);

        // Check for TABLE type with column definitions
        if self.check(TokenType::Table) {
            self.advance(); // consume TABLE
            if self.match_token(TokenType::LParen) {
                // Parse the TABLE column definitions using tokens_to_sql for proper spacing
                let start = self.current;
                let mut depth = 1;
                while depth > 0 && !self.is_at_end() {
                    if self.check(TokenType::LParen) {
                        depth += 1;
                    }
                    if self.check(TokenType::RParen) {
                        depth -= 1;
                        if depth == 0 {
                            break;
                        }
                    }
                    self.advance();
                }
                let col_defs_str = self.tokens_to_sql_uppercased(start, self.current);
                self.expect(TokenType::RParen)?;
                let kind_str = format!("TABLE ({})", col_defs_str);
                return Ok(Some(Expression::DeclareItem(Box::new(DeclareItem {
                    this: Box::new(var),
                    kind: Some(kind_str),
                    default: None,
                    has_as,
                    additional_names: Vec::new(),
                }))));
            } else {
                return Ok(Some(Expression::DeclareItem(Box::new(DeclareItem {
                    this: Box::new(var),
                    kind: Some("TABLE".to_string()),
                    default: None,
                    has_as,
                    additional_names: Vec::new(),
                }))));
            }
        }

        // Parse the data type
        let data_type = self.parse_data_type()?;
        let kind_str = self.data_type_to_sql(&data_type);

        // Parse optional DEFAULT value or = value (TSQL uses =)
        let default = if self.match_token(TokenType::Default) || self.match_token(TokenType::Eq) {
            Some(Box::new(self.parse_expression()?))
        } else {
            None
        };

        Ok(Some(Expression::DeclareItem(Box::new(DeclareItem {
            this: Box::new(var),
            kind: Some(kind_str),
            default,
            has_as,
            additional_names: Vec::new(),
        }))))
    }

    /// Convert a DataType to its SQL string representation
    fn data_type_to_sql(&self, dt: &DataType) -> String {
        match dt {
            DataType::Boolean => "BOOLEAN".to_string(),
            DataType::TinyInt { length } => {
                if let Some(n) = length {
                    format!("TINYINT({})", n)
                } else {
                    "TINYINT".to_string()
                }
            }
            DataType::SmallInt { length } => {
                if let Some(n) = length {
                    format!("SMALLINT({})", n)
                } else {
                    "SMALLINT".to_string()
                }
            }
            DataType::Int {
                length,
                integer_spelling,
            } => {
                if let Some(n) = length {
                    if *integer_spelling {
                        format!("INTEGER({})", n)
                    } else {
                        format!("INT({})", n)
                    }
                } else if *integer_spelling {
                    "INTEGER".to_string()
                } else {
                    "INT".to_string()
                }
            }
            DataType::BigInt { length } => {
                if let Some(n) = length {
                    format!("BIGINT({})", n)
                } else {
                    "BIGINT".to_string()
                }
            }
            DataType::Float {
                precision, scale, ..
            } => match (precision, scale) {
                (Some(p), Some(s)) => format!("FLOAT({}, {})", p, s),
                (Some(p), None) => format!("FLOAT({})", p),
                _ => "FLOAT".to_string(),
            },
            DataType::Double { precision, scale } => match (precision, scale) {
                (Some(p), Some(s)) => format!("DOUBLE({}, {})", p, s),
                (Some(p), None) => format!("DOUBLE({})", p),
                _ => "DOUBLE".to_string(),
            },
            DataType::Decimal { precision, scale } => match (precision, scale) {
                (Some(p), Some(s)) => format!("DECIMAL({}, {})", p, s),
                (Some(p), None) => format!("DECIMAL({})", p),
                _ => "DECIMAL".to_string(),
            },
            DataType::Char { length } => {
                if let Some(n) = length {
                    format!("CHAR({})", n)
                } else {
                    "CHAR".to_string()
                }
            }
            DataType::VarChar { length, .. } => {
                if let Some(n) = length {
                    format!("VARCHAR({})", n)
                } else {
                    "VARCHAR".to_string()
                }
            }
            DataType::Text => "TEXT".to_string(),
            DataType::Date => "DATE".to_string(),
            DataType::Time { precision, .. } => {
                if let Some(p) = precision {
                    format!("TIME({})", p)
                } else {
                    "TIME".to_string()
                }
            }
            DataType::Timestamp { precision, .. } => {
                if let Some(p) = precision {
                    format!("TIMESTAMP({})", p)
                } else {
                    "TIMESTAMP".to_string()
                }
            }
            DataType::Binary { length } => {
                if let Some(n) = length {
                    format!("BINARY({})", n)
                } else {
                    "BINARY".to_string()
                }
            }
            DataType::VarBinary { length } => {
                if let Some(n) = length {
                    format!("VARBINARY({})", n)
                } else {
                    "VARBINARY".to_string()
                }
            }
            DataType::Blob => "BLOB".to_string(),
            DataType::Json => "JSON".to_string(),
            DataType::Uuid => "UUID".to_string(),
            DataType::Custom { name } => name.clone(), // Custom types (INT64, FLOAT64, etc.)
            _ => format!("{:?}", dt),                  // Fallback for unknown types
        }
    }

    /// parse_decode - Ported from Python _parse_decode
    /// Parses Oracle-style DECODE or simple DECODE function
    /// If 3+ args: Oracle DECODE(expr, search1, result1, ..., default)
    /// If 2 args: character set decode (expr, charset)
    #[allow(unused_variables, unused_mut)]
    pub fn parse_decode(&mut self) -> Result<Option<Expression>> {
        // Parse comma-separated arguments
        let mut args: Vec<Expression> = Vec::new();
        loop {
            match self.parse_expression() {
                Ok(expr) => args.push(expr),
                Err(_) => break,
            }
            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        if args.len() < 3 {
            // Simple decode with charset
            return Ok(Some(Expression::DecodeCase(Box::new(DecodeCase {
                expressions: args,
            }))));
        }

        // Oracle DECODE: first arg is the expression being compared
        // Remaining args are search/result pairs, with optional default at end
        Ok(Some(Expression::DecodeCase(Box::new(DecodeCase {
            expressions: args,
        }))))
    }

    /// parse_definer - MySQL DEFINER property
    /// Parses: DEFINER = user@host
    #[allow(unused_variables, unused_mut)]
    pub fn parse_definer(&mut self) -> Result<Option<Expression>> {
        // Optionally consume = sign
        self.match_token(TokenType::Eq);

        // Parse the user part
        let user = self.parse_id_var()?;
        if user.is_none() {
            return Ok(None);
        }

        // Expect @ symbol
        if !self.match_token(TokenType::DAt) {
            return Ok(None);
        }

        // Parse the host part (can be identifier or % wildcard)
        let host = if let Some(id) = self.parse_id_var()? {
            id
        } else if self.match_token(TokenType::Mod) {
            // % wildcard for any host
            Expression::Identifier(Identifier::new(self.previous().text.clone()))
        } else {
            return Ok(None);
        };

        // Combine user@host into a string
        let user_str = match &user {
            Some(Expression::Identifier(id)) => id.name.clone(),
            _ => "".to_string(),
        };
        let host_str = match &host {
            Expression::Identifier(id) => id.name.clone(),
            _ => "".to_string(),
        };

        let definer_str = format!("{}@{}", user_str, host_str);

        Ok(Some(Expression::DefinerProperty(Box::new(
            DefinerProperty {
                this: Box::new(Expression::Literal(Literal::String(definer_str))),
            },
        ))))
    }

    /// parse_derived_table_values - Implemented from Python _parse_derived_table_values
    #[allow(unused_variables, unused_mut)]
    pub fn parse_derived_table_values(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["VALUES"]) {
            return Ok(Some(Expression::Values(Box::new(Values {
                expressions: Vec::new(),
                alias: None,
                column_aliases: Vec::new(),
            }))));
        }
        if self.match_text_seq(&["FORMAT", "VALUES"]) {
            // Matched: FORMAT VALUES
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_dict_property - ClickHouse dictionary property
    /// Parses: property_name(kind(key1 value1, key2 value2, ...))
    /// property_name should be the already matched property keyword (LAYOUT, SOURCE, etc.)
    #[allow(unused_variables, unused_mut)]
    pub fn parse_dict_property(&mut self, property_name: &str) -> Result<Option<Expression>> {
        // Expect opening paren
        if !self.match_token(TokenType::LParen) {
            return Ok(None);
        }

        // Parse the kind (e.g., HASHED, FLAT, CLICKHOUSE, CACHE, etc.)
        // Accept Var, Identifier, or keyword tokens as the kind name
        let kind_str = if self.is_identifier_token() || self.check_keyword() {
            self.advance().text.clone()
        } else {
            String::new()
        };
        if kind_str.is_empty() {
            return Err(self.parse_error("Expected dictionary property kind"));
        }

        // Parse optional settings in nested parens
        let settings = if self.match_token(TokenType::LParen) {
            let mut setting_pairs = Vec::new();
            loop {
                let key = if let Some(k) = self.parse_id_var()? {
                    Some(k)
                } else if self.is_safe_keyword_as_identifier() || self.check_keyword() {
                    let name = self.advance().text.clone();
                    Some(Expression::Identifier(Identifier::new(name)))
                } else if !self.check(TokenType::RParen) && !self.check(TokenType::Comma) {
                    let name = self.advance().text.clone();
                    Some(Expression::Identifier(Identifier::new(name)))
                } else {
                    None
                };
                // ClickHouse: STRUCTURE (...) contains column defs without commas — consume balanced parens
                let is_structure = key.as_ref().map_or(false, |k| {
                    matches!(k, Expression::Identifier(id) if id.name.eq_ignore_ascii_case("STRUCTURE"))
                });
                let value = if is_structure && self.check(TokenType::LParen) {
                    let mut raw = String::new();
                    let mut depth = 0i32;
                    while !self.is_at_end() {
                        let tok = self.advance();
                        match tok.token_type {
                            TokenType::LParen => {
                                depth += 1;
                                raw.push('(');
                            }
                            TokenType::RParen => {
                                depth -= 1;
                                if depth == 0 {
                                    raw.push(')');
                                    break;
                                }
                                raw.push(')');
                            }
                            _ => {
                                if !raw.is_empty() && !raw.ends_with('(') {
                                    raw.push(' ');
                                }
                                raw.push_str(&tok.text);
                            }
                        }
                    }
                    Some(Expression::Var(Box::new(Var { this: raw })))
                } else {
                    self.parse_primary_or_var()?
                };
                if key.is_none() && value.is_none() {
                    break;
                }
                if let (Some(k), Some(v)) = (key, value) {
                    // Store as a tuple-like expression
                    setting_pairs.push(Expression::Tuple(Box::new(Tuple {
                        expressions: vec![k, v],
                    })));
                }
                // ClickHouse dict properties are space-separated, not comma-separated
                // e.g. SOURCE(CLICKHOUSE(HOST 'localhost' PORT tcpPort() DB 'test'))
                // Accept optional comma but don't require it
                self.match_token(TokenType::Comma);
                // Break if we see RParen (end of settings)
                if self.check(TokenType::RParen) {
                    break;
                }
            }
            self.expect(TokenType::RParen)?;
            if !setting_pairs.is_empty() {
                Some(Box::new(Expression::Tuple(Box::new(Tuple {
                    expressions: setting_pairs,
                }))))
            } else {
                None
            }
        } else {
            None
        };

        self.expect(TokenType::RParen)?;

        Ok(Some(Expression::DictProperty(Box::new(DictProperty {
            this: Box::new(Expression::Identifier(Identifier::new(
                property_name.to_string(),
            ))),
            kind: kind_str,
            settings,
        }))))
    }

    /// parse_dict_range - Implemented from Python _parse_dict_range
    /// Parses dictionary range specification: (MIN min_val MAX max_val) or (max_val)
    pub fn parse_dict_range(&mut self, property_name: &str) -> Result<Option<Expression>> {
        // Expect opening paren
        self.expect(TokenType::LParen)?;

        // Prefer id/var first for dictionary bounds to avoid function-keyword ambiguity
        // such as `MIN discount_start_date MAX discount_end_date`.
        let parse_bound = |parser: &mut Parser| -> Result<Option<Expression>> {
            // Handle negative numbers: -1, -100, etc.
            if parser.check(TokenType::Dash)
                && parser
                    .peek_nth(1)
                    .is_some_and(|t| t.token_type == TokenType::Number)
            {
                parser.advance(); // consume -
                let num = parser.advance().text.clone();
                return Ok(Some(Expression::Literal(Literal::Number(format!(
                    "-{}",
                    num
                )))));
            }
            if let Some(id) = parser.parse_id_var()? {
                return Ok(Some(id));
            }
            parser.parse_primary_or_var()
        };

        let (min_val, max_val) = if self.peek().text.eq_ignore_ascii_case("MIN") {
            self.advance(); // consume MIN
            let min = parse_bound(self)?;
            if self.peek().text.eq_ignore_ascii_case("MAX") {
                self.advance(); // consume MAX
            }
            let max = parse_bound(self)?;
            (min, max)
        } else {
            let max = parse_bound(self)?;
            let min = Some(Expression::Literal(Literal::Number("0".to_string())));
            (min, max)
        };

        // Match closing paren
        self.expect(TokenType::RParen)?;

        Ok(Some(Expression::DictRange(Box::new(DictRange {
            this: Box::new(Expression::Var(Box::new(Var {
                this: property_name.to_string(),
            }))),
            min: min_val.map(Box::new),
            max: max_val.map(Box::new),
        }))))
    }

    /// parse_disjunction - Parses OR expressions
    /// Python: _parse_disjunction
    /// Delegates to the existing parse_or in the operator precedence chain
    pub fn parse_disjunction(&mut self) -> Result<Option<Expression>> {
        match self.parse_or() {
            Ok(expr) => Ok(Some(expr)),
            Err(_) => Ok(None),
        }
    }

    /// parse_distkey - Redshift DISTKEY property for distribution key
    /// Parses: DISTKEY(column_name)
    #[allow(unused_variables, unused_mut)]
    pub fn parse_distkey(&mut self) -> Result<Option<Expression>> {
        // Parse wrapped column identifier (in parentheses)
        if !self.match_token(TokenType::LParen) {
            return Ok(None);
        }

        let column = self.parse_id_var()?;
        if column.is_none() {
            return Ok(None);
        }

        self.match_token(TokenType::RParen);

        Ok(Some(Expression::DistKeyProperty(Box::new(
            DistKeyProperty {
                this: Box::new(column.unwrap()),
            },
        ))))
    }

    /// parse_distributed_property - Implemented from Python _parse_distributed_property
    #[allow(unused_variables, unused_mut)]
    /// parse_distributed_property - Parses DISTRIBUTED BY property
    /// Python: parser.py:2462-2481
    pub fn parse_distributed_property(&mut self) -> Result<Option<Expression>> {
        let mut kind = "HASH".to_string();
        let mut expressions = Vec::new();

        if self.match_text_seq(&["BY", "HASH"]) {
            // Parse column list: (col1, col2, ...)
            if let Some(wrapped) = self.parse_wrapped_id_vars()? {
                if let Expression::Tuple(t) = wrapped {
                    expressions = t.expressions;
                }
            }
        } else if self.match_text_seq(&["BY", "RANDOM"]) {
            kind = "RANDOM".to_string();
        } else {
            return Ok(None);
        }

        // Parse optional BUCKETS
        let buckets = if self.match_text_seq(&["BUCKETS"]) {
            if !self.match_text_seq(&["AUTO"]) {
                self.parse_number()?
            } else {
                None
            }
        } else {
            None
        };

        // Parse optional ORDER BY
        let order = self.parse_order()?;

        Ok(Some(Expression::DistributedByProperty(Box::new(
            DistributedByProperty {
                expressions,
                kind,
                buckets: buckets.map(Box::new),
                order: order.map(Box::new),
            },
        ))))
    }

    /// Parse DROP COLUMN in ALTER TABLE
    /// Note: Main ALTER TABLE DROP COLUMN logic is in parse_alter_table -> AlterTableAction::DropColumn
    pub fn parse_drop_column(&mut self) -> Result<Option<Expression>> {
        // Optionally match COLUMN keyword
        self.match_token(TokenType::Column);

        // Parse IF EXISTS
        let _if_exists = self.match_keywords(&[TokenType::If, TokenType::Exists]);

        // Parse the column identifier
        if let Some(column) = self.parse_identifier()? {
            // Check for CASCADE
            let _cascade = self.match_text_seq(&["CASCADE"]);
            // Return the column as an identifier (the caller handles the drop semantics)
            Ok(Some(column))
        } else {
            Ok(None)
        }
    }

    /// Parse DROP PARTITION in ALTER TABLE
    /// Note: Main ALTER TABLE DROP PARTITION logic is in parse_alter_table -> AlterTableAction::DropPartition
    pub fn parse_drop_partition(&mut self) -> Result<Option<Expression>> {
        self.parse_drop_partition_with_exists(false)
    }

    /// Parse DROP PARTITION with exists flag
    pub fn parse_drop_partition_with_exists(&mut self, exists: bool) -> Result<Option<Expression>> {
        // Parse one or more partitions
        let mut partitions = Vec::new();

        loop {
            // Parse PARTITION (key = value, ...)
            if self.match_token(TokenType::Partition) {
                if self.match_token(TokenType::LParen) {
                    // Parse partition expressions
                    let mut exprs = Vec::new();
                    loop {
                        let expr = self.parse_expression()?;
                        exprs.push(expr);
                        if !self.match_token(TokenType::Comma) {
                            break;
                        }
                    }
                    self.match_token(TokenType::RParen);
                    partitions.push(Expression::Tuple(Box::new(Tuple { expressions: exprs })));
                }
            } else {
                break;
            }

            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        if partitions.is_empty() {
            Ok(None)
        } else {
            Ok(Some(Expression::DropPartition(Box::new(DropPartition {
                expressions: partitions,
                exists,
            }))))
        }
    }

    /// parse_equality - Parses comparison/equality expressions (= <> < > <= >=)
    /// Python: _parse_equality
    /// Delegates to the existing parse_comparison in the operator precedence chain
    pub fn parse_equality(&mut self) -> Result<Option<Expression>> {
        match self.parse_comparison() {
            Ok(expr) => Ok(Some(expr)),
            Err(_) => Ok(None),
        }
    }

    /// parse_escape - Parses ESCAPE clause for LIKE patterns
    /// Python: _parse_escape
    /// Returns the escape character/expression if ESCAPE keyword is found
    pub fn parse_escape(&mut self) -> Result<Option<Expression>> {
        if !self.match_token(TokenType::Escape) {
            return Ok(None);
        }

        // Parse escape character (usually a string like '\')
        if let Some(escape_char) = self.parse_string()? {
            return Ok(Some(escape_char));
        }

        // Or parse NULL
        if let Some(null_expr) = self.parse_null()? {
            return Ok(Some(null_expr));
        }

        Ok(None)
    }

    /// parse_exists - Implemented from Python _parse_exists
    #[allow(unused_variables, unused_mut)]
    pub fn parse_exists(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["IF"]) {
            // Matched: IF
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_exponent - Parses exponent/power expressions
    /// Python: _parse_exponent
    /// In most dialects, EXPONENT is empty, so this delegates to parse_unary
    pub fn parse_exponent(&mut self) -> Result<Option<Expression>> {
        match self.parse_unary() {
            Ok(expr) => Ok(Some(expr)),
            Err(_) => Ok(None),
        }
    }

    /// parse_expressions - Parse comma-separated expressions
    /// Returns a Tuple containing all expressions, or None if empty
    #[allow(unused_variables, unused_mut)]
    pub fn parse_expressions(&mut self) -> Result<Option<Expression>> {
        let expressions = self.parse_expression_list()?;
        if expressions.is_empty() {
            return Ok(None);
        }
        if expressions.len() == 1 {
            return Ok(expressions.into_iter().next());
        }
        Ok(Some(Expression::Tuple(Box::new(Tuple { expressions }))))
    }

    /// parse_extract - Ported from Python _parse_extract
    /// Parses EXTRACT(field FROM expression) function
    #[allow(unused_variables, unused_mut)]
    pub fn parse_extract(&mut self) -> Result<Option<Expression>> {
        // Parse the field (YEAR, MONTH, DAY, HOUR, etc.)
        let field_name = if self.check(TokenType::Identifier) || self.check(TokenType::Var) {
            let token = self.advance();
            token.text.to_uppercase()
        } else {
            return Ok(None);
        };

        // Convert field name to DateTimeField
        let field = match field_name.as_str() {
            "YEAR" => DateTimeField::Year,
            "MONTH" => DateTimeField::Month,
            "DAY" => DateTimeField::Day,
            "HOUR" => DateTimeField::Hour,
            "MINUTE" => DateTimeField::Minute,
            "SECOND" => DateTimeField::Second,
            "MILLISECOND" | "MILLISECONDS" | "MS" => DateTimeField::Millisecond,
            "MICROSECOND" | "MICROSECONDS" | "US" => DateTimeField::Microsecond,
            "DOW" | "DAYOFWEEK" => DateTimeField::DayOfWeek,
            "DOY" | "DAYOFYEAR" => DateTimeField::DayOfYear,
            "WEEK" => DateTimeField::Week,
            "QUARTER" => DateTimeField::Quarter,
            "EPOCH" => DateTimeField::Epoch,
            "TIMEZONE" => DateTimeField::Timezone,
            "TIMEZONE_HOUR" => DateTimeField::TimezoneHour,
            "TIMEZONE_MINUTE" => DateTimeField::TimezoneMinute,
            "DATE" => DateTimeField::Date,
            "TIME" => DateTimeField::Time,
            other => DateTimeField::Custom(other.to_string()),
        };

        // Expect FROM or comma
        if !self.match_token(TokenType::From) && !self.match_token(TokenType::Comma) {
            return Err(self.parse_error("Expected FROM or comma after EXTRACT field"));
        }

        // Parse the expression to extract from
        let expression = self.parse_bitwise()?;
        let this = match expression {
            Some(expr) => self.try_clickhouse_func_arg_alias(expr),
            None => return Err(self.parse_error("Expected expression after FROM in EXTRACT")),
        };

        Ok(Some(Expression::Extract(Box::new(ExtractFunc {
            this,
            field,
        }))))
    }

    /// parse_factor - Parses multiplication/division expressions (* / % operators)
    /// Python: _parse_factor
    /// Delegates to the existing parse_multiplication in the operator precedence chain
    pub fn parse_factor(&mut self) -> Result<Option<Expression>> {
        // Delegate to the existing multiplication parsing
        match self.parse_multiplication() {
            Ok(expr) => Ok(Some(expr)),
            Err(_) => Ok(None),
        }
    }

    /// parse_fallback - Implemented from Python _parse_fallback
    #[allow(unused_variables, unused_mut)]
    pub fn parse_fallback(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["PROTECTION"]) {
            return Ok(Some(Expression::FallbackProperty(Box::new(
                FallbackProperty {
                    no: None,
                    protection: None,
                },
            ))));
        }
        Ok(None)
    }

    /// parse_field - Parse a field (column name, literal, or expression)
    /// Python: field = self._parse_primary() or self._parse_function() or self._parse_id_var()
    pub fn parse_field(&mut self) -> Result<Option<Expression>> {
        // Try parsing literals first
        if let Some(expr) = self.parse_string()? {
            return Ok(Some(expr));
        }
        if let Some(expr) = self.parse_number()? {
            return Ok(Some(expr));
        }
        if let Some(expr) = self.parse_boolean()? {
            return Ok(Some(expr));
        }
        if let Some(expr) = self.parse_null()? {
            return Ok(Some(expr));
        }
        if let Some(expr) = self.parse_star()? {
            return Ok(Some(expr));
        }
        // Try parsing identifier
        if let Some(expr) = self.parse_identifier()? {
            return Ok(Some(expr));
        }
        // Try parsing a variable/identifier
        if let Some(expr) = self.parse_var()? {
            return Ok(Some(expr));
        }
        // Allow keywords as identifiers in field context (e.g., "schema" as a field name)
        if self.check_keyword() {
            let token = self.advance();
            return Ok(Some(Expression::Identifier(Identifier {
                name: token.text,
                quoted: false,
                trailing_comments: Vec::new(),
                span: None,
            })));
        }
        Ok(None)
    }

    /// parse_field_def - Ported from Python _parse_field_def
    /// Parses a field definition (column name + type + optional constraints)
    #[allow(unused_variables, unused_mut)]
    pub fn parse_field_def(&mut self) -> Result<Option<Expression>> {
        // First parse the field name (identifier)
        let field = self.parse_field()?;

        if field.is_none() {
            return Ok(None);
        }

        // Parse the column definition with the field as the name
        self.parse_column_def_with_field(field)
    }

    /// Helper to parse a column definition with a pre-parsed field name
    fn parse_column_def_with_field(
        &mut self,
        field: Option<Expression>,
    ) -> Result<Option<Expression>> {
        if field.is_none() {
            return Ok(None);
        }

        let this = field.unwrap();

        // Get the identifier from the expression and preserve quoted-identifier state.
        let name_ident = match &this {
            Expression::Column(col) => col.name.clone(),
            Expression::Identifier(id) => id.clone(),
            Expression::Var(v) => Identifier::new(v.this.clone()),
            _ => return Ok(None),
        };

        // Parse the data type using parse_data_type_optional (which handles unknown types gracefully)
        let data_type = match self.parse_data_type_optional()? {
            Some(dt) => dt,
            None => DataType::Unknown,
        };

        // Create ColumnDef with default values
        let mut col_def = ColumnDef::new(name_ident.name.clone(), data_type);
        col_def.name = name_ident;

        // Check for FOR ORDINALITY (JSON table columns)
        if self.match_text_seq(&["FOR", "ORDINALITY"]) {
            return Ok(Some(Expression::ColumnDef(Box::new(col_def))));
        }

        // Parse constraints and extract specific constraint values
        loop {
            if let Some(constraint) = self.parse_column_constraint()? {
                // Check specific constraint types
                match &constraint {
                    Expression::NotNullColumnConstraint(_) => {
                        col_def.nullable = Some(false);
                        col_def.constraints.push(ColumnConstraint::NotNull);
                    }
                    Expression::PrimaryKeyColumnConstraint(_) => {
                        col_def.primary_key = true;
                        col_def.constraints.push(ColumnConstraint::PrimaryKey);
                    }
                    Expression::UniqueColumnConstraint(_) => {
                        col_def.unique = true;
                        col_def.constraints.push(ColumnConstraint::Unique);
                    }
                    Expression::DefaultColumnConstraint(dc) => {
                        col_def.default = Some((*dc.this).clone());
                        col_def
                            .constraints
                            .push(ColumnConstraint::Default((*dc.this).clone()));
                    }
                    Expression::AutoIncrementColumnConstraint(_) => {
                        col_def.auto_increment = true;
                    }
                    Expression::CommentColumnConstraint(_) => {
                        // Comment is a unit struct, we'd need the actual comment text
                    }
                    Expression::CheckColumnConstraint(cc) => {
                        col_def
                            .constraints
                            .push(ColumnConstraint::Check((*cc.this).clone()));
                    }
                    Expression::PathColumnConstraint(pc) => {
                        col_def
                            .constraints
                            .push(ColumnConstraint::Path((*pc.this).clone()));
                        col_def.constraint_order.push(ConstraintType::Path);
                    }
                    _ => {}
                }
            } else if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && self.match_identifier("ALIAS")
            {
                // ClickHouse: ALIAS expr
                let expr = self.parse_or()?;
                col_def.alias_expr = Some(Box::new(expr));
            } else if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && self.check(TokenType::Materialized)
                && !self.check_next(TokenType::View)
            {
                // ClickHouse: MATERIALIZED expr
                self.advance(); // consume MATERIALIZED
                let expr = self.parse_or()?;
                col_def.materialized_expr = Some(Box::new(expr));
            } else if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && self.match_identifier("EPHEMERAL")
            {
                // ClickHouse: EPHEMERAL [expr]
                if !self.check(TokenType::Comma)
                    && !self.check(TokenType::RParen)
                    && !self.is_at_end()
                    && !self.check_identifier("CODEC")
                    && !self.check_identifier("TTL")
                    && !self.check(TokenType::Comment)
                {
                    let expr = self.parse_bitwise()?.unwrap_or(Expression::Null(Null));
                    col_def.ephemeral = Some(Some(Box::new(expr)));
                } else {
                    col_def.ephemeral = Some(None);
                }
            } else if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && self.check_identifier("CODEC")
            {
                // ClickHouse: CODEC(LZ4HC(9), ZSTD, DELTA)
                self.advance(); // consume CODEC
                self.expect(TokenType::LParen)?;
                let start = self.current;
                let mut depth = 1;
                while !self.is_at_end() && depth > 0 {
                    if self.check(TokenType::LParen) {
                        depth += 1;
                    }
                    if self.check(TokenType::RParen) {
                        depth -= 1;
                        if depth == 0 {
                            break;
                        }
                    }
                    self.advance();
                }
                let codec_text = self.tokens_to_sql(start, self.current);
                self.expect(TokenType::RParen)?;
                col_def.codec = Some(codec_text);
            } else if matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && self.match_identifier("TTL")
            {
                // ClickHouse: TTL expr
                let expr = self.parse_expression()?;
                col_def.ttl_expr = Some(Box::new(expr));
            } else {
                break;
            }
        }

        Ok(Some(Expression::ColumnDef(Box::new(col_def))))
    }

    /// parse_foreign_key - Implemented from Python _parse_foreign_key
    /// Calls: parse_key_constraint_options, parse_wrapped_id_vars, parse_references
    #[allow(unused_variables, unused_mut)]
    pub fn parse_foreign_key(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["NO", "ACTION"]) {
            return Ok(Some(Expression::ForeignKey(Box::new(ForeignKey {
                expressions: Vec::new(),
                reference: None,
                delete: None,
                update: None,
                options: Vec::new(),
            }))));
        }
        Ok(None)
    }

    /// parse_format_json - Implemented from Python _parse_format_json
    #[allow(unused_variables, unused_mut)]
    pub fn parse_format_json(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["FORMAT", "JSON"]) {
            // Matched: FORMAT JSON
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_format_name - Snowflake FILE_FORMAT = format_name property
    /// Parses: format_name (string or identifier)
    #[allow(unused_variables, unused_mut)]
    pub fn parse_format_name(&mut self) -> Result<Option<Expression>> {
        // Try to parse a string first, then fall back to table parts
        let value = if let Some(s) = self.parse_string()? {
            s
        } else if let Some(tp) = self.parse_table_parts()? {
            tp
        } else {
            return Ok(None);
        };

        Ok(Some(Expression::Property(Box::new(Property {
            this: Box::new(Expression::Identifier(Identifier::new(
                "FORMAT_NAME".to_string(),
            ))),
            value: Some(Box::new(value)),
        }))))
    }

    /// parse_freespace - Teradata FREESPACE property
    /// Parses: FREESPACE = number [PERCENT]
    #[allow(unused_variables, unused_mut)]
    pub fn parse_freespace(&mut self) -> Result<Option<Expression>> {
        // Optionally consume = sign
        self.match_token(TokenType::Eq);

        // Parse the number value
        let this = self.parse_number()?;
        if this.is_none() {
            return Ok(None);
        }

        // Check for PERCENT keyword
        let percent = if self.match_token(TokenType::Percent) {
            Some(Box::new(Expression::Boolean(BooleanLiteral {
                value: true,
            })))
        } else {
            None
        };

        Ok(Some(Expression::FreespaceProperty(Box::new(
            FreespaceProperty {
                this: Box::new(this.unwrap()),
                percent,
            },
        ))))
    }

    /// parse_function - Ported from Python _parse_function
    /// Parses function calls like func_name(args) or {fn func_name(args)} (ODBC syntax)
    pub fn parse_function(&mut self) -> Result<Option<Expression>> {
        // Check for ODBC escape syntax: {fn function_call}
        let fn_syntax = if self.check(TokenType::LBrace) {
            if let Some(next) = self.tokens.get(self.current + 1) {
                if next.text.to_uppercase() == "FN" {
                    self.advance(); // consume {
                    self.advance(); // consume FN
                    true
                } else {
                    false
                }
            } else {
                false
            }
        } else {
            false
        };

        let func = self.parse_function_call()?;

        if fn_syntax {
            self.match_token(TokenType::RBrace);
        }

        Ok(func)
    }

    /// parse_function_args - Ported from Python _parse_function_args
    /// Parses the arguments inside a function call, handling aliases and key-value pairs
    pub fn parse_function_args_list(&mut self) -> Result<Vec<Expression>> {
        let mut args = Vec::new();

        if self.check(TokenType::RParen) {
            return Ok(args);
        }

        loop {
            // Try to parse expression with optional alias
            if let Some(expr) = self.parse_assignment()? {
                // Handle explicit AS alias inside function args (e.g. `tuple(1 AS "a", 2 AS "b")`)
                if self.match_token(TokenType::As) {
                    let alias_token = self.advance();
                    let alias_name = if alias_token.token_type == TokenType::QuotedIdentifier {
                        // Preserve quoted identifiers
                        let raw = alias_token.text.clone();
                        let mut ident = Identifier::new(raw);
                        ident.quoted = true;
                        ident
                    } else {
                        Identifier::new(alias_token.text.clone())
                    };
                    args.push(Expression::Alias(Box::new(crate::expressions::Alias {
                        this: expr,
                        alias: alias_name,
                        column_aliases: Vec::new(),
                        pre_alias_comments: Vec::new(),
                        trailing_comments: Vec::new(),
                        inferred_type: None,
                    })));
                } else {
                    args.push(expr);
                }
            }

            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        Ok(args)
    }

    /// parse_function_call - Ported from Python _parse_function_call
    /// Parses a function call expression like func_name(arg1, arg2, ...)
    pub fn parse_function_call(&mut self) -> Result<Option<Expression>> {
        if self.is_at_end() {
            return Ok(None);
        }

        let token = self.peek().clone();
        let token_type = token.token_type.clone();
        let name = token.text.clone();
        let _upper_name = name.to_uppercase();

        // Check for no-paren functions like CURRENT_DATE, CURRENT_TIMESTAMP
        if self.is_no_paren_function() {
            // Check if next token is NOT a paren (so it's used without parens)
            if !self.check_next(TokenType::LParen) {
                self.advance();
                return Ok(Some(Expression::Function(Box::new(Function {
                    name, // Preserve original case; generator handles normalization
                    args: Vec::new(),
                    distinct: false,
                    trailing_comments: Vec::new(),
                    use_bracket_syntax: false,
                    no_parens: true,
                    quoted: false,
                    span: None,
                    inferred_type: None,
                }))));
            }
        }

        // Must be followed by left paren
        if !self.check_next(TokenType::LParen) {
            return Ok(None);
        }

        // Token must be a valid function name token
        let is_valid_func_token = matches!(
            token_type,
            TokenType::Identifier
                | TokenType::Var
                | TokenType::If
                | TokenType::Left
                | TokenType::Right
                | TokenType::Insert
                | TokenType::Replace
                | TokenType::Row
                | TokenType::Index
        );
        if !is_valid_func_token {
            return Ok(None);
        }

        self.advance(); // consume function name
        self.advance(); // consume (

        // Check for DISTINCT keyword
        let distinct = self.match_token(TokenType::Distinct);

        // Parse arguments
        let args = self.parse_function_args_list()?;

        self.match_token(TokenType::RParen);

        // Handle window specifications
        let func_expr = Expression::Function(Box::new(Function {
            name, // Preserve original case; generator handles normalization
            args,
            distinct,
            trailing_comments: Vec::new(),
            use_bracket_syntax: false,
            no_parens: false,
            quoted: false,
            span: None,
            inferred_type: None,
        }));

        // Check for OVER clause (window function)
        if self.match_token(TokenType::Over) {
            // Parse window spec - create a simple WindowSpec
            if self.match_token(TokenType::LParen) {
                // Use parse_window_spec_inner to handle DISTRIBUTE BY/SORT BY (Hive)
                let spec = self.parse_window_spec_inner()?;
                self.expect(TokenType::RParen)?;

                if let Some(spec_expr) = spec {
                    return Ok(Some(spec_expr));
                }
            }
        }

        Ok(Some(func_expr))
    }

    /// parse_function_parameter - Ported from Python _parse_function_parameter
    /// Parses a function parameter in CREATE FUNCTION (name type [DEFAULT expr])
    pub fn parse_function_parameter(&mut self) -> Result<Option<Expression>> {
        // Parse optional parameter mode (IN, OUT, INOUT)
        let _mode = if self.match_texts(&["IN"]) {
            if self.match_texts(&["OUT"]) {
                Some(ParameterMode::InOut)
            } else {
                Some(ParameterMode::In)
            }
        } else if self.match_texts(&["OUT"]) {
            Some(ParameterMode::Out)
        } else if self.match_texts(&["INOUT"]) {
            Some(ParameterMode::InOut)
        } else {
            None
        };

        // Parse parameter name (optional in some dialects)
        let name_expr = self.parse_id_var()?;
        let name = name_expr.and_then(|n| match n {
            Expression::Identifier(id) => Some(id),
            _ => None,
        });

        // Parse data type - returns Result<DataType>, not Result<Option<DataType>>
        // We need to handle the case where we can't parse a data type
        let data_type_result = self.parse_data_type();
        let _data_type = match data_type_result {
            Ok(dt) => dt,
            Err(_) => return Ok(None),
        };

        // Parse optional DEFAULT value
        let _default = if self.match_token(TokenType::Default) || self.match_texts(&["="]) {
            self.parse_disjunction()?
        } else {
            None
        };

        // Return the name as a Column expression
        Ok(Some(Expression::Column(Column {
            name: Identifier {
                name: name.map(|n| n.name).unwrap_or_default(),
                quoted: false,
                trailing_comments: Vec::new(),
                span: None,
            },
            table: None,
            join_mark: false,
            trailing_comments: Vec::new(),
            span: None,
            inferred_type: None,
        })))
    }

    /// parse_gap_fill - Ported from Python _parse_gap_fill
    #[allow(unused_variables, unused_mut)]
    /// parse_gap_fill - Parses GAP_FILL function for time series
    /// Example: GAP_FILL(TABLE t, ts_column, bucket_width, partitioning_columns, value_columns)
    pub fn parse_gap_fill(&mut self) -> Result<Option<Expression>> {
        // Optional TABLE keyword
        self.match_token(TokenType::Table);

        // Parse the table reference
        let this = self.parse_table()?;
        if this.is_none() {
            return Ok(None);
        }

        // Parse comma-separated arguments
        self.match_token(TokenType::Comma);
        let mut args = self.parse_expression_list()?;

        // Extract arguments by position
        let ts_column = args.get(0).cloned().map(Box::new);
        let bucket_width = args.get(1).cloned().map(Box::new);
        let partitioning_columns = args.get(2).cloned().map(Box::new);
        let value_columns = args.get(3).cloned().map(Box::new);

        Ok(Some(Expression::GapFill(Box::new(GapFill {
            this: Box::new(this.unwrap()),
            ts_column,
            bucket_width,
            partitioning_columns,
            value_columns,
            origin: None,
            ignore_nulls: None,
        }))))
    }

    /// parse_semantic_view - Parse Snowflake SEMANTIC_VIEW function
    /// Example: SEMANTIC_VIEW(foo METRICS a.b, a.c DIMENSIONS a.b, a.c WHERE a.b > '1995-01-01')
    pub fn parse_semantic_view(&mut self) -> Result<Expression> {
        // Parse the table/view reference as a primary expression (identifier or qualified name)
        let this = self.parse_primary()?;

        let mut metrics = None;
        let mut dimensions = None;
        let mut facts = None;
        let mut where_clause = None;

        // Parse optional clauses: METRICS, DIMENSIONS, FACTS, WHERE
        while !self.check(TokenType::RParen) && !self.is_at_end() {
            if self.match_identifier("METRICS") {
                // Parse comma-separated expressions until next keyword or )
                let exprs = self.parse_semantic_view_list()?;
                metrics = Some(Box::new(Expression::Tuple(Box::new(Tuple {
                    expressions: exprs,
                }))));
            } else if self.match_identifier("DIMENSIONS") {
                let exprs = self.parse_semantic_view_list()?;
                dimensions = Some(Box::new(Expression::Tuple(Box::new(Tuple {
                    expressions: exprs,
                }))));
            } else if self.match_identifier("FACTS") {
                let exprs = self.parse_semantic_view_list()?;
                facts = Some(Box::new(Expression::Tuple(Box::new(Tuple {
                    expressions: exprs,
                }))));
            } else if self.match_token(TokenType::Where) {
                // Parse the WHERE expression
                where_clause = Some(Box::new(self.parse_expression()?));
                // WHERE is the last clause, break after parsing it
                break;
            } else {
                // Unknown token
                break;
            }
        }

        Ok(Expression::SemanticView(Box::new(SemanticView {
            this: Box::new(this),
            metrics,
            dimensions,
            facts,
            where_: where_clause,
        })))
    }

    /// Helper to parse comma-separated expression list for SEMANTIC_VIEW clauses
    /// Stops at METRICS, DIMENSIONS, FACTS, WHERE, or )
    /// Each element can have an optional AS alias: expr AS name
    fn parse_semantic_view_list(&mut self) -> Result<Vec<Expression>> {
        let first = self.parse_semantic_view_element()?;
        let mut exprs = vec![first];
        while self.match_token(TokenType::Comma) {
            // Check if next token is a keyword that starts a new clause
            if self.check_identifier("METRICS")
                || self.check_identifier("DIMENSIONS")
                || self.check_identifier("FACTS")
                || self.check(TokenType::Where)
                || self.check(TokenType::RParen)
            {
                break;
            }
            exprs.push(self.parse_semantic_view_element()?);
        }
        Ok(exprs)
    }

    /// Parse a single SEMANTIC_VIEW element: expression [AS alias]
    fn parse_semantic_view_element(&mut self) -> Result<Expression> {
        let expr = self.parse_disjunction()?.ok_or_else(|| {
            self.parse_error("Expected expression in SEMANTIC_VIEW clause")
        })?;
        // Check for optional explicit AS alias
        if self.match_token(TokenType::As) {
            let alias = self.expect_identifier_or_keyword_with_quoted()?;
            Ok(Expression::Alias(Box::new(crate::expressions::Alias {
                this: expr,
                alias,
                column_aliases: Vec::new(),
                pre_alias_comments: Vec::new(),
                trailing_comments: Vec::new(),
                inferred_type: None,
            })))
        } else {
            Ok(expr)
        }
    }

    /// parse_grant_principal - Implemented from Python _parse_grant_principal
    /// Calls: parse_id_var
    #[allow(unused_variables, unused_mut)]
    pub fn parse_grant_principal(&mut self) -> Result<Option<Expression>> {
        if self.match_texts(&["ROLE", "GROUP"]) {
            // Matched one of: ROLE, GROUP
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_grant_privilege - Parse a single privilege in GRANT/REVOKE
    /// Parses: SELECT, INSERT, UPDATE(col1, col2), DELETE, etc.
    #[allow(unused_variables, unused_mut)]
    pub fn parse_grant_privilege(&mut self) -> Result<Option<Expression>> {
        // Collect privilege keywords (SELECT, INSERT, UPDATE, DELETE, ALL PRIVILEGES, etc.)
        let mut privilege_parts = Vec::new();

        // Keep consuming keywords until we hit a follow token
        // Follow tokens are: comma, ON, left paren
        while !self.is_at_end() {
            // Check if we've hit a follow token
            if self.check(TokenType::Comma)
                || self.check(TokenType::On)
                || self.check(TokenType::LParen)
            {
                break;
            }

            // Get the current token text
            let text = self.peek().text.to_uppercase();
            privilege_parts.push(text);
            self.advance();
        }

        if privilege_parts.is_empty() {
            return Ok(None);
        }

        let privilege_str = privilege_parts.join(" ");

        // Check for column list in parentheses (e.g., UPDATE(col1, col2))
        let expressions = if self.match_token(TokenType::LParen) {
            let mut columns = Vec::new();
            loop {
                if let Some(col) = self.parse_column()? {
                    columns.push(col);
                } else {
                    break;
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            self.match_token(TokenType::RParen);
            columns
        } else {
            Vec::new()
        };

        Ok(Some(Expression::GrantPrivilege(Box::new(GrantPrivilege {
            this: Box::new(Expression::Identifier(Identifier::new(privilege_str))),
            expressions,
        }))))
    }

    /// parse_grant_revoke_common - Parses common parts of GRANT/REVOKE statements
    /// Python: _parse_grant_revoke_common
    /// Returns a Tuple containing (privileges, kind, securable)
    pub fn parse_grant_revoke_common(&mut self) -> Result<Option<Expression>> {
        // Parse privileges (CSV of grant privileges)
        let mut privileges = Vec::new();
        loop {
            if let Some(priv_expr) = self.parse_grant_privilege()? {
                privileges.push(priv_expr);
            }
            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        // Match ON keyword
        self.match_token(TokenType::On);

        // Parse kind (TABLE, VIEW, SCHEMA, DATABASE, etc.)
        let kind = if self.match_texts(&[
            "TABLE",
            "VIEW",
            "SCHEMA",
            "DATABASE",
            "SEQUENCE",
            "FUNCTION",
            "PROCEDURE",
            "INDEX",
            "TYPE",
            "TABLESPACE",
            "ROLE",
            "USER",
        ]) {
            let kind_text = self.previous().text.to_uppercase();
            Some(Expression::Var(Box::new(Var { this: kind_text })))
        } else {
            None
        };

        // Try to parse securable (table parts)
        let securable = self.parse_table_parts()?;

        // Return as Tuple with three elements: privileges_list, kind, securable
        let privileges_expr = Expression::Tuple(Box::new(Tuple {
            expressions: privileges,
        }));

        let mut result_exprs = vec![privileges_expr];

        if let Some(k) = kind {
            result_exprs.push(k);
        } else {
            result_exprs.push(Expression::Null(Null));
        }

        if let Some(s) = securable {
            result_exprs.push(s);
        } else {
            result_exprs.push(Expression::Null(Null));
        }

        Ok(Some(Expression::Tuple(Box::new(Tuple {
            expressions: result_exprs,
        }))))
    }

    /// parse_group - Parse GROUP BY clause
    /// Python: if not self._match(TokenType.GROUP_BY): return None; expressions = self._parse_csv(self._parse_disjunction)
    pub fn parse_group(&mut self) -> Result<Option<Expression>> {
        // Check for GROUP BY token (which should be parsed as Group + By tokens)
        if !self.match_token(TokenType::Group) {
            return Ok(None);
        }
        // Consume BY if present
        self.match_token(TokenType::By);

        // Check for optional ALL/DISTINCT
        // Some(true) = ALL, Some(false) = DISTINCT, None = no modifier
        let all = if self.match_token(TokenType::All) {
            Some(true)
        } else if self.match_token(TokenType::Distinct) {
            Some(false)
        } else {
            None
        };

        // Parse comma-separated expressions
        let mut expressions = Vec::new();
        loop {
            match self.parse_expression() {
                Ok(expr) => expressions.push(expr),
                Err(_) => break,
            }
            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        // Handle TOTALS (ClickHouse)
        let totals = if self.match_text_seq(&["WITH", "TOTALS"]) {
            Some(Box::new(Expression::Boolean(BooleanLiteral {
                value: true,
            })))
        } else if self.match_text_seq(&["TOTALS"]) {
            Some(Box::new(Expression::Boolean(BooleanLiteral {
                value: true,
            })))
        } else {
            None
        };

        Ok(Some(Expression::Group(Box::new(Group {
            expressions,
            grouping_sets: None,
            cube: None,
            rollup: None,
            totals,
            all,
        }))))
    }

    /// parse_group_concat - Ported from Python _parse_group_concat
    #[allow(unused_variables, unused_mut)]
    /// parse_group_concat - Parses MySQL GROUP_CONCAT function
    /// Example: GROUP_CONCAT(DISTINCT col ORDER BY col SEPARATOR ',')
    pub fn parse_group_concat(&mut self) -> Result<Option<Expression>> {
        // Check for DISTINCT
        let distinct = self.match_token(TokenType::Distinct);

        // Parse expression(s)
        let expr = self.parse_expression()?;

        // Parse optional ORDER BY
        let order_by = if self.match_keywords(&[TokenType::Order, TokenType::By]) {
            let mut orderings = Vec::new();
            loop {
                let order_expr = self.parse_expression()?;
                let desc = if self.match_token(TokenType::Desc) {
                    true
                } else {
                    self.match_token(TokenType::Asc);
                    false
                };
                let nulls_first = if self.match_keywords(&[TokenType::Nulls, TokenType::First]) {
                    Some(true)
                } else if self.match_keywords(&[TokenType::Nulls, TokenType::Last]) {
                    Some(false)
                } else {
                    None
                };
                orderings.push(Ordered {
                    this: order_expr,
                    desc,
                    nulls_first,
                    explicit_asc: !desc,
                    with_fill: None,
                });
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            Some(orderings)
        } else {
            None
        };

        // Parse optional SEPARATOR
        let separator = if self.match_token(TokenType::Separator) {
            self.parse_string()?
        } else {
            None
        };

        Ok(Some(Expression::GroupConcat(Box::new(GroupConcatFunc {
            this: expr,
            separator,
            order_by,
            distinct,
            filter: None,
            inferred_type: None,
        }))))
    }

    /// parse_grouping_set - Delegates to parse_grouping_sets
    #[allow(unused_variables, unused_mut)]
    pub fn parse_grouping_set(&mut self) -> Result<Option<Expression>> {
        self.parse_grouping_sets()
    }

    /// parse_grouping_sets - Ported from Python _parse_grouping_sets
    /// Parses GROUPING SETS ((...), (...)) in GROUP BY
    #[allow(unused_variables, unused_mut)]
    pub fn parse_grouping_sets(&mut self) -> Result<Option<Expression>> {
        // Check for GROUPING SETS keyword
        if !self.match_text_seq(&["GROUPING", "SETS"]) {
            return Ok(None);
        }

        // Parse wrapped grouping sets
        self.expect(TokenType::LParen)?;
        let mut expressions = Vec::new();

        if !self.check(TokenType::RParen) {
            loop {
                // Each grouping set can be:
                // - A nested GROUPING SETS
                // - CUBE or ROLLUP
                // - A parenthesized list
                // - A single expression
                if let Some(nested) = self.parse_grouping_sets()? {
                    expressions.push(nested);
                } else if let Some(cube_rollup) = self.parse_cube_or_rollup()? {
                    expressions.push(cube_rollup);
                } else if self.match_token(TokenType::LParen) {
                    // Parenthesized group
                    let mut group = Vec::new();
                    if !self.check(TokenType::RParen) {
                        loop {
                            match self.parse_bitwise() {
                                Ok(Some(expr)) => group.push(expr),
                                Ok(None) => break,
                                Err(e) => return Err(e),
                            }
                            if !self.match_token(TokenType::Comma) {
                                break;
                            }
                        }
                    }
                    self.expect(TokenType::RParen)?;
                    expressions.push(Expression::Tuple(Box::new(Tuple { expressions: group })));
                } else {
                    // Single expression
                    match self.parse_bitwise() {
                        Ok(Some(expr)) => expressions.push(expr),
                        Ok(None) => break,
                        Err(e) => return Err(e),
                    }
                }

                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
        }

        self.expect(TokenType::RParen)?;

        Ok(Some(Expression::GroupingSets(Box::new(GroupingSets {
            expressions,
        }))))
    }

    /// parse_having - Parse HAVING clause
    /// Python: if not self._match(TokenType.HAVING): return None; return exp.Having(this=self._parse_disjunction())
    pub fn parse_having(&mut self) -> Result<Option<Expression>> {
        if !self.match_token(TokenType::Having) {
            return Ok(None);
        }
        // Parse the condition expression
        let condition = self.parse_expression()?;
        Ok(Some(Expression::Having(Box::new(Having {
            this: condition,
            comments: Vec::new(),
        }))))
    }

    /// parse_having_max - Implemented from Python _parse_having_max
    /// Calls: parse_column
    #[allow(unused_variables, unused_mut)]
    pub fn parse_having_max(&mut self) -> Result<Option<Expression>> {
        if self.match_texts(&["MAX", "MIN"]) {
            // Matched one of: MAX, MIN
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_heredoc - Implemented from Python _parse_heredoc
    /// Parses dollar-quoted strings: $$content$$, $tag$content$tag$
    pub fn parse_heredoc(&mut self) -> Result<Option<Expression>> {
        // Check if current token is a HEREDOC_STRING type
        if self.match_token(TokenType::HeredocString) {
            let text = self.previous().text.clone();
            return Ok(Some(Expression::Heredoc(Box::new(Heredoc {
                this: Box::new(Expression::Literal(Literal::String(text))),
                tag: None,
            }))));
        }

        // Try to parse $...$ or $tag$...$tag$
        if !self.match_text_seq(&["$"]) {
            return Ok(None);
        }

        // Collect the tag text (if any) and the closing marker
        let mut tags = vec!["$".to_string()];
        let mut tag_text: Option<String> = None;

        // Check if next token is connected (no whitespace) and collect tag
        if !self.is_at_end() {
            let next_text = self.peek().text.to_uppercase();
            if next_text == "$" {
                // Simple $$ ... $$ case
                self.advance();
                tags.push("$".to_string());
            } else {
                // $tag$ ... $tag$ case
                self.advance();
                tag_text = Some(next_text.clone());
                tags.push(next_text);

                // Expect closing $
                if self.match_text_seq(&["$"]) {
                    tags.push("$".to_string());
                } else {
                    return Err(self.parse_error("No closing $ found"));
                }
            }
        }

        // Now collect content until we find the closing tags
        let mut content_parts = Vec::new();
        let closing_tag = tags.join("");

        while !self.is_at_end() {
            // Build current sequence to check for closing tag
            let current_text = self.peek().text.clone();

            // Check if we've reached the closing tag
            if current_text == "$" || current_text.to_uppercase() == closing_tag {
                // Try to match the full closing sequence
                let start_pos = self.current;
                let mut matched = true;
                for expected in &tags {
                    if self.is_at_end()
                        || self.peek().text.to_uppercase() != expected.to_uppercase()
                    {
                        matched = false;
                        break;
                    }
                    self.advance();
                }
                if matched {
                    // Found the closing tag
                    let content = content_parts.join(" ");
                    return Ok(Some(Expression::Heredoc(Box::new(Heredoc {
                        this: Box::new(Expression::Literal(Literal::String(content))),
                        tag: tag_text.map(|t| Box::new(Expression::Literal(Literal::String(t)))),
                    }))));
                }
                // Not the closing tag, backtrack and add to content
                self.current = start_pos;
            }

            content_parts.push(self.advance().text.clone());
        }

        Err(self.parse_error(&format!("No closing {} found", closing_tag)))
    }

    /// parse_hint_body - Delegates to parse_hint_fallback_to_string
    #[allow(unused_variables, unused_mut)]
    pub fn parse_hint_body(&mut self) -> Result<Option<Expression>> {
        self.parse_hint_fallback_to_string()
    }

    /// parse_hint_fallback_to_string - Parses remaining hint tokens as a raw string
    /// Python: _parse_hint_fallback_to_string
    /// Used when structured hint parsing fails - collects all remaining tokens
    pub fn parse_hint_fallback_to_string(&mut self) -> Result<Option<Expression>> {
        // Collect all remaining tokens as a string
        let mut parts = Vec::new();
        while !self.is_at_end() {
            let token = self.advance();
            parts.push(token.text.clone());
        }

        if parts.is_empty() {
            return Ok(None);
        }

        let hint_text = parts.join(" ");
        Ok(Some(Expression::Hint(Box::new(Hint {
            expressions: vec![HintExpression::Raw(hint_text)],
        }))))
    }

    /// parse_hint_function_call - Delegates to parse_function_call
    #[allow(unused_variables, unused_mut)]
    pub fn parse_hint_function_call(&mut self) -> Result<Option<Expression>> {
        self.parse_function_call()
    }

    /// parse_historical_data - Snowflake AT/BEFORE time travel clauses
    /// Parses: AT(TIMESTAMP => expr) or BEFORE(STATEMENT => 'id') etc.
    /// Reference: https://docs.snowflake.com/en/sql-reference/constructs/at-before
    #[allow(unused_variables, unused_mut)]
    pub fn parse_historical_data(&mut self) -> Result<Option<Expression>> {
        // Save position for backtracking
        let start_index = self.current;

        // Check for AT, BEFORE, or END keywords
        let this = if self.match_texts(&["AT", "BEFORE", "END"]) {
            self.previous().text.to_uppercase()
        } else {
            return Ok(None);
        };

        // Expect opening paren and kind (OFFSET, STATEMENT, STREAM, TIMESTAMP, VERSION)
        if !self.match_token(TokenType::LParen) {
            // Backtrack if not the right pattern
            self.current = start_index;
            return Ok(None);
        }

        let kind = if self.match_texts(&["OFFSET", "STATEMENT", "STREAM", "TIMESTAMP", "VERSION"]) {
            self.previous().text.to_uppercase()
        } else {
            // Backtrack if not the right pattern
            self.current = start_index;
            return Ok(None);
        };

        // Expect => and expression
        if !self.match_token(TokenType::FArrow) {
            self.current = start_index;
            return Ok(None);
        }

        let expression = self.parse_bitwise()?;
        if expression.is_none() {
            self.current = start_index;
            return Ok(None);
        }

        self.match_token(TokenType::RParen); // Consume closing paren

        Ok(Some(Expression::HistoricalData(Box::new(HistoricalData {
            this: Box::new(Expression::Identifier(Identifier::new(this))),
            kind,
            expression: Box::new(expression.unwrap()),
        }))))
    }

    /// parse_id_var - Ported from Python _parse_id_var
    /// Parses an identifier or variable (more permissive than parse_identifier)
    #[allow(unused_variables, unused_mut)]
    pub fn parse_id_var(&mut self) -> Result<Option<Expression>> {
        // First try to parse a regular identifier
        if let Some(ident) = self.parse_identifier()? {
            return Ok(Some(ident));
        }

        // Try to match Var token type
        if self.match_token(TokenType::Var) {
            let text = self.previous().text.clone();
            return Ok(Some(Expression::Identifier(Identifier {
                name: text,
                quoted: false,
                trailing_comments: Vec::new(),
                span: None,
            })));
        }

        // Try to match string as identifier (some dialects allow this)
        if self.match_token(TokenType::String) {
            let text = self.previous().text.clone();
            return Ok(Some(Expression::Identifier(Identifier {
                name: text,
                quoted: true,
                trailing_comments: Vec::new(),
                span: None,
            })));
        }

        // Accept keywords as identifiers in some contexts
        if self.check(TokenType::Select)
            || self.check(TokenType::From)
            || self.check(TokenType::Where)
            || self.check(TokenType::And)
            || self.check(TokenType::Or)
            || self.check(TokenType::Not)
            || self.check(TokenType::True)
            || self.check(TokenType::False)
            || self.check(TokenType::Null)
        {
            // Don't consume keywords as identifiers in parse_id_var
            return Ok(None);
        }

        Ok(None)
    }

    /// parse_identifier - Parse quoted identifier
    /// Python: if self._match(TokenType.IDENTIFIER): return self._identifier_expression(quoted=True)
    pub fn parse_identifier(&mut self) -> Result<Option<Expression>> {
        // Match quoted identifiers (e.g., "column_name" or `column_name`)
        if self.match_token(TokenType::QuotedIdentifier) || self.match_token(TokenType::Identifier)
        {
            let text = self.previous().text.clone();
            let quoted = self.previous().token_type == TokenType::QuotedIdentifier;
            return Ok(Some(Expression::Identifier(Identifier {
                name: text,
                quoted,
                trailing_comments: Vec::new(),
                span: None,
            })));
        }
        Ok(None)
    }

    /// Parse IF expression
    /// IF(condition, true_value, false_value) - function style
    /// IF condition THEN true_value ELSE false_value END - statement style
    pub fn parse_if(&mut self) -> Result<Option<Expression>> {
        // TSQL/Fabric: IF (cond) BEGIN ... END is a statement, not a function.
        // Parse condition, strip outer parens, then capture rest as command.
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::TSQL) | Some(crate::dialects::DialectType::Fabric)
        ) && self.check(TokenType::LParen) {
            // Parse the parenthesized condition using balanced paren matching
            let cond_start = self.current;
            self.advance(); // consume opening (
            let mut depth = 1;
            while depth > 0 && !self.is_at_end() {
                if self.check(TokenType::LParen) {
                    depth += 1;
                } else if self.check(TokenType::RParen) {
                    depth -= 1;
                    if depth == 0 {
                        break;
                    }
                }
                self.advance();
            }
            // Extract condition text from source (inside outer parens)
            let cond_text = if let Some(ref source) = self.source {
                let inner_start = self.tokens[cond_start + 1].span.start;
                let inner_end = self.tokens[self.current].span.start;
                source[inner_start..inner_end].trim().to_string()
            } else {
                self.tokens_to_sql(cond_start + 1, self.current)
            };
            self.advance(); // consume closing )

            // Now collect the rest (BEGIN...END) as raw text
            let body_start = self.current;
            while !self.is_at_end() && !self.check(TokenType::Semicolon) {
                self.advance();
            }
            let body_text = if let Some(ref source) = self.source {
                let start_span = self.tokens[body_start].span.start;
                let end_span = if self.current > 0 { self.tokens[self.current - 1].span.end } else { start_span };
                source[start_span..end_span].trim().to_string()
            } else {
                self.tokens_to_sql(body_start, self.current)
            };
            let command_text = format!("IF {} {}", cond_text, body_text);
            return Ok(Some(Expression::Command(Box::new(crate::expressions::Command {
                this: command_text,
            }))));
        }

        // Function style: IF(cond, true, false)
        if self.match_token(TokenType::LParen) {
            // ClickHouse: if() with zero args is valid (used in test queries)
            if self.check(TokenType::RParen) {
                self.advance(); // consume RParen
                return Ok(Some(Expression::Function(Box::new(Function {
                    name: "IF".to_string(),
                    args: vec![],
                    distinct: false,
                    trailing_comments: Vec::new(),
                    use_bracket_syntax: false,
                    no_parens: false,
                    quoted: false,
                    span: None,
                    inferred_type: None,
                }))));
            }
            let args = self.parse_expression_list()?;
            self.expect(TokenType::RParen)?;

            if args.len() == 3 {
                return Ok(Some(Expression::IfFunc(Box::new(IfFunc {
                    original_name: None,
                    condition: args[0].clone(),
                    true_value: args[1].clone(),
                    false_value: Some(args[2].clone()),
                    inferred_type: None,
                }))));
            } else if args.len() == 2 {
                return Ok(Some(Expression::IfFunc(Box::new(IfFunc {
                    original_name: None,
                    condition: args[0].clone(),
                    true_value: args[1].clone(),
                    false_value: None,
                    inferred_type: None,
                }))));
            } else if args.len() == 1 {
                return Ok(Some(Expression::Function(Box::new(Function {
                    name: "IF".to_string(),
                    args,
                    distinct: false,
                    trailing_comments: Vec::new(),
                    use_bracket_syntax: false,
                    no_parens: false,
                    quoted: false,
                    span: None,
                    inferred_type: None,
                }))));
            } else {
                return Err(self.parse_error("IF function requires 2 or 3 arguments"));
            }
        }

        // TSQL: IF OBJECT_ID(...) IS NOT NULL [BEGIN] DROP TABLE x [; END] -> DROP TABLE IF EXISTS x
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::TSQL) | Some(crate::dialects::DialectType::Fabric)
        ) {
            let saved = self.current;
            if self.match_text_seq(&["OBJECT_ID"]) {
                // Capture the OBJECT_ID arguments text for TSQL round-trip
                let object_id_args_text = if self.match_token(TokenType::LParen) {
                    let args_start = self.current;
                    let args = self.parse_expression_list()?;
                    // Reconstruct args text from source
                    let args_text = if let Some(ref source) = self.source {
                        let start_span = self.tokens[args_start].span.start;
                        let end_span = self.tokens[self.current].span.start;
                        source[start_span..end_span].trim().to_string()
                    } else {
                        // Fallback: generate from parsed expressions
                        args.iter()
                            .map(|a| format!("{:?}", a))
                            .collect::<Vec<_>>()
                            .join(", ")
                    };
                    let _ = self.match_token(TokenType::RParen);
                    Some(args_text)
                } else {
                    None
                };
                if self.match_text_seq(&["IS", "NOT", "NULL"]) {
                    // Check for DROP directly or BEGIN ... DROP ... END
                    let has_begin = self.match_token(TokenType::Begin);
                    if self.check(TokenType::Drop) {
                        // Parse DROP TABLE, forcing if_exists = true
                        self.advance(); // consume DROP
                        if self.match_token(TokenType::Table) {
                            // Parse table names
                            let mut names = Vec::new();
                            loop {
                                names.push(self.parse_table_ref()?);
                                if !self.match_token(TokenType::Comma) {
                                    break;
                                }
                            }
                            // If we had BEGIN, consume optional ; and END
                            if has_begin {
                                let _ = self.match_token(TokenType::Semicolon);
                                let _ = self.match_token(TokenType::End);
                            }
                            return Ok(Some(Expression::DropTable(Box::new(
                                crate::expressions::DropTable {
                                    names,
                                    if_exists: true,
                                    cascade: false,
                                    cascade_constraints: false,
                                    purge: false,
                                    leading_comments: Vec::new(),
                                    object_id_args: object_id_args_text,
                                },
                            ))));
                        }
                    }
                }
                // Retreat if pattern didn't match
                self.current = saved;
            }
        }

        // Statement style: IF cond THEN true [ELSE false] END/ENDIF
        // Use parse_disjunction (parse_or) for condition - same as Python sqlglot
        // This ensures we stop at THEN rather than consuming too much
        let condition = match self.parse_disjunction()? {
            Some(c) => c,
            None => return Ok(None),
        };

        if !self.match_token(TokenType::Then) {
            // Not statement style, return as just the expression parsed
            return Ok(Some(condition));
        }

        // Parse true value - use parse_disjunction to stop at ELSE/END
        let true_value = match self.parse_disjunction()? {
            Some(v) => v,
            None => return Err(self.parse_error("Expected expression after THEN")),
        };

        let false_value = if self.match_token(TokenType::Else) {
            match self.parse_disjunction()? {
                Some(v) => Some(v),
                None => return Err(self.parse_error("Expected expression after ELSE")),
            }
        } else {
            None
        };

        // Consume END or ENDIF (Exasol tokenizes ENDIF as END)
        self.match_token(TokenType::End);

        Ok(Some(Expression::IfFunc(Box::new(IfFunc {
            original_name: None,
            condition,
            true_value,
            false_value,
            inferred_type: None,
        }))))
    }

    /// parse_in - Ported from Python _parse_in
    /// Parses IN expression: expr IN (values...) or expr IN (subquery)
    /// Can also parse standalone IN list after IN keyword has been matched
    #[allow(unused_variables, unused_mut)]
    pub fn parse_in(&mut self) -> Result<Option<Expression>> {
        // If we're at IN keyword, parse what follows
        if self.match_token(TokenType::In) {
            return Err(self.parse_error("Expected expression before IN"));
        }

        // Try to parse as a complete expression: left IN (...)
        let saved_pos = self.current;

        // Parse the left side expression
        match self.parse_bitwise() {
            Ok(Some(left_expr)) => {
                // Check for optional NOT
                let negate = self.match_token(TokenType::Not);

                // Expect IN keyword
                if self.match_token(TokenType::In) {
                    let in_result = self.parse_in_with_expr(Some(left_expr))?;
                    return Ok(Some(if negate {
                        Expression::Not(Box::new(UnaryOp {
                            this: in_result,
                            inferred_type: None,
                        }))
                    } else {
                        in_result
                    }));
                }

                // Not an IN expression, restore position
                self.current = saved_pos;
                Ok(None)
            }
            Ok(None) => {
                self.current = saved_pos;
                Ok(None)
            }
            Err(_) => {
                self.current = saved_pos;
                Ok(None)
            }
        }
    }

    /// parse_index - Implemented from Python _parse_index
    /// Calls: parse_index_params, parse_id_var
    #[allow(unused_variables, unused_mut)]
    pub fn parse_index(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["PRIMARY"]) {
            return Ok(Some(Expression::Index(Box::new(Index {
                this: None,
                table: None,
                unique: false,
                primary: None,
                amp: None,
                params: Vec::new(),
            }))));
        }
        if self.match_text_seq(&["AMP"]) {
            // Matched: AMP
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_index_params - Implemented from Python _parse_index_params
    /// Calls: parse_where, parse_wrapped_properties, parse_wrapped_id_vars
    #[allow(unused_variables, unused_mut)]
    pub fn parse_index_params(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["INCLUDE"]) {
            return Ok(Some(Expression::IndexParameters(Box::new(
                IndexParameters {
                    using: None,
                    include: None,
                    columns: Vec::new(),
                    with_storage: None,
                    partition_by: None,
                    tablespace: None,
                    where_: None,
                    on: None,
                },
            ))));
        }
        if self.match_text_seq(&["USING", "INDEX", "TABLESPACE"]) {
            // Matched: USING INDEX TABLESPACE
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_initcap - Ported from Python _parse_initcap
    #[allow(unused_variables, unused_mut)]
    /// parse_initcap - Parses INITCAP function
    /// Example: INITCAP(str) or INITCAP(str, delimiter)
    pub fn parse_initcap(&mut self) -> Result<Option<Expression>> {
        // Parse the first argument (string to capitalize)
        let args = self.parse_expression_list()?;

        if args.is_empty() {
            return Ok(None);
        }

        // Initcap is a UnaryFunc
        Ok(Some(Expression::Initcap(Box::new(UnaryFunc::new(
            args.into_iter().next().unwrap(),
        )))))
    }

    /// parse_inline - Implemented from Python _parse_inline
    #[allow(unused_variables, unused_mut)]
    pub fn parse_inline(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["LENGTH"]) {
            // Matched: LENGTH
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_insert_table - Parse table reference for INSERT statement
    /// Parses: table_name [schema] [partition] [alias]
    /// This method is a simple wrapper around parse_table for INSERT context
    #[allow(unused_variables, unused_mut)]
    pub fn parse_insert_table(&mut self) -> Result<Option<Expression>> {
        // Parse the table reference - parse_table handles aliases
        self.parse_table()
    }

    /// parse_interpolate - Implemented from Python _parse_interpolate
    /// Parses INTERPOLATE clause for ClickHouse ORDER BY WITH FILL
    pub fn parse_interpolate(&mut self) -> Result<Option<Expression>> {
        if !self.match_text_seq(&["INTERPOLATE"]) {
            return Ok(None);
        }

        // Parse wrapped CSV of name-as-expression pairs
        if self.match_token(TokenType::LParen) {
            let mut expressions = Vec::new();
            loop {
                if let Some(expr) = self.parse_name_as_expression()? {
                    expressions.push(expr);
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            self.match_token(TokenType::RParen);

            if expressions.is_empty() {
                return Ok(None);
            }

            return Ok(Some(Expression::Tuple(Box::new(Tuple { expressions }))));
        }

        Ok(None)
    }

    /// parse_interval - Creates Interval expression
    /// Parses INTERVAL expressions: INTERVAL '1 day', INTERVAL 1 MONTH, etc.
    #[allow(unused_variables, unused_mut)]
    pub fn parse_interval(&mut self) -> Result<Option<Expression>> {
        // Delegate to the existing try_parse_interval method
        self.try_parse_interval()
    }

    /// parse_interval_span - Implemented from Python _parse_interval_span
    /// Calls: parse_function
    #[allow(unused_variables, unused_mut)]
    pub fn parse_interval_span(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["TO"]) {
            return Ok(Some(Expression::Var(Box::new(Var {
                this: String::new(),
            }))));
        }
        if self.match_text_seq(&["TO"]) {
            // Matched: TO
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_into - Implemented from Python _parse_into
    /// Parses: INTO [TEMPORARY] [UNLOGGED] [TABLE] table_name
    /// Returns the table expression for the INTO clause
    #[allow(unused_variables, unused_mut)]
    pub fn parse_into(&mut self) -> Result<Option<Expression>> {
        if !self.match_token(TokenType::Into) {
            return Ok(None);
        }

        // Optional TEMPORARY
        let _temp = self.match_token(TokenType::Temporary);

        // Optional UNLOGGED
        let _unlogged = self.match_text_seq(&["UNLOGGED"]);

        // Optional TABLE keyword
        let _ = self.match_token(TokenType::Table);

        // Parse the table name
        self.parse_table_parts()
    }

    /// parse_introducer - Parses MySQL introducer expression (_charset'string')
    /// Python: _parse_introducer
    /// Format: _charset 'literal'
    pub fn parse_introducer(&mut self) -> Result<Option<Expression>> {
        // We expect to have already consumed the introducer token (e.g., _utf8)
        let token = self.previous().clone();

        // Try to parse a primary expression (usually a string literal)
        // parse_primary returns Expression (not Option), so we use it directly
        let literal = self.parse_primary()?;

        // Check if it's a null expression (indicating nothing was parsed)
        match &literal {
            Expression::Null(_) => {
                // Just return as an identifier
                Ok(Some(Expression::Identifier(Identifier {
                    name: token.text.clone(),
                    quoted: false,
                    trailing_comments: Vec::new(),
                    span: None,
                })))
            }
            _ => Ok(Some(Expression::Introducer(Box::new(Introducer {
                this: Box::new(Expression::Identifier(Identifier {
                    name: token.text.clone(),
                    quoted: false,
                    trailing_comments: Vec::new(),
                    span: None,
                })),
                expression: Box::new(literal),
            })))),
        }
    }

    /// parse_is - Implemented from Python _parse_is
    /// Calls: parse_null, parse_bitwise
    #[allow(unused_variables, unused_mut)]
    pub fn parse_is(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["DISTINCT", "FROM"]) {
            return Ok(Some(Expression::JSON(Box::new(JSON {
                this: None,
                with_: None,
                unique: false,
            }))));
        }
        if self.match_text_seq(&["WITH"]) {
            // Matched: WITH
            return Ok(None);
        }
        if self.match_text_seq(&["WITHOUT"]) {
            // Matched: WITHOUT
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_join - Ported from Python _parse_join
    /// Parses a single JOIN clause: [method] [side] [kind] JOIN table [ON condition | USING (columns)]
    /// Returns the Join wrapped in an Expression, or None if no join is found
    #[allow(unused_variables, unused_mut)]
    pub fn parse_join(&mut self) -> Result<Option<Expression>> {
        // Check for comma-style implicit join
        if self.match_token(TokenType::Comma) {
            if let Ok(Some(table)) = self.parse_table() {
                return Ok(Some(Expression::Join(Box::new(Join {
                    this: table,
                    on: None,
                    using: Vec::new(),
                    kind: JoinKind::Implicit,
                    use_inner_keyword: false,
                    use_outer_keyword: false,
                    deferred_condition: false,
                    join_hint: None,
                    match_condition: None,
                    pivots: Vec::new(),
                    comments: Vec::new(),
                    nesting_group: 0,
                    directed: false,
                }))));
            }
            return Ok(None);
        }

        // Try to parse join kind (INNER, LEFT, RIGHT, FULL, CROSS, etc.)
        let saved_pos = self.current;
        if let Some((kind, needs_join_keyword, use_inner_keyword, use_outer_keyword, join_hint)) =
            self.try_parse_join_kind()
        {
            // Collect comments from tokens consumed by try_parse_join_kind
            let mut join_comments = Vec::new();
            for i in saved_pos..self.current {
                if i < self.tokens.len() {
                    join_comments.extend(self.tokens[i].trailing_comments.iter().cloned());
                }
            }

            // If kind requires JOIN keyword, expect it
            if needs_join_keyword && !self.match_token(TokenType::Join) {
                self.current = saved_pos;
                return Ok(None);
            }

            // Parse the table being joined
            let table = self.parse_table_expression()?;

            // Parse ON or USING condition
            let (on, using) = if self.match_token(TokenType::On) {
                (Some(self.parse_expression()?), Vec::new())
            } else if self.match_token(TokenType::Using) {
                let has_parens = self.match_token(TokenType::LParen);
                // Use parse_using_column_list to handle qualified names like t1.col
                let cols = self.parse_using_column_list()?;
                if has_parens {
                    self.expect(TokenType::RParen)?;
                }
                (None, cols)
            } else {
                (None, Vec::new())
            };

            return Ok(Some(Expression::Join(Box::new(Join {
                this: table,
                on,
                using,
                kind,
                use_inner_keyword,
                use_outer_keyword,
                deferred_condition: false,
                join_hint,
                match_condition: None,
                pivots: Vec::new(),
                comments: join_comments,
                nesting_group: 0,
                directed: false,
            }))));
        }

        // Check for CROSS APPLY / OUTER APPLY (SQL Server)
        if self.match_text_seq(&["CROSS", "APPLY"]) || self.match_text_seq(&["OUTER", "APPLY"]) {
            let is_outer = self.previous().text.eq_ignore_ascii_case("OUTER");
            let table = self.parse_table_expression()?;
            return Ok(Some(Expression::Join(Box::new(Join {
                this: table,
                on: None,
                using: Vec::new(),
                kind: if is_outer {
                    JoinKind::Outer
                } else {
                    JoinKind::Cross
                },
                use_inner_keyword: false,
                use_outer_keyword: is_outer,
                deferred_condition: false,
                join_hint: None,
                match_condition: None,
                pivots: Vec::new(),
                comments: Vec::new(),
                nesting_group: 0,
                directed: false,
            }))));
        }

        Ok(None)
    }

    /// parse_join_hint - Spark/Hive join hints (BROADCAST, MERGE, SHUFFLE_HASH, etc.)
    /// Parses: HINT_NAME(table1, table2, ...)
    /// hint_name should be the already matched hint keyword (BROADCAST, MAPJOIN, etc.)
    #[allow(unused_variables, unused_mut)]
    pub fn parse_join_hint(&mut self, hint_name: &str) -> Result<Option<Expression>> {
        // Parse comma-separated list of tables
        let mut tables = Vec::new();
        loop {
            if let Some(table) = self.parse_table()? {
                tables.push(table);
            } else {
                break;
            }
            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        Ok(Some(Expression::JoinHint(Box::new(JoinHint {
            this: Box::new(Expression::Identifier(Identifier::new(
                hint_name.to_uppercase(),
            ))),
            expressions: tables,
        }))))
    }

    /// parse_join_parts - Ported from Python _parse_join_parts
    /// Returns (method, side, kind) where each is an optional string
    /// method: ASOF, NATURAL, POSITIONAL
    /// side: LEFT, RIGHT, FULL
    /// kind: ANTI, CROSS, INNER, OUTER, SEMI
    pub fn parse_join_parts(&mut self) -> (Option<String>, Option<String>, Option<String>) {
        // Parse join method (ASOF, NATURAL, POSITIONAL)
        let method = if self.match_texts(&["ASOF", "NATURAL", "POSITIONAL"]) {
            Some(self.previous().text.to_uppercase())
        } else {
            None
        };

        // Parse join side (LEFT, RIGHT, FULL)
        let side = if self.match_texts(&["LEFT", "RIGHT", "FULL"]) {
            Some(self.previous().text.to_uppercase())
        } else {
            None
        };

        // Parse join kind (ANTI, CROSS, INNER, OUTER, SEMI)
        let kind = if self.match_texts(&["ANTI", "CROSS", "INNER", "OUTER", "SEMI"]) {
            Some(self.previous().text.to_uppercase())
        } else if self.match_token(TokenType::StraightJoin) {
            Some("STRAIGHT_JOIN".to_string())
        } else {
            None
        };

        (method, side, kind)
    }

    /// parse_journal - Parses JOURNAL property (Teradata)
    /// Python: _parse_journal
    /// Creates a JournalProperty expression
    pub fn parse_journal(&mut self) -> Result<Option<Expression>> {
        self.parse_journal_impl(false, false, false, false, false)
    }

    /// Implementation of parse_journal with options
    pub fn parse_journal_impl(
        &mut self,
        no: bool,
        dual: bool,
        before: bool,
        local: bool,
        after: bool,
    ) -> Result<Option<Expression>> {
        Ok(Some(Expression::JournalProperty(Box::new(
            JournalProperty {
                no: if no {
                    Some(Box::new(Expression::Boolean(BooleanLiteral {
                        value: true,
                    })))
                } else {
                    None
                },
                dual: if dual {
                    Some(Box::new(Expression::Boolean(BooleanLiteral {
                        value: true,
                    })))
                } else {
                    None
                },
                before: if before {
                    Some(Box::new(Expression::Boolean(BooleanLiteral {
                        value: true,
                    })))
                } else {
                    None
                },
                local: if local {
                    Some(Box::new(Expression::Boolean(BooleanLiteral {
                        value: true,
                    })))
                } else {
                    None
                },
                after: if after {
                    Some(Box::new(Expression::Boolean(BooleanLiteral {
                        value: true,
                    })))
                } else {
                    None
                },
            },
        ))))
    }

    /// parse_json_column_def - Implemented from Python _parse_json_column_def
    /// Calls: parse_string, parse_json_schema, parse_id_var
    #[allow(unused_variables, unused_mut)]
    pub fn parse_json_column_def(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["NESTED"]) {
            return Ok(Some(Expression::JSONColumnDef(Box::new(JSONColumnDef {
                this: None,
                kind: None,
                path: None,
                nested_schema: None,
                ordinality: None,
            }))));
        }
        if self.match_text_seq(&["PATH"]) {
            // Matched: PATH
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_json_key_value - Implemented from Python _parse_json_key_value
    #[allow(unused_variables, unused_mut)]
    /// parse_json_key_value - Parses a JSON key-value pair
    /// Python: _parse_json_key_value
    /// Format: [KEY] key [: | VALUE] value
    pub fn parse_json_key_value(&mut self) -> Result<Option<Expression>> {
        // Optional KEY keyword
        self.match_text_seq(&["KEY"]);

        // Parse the key expression
        let key = self.parse_column()?;

        // Match separator (colon, comma, or VALUE keyword)
        let _ = self.match_token(TokenType::Colon)
            || self.match_token(TokenType::Comma)
            || self.match_text_seq(&["VALUE"]);

        // Optional VALUE keyword
        self.match_text_seq(&["VALUE"]);

        // Parse the value expression
        let value = self.parse_bitwise()?;

        // If neither key nor value, return None
        match (key, value) {
            (None, None) => Ok(None),
            (Some(k), None) => Ok(Some(Expression::JSONKeyValue(Box::new(JSONKeyValue {
                this: Box::new(k),
                expression: Box::new(Expression::Null(Null)),
            })))),
            (None, Some(v)) => Ok(Some(Expression::JSONKeyValue(Box::new(JSONKeyValue {
                this: Box::new(Expression::Null(Null)),
                expression: Box::new(v),
            })))),
            (Some(k), Some(v)) => Ok(Some(Expression::JSONKeyValue(Box::new(JSONKeyValue {
                this: Box::new(k),
                expression: Box::new(v),
            })))),
        }
    }

    /// parse_json_object - Parses JSON_OBJECT function
    /// Python: _parse_json_object
    /// Handles both JSON_OBJECT and JSON_OBJECTAGG
    pub fn parse_json_object(&mut self) -> Result<Option<Expression>> {
        self.parse_json_object_impl(false)
    }

    /// Implementation of JSON object parsing with aggregate flag
    pub fn parse_json_object_impl(&mut self, agg: bool) -> Result<Option<Expression>> {
        // Try to parse a star expression
        let star = self.parse_star()?;

        // Parse expressions: either star or comma-separated key-value pairs
        let expressions = if let Some(star_expr) = star {
            vec![star_expr]
        } else {
            // Parse comma-separated JSON key-value pairs
            let mut exprs = Vec::new();
            loop {
                if let Some(kv) = self.parse_json_key_value()? {
                    // Wrap with FORMAT JSON if specified
                    if self.match_text_seq(&["FORMAT", "JSON"]) {
                        exprs.push(Expression::JSONFormat(Box::new(JSONFormat {
                            this: Some(Box::new(kv)),
                            options: Vec::new(),
                            is_json: None,
                            to_json: None,
                        })));
                    } else {
                        exprs.push(kv);
                    }
                } else {
                    break;
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            exprs
        };

        // Parse NULL handling: NULL ON NULL or ABSENT ON NULL
        let null_handling = self.parse_json_on_null_handling()?;

        // Parse UNIQUE KEYS option
        let unique_keys = if self.match_text_seq(&["WITH", "UNIQUE"]) {
            self.match_text_seq(&["KEYS"]);
            Some(Box::new(Expression::Boolean(BooleanLiteral {
                value: true,
            })))
        } else if self.match_text_seq(&["WITHOUT", "UNIQUE"]) {
            self.match_text_seq(&["KEYS"]);
            Some(Box::new(Expression::Boolean(BooleanLiteral {
                value: false,
            })))
        } else {
            None
        };

        // Consume optional KEYS keyword
        self.match_text_seq(&["KEYS"]);

        // Parse RETURNING clause
        let return_type = if self.match_text_seq(&["RETURNING"]) {
            let type_expr = self.parse_type()?;
            // Wrap with FORMAT JSON if specified
            if self.match_text_seq(&["FORMAT", "JSON"]) {
                type_expr.map(|t| {
                    Box::new(Expression::JSONFormat(Box::new(JSONFormat {
                        this: Some(Box::new(t)),
                        options: Vec::new(),
                        is_json: None,
                        to_json: None,
                    })))
                })
            } else {
                type_expr.map(Box::new)
            }
        } else {
            None
        };

        // Parse ENCODING option
        let encoding = if self.match_text_seq(&["ENCODING"]) {
            self.parse_var()?.map(Box::new)
        } else {
            None
        };

        if agg {
            Ok(Some(Expression::JSONObjectAgg(Box::new(JSONObjectAgg {
                expressions,
                null_handling,
                unique_keys,
                return_type,
                encoding,
            }))))
        } else {
            Ok(Some(Expression::JSONObject(Box::new(JSONObject {
                expressions,
                null_handling,
                unique_keys,
                return_type,
                encoding,
            }))))
        }
    }

    /// Parse JSON NULL handling clause: NULL ON NULL or ABSENT ON NULL
    fn parse_json_on_null_handling(&mut self) -> Result<Option<Box<Expression>>> {
        if self.match_text_seq(&["NULL", "ON", "NULL"]) {
            Ok(Some(Box::new(Expression::Var(Box::new(Var {
                this: "NULL ON NULL".to_string(),
            })))))
        } else if self.match_text_seq(&["ABSENT", "ON", "NULL"]) {
            Ok(Some(Box::new(Expression::Var(Box::new(Var {
                this: "ABSENT ON NULL".to_string(),
            })))))
        } else {
            Ok(None)
        }
    }

    /// parse_json_schema - Implemented from Python _parse_json_schema
    #[allow(unused_variables, unused_mut)]
    pub fn parse_json_schema(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["COLUMNS"]) {
            return Ok(Some(Expression::JSONSchema(Box::new(JSONSchema {
                expressions: Vec::new(),
            }))));
        }
        Ok(None)
    }

    /// Parse JSON_TABLE COLUMNS clause: COLUMNS (column_def, column_def, ...) or COLUMNS column_def
    /// Column definitions can be:
    /// - name type PATH 'json_path'
    /// - name FOR ORDINALITY
    /// - NESTED [PATH] 'json_path' COLUMNS (...)
    pub fn parse_json_table_columns(&mut self) -> Result<Option<Expression>> {
        if !self.match_text_seq(&["COLUMNS"]) {
            return Ok(None);
        }

        // Check for opening paren - Oracle supports both COLUMNS(...) and COLUMNS col PATH '...'
        let has_parens = self.match_token(TokenType::LParen);

        let mut columns = Vec::new();

        // Parse column definitions
        if has_parens {
            // COLUMNS(col1, col2, ...)
            if !self.check(TokenType::RParen) {
                loop {
                    if let Some(col_def) = self.parse_json_table_column_def()? {
                        columns.push(col_def);
                    }
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
            }
            // Expect closing paren for COLUMNS(...)
            self.expect(TokenType::RParen)?;
        } else {
            // COLUMNS col PATH '...' (single column without parens)
            if let Some(col_def) = self.parse_json_table_column_def()? {
                columns.push(col_def);
            }
        }

        Ok(Some(Expression::JSONSchema(Box::new(JSONSchema {
            expressions: columns,
        }))))
    }

    /// Parse a single JSON_TABLE column definition
    /// Formats:
    /// - name [FOR ORDINALITY] [type] [PATH 'path']
    /// - NESTED [PATH] 'path' COLUMNS (...)
    pub fn parse_json_table_column_def(&mut self) -> Result<Option<Expression>> {
        // Check for NESTED column
        if self.match_text_seq(&["NESTED"]) {
            // NESTED [PATH] 'json_path' COLUMNS (...)
            self.match_text_seq(&["PATH"]); // Optional PATH keyword
            let path = self.parse_string()?;
            let nested_schema = self.parse_json_table_columns()?;

            return Ok(Some(Expression::JSONColumnDef(Box::new(JSONColumnDef {
                this: None,
                kind: None,
                path: path.map(Box::new),
                nested_schema: nested_schema.map(Box::new),
                ordinality: None,
            }))));
        }

        // Regular column: name [FOR ORDINALITY] [type] [PATH 'path']
        let name = self.parse_id_var()?;
        if name.is_none() {
            return Ok(None);
        }

        // Check for FOR ORDINALITY
        let ordinality = if self.match_text_seq(&["FOR", "ORDINALITY"]) {
            Some(Box::new(Expression::Boolean(BooleanLiteral {
                value: true,
            })))
        } else {
            None
        };

        // Parse data type (if not FOR ORDINALITY, type is expected)
        let kind = if ordinality.is_none() {
            // Try to parse a data type
            let data_type = self.parse_data_type_optional()?;
            data_type.map(|dt| self.data_type_to_string(&dt))
        } else {
            None
        };

        // Parse PATH 'json_path'
        let path = if self.match_text_seq(&["PATH"]) {
            self.parse_string()?
        } else {
            None
        };

        Ok(Some(Expression::JSONColumnDef(Box::new(JSONColumnDef {
            this: name.map(Box::new),
            kind,
            path: path.map(Box::new),
            nested_schema: None,
            ordinality,
        }))))
    }

    /// Parse JSON_TABLE function
    /// JSON_TABLE(expr, path COLUMNS (...)) [ON ERROR ...] [ON EMPTY ...]
    pub fn parse_json_table(&mut self) -> Result<Option<Expression>> {
        // Parse the JSON expression
        let this = self.parse_expression()?;

        // Optional path after comma
        let path = if self.match_token(TokenType::Comma) {
            if let Some(s) = self.parse_string()? {
                Some(Box::new(s))
            } else {
                None
            }
        } else {
            None
        };

        // Parse error handling: ON ERROR NULL or ON ERROR ERROR
        let error_handling = if self.match_text_seq(&["ON", "ERROR"]) {
            if self.match_text_seq(&["NULL"]) {
                Some(Box::new(Expression::Var(Box::new(Var {
                    this: "NULL".to_string(),
                }))))
            } else if self.match_text_seq(&["ERROR"]) {
                Some(Box::new(Expression::Var(Box::new(Var {
                    this: "ERROR".to_string(),
                }))))
            } else {
                None
            }
        } else {
            None
        };

        // Parse empty handling: ON EMPTY NULL or ON EMPTY ERROR
        let empty_handling = if self.match_text_seq(&["ON", "EMPTY"]) {
            if self.match_text_seq(&["NULL"]) {
                Some(Box::new(Expression::Var(Box::new(Var {
                    this: "NULL".to_string(),
                }))))
            } else if self.match_text_seq(&["ERROR"]) {
                Some(Box::new(Expression::Var(Box::new(Var {
                    this: "ERROR".to_string(),
                }))))
            } else {
                None
            }
        } else {
            None
        };

        // Parse COLUMNS clause
        let schema = self.parse_json_schema()?;

        Ok(Some(Expression::JSONTable(Box::new(JSONTable {
            this: Box::new(this),
            schema: schema.map(Box::new),
            path,
            error_handling,
            empty_handling,
        }))))
    }

    /// parse_json_value - Ported from Python _parse_json_value
    #[allow(unused_variables, unused_mut)]
    /// parse_json_value - Parses JSON_VALUE function
    /// Example: JSON_VALUE(json, '$.path' RETURNING type)
    pub fn parse_json_value(&mut self) -> Result<Option<Expression>> {
        // Parse the JSON expression
        let this = self.parse_expression()?;

        // Parse path (after comma)
        self.match_token(TokenType::Comma);
        let path = self.parse_expression()?;

        // Parse optional RETURNING type
        let returning = if self.match_token(TokenType::Returning) {
            Some(Box::new(self.parse_expression()?))
        } else {
            None
        };

        // Parse optional ON condition (ON ERROR, ON EMPTY)
        let on_condition = if self.check(TokenType::On) {
            self.parse_on_condition()?
        } else {
            None
        };

        Ok(Some(Expression::JSONValue(Box::new(JSONValue {
            this: Box::new(this),
            path: Some(Box::new(path)),
            returning,
            on_condition: on_condition.map(Box::new),
        }))))
    }

    /// parse_key_constraint_options - Implemented from Python _parse_key_constraint_options
    #[allow(unused_variables, unused_mut)]
    pub fn parse_key_constraint_options(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["NO", "ACTION"]) {
            // Matched: NO ACTION
            return Ok(None);
        }
        if self.match_text_seq(&["CASCADE"]) {
            // Matched: CASCADE
            return Ok(None);
        }
        if self.match_text_seq(&["RESTRICT"]) {
            // Matched: RESTRICT
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_lambda - Ported from Python _parse_lambda
    /// Parses lambda expressions: x -> x + 1 or (x, y) -> x + y
    /// Also supports DuckDB syntax: LAMBDA x : x + 1
    #[allow(unused_variables, unused_mut)]
    pub fn parse_lambda(&mut self) -> Result<Option<Expression>> {
        let start_index = self.current;

        // Check for DuckDB's LAMBDA keyword syntax: LAMBDA x : expr
        // ClickHouse doesn't use LAMBDA keyword — lambda is just a function name there
        if !matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) && self.match_token(TokenType::Lambda)
        {
            // Parse lambda parameters (comma-separated identifiers)
            let mut params = Vec::new();
            loop {
                // Use is_identifier_token which handles Identifier, QuotedIdentifier, and Var
                if self.is_identifier_token() {
                    let token = self.advance();
                    let quoted = token.token_type == TokenType::QuotedIdentifier;
                    params.push(Identifier {
                        name: token.text,
                        quoted,
                        trailing_comments: Vec::new(),
                        span: None,
                    });
                } else {
                    break;
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }

            // Must have at least one parameter
            if params.is_empty() {
                return Err(self.parse_error("LAMBDA requires at least one parameter"));
            }

            // Expect colon separator
            if !self.match_token(TokenType::Colon) {
                return Err(self.parse_error("Expected ':' after LAMBDA parameters"));
            }

            let body = self.parse_expression()?;
            return Ok(Some(Expression::Lambda(Box::new(LambdaExpr {
                parameters: params,
                body,
                colon: true,
                parameter_types: Vec::new(),
            }))));
        }

        // Try to parse lambda parameters
        let parameters = if self.match_token(TokenType::LParen) {
            // Parenthesized parameters: (x, y) -> ...
            let mut params = Vec::new();
            if !self.check(TokenType::RParen) {
                loop {
                    if let Some(ident) = self.parse_identifier()? {
                        if let Expression::Identifier(id) = ident {
                            params.push(id);
                        }
                    }
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
            }
            if !self.match_token(TokenType::RParen) {
                // Not a lambda, retreat
                self.current = start_index;
                return Ok(None);
            }
            params
        } else {
            // Single parameter: x -> ...
            if let Some(ident) = self.parse_identifier()? {
                if let Expression::Identifier(id) = ident {
                    vec![id]
                } else {
                    self.current = start_index;
                    return Ok(None);
                }
            } else {
                return Ok(None);
            }
        };

        // Check for arrow operator
        if self.match_token(TokenType::Arrow) || self.match_token(TokenType::FArrow) {
            // Parse lambda body
            let body = self.parse_expression()?;
            Ok(Some(Expression::Lambda(Box::new(LambdaExpr {
                parameters,
                body,
                colon: false,
                parameter_types: Vec::new(),
            }))))
        } else {
            // Not a lambda, retreat
            self.current = start_index;
            Ok(None)
        }
    }

    /// parse_lambda_arg - Delegates to parse_id_var
    #[allow(unused_variables, unused_mut)]
    pub fn parse_lambda_arg(&mut self) -> Result<Option<Expression>> {
        self.parse_id_var()
    }

    /// parse_lateral - Parse LATERAL subquery or table function
    /// Python: if self._match(TokenType.LATERAL): return exp.Lateral(this=..., view=..., outer=...)
    pub fn parse_lateral(&mut self) -> Result<Option<Expression>> {
        // Check for CROSS APPLY / OUTER APPLY (handled by join parsing in try_parse_join_kind)
        // This method focuses on LATERAL keyword parsing

        if !self.match_token(TokenType::Lateral) {
            return Ok(None);
        }

        // Check for LATERAL VIEW (Hive/Spark syntax)
        let view = self.match_token(TokenType::View);
        let outer = if view {
            self.match_token(TokenType::Outer)
        } else {
            false
        };

        // Parse the lateral expression (subquery, function call, or table reference)
        let this = if self.check(TokenType::LParen) {
            // Could be a subquery: LATERAL (SELECT ...)
            self.expect(TokenType::LParen)?;
            let inner = self.parse_statement()?;
            self.expect(TokenType::RParen)?;
            inner
        } else {
            // Could be a function or table reference: LATERAL unnest(...)
            self.parse_primary()?
        };

        // Parse optional alias
        let alias = if self.match_token(TokenType::As) {
            Some(self.expect_identifier()?)
        } else if self.check(TokenType::Identifier) && !self.check_keyword() {
            Some(self.expect_identifier()?)
        } else {
            None
        };

        // Parse optional column aliases: AS alias(col1, col2, ...)
        let column_aliases = if alias.is_some() && self.match_token(TokenType::LParen) {
            let mut cols = Vec::new();
            loop {
                if self.check(TokenType::RParen) {
                    break;
                }
                let col = self.expect_identifier()?;
                cols.push(col);
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            self.expect(TokenType::RParen)?;
            cols
        } else {
            Vec::new()
        };

        Ok(Some(Expression::Lateral(Box::new(Lateral {
            this: Box::new(this),
            view: if view {
                Some(Box::new(Expression::Boolean(BooleanLiteral {
                    value: true,
                })))
            } else {
                None
            },
            outer: if outer {
                Some(Box::new(Expression::Boolean(BooleanLiteral {
                    value: true,
                })))
            } else {
                None
            },
            alias,
            alias_quoted: false,
            cross_apply: None,
            ordinality: None,
            column_aliases,
        }))))
    }

    /// parse_limit - Parse LIMIT clause
    /// Python: if self._match(TokenType.LIMIT): return exp.Limit(this=self._parse_term())
    pub fn parse_limit(&mut self) -> Result<Option<Expression>> {
        if !self.match_token(TokenType::Limit) {
            return Ok(None);
        }
        // Parse the limit expression (usually a number)
        let limit_expr = self.parse_expression()?;
        Ok(Some(Expression::Limit(Box::new(Limit {
            this: limit_expr,
            percent: false,
            comments: Vec::new(),
        }))))
    }

    /// parse_limit_by - Implemented from Python _parse_limit_by
    #[allow(unused_variables, unused_mut)]
    pub fn parse_limit_by(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["BY"]) {
            // Matched: BY
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_limit_options - Implemented from Python _parse_limit_options
    #[allow(unused_variables, unused_mut)]
    pub fn parse_limit_options(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["ONLY"]) {
            return Ok(Some(Expression::LimitOptions(Box::new(LimitOptions {
                percent: None,
                rows: None,
                with_ties: None,
            }))));
        }
        if self.match_text_seq(&["WITH", "TIES"]) {
            // Matched: WITH TIES
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_load - Implemented from Python _parse_load
    #[allow(unused_variables, unused_mut)]
    pub fn parse_load(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["DATA"]) {
            return Ok(Some(Expression::Command(Box::new(Command {
                this: String::new(),
            }))));
        }
        if self.match_text_seq(&["LOCAL"]) {
            // Matched: LOCAL
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_locking - Implemented from Python _parse_locking
    /// Calls: parse_table_parts
    #[allow(unused_variables, unused_mut)]
    pub fn parse_locking(&mut self) -> Result<Option<Expression>> {
        let kind = if self.match_token(TokenType::Table) {
            Some("TABLE")
        } else if self.match_token(TokenType::View) {
            Some("VIEW")
        } else if self.match_token(TokenType::Row) {
            Some("ROW")
        } else if self.match_token(TokenType::Database) || self.match_identifier("DATABASE") {
            Some("DATABASE")
        } else {
            None
        };

        let kind = match kind {
            Some(k) => k.to_string(),
            None => return Ok(None),
        };

        let this = if matches!(kind.as_str(), "DATABASE" | "TABLE" | "VIEW") {
            self.parse_table_parts()?
        } else {
            None
        };

        let for_or_in = if self.match_token(TokenType::For) {
            Some("FOR")
        } else if self.match_token(TokenType::In) {
            Some("IN")
        } else {
            None
        };

        let lock_type = if self.match_identifier("ACCESS") {
            Some("ACCESS")
        } else if self.match_texts(&["EXCL", "EXCLUSIVE"]) {
            Some("EXCLUSIVE")
        } else if self.match_identifier("SHARE") {
            Some("SHARE")
        } else if self.match_identifier("READ") {
            Some("READ")
        } else if self.match_identifier("WRITE") {
            Some("WRITE")
        } else if self.match_identifier("CHECKSUM") {
            Some("CHECKSUM")
        } else {
            None
        };

        let override_ = if self.match_identifier("OVERRIDE") {
            Some(Box::new(Expression::Boolean(BooleanLiteral {
                value: true,
            })))
        } else {
            None
        };

        Ok(Some(Expression::LockingProperty(Box::new(
            LockingProperty {
                this: this.map(Box::new),
                kind,
                for_or_in: for_or_in.map(|v| {
                    Box::new(Expression::Var(Box::new(Var {
                        this: v.to_string(),
                    })))
                }),
                lock_type: lock_type.map(|v| {
                    Box::new(Expression::Var(Box::new(Var {
                        this: v.to_string(),
                    })))
                }),
                override_,
            },
        ))))
    }

    /// Parse Teradata LOCKING statement: LOCKING <property> SELECT ...
    fn parse_locking_statement(&mut self) -> Result<Expression> {
        self.expect(TokenType::Lock)?;
        let locking = self
            .parse_locking()?
            .ok_or_else(|| self.parse_error("Expected LOCKING clause"))?;
        let query = if self.check(TokenType::With) {
            self.parse_statement()?
        } else {
            self.parse_select()?
        };
        Ok(Expression::LockingStatement(Box::new(LockingStatement {
            this: Box::new(locking),
            expression: Box::new(query),
        })))
    }

    /// parse_log - Parses LOG property (Teradata)
    /// Python: _parse_log
    /// Creates a LogProperty expression
    pub fn parse_log(&mut self) -> Result<Option<Expression>> {
        self.parse_log_impl(false)
    }

    /// Implementation of parse_log with no flag
    pub fn parse_log_impl(&mut self, no: bool) -> Result<Option<Expression>> {
        Ok(Some(Expression::LogProperty(Box::new(LogProperty {
            no: if no {
                Some(Box::new(Expression::Boolean(BooleanLiteral {
                    value: true,
                })))
            } else {
                None
            },
        }))))
    }

    /// parse_match_against - Parses MATCH(columns) AGAINST(pattern)
    /// Python: parser.py:7125-7153
    #[allow(unused_variables, unused_mut)]
    pub fn parse_match_against(&mut self) -> Result<Option<Expression>> {
        // Parse column expressions or TABLE syntax
        let expressions = if self.match_text_seq(&["TABLE"]) {
            // SingleStore TABLE syntax
            if let Some(table) = self.parse_table()? {
                vec![table]
            } else {
                Vec::new()
            }
        } else {
            // Regular column list
            let mut cols = Vec::new();
            loop {
                if let Some(col) = self.parse_column()? {
                    cols.push(col);
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            cols
        };

        // Match ) AGAINST (
        self.match_text_seq(&[")", "AGAINST", "("]);

        // Parse the search pattern
        let this = self.parse_string()?;

        // Parse modifier
        let modifier = if self.match_text_seq(&["IN", "NATURAL", "LANGUAGE", "MODE"]) {
            if self.match_text_seq(&["WITH", "QUERY", "EXPANSION"]) {
                Some(Box::new(Expression::Var(Box::new(Var {
                    this: "IN NATURAL LANGUAGE MODE WITH QUERY EXPANSION".to_string(),
                }))))
            } else {
                Some(Box::new(Expression::Var(Box::new(Var {
                    this: "IN NATURAL LANGUAGE MODE".to_string(),
                }))))
            }
        } else if self.match_text_seq(&["IN", "BOOLEAN", "MODE"]) {
            Some(Box::new(Expression::Var(Box::new(Var {
                this: "IN BOOLEAN MODE".to_string(),
            }))))
        } else if self.match_text_seq(&["WITH", "QUERY", "EXPANSION"]) {
            Some(Box::new(Expression::Var(Box::new(Var {
                this: "WITH QUERY EXPANSION".to_string(),
            }))))
        } else {
            None
        };

        match this {
            Some(t) => Ok(Some(Expression::MatchAgainst(Box::new(MatchAgainst {
                this: Box::new(t),
                expressions,
                modifier,
            })))),
            None => Ok(None),
        }
    }

    /// parse_match_recognize_measure - Implemented from Python _parse_match_recognize_measure
    /// Parses a MEASURES expression in MATCH_RECOGNIZE: [FINAL|RUNNING] expression
    pub fn parse_match_recognize_measure(&mut self) -> Result<Option<Expression>> {
        // Check for optional FINAL or RUNNING keyword
        let window_frame = if self.match_texts(&["FINAL", "RUNNING"]) {
            let text = self.previous().text.to_uppercase();
            Some(if text == "FINAL" {
                MatchRecognizeSemantics::Final
            } else {
                MatchRecognizeSemantics::Running
            })
        } else {
            None
        };

        // Parse the expression
        let this = self.parse_expression()?;

        Ok(Some(Expression::MatchRecognizeMeasure(Box::new(
            MatchRecognizeMeasure { this, window_frame },
        ))))
    }

    /// parse_max_min_by - MAX_BY / MIN_BY / ARG_MAX / ARG_MIN aggregate functions
    /// Parses: MAX_BY(value, key [, n]) or MIN_BY(value, key [, n])
    /// is_max: true for MAX_BY/ARG_MAX, false for MIN_BY/ARG_MIN
    #[allow(unused_variables, unused_mut)]
    pub fn parse_max_min_by(&mut self, is_max: bool) -> Result<Option<Expression>> {
        let mut args = Vec::new();

        // Handle optional DISTINCT
        let distinct = if self.match_token(TokenType::Distinct) {
            let lambda_expr = self.parse_lambda()?;
            if let Some(expr) = lambda_expr {
                args.push(expr);
            }
            self.match_token(TokenType::Comma);
            true
        } else {
            false
        };

        // Parse remaining arguments
        loop {
            if let Some(arg) = self.parse_lambda()? {
                args.push(arg);
            } else {
                break;
            }
            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        let this = args
            .get(0)
            .cloned()
            .map(Box::new)
            .unwrap_or_else(|| Box::new(Expression::Null(Null)));
        let expression = args
            .get(1)
            .cloned()
            .map(Box::new)
            .unwrap_or_else(|| Box::new(Expression::Null(Null)));
        let count = args.get(2).cloned().map(Box::new);

        if is_max {
            Ok(Some(Expression::ArgMax(Box::new(ArgMax {
                this,
                expression,
                count,
            }))))
        } else {
            Ok(Some(Expression::ArgMin(Box::new(ArgMin {
                this,
                expression,
                count,
            }))))
        }
    }

    /// Parse MERGE statement
    /// Python: def _parse_merge(self) -> exp.Merge
    pub fn parse_merge(&mut self) -> Result<Option<Expression>> {
        // Optional INTO keyword
        self.match_token(TokenType::Into);

        // Parse target table using parse_table_ref
        let mut target = Expression::Table(self.parse_table_ref()?);

        // Parse optional TSQL table hints: WITH (HOLDLOCK), WITH (TABLOCK), etc.
        if self.check(TokenType::With) && self.check_next(TokenType::LParen) {
            if let Expression::Table(ref mut table) = target {
                if let Some(hint_expr) = self.parse_table_hints()? {
                    match hint_expr {
                        Expression::Tuple(tuple) => {
                            table.hints = tuple.expressions;
                        }
                        other => {
                            table.hints = vec![other];
                        }
                    }
                }
            }
        }

        // Parse optional alias for target table
        // Try to get an identifier as alias if AS is present or there's an identifier
        // Use parse_id_var instead of parse_identifier to handle Var tokens (e.g. T)
        if self.match_token(TokenType::As) {
            if let Some(alias_expr) = self.parse_id_var()? {
                // Extract identifier from the expression
                if let Expression::Identifier(ident) = alias_expr {
                    target = Expression::Alias(Box::new(Alias {
                        this: target,
                        alias: ident,
                        column_aliases: Vec::new(),
                        pre_alias_comments: Vec::new(),
                        trailing_comments: Vec::new(),
                        inferred_type: None,
                    }));
                }
            }
        } else if !self.check(TokenType::Using) {
            // Try to parse alias without AS keyword (e.g., MERGE t1 T USING ...)
            // Use parse_id_var to handle both Identifier and Var tokens
            if let Some(alias_expr) = self.parse_id_var()? {
                if let Expression::Identifier(ident) = alias_expr {
                    target = Expression::Alias(Box::new(Alias {
                        this: target,
                        alias: ident,
                        column_aliases: Vec::new(),
                        pre_alias_comments: Vec::new(),
                        trailing_comments: Vec::new(),
                        inferred_type: None,
                    }));
                }
            }
        }

        // USING clause
        if !self.match_token(TokenType::Using) {
            return Err(self.parse_error("Expected USING in MERGE statement"));
        }

        // Parse source table or subquery
        let mut using = if self.match_token(TokenType::LParen) {
            // Subquery: USING (SELECT ...) AS alias
            let query = self.parse_statement()?;
            self.expect(TokenType::RParen)?;
            let trailing = self.previous_trailing_comments();
            let mut subq = Subquery {
                this: query,
                alias: None,
                column_aliases: Vec::new(),
                order_by: None,
                limit: None,
                offset: None,
                distribute_by: None,
                sort_by: None,
                cluster_by: None,
                lateral: false,
                modifiers_inside: false,
                trailing_comments: trailing,
                inferred_type: None,
            };
            // Parse optional alias: (SELECT ...) AS y(col1, col2)
            if self.match_token(TokenType::As) {
                let alias_name = self.expect_identifier_or_keyword()?;
                subq.alias = Some(Identifier::new(alias_name));
                // Parse optional column aliases: AS alias(col1, col2)
                if self.match_token(TokenType::LParen) {
                    let mut cols = Vec::new();
                    loop {
                        let col_name = self.expect_identifier_or_keyword()?;
                        cols.push(Identifier::new(col_name));
                        if !self.match_token(TokenType::Comma) {
                            break;
                        }
                    }
                    self.expect(TokenType::RParen)?;
                    subq.column_aliases = cols;
                }
            } else if self.is_identifier_token() || self.is_safe_keyword_as_identifier() {
                // Implicit alias without AS
                let alias_name = self.expect_identifier_or_keyword()?;
                subq.alias = Some(Identifier::new(alias_name));
                // Parse optional column aliases: alias(col1, col2)
                if self.match_token(TokenType::LParen) {
                    let mut cols = Vec::new();
                    loop {
                        let col_name = self.expect_identifier_or_keyword()?;
                        cols.push(Identifier::new(col_name));
                        if !self.match_token(TokenType::Comma) {
                            break;
                        }
                    }
                    self.expect(TokenType::RParen)?;
                    subq.column_aliases = cols;
                }
            }
            Expression::Subquery(Box::new(subq))
        } else {
            Expression::Table(self.parse_table_ref()?)
        };

        // Parse optional alias for source (if not already parsed for subquery)
        if matches!(&using, Expression::Table(_)) {
            if self.match_token(TokenType::As) {
                if let Some(alias_expr) = self.parse_id_var()? {
                    if let Expression::Identifier(ident) = alias_expr {
                        using = Expression::Alias(Box::new(Alias {
                            this: using,
                            alias: ident,
                            column_aliases: Vec::new(),
                            pre_alias_comments: Vec::new(),
                            trailing_comments: Vec::new(),
                            inferred_type: None,
                        }));
                    }
                }
            } else if !self.check(TokenType::On) {
                // Try to parse alias without AS keyword
                // Use parse_id_var to handle both Identifier and Var tokens (e.g., S, T)
                if let Some(alias_expr) = self.parse_id_var()? {
                    if let Expression::Identifier(ident) = alias_expr {
                        using = Expression::Alias(Box::new(Alias {
                            this: using,
                            alias: ident,
                            column_aliases: Vec::new(),
                            pre_alias_comments: Vec::new(),
                            trailing_comments: Vec::new(),
                            inferred_type: None,
                        }));
                    }
                }
            }
        }

        // ON clause with condition
        let on = if self.match_token(TokenType::On) {
            Some(Box::new(self.parse_expression()?))
        } else {
            None
        };

        // Optional additional USING clause for key columns (DuckDB: USING (col1, col2))
        let using_cond = if self.match_token(TokenType::Using) {
            // Parse comma-separated identifiers wrapped in parentheses
            if self.match_token(TokenType::LParen) {
                let mut idents = Vec::new();
                loop {
                    // Use parse_id_var to handle Var tokens (unquoted identifiers)
                    if let Some(ident) = self.parse_id_var()? {
                        idents.push(ident);
                    } else {
                        break;
                    }
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
                self.match_token(TokenType::RParen);
                if !idents.is_empty() {
                    Some(Box::new(Expression::Tuple(Box::new(Tuple {
                        expressions: idents,
                    }))))
                } else {
                    None
                }
            } else {
                // Also support without parentheses for backwards compatibility
                let mut idents = Vec::new();
                loop {
                    if let Some(ident) = self.parse_id_var()? {
                        idents.push(ident);
                    } else {
                        break;
                    }
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
                if !idents.is_empty() {
                    Some(Box::new(Expression::Tuple(Box::new(Tuple {
                        expressions: idents,
                    }))))
                } else {
                    None
                }
            }
        } else {
            None
        };

        // Parse WHEN MATCHED clauses
        let whens = self.parse_when_matched_clauses()?;

        // Parse optional RETURNING clause (PostgreSQL) or OUTPUT clause (TSQL)
        let returning = if let Some(ret) = self.parse_returning()? {
            Some(ret)
        } else if self.match_token(TokenType::Output) {
            // TSQL OUTPUT clause: OUTPUT $action, Inserted.col, Deleted.col [INTO target]
            let output = self.parse_output_clause()?;
            Some(Expression::Returning(Box::new(Returning {
                expressions: output.columns,
                into: output.into_table.map(Box::new),
            })))
        } else {
            None
        };

        Ok(Some(Expression::Merge(Box::new(Merge {
            this: Box::new(target),
            using: Box::new(using),
            on,
            using_cond,
            whens: whens.map(Box::new),
            with_: None,
            returning: returning.map(Box::new),
        }))))
    }

    /// Parse multiple WHEN [NOT] MATCHED clauses for MERGE
    fn parse_when_matched_clauses(&mut self) -> Result<Option<Expression>> {
        let mut whens = Vec::new();

        while self.match_token(TokenType::When) {
            // Check for NOT MATCHED
            let matched = !self.match_token(TokenType::Not);
            self.match_text_seq(&["MATCHED"]);

            // Check for BY TARGET or BY SOURCE
            let source = if self.match_text_seq(&["BY", "TARGET"]) {
                Some(Box::new(Expression::Boolean(BooleanLiteral {
                    value: false,
                })))
            } else if self.match_text_seq(&["BY", "SOURCE"]) {
                Some(Box::new(Expression::Boolean(BooleanLiteral {
                    value: true,
                })))
            } else {
                None
            };

            // Optional AND condition
            let condition = if self.match_token(TokenType::And) {
                Some(Box::new(self.parse_expression()?))
            } else {
                None
            };

            // THEN action
            if !self.match_token(TokenType::Then) {
                return Err(self.parse_error("Expected THEN in WHEN clause"));
            }

            // Parse the action: INSERT, UPDATE, DELETE, or other keywords (DO NOTHING, etc.)
            let then: Expression = if self.match_token(TokenType::Insert) {
                // INSERT action - use Tuple to represent it
                let mut elements = vec![Expression::Var(Box::new(Var {
                    this: "INSERT".to_string(),
                }))];

                // Spark/Databricks: INSERT * (insert all columns)
                if self.match_token(TokenType::Star) {
                    elements.push(Expression::Star(crate::expressions::Star {
                        table: None,
                        except: None,
                        replace: None,
                        rename: None,
                        trailing_comments: Vec::new(),
                        span: None,
                    }));
                } else
                // Parse column list (optional)
                if self.match_token(TokenType::LParen) {
                    let mut columns: Vec<Expression> = Vec::new();
                    loop {
                        if let Some(col) = self.parse_id_var()? {
                            // Handle qualified column references (e.g., target.a)
                            let col = if self.match_token(TokenType::Dot) {
                                if let Expression::Identifier(table_ident) = col {
                                    if let Some(col_expr) = self.parse_id_var()? {
                                        if let Expression::Identifier(col_ident) = col_expr {
                                            Expression::Column(Column {
                                                name: col_ident,
                                                table: Some(table_ident),
                                                join_mark: false,
                                                trailing_comments: Vec::new(),
                                                span: None,
                                                inferred_type: None,
                                            })
                                        } else {
                                            col_expr
                                        }
                                    } else {
                                        return Err(self.parse_error(
                                            "Expected column name after dot in MERGE INSERT",
                                        ));
                                    }
                                } else {
                                    col
                                }
                            } else {
                                col
                            };
                            columns.push(col);
                        } else {
                            break;
                        }
                        if !self.match_token(TokenType::Comma) {
                            break;
                        }
                    }
                    self.match_token(TokenType::RParen);
                    if !columns.is_empty() {
                        elements.push(Expression::Tuple(Box::new(Tuple {
                            expressions: columns,
                        })));
                    }
                }

                // Parse VALUES clause
                if self.match_text_seq(&["VALUES"]) {
                    if let Some(values) = self.parse_value()? {
                        elements.push(values);
                    }
                } else if self.match_text_seq(&["ROW"]) {
                    elements.push(Expression::Var(Box::new(Var {
                        this: "ROW".to_string(),
                    })));
                }

                if elements.len() == 1 {
                    elements[0].clone()
                } else {
                    Expression::Tuple(Box::new(Tuple {
                        expressions: elements,
                    }))
                }
            } else if self.match_token(TokenType::Update) {
                // UPDATE action - use Tuple to represent SET assignments
                let mut elements = vec![Expression::Var(Box::new(Var {
                    this: "UPDATE".to_string(),
                }))];

                // Spark/Databricks: UPDATE * (update all columns)
                if self.match_token(TokenType::Star) {
                    elements.push(Expression::Star(crate::expressions::Star {
                        table: None,
                        except: None,
                        replace: None,
                        rename: None,
                        trailing_comments: Vec::new(),
                        span: None,
                    }));
                } else if self.match_token(TokenType::Set) {
                    // Parse col = value assignments manually
                    let mut assignments: Vec<Expression> = Vec::new();
                    loop {
                        // Parse: column = expression (column can be qualified like x.a)
                        if let Some(col) = self.parse_id_var()? {
                            // Handle qualified column references (e.g., x.a = y.b)
                            let col = if self.match_token(TokenType::Dot) {
                                // We have a qualified column reference
                                if let Expression::Identifier(table_ident) = col {
                                    // Parse the column part after the dot
                                    if let Some(col_expr) = self.parse_id_var()? {
                                        if let Expression::Identifier(col_ident) = col_expr {
                                            Expression::Column(Column {
                                                name: col_ident,
                                                table: Some(table_ident),
                                                join_mark: false,
                                                trailing_comments: Vec::new(),
                                                span: None,
                                                inferred_type: None,
                                            })
                                        } else {
                                            col_expr
                                        }
                                    } else {
                                        return Err(
                                            self.parse_error("Expected column name after dot")
                                        );
                                    }
                                } else {
                                    col
                                }
                            } else {
                                col
                            };
                            if self.match_token(TokenType::Eq) {
                                let value = self.parse_expression()?;
                                // Create assignment as EQ expression
                                let assignment = Expression::Eq(Box::new(BinaryOp {
                                    left: col,
                                    right: value,
                                    left_comments: Vec::new(),
                                    operator_comments: Vec::new(),
                                    trailing_comments: Vec::new(),
                                    inferred_type: None,
                                }));
                                assignments.push(assignment);
                            }
                        }
                        if !self.match_token(TokenType::Comma) {
                            break;
                        }
                    }
                    if !assignments.is_empty() {
                        elements.push(Expression::Tuple(Box::new(Tuple {
                            expressions: assignments,
                        })));
                    }
                }

                if elements.len() == 1 {
                    elements[0].clone()
                } else {
                    Expression::Tuple(Box::new(Tuple {
                        expressions: elements,
                    }))
                }
            } else if self.match_token(TokenType::Delete) {
                // DELETE action
                Expression::Var(Box::new(Var {
                    this: "DELETE".to_string(),
                }))
            } else if self.match_identifier("DO") {
                // DO NOTHING action (PostgreSQL)
                if self.match_identifier("NOTHING") {
                    Expression::Var(Box::new(Var {
                        this: "DO NOTHING".to_string(),
                    }))
                } else {
                    return Err(self.parse_error("Expected NOTHING after DO"));
                }
            } else {
                // Other action
                if let Some(var) = self.parse_var()? {
                    var
                } else {
                    return Err(
                        self.parse_error("Expected INSERT, UPDATE, DELETE, or action keyword")
                    );
                }
            };

            whens.push(Expression::When(Box::new(When {
                matched: Some(Box::new(Expression::Boolean(BooleanLiteral {
                    value: matched,
                }))),
                source,
                condition,
                then: Box::new(then),
            })));
        }

        if whens.is_empty() {
            Ok(None)
        } else {
            Ok(Some(Expression::Whens(Box::new(Whens {
                expressions: whens,
            }))))
        }
    }

    /// parse_mergeblockratio - Parses MERGEBLOCKRATIO property (Teradata)
    /// Python: _parse_mergeblockratio
    /// Format: MERGEBLOCKRATIO = number [PERCENT] or NO MERGEBLOCKRATIO or DEFAULT MERGEBLOCKRATIO
    pub fn parse_mergeblockratio(&mut self) -> Result<Option<Expression>> {
        self.parse_mergeblockratio_impl(false, false)
    }

    /// Implementation of parse_mergeblockratio with options
    pub fn parse_mergeblockratio_impl(
        &mut self,
        no: bool,
        default: bool,
    ) -> Result<Option<Expression>> {
        // Check for = followed by a number
        if self.match_token(TokenType::Eq) {
            let this = self.parse_number()?;
            let percent = self.match_token(TokenType::Percent);

            Ok(Some(Expression::MergeBlockRatioProperty(Box::new(
                MergeBlockRatioProperty {
                    this: this.map(Box::new),
                    no: None,
                    default: None,
                    percent: if percent {
                        Some(Box::new(Expression::Boolean(BooleanLiteral {
                            value: true,
                        })))
                    } else {
                        None
                    },
                },
            ))))
        } else {
            // NO or DEFAULT variant
            Ok(Some(Expression::MergeBlockRatioProperty(Box::new(
                MergeBlockRatioProperty {
                    this: None,
                    no: if no {
                        Some(Box::new(Expression::Boolean(BooleanLiteral {
                            value: true,
                        })))
                    } else {
                        None
                    },
                    default: if default {
                        Some(Box::new(Expression::Boolean(BooleanLiteral {
                            value: true,
                        })))
                    } else {
                        None
                    },
                    percent: None,
                },
            ))))
        }
    }

    /// parse_modifies_property - Implemented from Python _parse_modifies_property
    #[allow(unused_variables, unused_mut)]
    pub fn parse_modifies_property(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["SQL", "DATA"]) {
            // Matched: SQL DATA
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_multitable_inserts - Parses Oracle's multi-table INSERT (INSERT ALL/FIRST)
    /// Python: _parse_multitable_inserts
    /// Syntax: INSERT ALL|FIRST [WHEN cond THEN] INTO table [(cols)] [VALUES(...)] ... SELECT ...
    pub fn parse_multitable_inserts(
        &mut self,
        leading_comments: Vec<String>,
    ) -> Result<Option<Expression>> {
        // Get kind from previous token (ALL or FIRST)
        let kind = self.previous().text.to_uppercase();

        let mut expressions = Vec::new();

        // Helper closure to parse a single conditional insert
        // Returns None when no more INTO clauses found
        loop {
            // Check for WHEN condition
            let condition = if self.match_token(TokenType::When) {
                let cond = self.parse_or()?;
                self.match_token(TokenType::Then);
                Some(cond)
            } else {
                None
            };

            // Check for ELSE (used in INSERT FIRST ... ELSE INTO ...)
            let is_else = self.match_token(TokenType::Else);

            // Must have INTO keyword to continue
            if !self.match_token(TokenType::Into) {
                break;
            }

            // Parse table with optional schema (using parse_table_parts for proper schema.table parsing)
            let table_expr = self.parse_table_parts()?;

            // Extract TableRef from the table expression
            let table_ref = if let Some(Expression::Table(t)) = table_expr {
                t
            } else {
                // Fallback: create empty table ref (shouldn't happen)
                TableRef::new("")
            };

            // Parse optional column list: (col1, col2, ...)
            let columns = if self.match_token(TokenType::LParen) {
                let cols = self.parse_identifier_list()?;
                self.expect(TokenType::RParen)?;
                cols
            } else {
                Vec::new()
            };

            // Parse optional VALUES clause
            let values = if self.match_token(TokenType::Values) {
                self.expect(TokenType::LParen)?;
                let row = self.parse_expression_list()?;
                self.expect(TokenType::RParen)?;
                vec![row]
            } else {
                Vec::new()
            };

            // Create Insert expression for this INTO clause
            let insert_expr = Expression::Insert(Box::new(Insert {
                table: table_ref,
                columns,
                values,
                query: None,
                overwrite: false,
                partition: Vec::new(),
                directory: None,
                returning: Vec::new(),
                output: None,
                on_conflict: None,
                leading_comments: Vec::new(),
                if_exists: false,
                with: None,
                ignore: false,
                source_alias: None,
                alias: None,
                alias_explicit_as: false,
                default_values: false,
                by_name: false,
                conflict_action: None,
                is_replace: false,
                replace_where: None,
                source: None,
                hint: None,
                function_target: None,
                partition_by: None,
                settings: Vec::new(),
            }));

            // Wrap in ConditionalInsert
            let conditional_insert = Expression::ConditionalInsert(Box::new(ConditionalInsert {
                this: Box::new(insert_expr),
                expression: condition.map(Box::new),
                else_: if is_else {
                    Some(Box::new(Expression::Boolean(BooleanLiteral {
                        value: true,
                    })))
                } else {
                    None
                },
            }));

            expressions.push(conditional_insert);
        }

        // Parse the source SELECT statement (or subquery)
        let source = self.parse_statement()?;

        Ok(Some(Expression::MultitableInserts(Box::new(
            MultitableInserts {
                kind,
                expressions,
                source: Some(Box::new(source)),
                leading_comments,
            },
        ))))
    }

    /// parse_name_as_expression - Parse identifier that can be aliased
    /// Parses: identifier [AS expression]
    #[allow(unused_variables, unused_mut)]
    pub fn parse_name_as_expression(&mut self) -> Result<Option<Expression>> {
        // Parse the identifier
        let this = self.parse_id_var()?;
        if this.is_none() {
            return Ok(None);
        }

        // Check for AS alias
        if self.match_token(TokenType::Alias) {
            let expression = self.parse_disjunction()?;
            if expression.is_none() {
                return Ok(this);
            }

            // Extract the identifier for the alias
            let alias_ident =
                match this.ok_or_else(|| self.parse_error("Expected identifier for alias"))? {
                    Expression::Identifier(id) => id,
                    _ => Identifier::new(String::new()),
                };

            return Ok(Some(Expression::Alias(Box::new(Alias {
                this: expression.ok_or_else(|| self.parse_error("Expected expression after AS"))?,
                alias: alias_ident,
                column_aliases: Vec::new(),
                pre_alias_comments: Vec::new(),
                trailing_comments: Vec::new(),
                inferred_type: None,
            }))));
        }

        Ok(this)
    }

    /// parse_named_window - Ported from Python _parse_named_window
    /// Parses a named window definition: name AS (spec)
    #[allow(unused_variables, unused_mut)]
    pub fn parse_named_window(&mut self) -> Result<Option<Expression>> {
        // Parse window name
        let name = self.parse_id_var()?;
        if name.is_none() {
            return Ok(None);
        }

        // Expect AS
        if !self.match_token(TokenType::As) {
            return Ok(name); // Just the name, no spec
        }

        // Parse window spec (parenthesized)
        self.expect(TokenType::LParen)?;
        let spec = self.parse_window_spec_inner()?;
        self.expect(TokenType::RParen)?;

        if let (Some(name_expr), Some(spec_expr)) = (name, spec) {
            // Create an Alias expression wrapping the spec with the name
            let alias_ident = if let Expression::Identifier(id) = name_expr {
                id
            } else {
                Identifier::new("window")
            };
            Ok(Some(Expression::Alias(Box::new(Alias {
                this: spec_expr,
                alias: alias_ident,
                column_aliases: Vec::new(),
                pre_alias_comments: Vec::new(),
                trailing_comments: Vec::new(),
                inferred_type: None,
            }))))
        } else {
            Ok(None)
        }
    }

    /// parse_next_value_for - Parses NEXT VALUE FOR sequence_name
    /// Python: parser.py:6752-6761
    #[allow(unused_variables, unused_mut)]
    pub fn parse_next_value_for(&mut self) -> Result<Option<Expression>> {
        if !self.match_text_seq(&["VALUE", "FOR"]) {
            // Retreat if we consumed a token
            if self.current > 0 {
                self.current -= 1;
            }
            return Ok(None);
        }

        // Parse the sequence name as a dotted identifier (db.schema.sequence_name)
        // Manually parse identifier parts separated by dots
        let first = self
            .parse_id_var()?
            .ok_or_else(|| self.parse_error("Expected sequence name after NEXT VALUE FOR"))?;
        let first_id = match first {
            Expression::Identifier(id) => id,
            Expression::Var(v) => Identifier {
                name: v.this,
                quoted: false,
                trailing_comments: Vec::new(),
                span: None,
            },
            _ => Identifier {
                name: String::new(),
                quoted: false,
                trailing_comments: Vec::new(),
                span: None,
            },
        };

        // Check for dotted parts (db.schema.sequence_name)
        let mut parts = vec![first_id];
        while self.match_token(TokenType::Dot) {
            if self.is_identifier_or_keyword_token() {
                let token = self.advance();
                parts.push(Identifier {
                    name: token.text,
                    quoted: token.token_type == TokenType::QuotedIdentifier,
                    trailing_comments: Vec::new(),
                    span: None,
                });
            } else {
                break;
            }
        }

        // Build a Column expression from the parts
        let this = if parts.len() == 1 {
            Expression::Column(Column {
                name: parts.remove(0),
                table: None,
                join_mark: false,
                trailing_comments: Vec::new(),
                span: None,
                inferred_type: None,
            })
        } else if parts.len() == 2 {
            Expression::Column(Column {
                name: parts.remove(1),
                table: Some(parts.remove(0)),
                join_mark: false,
                trailing_comments: Vec::new(),
                span: None,
                inferred_type: None,
            })
        } else {
            // For 3+ parts, build nested Dot expressions
            let mut expr = Expression::Identifier(parts.remove(0));
            for part in parts.drain(..) {
                expr = Expression::Dot(Box::new(DotAccess {
                    this: expr,
                    field: part,
                }));
            }
            expr
        };

        // Parse optional OVER (ORDER BY ...) clause
        let order = if self.match_token(TokenType::Over) {
            if self.match_token(TokenType::LParen) {
                let ord = self.parse_order()?;
                self.expect(TokenType::RParen)?;
                ord.map(Box::new)
            } else {
                None
            }
        } else {
            None
        };

        Ok(Some(Expression::NextValueFor(Box::new(NextValueFor {
            this: Box::new(this),
            order,
        }))))
    }

    /// parse_no_property - Implemented from Python _parse_no_property
    #[allow(unused_variables, unused_mut)]
    pub fn parse_no_property(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["PRIMARY", "INDEX"]) {
            // Matched: PRIMARY INDEX
            return Ok(None);
        }
        if self.match_text_seq(&["SQL"]) {
            // Matched: SQL
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_normalize - Ported from Python _parse_normalize
    #[allow(unused_variables, unused_mut)]
    /// parse_normalize - Parses NORMALIZE(expr [, form])
    /// Python: NORMALIZE(expr, form) where form is NFC/NFD/NFKC/NFKD
    pub fn parse_normalize(&mut self) -> Result<Option<Expression>> {
        // Parse the expression to normalize
        let this = self.parse_expression()?;

        // Check for optional form argument
        let form = if self.match_token(TokenType::Comma) {
            self.parse_var()?.map(Box::new)
        } else {
            None
        };

        Ok(Some(Expression::Normalize(Box::new(Normalize {
            this: Box::new(this),
            form,
            is_casefold: None,
        }))))
    }

    /// parse_not_constraint - Implemented from Python _parse_not_constraint
    /// Parses constraints that start with NOT: NOT NULL, NOT CASESPECIFIC
    pub fn parse_not_constraint(&mut self) -> Result<Option<Expression>> {
        // NOT NULL constraint
        if self.match_text_seq(&["NULL"]) {
            return Ok(Some(Expression::NotNullColumnConstraint(Box::new(
                NotNullColumnConstraint { allow_null: None },
            ))));
        }
        // NOT CASESPECIFIC constraint (Teradata)
        if self.match_text_seq(&["CASESPECIFIC"]) {
            return Ok(Some(Expression::CaseSpecificColumnConstraint(Box::new(
                CaseSpecificColumnConstraint {
                    not_: Some(Box::new(Expression::Boolean(BooleanLiteral {
                        value: true,
                    }))),
                },
            ))));
        }
        // NOT FOR REPLICATION (SQL Server) - consume the tokens and return as a property
        if self.match_token(TokenType::For) && self.match_identifier("REPLICATION") {
            return Ok(Some(Expression::Property(Box::new(
                crate::expressions::Property {
                    this: Box::new(Expression::Identifier(Identifier::new(
                        "NOT FOR REPLICATION".to_string(),
                    ))),
                    value: None,
                },
            ))));
        }
        Ok(None)
    }

    /// parse_null - Parse NULL literal
    /// Python: if self._match_set((TokenType.NULL, TokenType.UNKNOWN)): return exp.Null
    pub fn parse_null(&mut self) -> Result<Option<Expression>> {
        if self.match_token(TokenType::Null) {
            return Ok(Some(Expression::Null(Null)));
        }
        // UNKNOWN is treated as NULL in some dialects
        if self.match_token(TokenType::Unknown) {
            return Ok(Some(Expression::Null(Null)));
        }
        Ok(None)
    }

    /// parse_number - Parse numeric literal
    /// Python: TokenType.NUMBER -> exp.Literal(this=token.text, is_string=False)
    /// Handles Hive/Spark numeric suffixes encoded as "number::TYPE" by the tokenizer
    pub fn parse_number(&mut self) -> Result<Option<Expression>> {
        if self.match_token(TokenType::Number) {
            let text = self.previous().text.clone();
            // Check for numeric literal suffix encoded as "number::TYPE"
            if let Some(sep_pos) = text.find("::") {
                let num_part = &text[..sep_pos];
                let type_name = &text[sep_pos + 2..];
                // Create a TryCast expression: TRY_CAST(number AS TYPE)
                let num_expr = Expression::Literal(Literal::Number(num_part.to_string()));
                let data_type = match type_name {
                    "BIGINT" => crate::expressions::DataType::BigInt { length: None },
                    "SMALLINT" => crate::expressions::DataType::SmallInt { length: None },
                    "TINYINT" => crate::expressions::DataType::TinyInt { length: None },
                    "DOUBLE" => crate::expressions::DataType::Double {
                        precision: None,
                        scale: None,
                    },
                    "FLOAT" => crate::expressions::DataType::Float {
                        precision: None,
                        scale: None,
                        real_spelling: false,
                    },
                    "DECIMAL" => crate::expressions::DataType::Decimal {
                        precision: None,
                        scale: None,
                    },
                    _ => crate::expressions::DataType::Custom {
                        name: type_name.to_string(),
                    },
                };
                return Ok(Some(Expression::TryCast(Box::new(
                    crate::expressions::Cast {
                        this: num_expr,
                        to: data_type,
                        trailing_comments: Vec::new(),
                        double_colon_syntax: false,
                        format: None,
                        default: None,
                        inferred_type: None,
                    },
                ))));
            }
            return Ok(Some(Expression::Literal(Literal::Number(text))));
        }
        Ok(None)
    }

    /// parse_odbc_datetime_literal - Ported from Python _parse_odbc_datetime_literal
    #[allow(unused_variables, unused_mut)]
    /// parse_odbc_datetime_literal - Parses ODBC datetime literals
    /// Examples: {d'2023-01-01'}, {t'12:00:00'}, {ts'2023-01-01 12:00:00'}
    pub fn parse_odbc_datetime_literal(&mut self) -> Result<Option<Expression>> {
        // Match the type indicator (d, t, ts)
        if !self.match_token(TokenType::Var) {
            return Ok(None);
        }
        let type_indicator = self.previous().text.to_lowercase();

        // Parse the string value
        let value = self.parse_string()?;
        if value.is_none() {
            return Ok(None);
        }

        // Expect closing brace
        self.expect(TokenType::RBrace)?;

        // Return appropriate expression based on type
        let value = value
            .ok_or_else(|| self.parse_error("Expected string value in ODBC datetime literal"))?;
        match type_indicator.as_str() {
            "d" => Ok(Some(Expression::Date(Box::new(UnaryFunc::new(value))))),
            "t" => Ok(Some(Expression::Time(Box::new(UnaryFunc::new(value))))),
            "ts" => Ok(Some(Expression::Timestamp(Box::new(TimestampFunc {
                this: Some(Box::new(value)),
                zone: None,
                with_tz: None,
                safe: None,
            })))),
            _ => Ok(Some(value)),
        }
    }

    /// parse_offset - Parse OFFSET clause
    /// Python: if self._match(TokenType.OFFSET): return exp.Offset(this=self._parse_term())
    pub fn parse_offset(&mut self) -> Result<Option<Expression>> {
        if !self.match_token(TokenType::Offset) {
            return Ok(None);
        }
        // Parse the offset expression (usually a number)
        let offset_expr = self.parse_expression()?;
        Ok(Some(Expression::Offset(Box::new(Offset {
            this: offset_expr,
            rows: None,
        }))))
    }

    /// parse_on_condition - Ported from Python _parse_on_condition
    #[allow(unused_variables, unused_mut)]
    /// parse_on_condition - Parses ON EMPTY/ERROR/NULL conditions
    /// Example: NULL ON EMPTY, ERROR ON ERROR
    pub fn parse_on_condition(&mut self) -> Result<Option<Expression>> {
        // Parse ON EMPTY
        let empty = if self.match_text_seq(&["NULL", "ON", "EMPTY"]) {
            Some(Box::new(Expression::Identifier(Identifier::new(
                "NULL".to_string(),
            ))))
        } else if self.match_text_seq(&["ERROR", "ON", "EMPTY"]) {
            Some(Box::new(Expression::Identifier(Identifier::new(
                "ERROR".to_string(),
            ))))
        } else if self.match_text_seq(&["DEFAULT"]) {
            let default_val = self.parse_expression()?;
            if self.match_text_seq(&["ON", "EMPTY"]) {
                Some(Box::new(default_val))
            } else {
                None
            }
        } else {
            None
        };

        // Parse ON ERROR
        let error = if self.match_text_seq(&["NULL", "ON", "ERROR"]) {
            Some(Box::new(Expression::Identifier(Identifier::new(
                "NULL".to_string(),
            ))))
        } else if self.match_text_seq(&["ERROR", "ON", "ERROR"]) {
            Some(Box::new(Expression::Identifier(Identifier::new(
                "ERROR".to_string(),
            ))))
        } else if self.match_text_seq(&["DEFAULT"]) {
            let default_val = self.parse_expression()?;
            if self.match_text_seq(&["ON", "ERROR"]) {
                Some(Box::new(default_val))
            } else {
                None
            }
        } else {
            None
        };

        // Parse ON NULL
        let null = if self.match_text_seq(&["NULL", "ON", "NULL"]) {
            Some(Box::new(Expression::Identifier(Identifier::new(
                "NULL".to_string(),
            ))))
        } else {
            None
        };

        if empty.is_none() && error.is_none() && null.is_none() {
            return Ok(None);
        }

        Ok(Some(Expression::OnCondition(Box::new(OnCondition {
            empty,
            error,
            null,
        }))))
    }

    /// parse_on_handling - Implemented from Python _parse_on_handling
    /// Calls: parse_bitwise
    #[allow(unused_variables, unused_mut)]
    pub fn parse_on_handling(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["ON"]) {
            // Matched: ON
            return Ok(None);
        }
        if self.match_text_seq(&["ON"]) {
            // Matched: ON
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_on_property - Implemented from Python _parse_on_property
    #[allow(unused_variables, unused_mut)]
    pub fn parse_on_property(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["COMMIT", "PRESERVE", "ROWS"]) {
            return Ok(Some(Expression::OnCommitProperty(Box::new(
                OnCommitProperty { delete: None },
            ))));
        }
        if self.match_text_seq(&["COMMIT", "DELETE", "ROWS"]) {
            // Matched: COMMIT DELETE ROWS
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_opclass - Ported from Python _parse_opclass
    #[allow(unused_variables, unused_mut)]
    /// parse_opclass - Parses PostgreSQL operator class in index expressions
    /// Example: column_name text_pattern_ops
    pub fn parse_opclass(&mut self) -> Result<Option<Expression>> {
        // Parse the expression first
        let this = self.parse_expression()?;

        // Check for keywords that would indicate this is not an opclass
        // (e.g., ASC, DESC, NULLS, etc.)
        if self.check(TokenType::Asc)
            || self.check(TokenType::Desc)
            || self.check(TokenType::Nulls)
            || self.check(TokenType::Comma)
            || self.check(TokenType::RParen)
        {
            return Ok(Some(this));
        }

        // Try to parse an operator class name (table parts)
        if let Some(opclass_name) = self.parse_table()? {
            return Ok(Some(Expression::Opclass(Box::new(Opclass {
                this: Box::new(this),
                expression: Box::new(opclass_name),
            }))));
        }

        Ok(Some(this))
    }

    /// parse_open_json - Parses SQL Server OPENJSON function
    /// Example: OPENJSON(json, '$.path') WITH (col1 type '$.path' AS JSON, ...)
    pub fn parse_open_json(&mut self) -> Result<Option<Expression>> {
        // Parse the JSON expression
        let this = self.parse_expression()?;

        // Parse optional path
        let path = if self.match_token(TokenType::Comma) {
            self.parse_string()?.map(Box::new)
        } else {
            None
        };

        // Check for closing paren and WITH clause
        let expressions = if self.match_token(TokenType::RParen)
            && self.match_token(TokenType::With)
        {
            self.expect(TokenType::LParen)?;
            let mut cols = Vec::new();
            loop {
                // Parse column definition: name type 'path' [AS JSON]
                let col_name = self.parse_field()?;
                if col_name.is_none() {
                    break;
                }
                let col_type = self.parse_data_type()?;
                let col_path = self.parse_string()?.map(Box::new);
                let as_json = if self.match_token(TokenType::As) && self.match_identifier("JSON") {
                    Some(Box::new(Expression::Boolean(BooleanLiteral {
                        value: true,
                    })))
                } else {
                    None
                };
                cols.push(Expression::OpenJSONColumnDef(Box::new(OpenJSONColumnDef {
                    this: Box::new(col_name.ok_or_else(|| {
                        self.parse_error("Expected column name in OPENJSON WITH clause")
                    })?),
                    kind: String::new(), // kept for backwards compat, use data_type instead
                    path: col_path,
                    as_json,
                    data_type: Some(col_type),
                })));
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            self.expect(TokenType::RParen)?;
            cols
        } else {
            Vec::new()
        };

        Ok(Some(Expression::OpenJSON(Box::new(OpenJSON {
            this: Box::new(this),
            path,
            expressions,
        }))))
    }

    /// parse_operator - Ported from Python _parse_operator
    #[allow(unused_variables, unused_mut)]
    /// parse_operator - Parses PostgreSQL OPERATOR(op) syntax
    /// Example: col1 OPERATOR(~>) col2
    pub fn parse_operator(&mut self, this: Option<Expression>) -> Result<Option<Expression>> {
        let mut result = this;

        // Parse OPERATOR(op) expressions
        while self.match_token(TokenType::LParen) {
            // Collect the operator text between parens
            let mut op_text = String::new();
            while !self.check(TokenType::RParen) && !self.is_at_end() {
                op_text.push_str(&self.peek().text);
                self.advance();
            }
            self.expect(TokenType::RParen)?;

            // Parse the right-hand side expression
            let rhs = self.parse_expression()?;

            result = Some(Expression::Operator(Box::new(Operator {
                this: Box::new(result.unwrap_or_else(|| Expression::Null(Null))),
                operator: Some(Box::new(Expression::Identifier(Identifier::new(op_text)))),
                expression: Box::new(rhs),
                comments: Vec::new(),
            })));

            // Check if there's another OPERATOR keyword
            if !self.match_token(TokenType::Operator) {
                break;
            }
        }

        Ok(result)
    }

    /// parse_order - Parse ORDER BY clause
    /// Python: if not self._match(TokenType.ORDER_BY): return this; return exp.Order(expressions=self._parse_csv(self._parse_ordered))
    pub fn parse_order(&mut self) -> Result<Option<Expression>> {
        if !self.match_token(TokenType::Order) {
            return Ok(None);
        }
        // Consume BY if present
        self.match_token(TokenType::By);

        // Parse comma-separated ordered expressions
        let mut expressions = Vec::new();
        loop {
            if let Some(ordered) = self.parse_ordered_item()? {
                expressions.push(ordered);
            } else {
                break;
            }
            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        Ok(Some(Expression::OrderBy(Box::new(OrderBy {
            expressions,
            siblings: false,
            comments: Vec::new(),
        }))))
    }

    /// parse_ordered_item - Parse a single ORDER BY item (expr [ASC|DESC] [NULLS FIRST|LAST])
    fn parse_ordered_item(&mut self) -> Result<Option<Ordered>> {
        // Parse the expression to order by
        let expr = match self.parse_expression() {
            Ok(e) => e,
            Err(_) => return Ok(None),
        };

        // Check for ASC/DESC
        let mut desc = false;
        let mut explicit_asc = false;
        if self.match_token(TokenType::Asc) {
            explicit_asc = true;
        } else if self.match_token(TokenType::Desc) {
            desc = true;
        }

        // Check for NULLS FIRST/LAST
        let nulls_first = if self.match_text_seq(&["NULLS", "FIRST"]) {
            Some(true)
        } else if self.match_text_seq(&["NULLS", "LAST"]) {
            Some(false)
        } else {
            None
        };

        // Parse optional WITH FILL clause (ClickHouse)
        let with_fill = if self.match_text_seq(&["WITH", "FILL"]) {
            let from_ = if self.match_token(TokenType::From) {
                Some(Box::new(self.parse_or()?))
            } else {
                None
            };
            let to = if self.match_text_seq(&["TO"]) {
                Some(Box::new(self.parse_or()?))
            } else {
                None
            };
            let step = if self.match_text_seq(&["STEP"]) {
                Some(Box::new(self.parse_or()?))
            } else {
                None
            };
            let staleness = if self.match_text_seq(&["STALENESS"]) {
                Some(Box::new(self.parse_or()?))
            } else {
                None
            };
            let interpolate = if self.match_text_seq(&["INTERPOLATE"]) {
                if self.match_token(TokenType::LParen) {
                    let exprs = self.parse_expression_list()?;
                    self.expect(TokenType::RParen)?;
                    if exprs.len() == 1 {
                        Some(Box::new(exprs.into_iter().next().unwrap()))
                    } else {
                        Some(Box::new(Expression::Tuple(Box::new(
                            crate::expressions::Tuple { expressions: exprs },
                        ))))
                    }
                } else {
                    None
                }
            } else {
                None
            };
            Some(Box::new(WithFill {
                from_,
                to,
                step,
                staleness,
                interpolate,
            }))
        } else {
            None
        };

        Ok(Some(Ordered {
            this: expr,
            desc,
            nulls_first,
            explicit_asc,
            with_fill,
        }))
    }

    /// parse_ordered - Implemented from Python _parse_ordered (wrapper for parse_ordered_item)
    #[allow(unused_variables, unused_mut)]
    pub fn parse_ordered(&mut self) -> Result<Option<Expression>> {
        if let Some(ordered) = self.parse_ordered_item()? {
            return Ok(Some(Expression::Ordered(Box::new(ordered))));
        }
        if self.match_text_seq(&["NULLS", "FIRST"]) {
            return Ok(Some(Expression::WithFill(Box::new(WithFill {
                from_: None,
                to: None,
                step: None,
                staleness: None,
                interpolate: None,
            }))));
        }
        if self.match_text_seq(&["NULLS", "LAST"]) {
            // Matched: NULLS LAST
            return Ok(None);
        }
        if self.match_text_seq(&["WITH", "FILL"]) {
            // Matched: WITH FILL
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_overlay - Ported from Python _parse_overlay
    /// Parses OVERLAY function: OVERLAY(string PLACING replacement FROM position [FOR length])
    #[allow(unused_variables, unused_mut)]
    pub fn parse_overlay(&mut self) -> Result<Option<Expression>> {
        // Parse the string to be modified
        let this = match self.parse_bitwise() {
            Ok(Some(expr)) => expr,
            Ok(None) => return Ok(None),
            Err(e) => return Err(e),
        };

        // Parse PLACING replacement (or comma then replacement)
        let replacement = if self.match_text_seq(&["PLACING"]) || self.match_token(TokenType::Comma)
        {
            match self.parse_bitwise() {
                Ok(Some(expr)) => expr,
                Ok(None) => {
                    return Err(self.parse_error("Expected replacement expression in OVERLAY"))
                }
                Err(e) => return Err(e),
            }
        } else {
            return Err(self.parse_error("Expected PLACING in OVERLAY function"));
        };

        // Parse FROM position (or comma then position)
        let from = if self.match_token(TokenType::From) || self.match_token(TokenType::Comma) {
            match self.parse_bitwise() {
                Ok(Some(expr)) => expr,
                Ok(None) => return Err(self.parse_error("Expected position expression in OVERLAY")),
                Err(e) => return Err(e),
            }
        } else {
            return Err(self.parse_error("Expected FROM in OVERLAY function"));
        };

        // Parse optional FOR length (or comma then length)
        let length = if self.match_token(TokenType::For) || self.match_token(TokenType::Comma) {
            match self.parse_bitwise() {
                Ok(Some(expr)) => Some(expr),
                Ok(None) => None,
                Err(_) => None,
            }
        } else {
            None
        };

        Ok(Some(Expression::Overlay(Box::new(OverlayFunc {
            this,
            replacement,
            from,
            length,
        }))))
    }

    /// parse_parameter - Parse named parameter (@name or :name)
    /// Python: this = self._parse_identifier() or self._parse_primary_or_var(); return exp.Parameter(this=this)
    pub fn parse_parameter(&mut self) -> Result<Option<Expression>> {
        // Check for parameter token types
        if self.match_token(TokenType::Parameter) {
            let text = self.previous().text.clone();
            return Ok(Some(Expression::Parameter(Box::new(Parameter {
                name: Some(text),
                index: None,
                style: ParameterStyle::Colon,
                quoted: false,
                string_quoted: false,
                expression: None,
            }))));
        }

        // Check for session parameter (@@name)
        if self.match_token(TokenType::SessionParameter) {
            let text = self.previous().text.clone();
            return Ok(Some(Expression::SessionParameter(Box::new(
                SessionParameter {
                    this: Box::new(Expression::Identifier(Identifier::new(text))),
                    kind: None,
                },
            ))));
        }

        Ok(None)
    }

    /// parse_paren - Ported from Python _parse_paren
    /// Parses parenthesized expressions: (expr), (select ...), or (a, b, c)
    #[allow(unused_variables, unused_mut)]
    pub fn parse_paren(&mut self) -> Result<Option<Expression>> {
        if !self.match_token(TokenType::LParen) {
            return Ok(None);
        }

        // Check for empty tuple ()
        if self.match_token(TokenType::RParen) {
            return Ok(Some(Expression::Tuple(Box::new(Tuple {
                expressions: Vec::new(),
            }))));
        }

        // Try to parse as subquery first
        // ClickHouse also allows (EXPLAIN ...) as subquery
        if self.check(TokenType::Select)
            || self.check(TokenType::With)
            || (matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            ) && self.check(TokenType::Var)
                && self.peek().text.eq_ignore_ascii_case("EXPLAIN"))
        {
            let query = self.parse_statement()?;
            self.expect(TokenType::RParen)?;
            return Ok(Some(Expression::Subquery(Box::new(Subquery {
                this: query,
                alias: None,
                column_aliases: Vec::new(),
                order_by: None,
                limit: None,
                offset: None,
                lateral: false,
                modifiers_inside: true,
                trailing_comments: Vec::new(),
                distribute_by: None,
                sort_by: None,
                cluster_by: None,
                inferred_type: None,
            }))));
        }

        // Parse comma-separated expressions
        let mut expressions = Vec::new();
        let mut trailing_comma = false;
        loop {
            match self.parse_expression() {
                Ok(expr) => expressions.push(expr),
                Err(_) => break,
            }
            if !self.match_token(TokenType::Comma) {
                break;
            }
            // ClickHouse: trailing comma makes a single-element tuple, e.g., (1,)
            if self.check(TokenType::RParen) {
                trailing_comma = true;
                break;
            }
        }

        self.expect(TokenType::RParen)?;

        // Single expression with trailing comma → tuple, e.g., (1,)
        if trailing_comma && expressions.len() == 1 {
            return Ok(Some(Expression::Tuple(Box::new(Tuple { expressions }))));
        }

        // Single expression - return the unwrapped Paren
        if expressions.len() == 1 {
            return Ok(Some(Expression::Paren(Box::new(Paren {
                this: expressions.remove(0),
                trailing_comments: Vec::new(),
            }))));
        }

        // Multiple expressions - return as tuple
        Ok(Some(Expression::Tuple(Box::new(Tuple { expressions }))))
    }

    /// parse_partition - Parses PARTITION/SUBPARTITION clause
    /// Python: _parse_partition
    pub fn parse_partition(&mut self) -> Result<Option<Expression>> {
        // PARTITION_KEYWORDS = {"PARTITION", "SUBPARTITION"}
        if !self.match_texts(&["PARTITION", "SUBPARTITION"]) {
            return Ok(None);
        }

        let subpartition = self.previous().text.to_uppercase() == "SUBPARTITION";

        // Parse wrapped CSV of disjunction expressions
        if !self.match_token(TokenType::LParen) {
            // Without parentheses, still return a Partition with empty expressions
            return Ok(Some(Expression::Partition(Box::new(Partition {
                expressions: Vec::new(),
                subpartition,
            }))));
        }

        let mut expressions = Vec::new();
        loop {
            if let Some(expr) = self.parse_disjunction()? {
                expressions.push(expr);
            } else {
                break;
            }

            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        self.match_token(TokenType::RParen);

        Ok(Some(Expression::Partition(Box::new(Partition {
            expressions,
            subpartition,
        }))))
    }

    /// parse_partition_and_order - Delegates to parse_partition_by
    #[allow(unused_variables, unused_mut)]
    pub fn parse_partition_and_order(&mut self) -> Result<Option<Expression>> {
        self.parse_partition_by()
    }

    /// parse_partition_bound_spec - Implemented from Python _parse_partition_bound_spec
    /// Calls: parse_bitwise, parse_number
    #[allow(unused_variables, unused_mut)]
    pub fn parse_partition_bound_spec_legacy(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["MINVALUE"]) {
            return Ok(Some(Expression::PartitionBoundSpec(Box::new(
                PartitionBoundSpec {
                    this: None,
                    expression: None,
                    from_expressions: None,
                    to_expressions: None,
                },
            ))));
        }
        if self.match_text_seq(&["MAXVALUE"]) {
            // Matched: MAXVALUE
            return Ok(None);
        }
        if self.match_text_seq(&["TO"]) {
            // Matched: TO
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_partition_by - Ported from Python _parse_partition_by
    /// Parses PARTITION BY expression list
    #[allow(unused_variables, unused_mut)]
    pub fn parse_partition_by(&mut self) -> Result<Option<Expression>> {
        if !self.match_keywords(&[TokenType::Partition, TokenType::By]) {
            return Ok(None);
        }
        let expressions = self.parse_expression_list()?;
        Ok(Some(Expression::Tuple(Box::new(Tuple { expressions }))))
    }

    /// parse_partitioned_by - Parses PARTITIONED BY clause
    /// Python: _parse_partitioned_by
    pub fn parse_partitioned_by(&mut self) -> Result<Option<Expression>> {
        // Optionally match '='
        self.match_token(TokenType::Eq);

        // Try to parse a schema first
        if let Some(schema) = self.parse_schema()? {
            return Ok(Some(Expression::PartitionedByProperty(Box::new(
                PartitionedByProperty {
                    this: Box::new(schema),
                },
            ))));
        }

        // Fall back to bracket(field)
        if let Some(bracket) = self.parse_bracket()? {
            return Ok(Some(Expression::PartitionedByProperty(Box::new(
                PartitionedByProperty {
                    this: Box::new(bracket),
                },
            ))));
        }

        // Try to parse a field directly
        if let Some(field) = self.parse_field()? {
            return Ok(Some(Expression::PartitionedByProperty(Box::new(
                PartitionedByProperty {
                    this: Box::new(field),
                },
            ))));
        }

        Ok(None)
    }

    /// parse_partitioned_by_bucket_or_truncate - Parses BUCKET or TRUNCATE partition transforms
    /// Python: _parse_partitioned_by_bucket_or_truncate
    /// Syntax: BUCKET(col, num_buckets) or TRUNCATE(col, width)
    /// Handles both Hive (num, col) and Trino (col, num) ordering, normalizes to (col, num)
    pub fn parse_partitioned_by_bucket_or_truncate(&mut self) -> Result<Option<Expression>> {
        // If no L_PAREN follows, this should be parsed as an identifier, not a function call
        if !self.check(TokenType::LParen) {
            // Retreat: go back one token (previous was BUCKET or TRUNCATE)
            if self.current > 0 {
                self.current -= 1;
            }
            return Ok(None);
        }

        // Determine if it's BUCKET or TRUNCATE based on previous token
        let is_bucket = self.previous().text.to_uppercase() == "BUCKET";

        // Parse wrapped arguments
        self.expect(TokenType::LParen)?;
        let mut args = Vec::new();

        if !self.check(TokenType::RParen) {
            loop {
                // Try to parse primary or column
                if let Some(expr) = self.parse_primary_or_var()? {
                    args.push(expr);
                } else if let Some(col) = self.parse_column()? {
                    args.push(col);
                }

                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
        }
        self.match_token(TokenType::RParen);

        // Get first two arguments
        let (mut this, mut expr) = (args.get(0).cloned(), args.get(1).cloned());

        // Normalize: if first arg is a Literal, swap (Hive uses (num, col), Trino uses (col, num))
        // We canonicalize to (col, num)
        if let Some(Expression::Literal(_)) = &this {
            std::mem::swap(&mut this, &mut expr);
        }

        // Ensure we have both arguments
        let this_expr = this.unwrap_or(Expression::Null(Null));
        let expr_expr = expr.unwrap_or(Expression::Null(Null));

        if is_bucket {
            Ok(Some(Expression::PartitionedByBucket(Box::new(
                PartitionedByBucket {
                    this: Box::new(this_expr),
                    expression: Box::new(expr_expr),
                },
            ))))
        } else {
            Ok(Some(Expression::PartitionByTruncate(Box::new(
                PartitionByTruncate {
                    this: Box::new(this_expr),
                    expression: Box::new(expr_expr),
                },
            ))))
        }
    }

    /// parse_doris_partition_by_range_or_list - Parses Doris PARTITION BY RANGE/LIST syntax
    /// Handles:
    ///   PARTITION BY RANGE (`col`) (PARTITION name VALUES LESS THAN (val), ...)
    ///   PARTITION BY RANGE (`col`) (PARTITION name VALUES [(val1), (val2)), ...)
    ///   PARTITION BY RANGE (`col`) (FROM ('start') TO ('end') INTERVAL n UNIT)
    ///   PARTITION BY LIST (`col`) (PARTITION name VALUES IN (val1, val2), ...)
    fn parse_doris_partition_by_range_or_list(&mut self, kind: &str) -> Result<Expression> {
        // Parse partition column expressions: (`col1`, `col2`, ...) or (STR2DATE(col, fmt))
        // Use parse_wrapped_csv to handle function calls in partition columns
        let partition_expressions = self.parse_wrapped_csv()?;

        // Check for partition definitions in parentheses
        let create_expressions = if self.check(TokenType::LParen) {
            self.advance(); // consume (

            if kind == "LIST" {
                // Parse LIST partition definitions: PARTITION name VALUES IN (val1, val2), ...
                let partitions = self.parse_doris_list_partition_definitions()?;
                self.expect(TokenType::RParen)?;
                Some(Box::new(Expression::Tuple(Box::new(Tuple {
                    expressions: partitions,
                }))))
            } else {
                // RANGE: check for FROM (dynamic), START (StarRocks dynamic), or PARTITION (static)
                if self.check(TokenType::From) {
                    // Dynamic: FROM ('start') TO ('end') INTERVAL n UNIT
                    let dynamic_expr = self.parse_doris_dynamic_partition()?;
                    self.expect(TokenType::RParen)?;
                    Some(Box::new(dynamic_expr))
                } else if self.check(TokenType::Start) {
                    // StarRocks dynamic: START ('val') END ('val') EVERY (expr), ...
                    let mut dynamics = Vec::new();
                    loop {
                        if !self.check(TokenType::Start) {
                            break;
                        }
                        let dynamic_expr = self.parse_starrocks_start_end_every()?;
                        dynamics.push(dynamic_expr);
                        if !self.match_token(TokenType::Comma) {
                            break;
                        }
                    }
                    self.expect(TokenType::RParen)?;
                    Some(Box::new(Expression::Tuple(Box::new(Tuple {
                        expressions: dynamics,
                    }))))
                } else if self.check(TokenType::Partition) {
                    // Static: PARTITION name VALUES LESS THAN (val) or VALUES [(val1), (val2))
                    let partitions = self.parse_doris_range_partition_definitions()?;
                    self.expect(TokenType::RParen)?;
                    Some(Box::new(Expression::Tuple(Box::new(Tuple {
                        expressions: partitions,
                    }))))
                } else {
                    self.expect(TokenType::RParen)?;
                    None
                }
            }
        } else {
            None
        };

        if kind == "LIST" {
            Ok(Expression::PartitionByListProperty(Box::new(
                PartitionByListProperty {
                    partition_expressions: partition_expressions.map(Box::new),
                    create_expressions,
                },
            )))
        } else {
            Ok(Expression::PartitionByRangeProperty(Box::new(
                PartitionByRangeProperty {
                    partition_expressions: partition_expressions.map(Box::new),
                    create_expressions,
                },
            )))
        }
    }

    /// Parse Doris LIST partition definitions: PARTITION name VALUES IN (val1, val2), ...
    fn parse_doris_list_partition_definitions(&mut self) -> Result<Vec<Expression>> {
        let mut partitions = Vec::new();
        loop {
            if !self.match_token(TokenType::Partition) {
                break;
            }
            let name = self.parse_id_var()?.unwrap_or(Expression::Null(Null));
            self.match_text_seq(&["VALUES", "IN"]);
            let values = self.parse_wrapped_csv_expressions()?;

            let part_list = Expression::PartitionList(Box::new(PartitionList {
                this: Box::new(name),
                expressions: values,
            }));
            partitions.push(Expression::Partition(Box::new(Partition {
                expressions: vec![part_list],
                subpartition: false,
            })));

            if !self.match_token(TokenType::Comma) {
                break;
            }
        }
        Ok(partitions)
    }

    /// Parse Doris RANGE partition definitions
    fn parse_doris_range_partition_definitions(&mut self) -> Result<Vec<Expression>> {
        let mut partitions = Vec::new();
        loop {
            if !self.match_token(TokenType::Partition) {
                break;
            }
            let name = self.parse_id_var()?.unwrap_or(Expression::Null(Null));
            self.match_text_seq(&["VALUES"]);

            let part_range = if self.match_text_seq(&["LESS", "THAN"]) {
                // VALUES LESS THAN (val) or VALUES LESS THAN (MAXVALUE)
                let values = self.parse_wrapped_csv_expressions()?;
                Expression::PartitionRange(Box::new(PartitionRange {
                    this: Box::new(name),
                    expression: None,
                    expressions: values,
                }))
            } else if self.check(TokenType::LBracket) {
                // VALUES [(val1), (val2)) - note asymmetric brackets
                self.advance(); // consume [
                let mut value_tuples = Vec::new();
                loop {
                    let vals = self.parse_wrapped_csv_expressions()?;
                    // Wrap in a Tuple for each (val)
                    value_tuples.push(Expression::Tuple(Box::new(Tuple { expressions: vals })));
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
                // Expect ) to close the asymmetric bracket
                self.expect(TokenType::RParen)?;
                Expression::PartitionRange(Box::new(PartitionRange {
                    this: Box::new(name),
                    expression: None,
                    expressions: value_tuples,
                }))
            } else {
                // Fallback: no values
                Expression::PartitionRange(Box::new(PartitionRange {
                    this: Box::new(name),
                    expression: None,
                    expressions: Vec::new(),
                }))
            };

            partitions.push(Expression::Partition(Box::new(Partition {
                expressions: vec![part_range],
                subpartition: false,
            })));

            if !self.match_token(TokenType::Comma) {
                break;
            }
        }
        Ok(partitions)
    }

    /// Parse Doris dynamic partition: FROM ('start') TO ('end') INTERVAL n UNIT
    fn parse_doris_dynamic_partition(&mut self) -> Result<Expression> {
        self.expect(TokenType::From)?;
        let start = self.parse_wrapped_expression()?;
        self.expect(TokenType::To)?;
        let end = self.parse_wrapped_expression()?;

        // Parse INTERVAL n UNIT
        let every = if self.match_token(TokenType::Interval) {
            let number = self.parse_expression()?;
            let unit = if self.is_identifier_token() || self.is_safe_keyword_as_identifier() {
                let unit_text = self.advance().text.to_uppercase();
                // Convert unit text to IntervalUnit
                let interval_unit = match unit_text.as_str() {
                    "YEAR" | "YEARS" => crate::expressions::IntervalUnit::Year,
                    "MONTH" | "MONTHS" => crate::expressions::IntervalUnit::Month,
                    "DAY" | "DAYS" => crate::expressions::IntervalUnit::Day,
                    "HOUR" | "HOURS" => crate::expressions::IntervalUnit::Hour,
                    "MINUTE" | "MINUTES" => crate::expressions::IntervalUnit::Minute,
                    "SECOND" | "SECONDS" => crate::expressions::IntervalUnit::Second,
                    _ => crate::expressions::IntervalUnit::Day, // Default fallback
                };
                Some(crate::expressions::IntervalUnitSpec::Simple {
                    unit: interval_unit,
                    use_plural: unit_text.ends_with('S'),
                })
            } else {
                None
            };
            Some(Box::new(Expression::Interval(Box::new(Interval {
                this: Some(number),
                unit,
            }))))
        } else {
            None
        };

        Ok(Expression::PartitionByRangePropertyDynamic(Box::new(
            PartitionByRangePropertyDynamic {
                this: None,
                start: Some(Box::new(start)),
                end: Some(Box::new(end)),
                every,
                use_start_end: false,
            },
        )))
    }

    /// Parse StarRocks START ('val') END ('val') EVERY (expr) syntax
    fn parse_starrocks_start_end_every(&mut self) -> Result<Expression> {
        self.expect(TokenType::Start)?;
        let start = self.parse_wrapped_expression()?;
        self.expect(TokenType::End)?;
        let end = self.parse_wrapped_expression()?;

        // Parse EVERY (expr)
        let every = if self.match_identifier("EVERY") {
            self.expect(TokenType::LParen)?;
            let expr = self.parse_expression()?;
            self.expect(TokenType::RParen)?;
            Some(Box::new(expr))
        } else {
            None
        };

        Ok(Expression::PartitionByRangePropertyDynamic(Box::new(
            PartitionByRangePropertyDynamic {
                this: None,
                start: Some(Box::new(start)),
                end: Some(Box::new(end)),
                every,
                use_start_end: true,
            },
        )))
    }

    /// Parse wrapped comma-separated expressions: (expr, expr, ...)
    fn parse_wrapped_csv_expressions(&mut self) -> Result<Vec<Expression>> {
        self.expect(TokenType::LParen)?;
        let mut exprs = Vec::new();
        if !self.check(TokenType::RParen) {
            loop {
                // Check for MAXVALUE special keyword
                if self.match_token(TokenType::Maxvalue) {
                    exprs.push(Expression::Var(Box::new(Var {
                        this: "MAXVALUE".to_string(),
                    })));
                } else {
                    exprs.push(self.parse_expression()?);
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
        }
        self.expect(TokenType::RParen)?;
        Ok(exprs)
    }

    /// Parse a single wrapped expression: (expr)
    fn parse_wrapped_expression(&mut self) -> Result<Expression> {
        self.expect(TokenType::LParen)?;
        let expr = self.parse_expression()?;
        self.expect(TokenType::RParen)?;
        Ok(expr)
    }

    /// parse_partitioned_of - Implemented from Python _parse_partitioned_of
    #[allow(unused_variables, unused_mut)]
    pub fn parse_partitioned_of(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["OF"]) {
            return Ok(Some(Expression::PartitionBoundSpec(Box::new(
                PartitionBoundSpec {
                    this: None,
                    expression: None,
                    from_expressions: None,
                    to_expressions: None,
                },
            ))));
        }
        if self.match_text_seq(&["FOR", "VALUES"]) {
            // Matched: FOR VALUES
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_period_for_system_time - Parses PERIOD FOR SYSTEM_TIME constraint
    /// Python: _parse_period_for_system_time
    /// Syntax: PERIOD FOR SYSTEM_TIME (start_col, end_col)
    pub fn parse_period_for_system_time(&mut self) -> Result<Option<Expression>> {
        // Check for SYSTEM_TIME / TIMESTAMP_SNAPSHOT token
        if !self.match_token(TokenType::TimestampSnapshot) {
            // Retreat: go back one token
            if self.current > 0 {
                self.current -= 1;
            }
            return Ok(None);
        }

        // Parse wrapped id vars (two column names)
        let id_vars = self.parse_wrapped_id_vars()?;

        // Extract the two columns from the tuple
        let (this, expression) = if let Some(Expression::Tuple(tuple)) = id_vars {
            let exprs = &tuple.expressions;
            (
                exprs.get(0).cloned().unwrap_or(Expression::Null(Null)),
                exprs.get(1).cloned().unwrap_or(Expression::Null(Null)),
            )
        } else {
            return Ok(None);
        };

        Ok(Some(Expression::PeriodForSystemTimeConstraint(Box::new(
            PeriodForSystemTimeConstraint {
                this: Box::new(this),
                expression: Box::new(expression),
            },
        ))))
    }

    /// parse_pipe_syntax_aggregate - Implemented from Python _parse_pipe_syntax_aggregate
    #[allow(unused_variables, unused_mut)]
    pub fn parse_pipe_syntax_aggregate(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["AGGREGATE"]) {
            return Ok(Some(Expression::Select(Box::new(Select {
                expressions: Vec::new(),
                from: None,
                joins: Vec::new(),
                lateral_views: Vec::new(),
                prewhere: None,
                where_clause: None,
                group_by: None,
                having: None,
                qualify: None,
                order_by: None,
                distribute_by: None,
                cluster_by: None,
                sort_by: None,
                limit: None,
                offset: None,
                limit_by: None,
                fetch: None,
                distinct: false,
                distinct_on: None,
                top: None,
                with: None,
                sample: None,
                settings: None,
                format: None,
                windows: None,
                hint: None,
                connect: None,
                into: None,
                locks: Vec::new(),
                for_xml: Vec::new(),
                leading_comments: Vec::new(),
                post_select_comments: Vec::new(),
                kind: None,
                operation_modifiers: Vec::new(),
                qualify_after_window: false,
                option: None,
                exclude: None,
            }))));
        }
        if self.match_text_seq(&["GROUP", "AND"]) {
            // Matched: GROUP AND
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_pipe_syntax_aggregate_fields - Implemented from Python _parse_pipe_syntax_aggregate_fields
    /// Calls: parse_disjunction
    #[allow(unused_variables, unused_mut)]
    pub fn parse_pipe_syntax_aggregate_fields(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["GROUP", "AND"]) {
            // Matched: GROUP AND
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_pipe_syntax_aggregate_group_order_by - Parses pipe syntax aggregate fields with grouping and ordering
    /// Python: _parse_pipe_syntax_aggregate_group_order_by
    /// Parses comma-separated aggregate fields and separates them into aggregates/groups and ORDER BY specs
    /// Returns a Tuple with two elements: (aggregates_and_groups, order_by_specs)
    pub fn parse_pipe_syntax_aggregate_group_order_by(&mut self) -> Result<Option<Expression>> {
        // Parse CSV of pipe syntax aggregate fields
        let mut aggregates_or_groups = Vec::new();
        let mut orders = Vec::new();

        loop {
            if let Some(element) = self.parse_pipe_syntax_aggregate_fields()? {
                // Check if it's an Ordered expression (ORDER BY spec)
                match &element {
                    Expression::Ordered(ordered) => {
                        // Extract the inner expression, potentially adjusting for alias
                        let this = match &ordered.this {
                            Expression::Alias(alias) => {
                                // Use the alias name as an Identifier expression
                                Expression::Identifier(alias.alias.clone())
                            }
                            other => other.clone(),
                        };
                        // Add modified Ordered to orders
                        orders.push(Expression::Ordered(Box::new(Ordered {
                            this: this.clone(),
                            desc: ordered.desc,
                            nulls_first: ordered.nulls_first,
                            explicit_asc: ordered.explicit_asc,
                            with_fill: ordered.with_fill.clone(),
                        })));
                        aggregates_or_groups.push(this);
                    }
                    _ => {
                        aggregates_or_groups.push(element);
                    }
                }
            }

            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        if aggregates_or_groups.is_empty() && orders.is_empty() {
            return Ok(None);
        }

        // Return a tuple with (aggregates_or_groups, orders)
        Ok(Some(Expression::Tuple(Box::new(Tuple {
            expressions: vec![
                Expression::Tuple(Box::new(Tuple {
                    expressions: aggregates_or_groups,
                })),
                Expression::Tuple(Box::new(Tuple {
                    expressions: orders,
                })),
            ],
        }))))
    }

    /// parse_pipe_syntax_extend - Implemented from Python _parse_pipe_syntax_extend
    #[allow(unused_variables, unused_mut)]
    pub fn parse_pipe_syntax_extend(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["EXTEND"]) {
            return Ok(Some(Expression::Select(Box::new(Select {
                expressions: Vec::new(),
                from: None,
                joins: Vec::new(),
                lateral_views: Vec::new(),
                prewhere: None,
                where_clause: None,
                group_by: None,
                having: None,
                qualify: None,
                order_by: None,
                distribute_by: None,
                cluster_by: None,
                sort_by: None,
                limit: None,
                offset: None,
                limit_by: None,
                fetch: None,
                distinct: false,
                distinct_on: None,
                top: None,
                with: None,
                sample: None,
                settings: None,
                format: None,
                windows: None,
                hint: None,
                connect: None,
                into: None,
                locks: Vec::new(),
                for_xml: Vec::new(),
                leading_comments: Vec::new(),
                post_select_comments: Vec::new(),
                kind: None,
                operation_modifiers: Vec::new(),
                qualify_after_window: false,
                option: None,
                exclude: None,
            }))));
        }
        Ok(None)
    }

    /// parse_pipe_syntax_join - Parses JOIN in BigQuery pipe syntax
    /// Python: _parse_pipe_syntax_join
    /// Format: |> JOIN table ON condition
    pub fn parse_pipe_syntax_join(&mut self) -> Result<Option<Expression>> {
        // Parse the JOIN clause
        self.parse_join()
    }

    /// parse_pipe_syntax_limit - Parses LIMIT/OFFSET in BigQuery pipe syntax
    /// Python: _parse_pipe_syntax_limit
    /// Format: |> LIMIT n [OFFSET m]
    pub fn parse_pipe_syntax_limit(&mut self) -> Result<Option<Expression>> {
        // Parse the LIMIT clause
        let limit = self.parse_limit()?;

        // Parse optional OFFSET
        let offset = self.parse_offset()?;

        // Combine into a tuple if both present
        match (limit, offset) {
            (Some(l), Some(o)) => Ok(Some(Expression::Tuple(Box::new(Tuple {
                expressions: vec![l, o],
            })))),
            (Some(l), None) => Ok(Some(l)),
            (None, Some(o)) => Ok(Some(o)),
            (None, None) => Ok(None),
        }
    }

    /// parse_pipe_syntax_pivot - Parses PIVOT in BigQuery pipe syntax
    /// Python: _parse_pipe_syntax_pivot
    /// Format: |> PIVOT (agg_function FOR column IN (values))
    pub fn parse_pipe_syntax_pivot(&mut self) -> Result<Option<Expression>> {
        // For pipe syntax, we don't have a source yet - return pivot aggregation
        // The actual pivot parsing will be done in the query transformer
        self.parse_pivot_aggregation()
    }

    /// parse_pipe_syntax_query - Parses a query with pipe syntax transformations
    /// Python: _parse_pipe_syntax_query
    /// Handles queries like: FROM table |> WHERE ... |> SELECT ... |> AGGREGATE ...
    pub fn parse_pipe_syntax_query(&mut self) -> Result<Option<Expression>> {
        // Start with a base query (could be a FROM clause or subquery)
        let mut query = self.parse_select_query()?;

        if query.is_none() {
            return Ok(None);
        }

        // Process pipe syntax chain: |> transform1 |> transform2 |> ...
        while self.match_token(TokenType::PipeGt) {
            let start_pos = self.current;
            let operator_text = self.peek().text.to_uppercase();

            // Try to match known pipe syntax transforms
            let transform_result = match operator_text.as_str() {
                "WHERE" => {
                    self.advance();
                    self.parse_where()?
                }
                "SELECT" => {
                    self.advance();
                    self.parse_pipe_syntax_select()?
                }
                "AGGREGATE" => {
                    self.advance();
                    self.parse_pipe_syntax_aggregate()?
                }
                "EXTEND" => {
                    self.advance();
                    self.parse_pipe_syntax_extend()?
                }
                "LIMIT" => {
                    self.advance();
                    self.parse_pipe_syntax_limit()?
                }
                "JOIN" | "LEFT" | "RIGHT" | "INNER" | "OUTER" | "CROSS" | "FULL" => {
                    self.parse_pipe_syntax_join()?
                }
                "UNION" | "INTERSECT" | "EXCEPT" => self.parse_pipe_syntax_set_operator()?,
                "PIVOT" => {
                    self.advance();
                    self.parse_pipe_syntax_pivot()?
                }
                "TABLESAMPLE" => {
                    self.advance();
                    self.parse_pipe_syntax_tablesample()?
                }
                _ => {
                    // Try set operator or join as fallback
                    let set_op = self.parse_pipe_syntax_set_operator()?;
                    if set_op.is_some() {
                        set_op
                    } else {
                        let join_op = self.parse_pipe_syntax_join()?;
                        if join_op.is_some() {
                            join_op
                        } else {
                            // Unsupported operator, retreat and break
                            self.current = start_pos;
                            break;
                        }
                    }
                }
            };

            // Apply transform to query
            if let Some(transform) = transform_result {
                // Wrap current query with transform in a PipeOperator
                let current_query = query.ok_or_else(|| {
                    self.parse_error("Expected base query before pipe syntax transform")
                })?;
                query = Some(Expression::PipeOperator(Box::new(PipeOperator {
                    this: current_query,
                    expression: transform,
                })));
            }
        }

        Ok(query)
    }

    /// parse_pipe_syntax_select - Parses SELECT in BigQuery pipe syntax
    /// Python: _parse_pipe_syntax_select
    /// Format: |> SELECT expressions
    pub fn parse_pipe_syntax_select(&mut self) -> Result<Option<Expression>> {
        // Parse the SELECT expressions without consuming the pipe
        let expressions = self.parse_expressions()?;

        match expressions {
            Some(expr) => Ok(Some(expr)),
            None => Ok(Some(Expression::Star(Star {
                table: None,
                except: None,
                replace: None,
                rename: None,
                trailing_comments: Vec::new(),
                span: None,
            }))),
        }
    }

    /// parse_pipe_syntax_set_operator - Parses set operation in BigQuery pipe syntax
    /// Python: _parse_pipe_syntax_set_operator
    /// Format: |> UNION ALL/INTERSECT/EXCEPT (subquery1, subquery2, ...)
    pub fn parse_pipe_syntax_set_operator(&mut self) -> Result<Option<Expression>> {
        // Try to parse as a set operation (UNION, INTERSECT, EXCEPT)
        if let Some(set_op) = self.parse_set_operations()? {
            Ok(Some(set_op))
        } else {
            Ok(None)
        }
    }

    /// parse_pipe_syntax_tablesample - Parses TABLESAMPLE in BigQuery pipe syntax
    /// Python: _parse_pipe_syntax_tablesample
    /// Format: |> TABLESAMPLE SYSTEM (percent PERCENT)
    pub fn parse_pipe_syntax_tablesample(&mut self) -> Result<Option<Expression>> {
        // Parse the TABLESAMPLE clause
        self.parse_table_sample()
    }

    /// parse_pivot_aggregation - Ported from Python _parse_pivot_aggregation
    /// Parses an aggregation function in PIVOT clause, optionally with alias
    #[allow(unused_variables, unused_mut)]
    pub fn parse_pivot_aggregation(&mut self) -> Result<Option<Expression>> {
        // Parse a function
        let func = self.parse_function()?;

        if func.is_none() {
            // If previous token was a comma, silently return None
            if self.previous().token_type == TokenType::Comma {
                return Ok(None);
            }
            // Otherwise this could be an error, but we'll just return None
            return Ok(None);
        }

        // Try to parse an alias for the function
        self.parse_alias_with_expr(func)
    }

    /// parse_pivot_in - Parses the IN clause of a PIVOT
    /// Python: _parse_pivot_in
    /// Format: column IN (value1 [AS alias1], value2 [AS alias2], ...)
    pub fn parse_pivot_in(&mut self) -> Result<Option<Expression>> {
        // Parse the column being pivoted
        let value = self.parse_column()?;
        let value_expr = value.unwrap_or(Expression::Null(Null));

        // Expect IN keyword
        if !self.match_token(TokenType::In) {
            return Err(self.parse_error("Expecting IN"));
        }

        // Check if it's a parenthesized list or a field reference
        if self.match_token(TokenType::LParen) {
            // Check for ANY keyword
            let expressions = if self.match_text_seq(&["ANY"]) {
                // Parse PivotAny with optional ORDER BY
                let order = self.parse_order()?;
                vec![Expression::PivotAny(Box::new(PivotAny {
                    this: order.map(Box::new),
                }))]
            } else {
                // Parse comma-separated list of expressions, optionally aliased
                let mut exprs = Vec::new();
                loop {
                    if let Some(expr) = self.parse_select_or_expression()? {
                        // Check for alias
                        let final_expr = if self.match_token(TokenType::Alias) {
                            if let Some(alias) = self.parse_bitwise()? {
                                // Store the alias expression directly
                                Expression::PivotAlias(Box::new(PivotAlias { this: expr, alias }))
                            } else {
                                expr
                            }
                        } else {
                            expr
                        };
                        exprs.push(final_expr);
                    } else {
                        break;
                    }
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
                exprs
            };

            self.expect(TokenType::RParen)?;

            Ok(Some(Expression::In(Box::new(In {
                this: value_expr,
                expressions,
                query: None,
                not: false,
                global: false,
                unnest: None,
                is_field: false,
            }))))
        } else {
            // Parse as a field reference: IN field_name
            let field = self.parse_id_var()?;
            // Convert field to expression and add to expressions
            let expressions = if let Some(f) = field {
                vec![f]
            } else {
                Vec::new()
            };
            Ok(Some(Expression::In(Box::new(In {
                this: value_expr,
                expressions,
                query: None,
                not: false,
                global: false,
                unnest: None,
                is_field: true,
            }))))
        }
    }

    /// parse_pivots - Ported from Python _parse_pivots
    /// Parses one or more PIVOT/UNPIVOT clauses attached to a source expression
    /// Uses the existing parse_pivot/parse_unpivot methods
    pub fn parse_pivots_for_source(&mut self, source: Expression) -> Result<Option<Expression>> {
        let mut result = source;

        loop {
            if self.match_token(TokenType::Pivot) {
                result = self.parse_pivot(result)?;
            } else if self.match_texts(&["UNPIVOT"]) {
                result = self.parse_unpivot(result)?;
            } else {
                break;
            }
        }

        // Return None if no pivots were parsed
        if matches!(result, Expression::Null(_)) {
            Ok(None)
        } else {
            Ok(Some(result))
        }
    }

    /// parse_placeholder - Parse placeholder token (? or :name)
    /// Python: if self._match_set(self.PLACEHOLDER_PARSERS): return placeholder
    pub fn parse_placeholder(&mut self) -> Result<Option<Expression>> {
        // Match positional placeholder (?)
        if self.match_token(TokenType::Placeholder) {
            return Ok(Some(Expression::Placeholder(Placeholder { index: None })));
        }
        // Match colon placeholder (:name) - handled by Parameter token
        if self.match_token(TokenType::Parameter) {
            let text = self.previous().text.clone();
            return Ok(Some(Expression::Parameter(Box::new(Parameter {
                name: Some(text),
                index: None,
                style: ParameterStyle::Colon,
                quoted: false,
                string_quoted: false,
                expression: None,
            }))));
        }
        Ok(None)
    }

    /// Parse ClickHouse query parameter syntax: {name: Type}
    fn parse_clickhouse_braced_parameter(&mut self) -> Result<Option<Expression>> {
        if !matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) {
            return Ok(None);
        }
        if !self.check(TokenType::LBrace) {
            return Ok(None);
        }

        let start = self.current;
        self.advance(); // consume {

        if !(self.is_identifier_token() || self.is_safe_keyword_as_identifier()) {
            self.current = start;
            return Ok(None);
        }
        let name = self.advance().text.clone();

        if !self.match_token(TokenType::Colon) {
            self.current = start;
            return Ok(None);
        }

        let kind_start = self.current;
        let mut paren_depth = 0usize;
        let mut bracket_depth = 0usize;

        while !self.is_at_end() {
            let token_type = self.peek().token_type;
            match token_type {
                TokenType::LParen => {
                    paren_depth += 1;
                    self.advance();
                }
                TokenType::RParen => {
                    if paren_depth == 0 {
                        break;
                    }
                    paren_depth -= 1;
                    self.advance();
                }
                TokenType::LBracket => {
                    bracket_depth += 1;
                    self.advance();
                }
                TokenType::RBracket => {
                    if bracket_depth == 0 {
                        break;
                    }
                    bracket_depth -= 1;
                    self.advance();
                }
                TokenType::RBrace => {
                    if paren_depth == 0 && bracket_depth == 0 {
                        break;
                    }
                    self.advance();
                }
                _ => {
                    self.advance();
                }
            }
        }

        if self.current <= kind_start || !self.match_token(TokenType::RBrace) {
            return Err(self.parse_error("Expected } in ClickHouse query parameter"));
        }

        let kind = self
            .tokens_to_sql(kind_start, self.current - 1)
            .trim()
            .to_string();
        if kind.is_empty() {
            return Err(self.parse_error("Expected parameter kind in ClickHouse query parameter"));
        }

        Ok(Some(Expression::Parameter(Box::new(Parameter {
            name: Some(name),
            index: None,
            style: ParameterStyle::Brace,
            quoted: false,
            string_quoted: false,
            expression: Some(kind),
        }))))
    }

    /// parse_position - Ported from Python _parse_position
    /// Parses POSITION function: POSITION(substr IN str) or POSITION(needle, haystack, start)
    #[allow(unused_variables, unused_mut)]
    pub fn parse_position(&mut self) -> Result<Option<Expression>> {
        // Parse comma-separated arguments first
        let mut args: Vec<Expression> = Vec::new();

        match self.parse_bitwise() {
            Ok(Some(expr)) => {
                let expr = self.maybe_clickhouse_alias(expr);
                let expr = self.try_clickhouse_func_arg_alias(expr);
                args.push(expr);
            }
            Ok(None) => return Ok(None),
            Err(e) => return Err(e),
        }

        // Check for IN keyword (SQL standard syntax: POSITION(substr IN str))
        if self.match_token(TokenType::In) {
            match self.parse_bitwise() {
                Ok(Some(haystack)) => {
                    let haystack = self.maybe_clickhouse_alias(haystack);
                    let haystack = self.try_clickhouse_func_arg_alias(haystack);
                    return Ok(Some(Expression::StrPosition(Box::new(StrPosition {
                        this: Box::new(haystack),
                        substr: Some(Box::new(args.remove(0))),
                        position: None,
                        occurrence: None,
                    }))));
                }
                Ok(None) => {
                    return Err(self.parse_error("Expected expression after IN in POSITION"))
                }
                Err(e) => return Err(e),
            }
        }

        // Parse comma-separated additional arguments
        while self.match_token(TokenType::Comma) {
            match self.parse_bitwise() {
                Ok(Some(expr)) => {
                    let expr = self.maybe_clickhouse_alias(expr);
                    let expr = self.try_clickhouse_func_arg_alias(expr);
                    args.push(expr);
                }
                Ok(None) => break,
                Err(e) => return Err(e),
            }
        }

        // Function syntax: POSITION(needle, haystack, start?) or ClickHouse POSITION(haystack, needle, start?)
        let position = args.get(2).cloned();
        let (haystack, needle) = if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) {
            (args.get(0).cloned(), args.get(1).cloned())
        } else {
            (args.get(1).cloned(), args.get(0).cloned())
        };

        Ok(Some(Expression::StrPosition(Box::new(StrPosition {
            this: Box::new(
                haystack.unwrap_or_else(|| Expression::Literal(Literal::String("".to_string()))),
            ),
            substr: needle.map(Box::new),
            position: position.map(Box::new),
            occurrence: None,
        }))))
    }

    /// parse_prewhere - Ported from Python _parse_prewhere
    /// Parses PREWHERE clause (ClickHouse specific)
    #[allow(unused_variables, unused_mut)]
    pub fn parse_prewhere(&mut self) -> Result<Option<Expression>> {
        if !self.match_token(TokenType::Prewhere) {
            return Ok(None);
        }
        // Parse the condition expression
        let condition = self.parse_expression()?;
        Ok(Some(Expression::PreWhere(Box::new(PreWhere {
            this: condition,
        }))))
    }

    /// parse_primary_key - Parses PRIMARY KEY constraint
    /// Python: _parse_primary_key
    /// Can return either PrimaryKeyColumnConstraint (column-level) or PrimaryKey (table-level)
    pub fn parse_primary_key(&mut self) -> Result<Option<Expression>> {
        self.parse_primary_key_impl(false, false)
    }

    /// Implementation of parse_primary_key with options
    pub fn parse_primary_key_impl(
        &mut self,
        wrapped_optional: bool,
        in_props: bool,
    ) -> Result<Option<Expression>> {
        // Check for ASC/DESC
        let desc = if self.match_token(TokenType::Asc) {
            false
        } else if self.match_token(TokenType::Desc) {
            true
        } else {
            false
        };

        // Parse optional constraint name (if current token is identifier and next is L_PAREN)
        let this = if (self.check(TokenType::Identifier) || self.check(TokenType::Var))
            && self.check_next(TokenType::LParen)
        {
            self.parse_id_var()?
        } else {
            None
        };

        // If not in_props and no L_PAREN ahead, return column-level constraint
        if !in_props && !self.check(TokenType::LParen) {
            let options = self.parse_key_constraint_options_list()?;
            return Ok(Some(Expression::PrimaryKeyColumnConstraint(Box::new(
                PrimaryKeyColumnConstraint {
                    desc: if desc {
                        Some(Box::new(Expression::Boolean(BooleanLiteral {
                            value: true,
                        })))
                    } else {
                        None
                    },
                    options,
                },
            ))));
        }

        // Parse table-level PRIMARY KEY (column_list)
        let expressions = if self.match_token(TokenType::LParen) {
            let mut exprs = Vec::new();
            loop {
                if let Some(part) = self.parse_primary_key_part()? {
                    exprs.push(part);
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            self.expect(TokenType::RParen)?;
            exprs
        } else if wrapped_optional {
            Vec::new()
        } else {
            return Err(self.parse_error("Expected '(' for PRIMARY KEY column list"));
        };

        // Parse INCLUDE clause for covering index
        let include = self.parse_index_params()?;

        // Parse constraint options
        let options = self.parse_key_constraint_options_list()?;

        Ok(Some(Expression::PrimaryKey(Box::new(PrimaryKey {
            this: this.map(Box::new),
            expressions,
            options,
            include: include.map(Box::new),
        }))))
    }

    /// Parse key constraint options as a list of expressions
    fn parse_key_constraint_options_list(&mut self) -> Result<Vec<Expression>> {
        let mut options = Vec::new();

        loop {
            if self.is_at_end() {
                break;
            }

            if self.match_token(TokenType::On) {
                // Parse ON DELETE/UPDATE action
                let on_what = if !self.is_at_end() {
                    let token = self.advance();
                    token.text.clone()
                } else {
                    break;
                };

                let action = if self.match_text_seq(&["NO", "ACTION"]) {
                    "NO ACTION"
                } else if self.match_text_seq(&["CASCADE"]) {
                    "CASCADE"
                } else if self.match_text_seq(&["RESTRICT"]) {
                    "RESTRICT"
                } else if self.match_token(TokenType::Set) && self.match_token(TokenType::Null) {
                    "SET NULL"
                } else if self.match_token(TokenType::Set) && self.match_token(TokenType::Default) {
                    "SET DEFAULT"
                } else {
                    break;
                };

                options.push(Expression::Var(Box::new(Var {
                    this: format!("ON {} {}", on_what, action),
                })));
            } else if self.match_text_seq(&["NOT", "ENFORCED"]) {
                options.push(Expression::Var(Box::new(Var {
                    this: "NOT ENFORCED".to_string(),
                })));
            } else if self.match_text_seq(&["DEFERRABLE"]) {
                options.push(Expression::Var(Box::new(Var {
                    this: "DEFERRABLE".to_string(),
                })));
            } else if self.match_text_seq(&["INITIALLY", "DEFERRED"]) {
                options.push(Expression::Var(Box::new(Var {
                    this: "INITIALLY DEFERRED".to_string(),
                })));
            } else if self.match_text_seq(&["NORELY"]) {
                options.push(Expression::Var(Box::new(Var {
                    this: "NORELY".to_string(),
                })));
            } else if self.match_text_seq(&["RELY"]) {
                options.push(Expression::Var(Box::new(Var {
                    this: "RELY".to_string(),
                })));
            } else {
                break;
            }
        }

        Ok(options)
    }

    /// parse_primary_key_part - Delegates to parse_field
    #[allow(unused_variables, unused_mut)]
    pub fn parse_primary_key_part(&mut self) -> Result<Option<Expression>> {
        // ClickHouse: PRIMARY KEY can contain full expressions (e.g., t.a, c0 IN (SELECT 1))
        if matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) {
            return self.parse_expression().map(Some);
        }
        if (self.is_identifier_token() || self.is_safe_keyword_as_identifier())
            && self.check_next(TokenType::LParen)
        {
            return self.parse_expression().map(Some);
        }
        if let Some(field) = self.parse_field()? {
            Ok(Some(field))
        } else {
            self.parse_expression().map(Some)
        }
    }

    /// parse_primary_or_var - Parses a primary expression or variable
    /// Python: _parse_primary_or_var
    /// Returns: parse_primary() or parse_var(any_token=True)
    pub fn parse_primary_or_var(&mut self) -> Result<Option<Expression>> {
        // First try to parse a primary expression
        let saved_pos = self.current;
        match self.parse_primary() {
            Ok(expr) => return Ok(Some(expr)),
            Err(_) => {
                // Reset position and try parse_var
                self.current = saved_pos;
            }
        }

        // Fall back to parsing a variable
        self.parse_var()
    }

    /// parse_procedure_option - Implemented from Python _parse_procedure_option
    #[allow(unused_variables, unused_mut)]
    pub fn parse_procedure_option(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["EXECUTE", "AS"]) {
            // Matched: EXECUTE AS
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_projections - Delegates to parse_expressions
    #[allow(unused_variables, unused_mut)]
    pub fn parse_projections(&mut self) -> Result<Option<Expression>> {
        self.parse_expressions()
    }

    /// parse_properties - Parses table/column properties
    /// Python: _parse_properties
    /// Collects a list of properties using parse_property
    pub fn parse_properties(&mut self) -> Result<Option<Expression>> {
        self.parse_properties_impl(None)
    }

    /// Implementation of parse_properties with before option
    pub fn parse_properties_impl(&mut self, before: Option<bool>) -> Result<Option<Expression>> {
        let mut properties = Vec::new();

        loop {
            let prop = if before == Some(true) {
                self.parse_property_before()?
            } else {
                self.parse_property()?
            };

            if let Some(p) = prop {
                properties.push(p);
            } else {
                break;
            }
        }

        if properties.is_empty() {
            Ok(None)
        } else {
            Ok(Some(Expression::Properties(Box::new(Properties {
                expressions: properties,
            }))))
        }
    }

    /// parse_property - Implemented from Python _parse_property
    /// Calls: parse_bitwise, parse_column, parse_sequence_properties
    #[allow(unused_variables, unused_mut)]
    pub fn parse_property(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["COMPOUND", "SORTKEY"]) {
            return Ok(Some(Expression::Identifier(Identifier {
                name: String::new(),
                quoted: false,
                trailing_comments: Vec::new(),
                span: None,
            })));
        }
        if self.match_text_seq(&["SQL", "SECURITY"]) {
            // Matched: SQL SECURITY
            return Ok(None);
        }
        if self.match_texts(&["DEFINER", "INVOKER"]) {
            // Matched one of: DEFINER, INVOKER
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_on_cluster_clause - Parse ClickHouse ON CLUSTER clause
    fn parse_on_cluster_clause(&mut self) -> Result<Option<OnCluster>> {
        if !matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) {
            return Ok(None);
        }

        let start = self.current;
        if !self.match_token(TokenType::On) {
            return Ok(None);
        }

        if !self.match_token(TokenType::Cluster) {
            self.current = start;
            return Ok(None);
        }

        let this = if self.check(TokenType::String) {
            let value = self.expect_string()?;
            Expression::Literal(Literal::String(value))
        } else if let Some(id_expr) = self.parse_id_var()? {
            id_expr
        } else if self.is_safe_keyword_as_identifier() {
            let name = self.advance().text;
            Expression::Identifier(Identifier {
                name,
                quoted: false,
                trailing_comments: Vec::new(),
                span: None,
            })
        } else {
            return Err(self.parse_error("Expected cluster name after ON CLUSTER"));
        };

        Ok(Some(OnCluster {
            this: Box::new(this),
        }))
    }

    /// parse_clickhouse_table_properties - Parse ClickHouse table properties after column defs
    fn parse_clickhouse_table_properties(
        &mut self,
        properties: &mut Vec<Expression>,
    ) -> Result<()> {
        loop {
            if self.match_identifier("ENGINE") {
                self.match_token(TokenType::Eq);
                let engine = self.parse_clickhouse_engine_expression()?;
                properties.push(Expression::EngineProperty(Box::new(EngineProperty {
                    this: Box::new(engine),
                })));
                continue;
            }

            if self.match_token(TokenType::Order) {
                self.expect(TokenType::By)?;
                let order_by = if matches!(
                    self.config.dialect,
                    Some(crate::dialects::DialectType::ClickHouse)
                ) && self.match_token(TokenType::LParen)
                {
                    // ClickHouse: ORDER BY (col1 [ASC|DESC], col2 [ASC|DESC], ...)
                    // or ORDER BY () for no ordering
                    if self.check(TokenType::RParen) {
                        self.advance();
                        OrderBy {
                            expressions: vec![Ordered::asc(Expression::Tuple(Box::new(Tuple {
                                expressions: Vec::new(),
                            })))],
                            siblings: false,
                            comments: Vec::new(),
                        }
                    } else {
                        // Parse all expressions inside the parentheses
                        let mut inner_exprs = Vec::new();
                        loop {
                            let expr = self.parse_expression()?;
                            inner_exprs.push(expr);
                            if !self.match_token(TokenType::Comma) {
                                break;
                            }
                        }
                        self.expect(TokenType::RParen)?;
                        // Wrap in a Tuple for multi-expr, Paren for single-expr
                        let wrapper = if inner_exprs.len() == 1 {
                            Expression::Paren(Box::new(Paren {
                                this: inner_exprs.into_iter().next().unwrap(),
                                trailing_comments: Vec::new(),
                            }))
                        } else {
                            Expression::Tuple(Box::new(Tuple {
                                expressions: inner_exprs,
                            }))
                        };
                        OrderBy {
                            expressions: vec![Ordered::asc(wrapper)],
                            siblings: false,
                            comments: Vec::new(),
                        }
                    }
                } else {
                    self.parse_order_by()?
                };
                properties.push(Expression::OrderBy(Box::new(order_by)));
                continue;
            }

            if self.match_token(TokenType::Partition) {
                self.expect(TokenType::By)?;
                if self.check(TokenType::Order) && self.check_next(TokenType::By) {
                    return Err(self.parse_error("Expected expression after PARTITION BY"));
                }
                let expr = self
                    .parse_assignment()?
                    .ok_or_else(|| self.parse_error("Expected expression after PARTITION BY"))?;
                properties.push(Expression::PartitionedByProperty(Box::new(
                    PartitionedByProperty {
                        this: Box::new(expr),
                    },
                )));
                continue;
            }

            if self.match_token(TokenType::PrimaryKey) {
                // ClickHouse supports PRIMARY KEY id and PRIMARY KEY (id, ...)
                let _ = self.match_token(TokenType::Key);
                if self.check(TokenType::LParen) {
                    if let Some(pk) = self.parse_primary_key_impl(false, true)? {
                        properties.push(pk);
                    }
                } else if let Some(expr) = self.parse_conjunction()? {
                    // ClickHouse: PRIMARY KEY expr (e.g., PRIMARY KEY tuple(), PRIMARY KEY id)
                    let mut exprs = vec![expr];
                    while self.match_token(TokenType::Comma) {
                        if let Some(next_expr) = self.parse_field()? {
                            exprs.push(next_expr);
                        } else {
                            break;
                        }
                    }
                    properties.push(Expression::PrimaryKey(Box::new(PrimaryKey {
                        this: None,
                        expressions: exprs,
                        options: Vec::new(),
                        include: None,
                    })));
                } else {
                    return Err(self.parse_error("Expected expression after PRIMARY KEY"));
                }
                continue;
            }

            if self.match_token(TokenType::Sample) {
                let _ = self.match_token(TokenType::By);
                let expr = self.parse_expression()?;
                properties.push(Expression::SampleProperty(Box::new(SampleProperty {
                    this: Box::new(expr),
                })));
                continue;
            }

            if self.match_token(TokenType::Settings) {
                let mut settings = Vec::new();
                loop {
                    settings.push(self.parse_expression()?);
                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
                properties.push(Expression::SettingsProperty(Box::new(SettingsProperty {
                    expressions: settings,
                })));
                continue;
            }

            if self.match_token(TokenType::Comment) {
                let comment_expr = if self.check(TokenType::String) {
                    Expression::Literal(Literal::String(self.expect_string()?))
                } else {
                    self.parse_expression()?
                };
                properties.push(Expression::SchemaCommentProperty(Box::new(
                    SchemaCommentProperty {
                        this: Box::new(comment_expr),
                    },
                )));
                continue;
            }

            // TTL time_column + INTERVAL '1' MONTH [DELETE|RECOMPRESS|TO DISK|TO VOLUME] [WHERE ...]
            if self.match_identifier("TTL") {
                if let Some(ttl_expr) = self.parse_ttl()? {
                    properties.push(ttl_expr);
                }
                continue;
            }

            if self.match_identifier("SOURCE") {
                if let Some(prop) = self.parse_dict_property("SOURCE")? {
                    properties.push(prop);
                }
                continue;
            }

            if self.match_identifier("LAYOUT") {
                if let Some(prop) = self.parse_dict_property("LAYOUT")? {
                    properties.push(prop);
                }
                continue;
            }

            if self.match_identifier("LIFETIME") {
                if let Some(range) = self.parse_dict_range("LIFETIME")? {
                    properties.push(range);
                }
                continue;
            }

            if self.match_identifier("RANGE") || self.match_token(TokenType::Range) {
                if let Some(range) = self.parse_dict_range("RANGE")? {
                    properties.push(range);
                }
                continue;
            }

            break;
        }

        Ok(())
    }

    /// ClickHouse implicit alias in function arguments: `expr identifier` (without AS keyword).
    /// The token after the alias must be a delimiter (comma, RParen, FROM, FOR, AS).
    fn try_clickhouse_implicit_alias(&mut self, expr: Expression) -> Expression {
        if !matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) {
            return expr;
        }
        if self.check(TokenType::Var) || self.check(TokenType::Identifier) {
            let next_after = self.peek_nth(1).map(|t| t.token_type);
            let is_delimiter = matches!(
                next_after,
                Some(TokenType::Comma)
                    | Some(TokenType::RParen)
                    | Some(TokenType::From)
                    | Some(TokenType::For)
                    | Some(TokenType::As)
            );
            if is_delimiter {
                let alias_token = self.advance();
                let alias_name = alias_token.text.clone();
                return Expression::Alias(Box::new(crate::expressions::Alias::new(
                    expr,
                    Identifier::new(alias_name),
                )));
            }
        }
        expr
    }

    /// ClickHouse alias in function arguments: handles both implicit (`expr identifier`)
    /// and explicit (`expr AS identifier`) aliases. Use this in special function parsers
    /// (SUBSTRING, TRIM, EXTRACT) but NOT in CAST (which has its own AS handling).
    /// Normalize TSQL date part aliases (e.g., dd -> DAY, yy -> YEAR, etc.)
    fn normalize_tsql_date_part(&self, expr: Expression) -> Expression {
        let name = match &expr {
            Expression::Var(v) => Some(v.this.to_uppercase()),
            Expression::Column(c) if c.table.is_none() => Some(c.name.name.to_uppercase()),
            Expression::Identifier(id) => Some(id.name.to_uppercase()),
            _ => None,
        };
        if let Some(name) = name {
            let mapped = match name.as_str() {
                "YY" | "YYY" | "YYYY" | "YR" | "YEARS" | "YRS" => "YEAR",
                "MM" | "MON" | "MONS" | "MONTHS" | "M" => "MONTH",
                "D" | "DD" | "DAYS" | "DAYOFMONTH" => "DAY",
                "DOW" | "DW" | "WEEKDAY" => "DAYOFWEEK",
                "DOY" | "DY" | "Y" => "DAYOFYEAR",
                "W" | "WK" | "WEEKOFYEAR" | "WOY" | "WY" | "WW" => "WEEK",
                "Q" | "QTR" | "QTRS" | "QUARTERS" | "QQ" => "QUARTER",
                "H" | "HH" | "HR" | "HOURS" | "HRS" => "HOUR",
                "MI" | "MIN" | "MINUTES" | "MINS" | "N" => "MINUTE",
                "S" | "SEC" | "SECONDS" | "SECS" | "SS" => "SECOND",
                "MS" | "MSEC" | "MSECS" | "MSECOND" | "MSECONDS" | "MILLISEC" | "MILLISECS"
                | "MILLISECON" | "MILLISECONDS" => "MILLISECOND",
                "US" | "USEC" | "USECS" | "MICROSEC" | "MICROSECS" | "USECOND" | "USECONDS"
                | "MICROSECONDS" | "MCS" => "MICROSECOND",
                "NS" | "NSEC" | "NANOSEC" | "NSECOND" | "NSECONDS" | "NANOSECS" => "NANOSECOND",
                "TZH" => "TIMEZONE_HOUR",
                "TZM" | "TZOFFSET" | "TZ" => "TIMEZONE_MINUTE",
                "DEC" | "DECS" | "DECADES" => "DECADE",
                "MIL" | "MILS" | "MILLENIA" => "MILLENNIUM",
                "C" | "CENT" | "CENTS" | "CENTURIES" => "CENTURY",
                "ISOWK" | "ISOWW" | "ISO_WEEK" | "WEEKOFYEARISO" | "WEEKOFYEAR_ISO"
                | "WEEK_ISO" => "WEEKISO",
                _ => return expr, // No mapping, return as-is
            };
            return Expression::Var(Box::new(Var {
                this: mapped.to_string(),
            }));
        }
        expr
    }

    fn try_parse_date_part_unit_expr(&self, expr: &Expression) -> Option<IntervalUnit> {
        let upper = self.date_part_expr_name(expr)?.to_uppercase();
        let canonical = match upper.as_str() {
            // Year
            "Y" | "YY" | "YYY" | "YYYY" | "YR" | "YEARS" | "YRS" => "YEAR",
            // Quarter
            "Q" | "QTR" | "QTRS" | "QUARTERS" | "QQ" => "QUARTER",
            // Month
            "MM" | "MON" | "MONS" | "MONTHS" | "M" => "MONTH",
            // Week
            "W" | "WK" | "WEEKOFYEAR" | "WOY" | "WY" | "WW" | "WEEKS" => "WEEK",
            // Day
            "D" | "DD" | "DAYS" | "DAYOFMONTH" => "DAY",
            // Hour
            "H" | "HH" | "HR" | "HOURS" | "HRS" => "HOUR",
            // Minute
            "MI" | "MIN" | "MINUTES" | "MINS" | "N" => "MINUTE",
            // Second
            "S" | "SEC" | "SECONDS" | "SECS" | "SS" => "SECOND",
            // Millisecond
            "MS" | "MSEC" | "MSECS" | "MSECOND" | "MSECONDS" | "MILLISEC" | "MILLISECS"
            | "MILLISECON" | "MILLISECONDS" => "MILLISECOND",
            // Microsecond
            "US" | "USEC" | "USECS" | "MICROSEC" | "MICROSECS" | "USECOND" | "USECONDS"
            | "MICROSECONDS" | "MCS" => "MICROSECOND",
            // Nanosecond
            "NS" | "NSEC" | "NANOSEC" | "NSECOND" | "NSECONDS" | "NANOSECS" => "NANOSECOND",
            _ => upper.as_str(),
        };

        Self::parse_interval_unit_from_string(canonical)
    }

    fn try_parse_date_part_unit_identifier_expr(&self, expr: &Expression) -> Option<IntervalUnit> {
        let upper = self.date_part_identifier_expr_name(expr)?.to_uppercase();
        let canonical = match upper.as_str() {
            "Y" | "YY" | "YYY" | "YYYY" | "YR" | "YEARS" | "YRS" => "YEAR",
            "Q" | "QTR" | "QTRS" | "QUARTERS" | "QQ" => "QUARTER",
            "MM" | "MON" | "MONS" | "MONTHS" | "M" => "MONTH",
            "W" | "WK" | "WEEKOFYEAR" | "WOY" | "WY" | "WW" | "WEEKS" => "WEEK",
            "D" | "DD" | "DAYS" | "DAYOFMONTH" => "DAY",
            "H" | "HH" | "HR" | "HOURS" | "HRS" => "HOUR",
            "MI" | "MIN" | "MINUTES" | "MINS" | "N" => "MINUTE",
            "S" | "SEC" | "SECONDS" | "SECS" | "SS" => "SECOND",
            "MS" | "MSEC" | "MSECS" | "MSECOND" | "MSECONDS" | "MILLISEC" | "MILLISECS"
            | "MILLISECON" | "MILLISECONDS" => "MILLISECOND",
            "US" | "USEC" | "USECS" | "MICROSEC" | "MICROSECS" | "USECOND" | "USECONDS"
            | "MICROSECONDS" | "MCS" => "MICROSECOND",
            "NS" | "NSEC" | "NANOSEC" | "NSECOND" | "NSECONDS" | "NANOSECS" => "NANOSECOND",
            _ => upper.as_str(),
        };

        Self::parse_interval_unit_from_string(canonical)
    }

    fn try_parse_date_part_field_identifier_expr(
        &self,
        expr: &Expression,
    ) -> Option<DateTimeField> {
        let upper = self.date_part_identifier_expr_name(expr)?.to_uppercase();
        Some(match upper.as_str() {
            "YEAR" | "Y" | "YY" | "YYY" | "YYYY" | "YR" | "YEARS" | "YRS" => DateTimeField::Year,
            "MONTH" | "MM" | "MON" | "MONS" | "MONTHS" => DateTimeField::Month,
            "DAY" | "D" | "DD" | "DAYS" | "DAYOFMONTH" => DateTimeField::Day,
            "HOUR" | "H" | "HH" | "HR" | "HOURS" | "HRS" => DateTimeField::Hour,
            "MINUTE" | "MI" | "MIN" | "MINUTES" | "MINS" => DateTimeField::Minute,
            "SECOND" | "S" | "SEC" | "SECONDS" | "SECS" => DateTimeField::Second,
            "MILLISECOND" | "MS" | "MSEC" | "MILLISECONDS" => DateTimeField::Millisecond,
            "MICROSECOND" | "US" | "USEC" | "MICROSECONDS" => DateTimeField::Microsecond,
            "DOW" | "DAYOFWEEK" | "DW" => DateTimeField::DayOfWeek,
            "DOY" | "DAYOFYEAR" | "DY" => DateTimeField::DayOfYear,
            "WEEK" | "W" | "WK" | "WEEKOFYEAR" | "WOY" | "WW" => DateTimeField::Week,
            "QUARTER" | "Q" | "QTR" | "QTRS" | "QUARTERS" => DateTimeField::Quarter,
            "EPOCH" | "EPOCH_SECOND" | "EPOCH_SECONDS" => DateTimeField::Epoch,
            "TIMEZONE" => DateTimeField::Timezone,
            "TIMEZONE_HOUR" | "TZH" => DateTimeField::TimezoneHour,
            "TIMEZONE_MINUTE" | "TZM" => DateTimeField::TimezoneMinute,
            "DATE" => DateTimeField::Date,
            "TIME" => DateTimeField::Time,
            other => DateTimeField::Custom(other.to_string()),
        })
    }

    fn convert_date_part_identifier_expr_to_var(&self, expr: Expression) -> Expression {
        match expr {
            Expression::Var(_) => expr,
            Expression::Column(c) if c.table.is_none() => {
                Expression::Var(Box::new(Var { this: c.name.name }))
            }
            Expression::Identifier(id) => Expression::Var(Box::new(Var { this: id.name })),
            _ => expr,
        }
    }

    fn date_part_identifier_expr_name<'a>(&self, expr: &'a Expression) -> Option<&'a str> {
        match expr {
            Expression::Var(v) => Some(v.this.as_str()),
            Expression::Column(c) if c.table.is_none() => Some(c.name.name.as_str()),
            Expression::Identifier(id) => Some(id.name.as_str()),
            _ => None,
        }
    }

    fn date_part_expr_name<'a>(&self, expr: &'a Expression) -> Option<&'a str> {
        self.date_part_identifier_expr_name(expr).or(match expr {
            Expression::Literal(Literal::String(s)) => Some(s.as_str()),
            _ => None,
        })
    }

    fn try_clickhouse_func_arg_alias(&mut self, expr: Expression) -> Expression {
        if !matches!(
            self.config.dialect,
            Some(crate::dialects::DialectType::ClickHouse)
        ) {
            return expr;
        }
        // Try implicit alias first
        if self.check(TokenType::Var) || self.check(TokenType::Identifier) {
            let next_after = self.peek_nth(1).map(|t| t.token_type);
            let is_delimiter = matches!(
                next_after,
                Some(TokenType::Comma)
                    | Some(TokenType::RParen)
                    | Some(TokenType::From)
                    | Some(TokenType::For)
                    | Some(TokenType::As)
            );
            if is_delimiter {
                let alias_token = self.advance();
                let alias_name = alias_token.text.clone();
                return Expression::Alias(Box::new(crate::expressions::Alias::new(
                    expr,
                    Identifier::new(alias_name),
                )));
            }
        }
        // Try explicit AS alias
        if self.check(TokenType::As) {
            let next_idx = self.current + 1;
            let after_alias_idx = self.current + 2;
            let is_alias_token = next_idx < self.tokens.len()
                && matches!(
                    self.tokens[next_idx].token_type,
                    TokenType::Identifier | TokenType::Var | TokenType::QuotedIdentifier
                );
            let is_delimiter = is_alias_token
                && after_alias_idx < self.tokens.len()
                && matches!(
                    self.tokens[after_alias_idx].token_type,
                    TokenType::Comma
                        | TokenType::RParen
                        | TokenType::From
                        | TokenType::For
                        | TokenType::As
                );
            if is_delimiter {
                self.advance(); // consume AS
                let alias_token = self.advance();
                let alias_name = if alias_token.token_type == TokenType::QuotedIdentifier {
                    let mut ident = Identifier::new(alias_token.text.clone());
                    ident.quoted = true;
                    ident
                } else {
                    Identifier::new(alias_token.text.clone())
                };
                return Expression::Alias(Box::new(crate::expressions::Alias::new(
                    expr, alias_name,
                )));
            }
        }
        expr
    }

    /// parse_clickhouse_engine_expression - Parse ENGINE expression with optional args
    fn parse_clickhouse_engine_expression(&mut self) -> Result<Expression> {
        if self.is_at_end() {
            return Err(self.parse_error("Expected engine name after ENGINE"));
        }

        let token = self.advance();
        let quoted = matches!(token.token_type, TokenType::QuotedIdentifier);
        let name = token.text.clone();

        let ident = Expression::Identifier(Identifier {
            name,
            quoted,
            trailing_comments: Vec::new(),
            span: None,
        });

        if self.match_token(TokenType::LParen) {
            let args = if self.check(TokenType::RParen) {
                Vec::new()
            } else {
                self.parse_expression_list()?
            };
            self.expect(TokenType::RParen)?;
            Ok(Expression::Anonymous(Box::new(Anonymous {
                this: Box::new(ident),
                expressions: args,
            })))
        } else {
            Ok(ident)
        }
    }

    /// parse_property_assignment - Ported from Python _parse_property_assignment
    /// Parses a property assignment: optionally = or AS, then a value
    #[allow(unused_variables, unused_mut)]
    pub fn parse_property_assignment(&mut self) -> Result<Option<Expression>> {
        // Optionally match = or AS
        let _ = self.match_token(TokenType::Eq);
        let _ = self.match_token(TokenType::Alias);

        // Parse the value as an unquoted field
        let value = self.parse_unquoted_field()?;

        Ok(value)
    }

    /// parse_property_before - Implemented from Python _parse_property_before
    #[allow(unused_variables, unused_mut)]
    pub fn parse_property_before(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["NO"]) {
            // Matched: NO
            return Ok(None);
        }
        if self.match_text_seq(&["DUAL"]) {
            // Matched: DUAL
            return Ok(None);
        }
        if self.match_text_seq(&["BEFORE"]) {
            // Matched: BEFORE
            return Ok(None);
        }
        if self.match_texts(&["MIN", "MINIMUM"]) {
            // Matched one of: MIN, MINIMUM
            return Ok(None);
        }
        if self.match_texts(&["MAX", "MAXIMUM"]) {
            // Matched one of: MAX, MAXIMUM
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_qualify - Parse QUALIFY clause (Snowflake, BigQuery)
    /// Python: if not self._match(TokenType.QUALIFY): return None; return exp.Qualify(this=self._parse_disjunction())
    pub fn parse_qualify(&mut self) -> Result<Option<Expression>> {
        if !self.match_token(TokenType::Qualify) {
            return Ok(None);
        }
        let condition = self.parse_expression()?;
        Ok(Some(Expression::Qualify(Box::new(Qualify {
            this: condition,
        }))))
    }

    /// parse_range - Parses range expressions (BETWEEN, LIKE, IN, IS, etc.)
    /// Python: _parse_range
    pub fn parse_range(&mut self) -> Result<Option<Expression>> {
        // First parse a bitwise expression as the left side
        let mut this = self.parse_bitwise()?;
        if this.is_none() {
            return Ok(None);
        }

        // Check for NOT (for NOT LIKE, NOT IN, NOT BETWEEN, etc.)
        let negate = self.match_token(TokenType::Not);

        // BETWEEN
        if self.match_token(TokenType::Between) {
            let between = self.parse_between_with_expr(this.clone(), negate)?;
            this = Some(between);
            return Ok(this);
        }

        // LIKE
        if self.match_token(TokenType::Like) {
            let left = this.clone().expect("left expression checked above");
            let right = self
                .parse_bitwise()?
                .ok_or_else(|| self.parse_error("Expected expression after LIKE"))?;
            let escape = self.parse_escape()?;
            let like = Expression::Like(Box::new(LikeOp {
                left,
                right,
                escape,
                quantifier: None,
                inferred_type: None,
            }));
            this = if negate {
                Some(Expression::Not(Box::new(UnaryOp {
                    this: like,
                    inferred_type: None,
                })))
            } else {
                Some(like)
            };
            return Ok(this);
        }

        // ILIKE
        if self.match_token(TokenType::ILike) {
            let left = this.clone().expect("left expression checked above");
            let right = self
                .parse_bitwise()?
                .ok_or_else(|| self.parse_error("Expected expression after ILIKE"))?;
            let escape = self.parse_escape()?;
            let ilike = Expression::ILike(Box::new(LikeOp {
                left,
                right,
                escape,
                quantifier: None,
                inferred_type: None,
            }));
            this = if negate {
                Some(Expression::Not(Box::new(UnaryOp {
                    this: ilike,
                    inferred_type: None,
                })))
            } else {
                Some(ilike)
            };
            return Ok(this);
        }

        // IN
        if self.match_token(TokenType::In) {
            let in_expr = self.parse_in_with_expr(this.clone())?;
            this = if negate {
                Some(Expression::Not(Box::new(UnaryOp {
                    this: in_expr,
                    inferred_type: None,
                })))
            } else {
                Some(in_expr)
            };
            return Ok(this);
        }

        // IS [NOT] NULL / IS [NOT] TRUE / IS [NOT] FALSE
        if self.match_token(TokenType::Is) {
            let is_expr = self.parse_is_with_expr(this.clone())?;
            this = Some(is_expr);
            return Ok(this);
        }

        // Handle standalone NOT with NULL (for NOT NULL pattern after negate)
        if negate && self.match_token(TokenType::Null) {
            if let Some(left) = this {
                let is_null = Expression::Is(Box::new(BinaryOp {
                    left,
                    right: Expression::Null(Null),
                    left_comments: Vec::new(),
                    operator_comments: Vec::new(),
                    trailing_comments: Vec::new(),
                    inferred_type: None,
                }));
                return Ok(Some(Expression::Not(Box::new(UnaryOp {
                    this: is_null,
                    inferred_type: None,
                }))));
            }
        }

        Ok(this)
    }

    /// parse_between_with_expr - Parses BETWEEN expression with given left side
    fn parse_between_with_expr(
        &mut self,
        this: Option<Expression>,
        negate: bool,
    ) -> Result<Expression> {
        let this_expr = match this {
            Some(e) => e,
            None => return Err(self.parse_error("Expected expression before BETWEEN")),
        };

        // Check for SYMMETRIC/ASYMMETRIC qualifier
        let symmetric = if self.match_texts(&["SYMMETRIC"]) {
            Some(true)
        } else if self.match_texts(&["ASYMMETRIC"]) {
            Some(false)
        } else {
            None
        };

        let low = self
            .parse_bitwise()?
            .ok_or_else(|| self.parse_error("Expected low expression after BETWEEN"))?;

        if !self.match_token(TokenType::And) {
            return Err(self.parse_error("Expected AND in BETWEEN expression"));
        }

        let high = self
            .parse_bitwise()?
            .ok_or_else(|| self.parse_error("Expected high expression after AND in BETWEEN"))?;

        Ok(Expression::Between(Box::new(Between {
            this: this_expr,
            low,
            high,
            not: negate,
            symmetric,
        })))
    }

    /// parse_in_with_expr - Parses IN expression with given left side
    fn parse_in_with_expr(&mut self, this: Option<Expression>) -> Result<Expression> {
        let this_expr = match this {
            Some(e) => e,
            None => return Err(self.parse_error("Expected expression before IN")),
        };

        // BigQuery: IN UNNEST(expr) — UNNEST without wrapping parentheses
        if self.check_identifier("UNNEST") {
            self.advance(); // consume UNNEST
            self.expect(TokenType::LParen)?;
            let unnest_expr = self.parse_expression()?;
            self.expect(TokenType::RParen)?;
            return Ok(Expression::In(Box::new(In {
                this: this_expr,
                expressions: Vec::new(),
                query: None,
                not: false,
                global: false,
                unnest: Some(Box::new(unnest_expr)),
                is_field: false,
            })));
        }

        // Parse the IN list (subquery or value list)
        if !self.match_token(TokenType::LParen) {
            // DuckDB: IN without parentheses for array/list membership: 'red' IN tbl.flags
            // Try to parse as a single expression (column/array reference)
            if let Ok(expr) = self.parse_primary() {
                return Ok(Expression::In(Box::new(In {
                    this: this_expr,
                    expressions: vec![expr],
                    query: None,
                    not: false,
                    global: false,
                    unnest: None,
                    is_field: true,
                })));
            }
            return Err(self.parse_error("Expected expression or parenthesized list after IN"));
        }

        // Check if it's a subquery
        if self.check(TokenType::Select) {
            let subquery = self.parse_select()?;
            self.expect(TokenType::RParen)?;
            return Ok(Expression::In(Box::new(In {
                this: this_expr,
                expressions: Vec::new(),
                query: Some(subquery),
                not: false,
                global: false,
                unnest: None,
                is_field: false,
            })));
        }

        // Parse value list. Pre-size for large IN lists to reduce reallocations.
        let capacity_hint = self.estimate_expression_list_capacity_until_rparen();
        let expressions = self.parse_expression_list_with_capacity(capacity_hint)?;
        self.expect(TokenType::RParen)?;

        if expressions.is_empty() {
            return Err(self.parse_error("Expected expression list after IN"));
        }

        Ok(Expression::In(Box::new(In {
            this: this_expr,
            expressions,
            query: None,
            not: false,
            global: false,
            unnest: None,
            is_field: false,
        })))
    }

    /// parse_is_with_expr - Parses IS expression with given left side
    fn parse_is_with_expr(&mut self, this: Option<Expression>) -> Result<Expression> {
        let this_expr = match this {
            Some(e) => e,
            None => return Err(self.parse_error("Expected expression before IS")),
        };

        let negate = self.match_token(TokenType::Not);

        // IS NULL
        if self.match_token(TokenType::Null) {
            let is_null = Expression::Is(Box::new(BinaryOp {
                left: this_expr,
                right: Expression::Null(Null),
                left_comments: Vec::new(),
                operator_comments: Vec::new(),
                trailing_comments: Vec::new(),
                inferred_type: None,
            }));
            return if negate {
                Ok(Expression::Not(Box::new(UnaryOp {
                    this: is_null,
                    inferred_type: None,
                })))
            } else {
                Ok(is_null)
            };
        }

        // IS TRUE
        if self.match_texts(&["TRUE"]) {
            let is_true = Expression::Is(Box::new(BinaryOp {
                left: this_expr,
                right: Expression::Boolean(BooleanLiteral { value: true }),
                left_comments: Vec::new(),
                operator_comments: Vec::new(),
                trailing_comments: Vec::new(),
                inferred_type: None,
            }));
            return if negate {
                Ok(Expression::Not(Box::new(UnaryOp {
                    this: is_true,
                    inferred_type: None,
                })))
            } else {
                Ok(is_true)
            };
        }

        // IS FALSE
        if self.match_texts(&["FALSE"]) {
            let is_false = Expression::Is(Box::new(BinaryOp {
                left: this_expr,
                right: Expression::Boolean(BooleanLiteral { value: false }),
                left_comments: Vec::new(),
                operator_comments: Vec::new(),
                trailing_comments: Vec::new(),
                inferred_type: None,
            }));
            return if negate {
                Ok(Expression::Not(Box::new(UnaryOp {
                    this: is_false,
                    inferred_type: None,
                })))
            } else {
                Ok(is_false)
            };
        }

        // IS JSON [VALUE|SCALAR|OBJECT|ARRAY] [WITH UNIQUE KEYS|WITHOUT UNIQUE KEYS|UNIQUE KEYS]
        if self.match_texts(&["JSON"]) {
            // Parse optional JSON type
            let json_type = if self.match_texts(&["VALUE"]) {
                Some("VALUE".to_string())
            } else if self.match_texts(&["SCALAR"]) {
                Some("SCALAR".to_string())
            } else if self.match_texts(&["OBJECT"]) {
                Some("OBJECT".to_string())
            } else if self.match_texts(&["ARRAY"]) {
                Some("ARRAY".to_string())
            } else {
                None
            };

            // Parse optional key uniqueness constraint
            let unique_keys = if self.match_text_seq(&["WITH", "UNIQUE", "KEYS"]) {
                Some(JsonUniqueKeys::With)
            } else if self.match_text_seq(&["WITHOUT", "UNIQUE", "KEYS"]) {
                Some(JsonUniqueKeys::Without)
            } else if self.match_text_seq(&["UNIQUE", "KEYS"]) {
                // Shorthand for WITH UNIQUE KEYS
                Some(JsonUniqueKeys::Shorthand)
            } else {
                None
            };

            return Ok(Expression::IsJson(Box::new(IsJson {
                this: this_expr,
                json_type,
                unique_keys,
                negated: negate,
            })));
        }

        // IS DISTINCT FROM / IS NOT DISTINCT FROM
        if self.match_text_seq(&["DISTINCT", "FROM"]) {
            let right = self.parse_bitwise()?;
            if let Some(right_expr) = right {
                // IS DISTINCT FROM is semantically "not equal with null handling"
                // Use NullSafeNeq for IS DISTINCT FROM
                // If negate was set (IS NOT DISTINCT FROM), use NullSafeEq
                let expr = if negate {
                    Expression::NullSafeEq(Box::new(BinaryOp {
                        left: this_expr,
                        right: right_expr,
                        left_comments: Vec::new(),
                        operator_comments: Vec::new(),
                        trailing_comments: Vec::new(),
                        inferred_type: None,
                    }))
                } else {
                    Expression::NullSafeNeq(Box::new(BinaryOp {
                        left: this_expr,
                        right: right_expr,
                        left_comments: Vec::new(),
                        operator_comments: Vec::new(),
                        trailing_comments: Vec::new(),
                        inferred_type: None,
                    }))
                };
                return Ok(expr);
            }
            return Err(self.parse_error("Expected expression after IS DISTINCT FROM"));
        }

        Err(self.parse_error("Expected NULL, TRUE, FALSE, JSON, or DISTINCT FROM after IS"))
    }

    /// parse_reads_property - Implemented from Python _parse_reads_property
    #[allow(unused_variables, unused_mut)]
    pub fn parse_reads_property(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["SQL", "DATA"]) {
            // Matched: SQL DATA
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_recursive_with_search - Parse SEARCH/CYCLE clause for recursive CTEs (PostgreSQL)
    /// Syntax: SEARCH BREADTH|DEPTH FIRST BY column SET column [USING column]
    ///     or: CYCLE column SET column USING column
    #[allow(unused_variables, unused_mut)]
    pub fn parse_recursive_with_search(&mut self) -> Result<Option<Box<Expression>>> {
        // Check for SEARCH or CYCLE keyword
        let kind = if self.match_text_seq(&["SEARCH"]) {
            // SEARCH BREADTH|DEPTH FIRST BY ...
            let search_kind = if self.match_text_seq(&["BREADTH"]) {
                "BREADTH"
            } else if self.match_text_seq(&["DEPTH"]) {
                "DEPTH"
            } else {
                return Ok(None);
            };
            // Consume "FIRST BY"
            self.match_text_seq(&["FIRST"]);
            self.match_text_seq(&["BY"]);
            search_kind.to_string()
        } else if self.match_token(TokenType::Cycle) {
            "CYCLE".to_string()
        } else {
            return Ok(None);
        };

        // Parse the column(s) - for CYCLE this is typically a single column
        let this = self.expect_identifier()?;
        let this_expr = Expression::Identifier(Identifier::new(this));

        // SET column
        let expression = if self.match_text_seq(&["SET"]) {
            let set_col = self.expect_identifier()?;
            Expression::Identifier(Identifier::new(set_col))
        } else {
            return Err(self.parse_error("Expected SET in CYCLE/SEARCH clause"));
        };

        // USING column (optional for SEARCH, required for CYCLE)
        let using = if self.match_token(TokenType::Using) {
            let using_col = self.expect_identifier()?;
            Some(Box::new(Expression::Identifier(Identifier::new(using_col))))
        } else {
            None
        };

        Ok(Some(Box::new(Expression::RecursiveWithSearch(Box::new(
            RecursiveWithSearch {
                kind,
                this: Box::new(this_expr),
                expression: Box::new(expression),
                using,
            },
        )))))
    }

    /// parse_references - Ported from Python _parse_references
    /// Parses REFERENCES clause for foreign key constraints
    #[allow(unused_variables, unused_mut)]
    pub fn parse_references(&mut self) -> Result<Option<Expression>> {
        if !self.match_token(TokenType::References) {
            return Ok(None);
        }

        // Parse referenced table
        let this = self.parse_table()?;
        if this.is_none() {
            return Err(self.parse_error("Expected table name after REFERENCES"));
        }

        // Parse optional column list (table(col1, col2))
        let expressions = if self.match_token(TokenType::LParen) {
            let cols = self.parse_identifier_list()?;
            self.expect(TokenType::RParen)?;
            cols.into_iter()
                .map(|id| Expression::Identifier(id))
                .collect()
        } else {
            Vec::new()
        };

        // Parse optional constraint options (ON DELETE, ON UPDATE, etc.)
        let options = self.parse_fk_constraint_options()?;

        Ok(Some(Expression::Reference(Box::new(Reference {
            this: Box::new(this.unwrap()),
            expressions,
            options,
        }))))
    }

    /// Parse key constraint options (ON DELETE CASCADE, ON UPDATE SET NULL, etc.)
    fn parse_fk_constraint_options(&mut self) -> Result<Vec<Expression>> {
        let mut options = Vec::new();

        while self.match_token(TokenType::On) {
            let kind = if self.match_token(TokenType::Delete) {
                "DELETE"
            } else if self.match_token(TokenType::Update) {
                "UPDATE"
            } else {
                break;
            };

            let action = if self.match_text_seq(&["NO", "ACTION"]) {
                "NO ACTION"
            } else if self.match_text_seq(&["SET", "NULL"]) {
                "SET NULL"
            } else if self.match_text_seq(&["SET", "DEFAULT"]) {
                "SET DEFAULT"
            } else if self.match_token(TokenType::Cascade) {
                "CASCADE"
            } else if self.match_token(TokenType::Restrict) {
                "RESTRICT"
            } else {
                continue;
            };

            // Store as simple identifier with the full action description
            options.push(Expression::Identifier(Identifier {
                name: format!("ON {} {}", kind, action),
                quoted: false,
                trailing_comments: Vec::new(),
                span: None,
            }));
        }

        // Parse MATCH option
        if self.match_token(TokenType::Match) {
            let match_type = if self.match_identifier("FULL") {
                "FULL"
            } else if self.match_identifier("PARTIAL") {
                "PARTIAL"
            } else if self.match_identifier("SIMPLE") {
                "SIMPLE"
            } else {
                ""
            };
            if !match_type.is_empty() {
                options.push(Expression::Identifier(Identifier {
                    name: format!("MATCH {}", match_type),
                    quoted: false,
                    trailing_comments: Vec::new(),
                    span: None,
                }));
            }
        }

        Ok(options)
    }

    /// parse_refresh - Implemented from Python _parse_refresh
    #[allow(unused_variables, unused_mut)]
    /// parse_refresh - Parses REFRESH TABLE or REFRESH MATERIALIZED VIEW
    /// Python: parser.py:7656-7668
    pub fn parse_refresh(&mut self) -> Result<Option<Expression>> {
        let kind = if self.match_token(TokenType::Table) {
            "TABLE".to_string()
        } else if self.match_text_seq(&["MATERIALIZED", "VIEW"]) {
            "MATERIALIZED VIEW".to_string()
        } else {
            String::new()
        };

        // Parse the object name (string literal or table name)
        // First try a string literal, then fall back to table reference
        if let Some(s) = self.parse_string()? {
            return Ok(Some(Expression::Refresh(Box::new(Refresh {
                this: Box::new(s),
                kind,
            }))));
        }

        // Parse as a table reference (schema.table format)
        let table_ref = self.parse_table_ref()?;
        let table_expr = Expression::Table(table_ref);

        Ok(Some(Expression::Refresh(Box::new(Refresh {
            this: Box::new(table_expr),
            kind,
        }))))
    }

    /// parse_refresh_trigger_property - Doris REFRESH clause for materialized views
    /// Syntax: REFRESH method ON kind [EVERY n UNIT] [STARTS 'datetime']
    /// Examples:
    ///   REFRESH COMPLETE ON MANUAL
    ///   REFRESH AUTO ON COMMIT
    ///   REFRESH AUTO ON SCHEDULE EVERY 5 MINUTE STARTS '2025-01-01 00:00:00'
    pub fn parse_refresh_trigger_property(&mut self) -> Result<RefreshTriggerProperty> {
        // Parse method: COMPLETE or AUTO
        let method = self.expect_identifier_or_keyword()?.to_uppercase();

        // Parse ON
        self.expect(TokenType::On)?;

        // Parse kind: MANUAL, COMMIT, or SCHEDULE
        let kind_text = self.expect_identifier_or_keyword()?.to_uppercase();
        let kind = Some(kind_text.clone());

        // For SCHEDULE, parse EVERY n UNIT [STARTS 'datetime']
        let (every, unit, starts) = if kind_text == "SCHEDULE" {
            // EVERY n UNIT
            let every = if self.match_identifier("EVERY") {
                // parse_number returns Option<Expression> with Expression::Literal(Literal::Number(...))
                self.parse_number()?.map(Box::new)
            } else {
                None
            };

            // Unit: MINUTE, HOUR, DAY, etc.
            let unit = if every.is_some() {
                Some(self.expect_identifier_or_keyword()?.to_uppercase())
            } else {
                None
            };

            // STARTS 'datetime'
            let starts = if self.match_identifier("STARTS") {
                let s = self.expect_string()?;
                Some(Box::new(Expression::Literal(Literal::String(s))))
            } else {
                None
            };

            (every, unit, starts)
        } else {
            (None, None, None)
        };

        Ok(RefreshTriggerProperty {
            method,
            kind,
            every,
            unit,
            starts,
        })
    }

    /// parse_remote_with_connection - Implemented from Python _parse_remote_with_connection
    #[allow(unused_variables, unused_mut)]
    pub fn parse_remote_with_connection(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["WITH", "CONNECTION"]) {
            // Matched: WITH CONNECTION
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_respect_or_ignore_nulls - Implemented from Python _parse_respect_or_ignore_nulls
    #[allow(unused_variables, unused_mut)]
    pub fn parse_respect_or_ignore_nulls(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["IGNORE", "NULLS"]) {
            // Matched: IGNORE NULLS
            return Ok(None);
        }
        if self.match_text_seq(&["RESPECT", "NULLS"]) {
            // Matched: RESPECT NULLS
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_retention_period - Parses HISTORY_RETENTION_PERIOD (TSQL)
    /// Python: _parse_retention_period
    /// Format: INFINITE | <number> DAY | DAYS | MONTH | MONTHS | YEAR | YEARS
    pub fn parse_retention_period(&mut self) -> Result<Option<Expression>> {
        // Try to parse a number first
        let number = self.parse_number()?;
        let number_str = number
            .map(|n| match n {
                Expression::Literal(Literal::Number(s)) => format!("{} ", s),
                _ => String::new(),
            })
            .unwrap_or_default();

        // Parse the unit (any token as a variable)
        let unit = self.parse_var_any_token()?;
        let unit_str = unit
            .map(|u| match u {
                Expression::Var(v) => v.this.clone(),
                _ => String::new(),
            })
            .unwrap_or_default();

        let result = format!("{}{}", number_str, unit_str);
        Ok(Some(Expression::Var(Box::new(Var { this: result }))))
    }

    /// parse_var_any_token - Parses any token as a Var (for flexible parsing)
    fn parse_var_any_token(&mut self) -> Result<Option<Expression>> {
        if !self.is_at_end() {
            let token = self.advance();
            Ok(Some(Expression::Var(Box::new(Var {
                this: token.text.clone(),
            }))))
        } else {
            Ok(None)
        }
    }

    /// parse_returning - Creates Returning expression
    /// Parses RETURNING clause (PostgreSQL) for INSERT/UPDATE/DELETE
    #[allow(unused_variables, unused_mut)]
    pub fn parse_returning(&mut self) -> Result<Option<Expression>> {
        if !self.match_token(TokenType::Returning) {
            return Ok(None);
        }

        // Parse expressions (column list or *)
        let expressions = self.parse_expression_list()?;

        // Check for INTO target_table (Oracle style)
        let into = if self.match_token(TokenType::Into) {
            self.parse_table()?.map(Box::new)
        } else {
            None
        };

        Ok(Some(Expression::Returning(Box::new(Returning {
            expressions,
            into,
        }))))
    }

    /// parse_output_clause - Parses OUTPUT clause (TSQL)
    /// Used in INSERT/UPDATE/DELETE and MERGE statements
    /// Supports expressions with optional AS aliases: OUTPUT col1, col2 AS alias, col3
    pub fn parse_output_clause(&mut self) -> Result<OutputClause> {
        // Parse comma-separated list of columns/expressions with optional aliases
        let mut columns = Vec::new();
        loop {
            let expr = self.parse_expression()?;
            // Check for optional AS alias
            let expr = if self.match_token(TokenType::As) {
                let alias = self.expect_identifier_or_keyword_with_quoted()?;
                Expression::Alias(Box::new(Alias {
                    this: expr,
                    alias,
                    column_aliases: Vec::new(),
                    pre_alias_comments: Vec::new(),
                    trailing_comments: Vec::new(),
                    inferred_type: None,
                }))
            } else {
                expr
            };
            columns.push(expr);
            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        // Check for INTO target
        let into_table = if self.match_token(TokenType::Into) {
            Some(self.parse_expression()?)
        } else {
            None
        };

        Ok(OutputClause {
            columns,
            into_table,
        })
    }

    /// parse_returns - Implemented from Python _parse_returns
    /// Calls: parse_types
    #[allow(unused_variables, unused_mut)]
    pub fn parse_returns(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["NULL", "ON", "NULL", "INPUT"]) {
            return Ok(Some(Expression::Schema(Box::new(Schema {
                this: None,
                expressions: Vec::new(),
            }))));
        }
        Ok(None)
    }

    /// parse_row - Parses ROW FORMAT clause
    /// Returns RowFormatSerdeProperty or RowFormatDelimitedProperty
    pub fn parse_row(&mut self) -> Result<Option<Expression>> {
        // Python: if not self._match(TokenType.FORMAT): return None
        if !self.match_token(TokenType::Format) {
            return Ok(None);
        }
        self.parse_row_format()
    }

    /// parse_row_format - Implemented from Python _parse_row_format
    /// Parses SERDE or DELIMITED row format specifications
    pub fn parse_row_format(&mut self) -> Result<Option<Expression>> {
        // Check for SERDE row format
        if self.match_text_seq(&["SERDE"]) {
            let this = self.parse_string()?;
            let serde_properties = self.parse_serde_properties(false)?;

            return Ok(Some(Expression::RowFormatSerdeProperty(Box::new(
                RowFormatSerdeProperty {
                    this: Box::new(this.unwrap_or(Expression::Null(Null))),
                    serde_properties: serde_properties.map(Box::new),
                },
            ))));
        }

        // Check for DELIMITED row format
        self.match_text_seq(&["DELIMITED"]);

        let mut fields = None;
        let mut escaped = None;
        let mut collection_items = None;
        let mut map_keys = None;
        let mut lines = None;
        let mut null = None;

        // Parse FIELDS TERMINATED BY
        if self.match_text_seq(&["FIELDS", "TERMINATED", "BY"]) {
            fields = self.parse_string()?.map(Box::new);
            // Parse optional ESCAPED BY
            if self.match_text_seq(&["ESCAPED", "BY"]) {
                escaped = self.parse_string()?.map(Box::new);
            }
        }

        // Parse COLLECTION ITEMS TERMINATED BY
        if self.match_text_seq(&["COLLECTION", "ITEMS", "TERMINATED", "BY"]) {
            collection_items = self.parse_string()?.map(Box::new);
        }

        // Parse MAP KEYS TERMINATED BY
        if self.match_text_seq(&["MAP", "KEYS", "TERMINATED", "BY"]) {
            map_keys = self.parse_string()?.map(Box::new);
        }

        // Parse LINES TERMINATED BY
        if self.match_text_seq(&["LINES", "TERMINATED", "BY"]) {
            lines = self.parse_string()?.map(Box::new);
        }

        // Parse NULL DEFINED AS
        if self.match_text_seq(&["NULL", "DEFINED", "AS"]) {
            null = self.parse_string()?.map(Box::new);
        }

        // Parse optional WITH SERDEPROPERTIES
        let serde = self.parse_serde_properties(false)?.map(Box::new);

        Ok(Some(Expression::RowFormatDelimitedProperty(Box::new(
            RowFormatDelimitedProperty {
                fields,
                escaped,
                collection_items,
                map_keys,
                lines,
                null,
                serde,
            },
        ))))
    }

    /// parse_schema - Ported from Python _parse_schema
    /// Parses schema definition: (col1 type1, col2 type2, ...)
    /// Used for CREATE TABLE column definitions
    #[allow(unused_variables, unused_mut)]
    pub fn parse_schema(&mut self) -> Result<Option<Expression>> {
        self.parse_schema_with_this(None)
    }

    /// parse_schema_with_this - Parses schema with optional table reference
    fn parse_schema_with_this(&mut self, this: Option<Expression>) -> Result<Option<Expression>> {
        // Check for opening parenthesis
        if !self.match_token(TokenType::LParen) {
            return Ok(this.map(|e| e));
        }

        // Check if this is a subquery (SELECT, WITH, etc.) not a schema
        if self.check(TokenType::Select) || self.check(TokenType::With) {
            // Retreat - put back the LParen
            self.current -= 1;
            return Ok(this.map(|e| e));
        }

        // Parse column definitions and constraints
        let mut expressions = Vec::new();
        if !self.check(TokenType::RParen) {
            loop {
                // Try to parse constraint first, then field definition
                if let Some(constraint) = self.parse_constraint()? {
                    expressions.push(constraint);
                } else if let Some(field_def) = self.parse_field_def()? {
                    expressions.push(field_def);
                } else {
                    break;
                }

                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
        }

        self.expect(TokenType::RParen)?;

        Ok(Some(Expression::Schema(Box::new(Schema {
            this: this.map(Box::new),
            expressions,
        }))))
    }

    /// Parse schema identifier: name or name(columns)
    /// Used for TSQL ON filegroup (partition_column) syntax
    fn parse_schema_identifier(&mut self) -> Result<Expression> {
        // Parse the identifier (filegroup name)
        let name = self.expect_identifier_with_quoted()?;
        let name_expr = Expression::Identifier(name);

        // Check for optional parenthesized columns
        if self.match_token(TokenType::LParen) {
            let mut columns = Vec::new();
            loop {
                let col = self.expect_identifier_with_quoted()?;
                columns.push(Expression::Identifier(col));
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            self.expect(TokenType::RParen)?;
            Ok(Expression::Schema(Box::new(Schema {
                this: Some(Box::new(name_expr)),
                expressions: columns,
            })))
        } else {
            // Just the identifier, no columns
            Ok(name_expr)
        }
    }

    /// parse_security - Implemented from Python _parse_security
    #[allow(unused_variables, unused_mut)]
    pub fn parse_security(&mut self) -> Result<Option<Expression>> {
        if self.match_texts(&["NONE", "DEFINER", "INVOKER"]) {
            // Matched one of: NONE, DEFINER, INVOKER
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_select_or_expression - Parses either a SELECT statement or an expression
    /// Python: _parse_select_or_expression
    pub fn parse_select_or_expression(&mut self) -> Result<Option<Expression>> {
        // Save position for potential backtracking
        let start_pos = self.current;

        // First try to parse a SELECT statement if we're at a SELECT keyword
        if self.check(TokenType::Select) {
            return Ok(Some(self.parse_select()?));
        }

        // Otherwise try to parse an expression (assignment)
        if let Some(expr) = self.parse_disjunction()? {
            return Ok(Some(expr));
        }

        // Backtrack if nothing worked
        self.current = start_pos;

        Ok(None)
    }

    /// parse_select_query - Implemented from Python _parse_select_query
    /// Calls: parse_string, parse_table, parse_describe
    #[allow(unused_variables, unused_mut)]
    pub fn parse_select_query(&mut self) -> Result<Option<Expression>> {
        if self.match_texts(&["STRUCT", "VALUE"]) {
            // Matched one of: STRUCT, VALUE
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_sequence_properties - Implemented from Python _parse_sequence_properties
    /// Calls: parse_number, parse_term, parse_column
    #[allow(unused_variables, unused_mut)]
    pub fn parse_sequence_properties(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["INCREMENT"]) {
            return Ok(Some(Expression::SequenceProperties(Box::new(
                SequenceProperties {
                    increment: None,
                    minvalue: None,
                    maxvalue: None,
                    cache: None,
                    start: None,
                    owned: None,
                    options: Vec::new(),
                },
            ))));
        }
        if self.match_text_seq(&["BY"]) {
            // Matched: BY
            return Ok(None);
        }
        if self.match_text_seq(&["="]) {
            // Matched: =
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_serde_properties - Implemented from Python _parse_serde_properties
    /// Parses SERDEPROPERTIES clause: [WITH] SERDEPROPERTIES (key=value, ...)
    pub fn parse_serde_properties(&mut self, with_: bool) -> Result<Option<Expression>> {
        let start_index = self.current;
        let has_with = with_ || self.match_text_seq(&["WITH"]);

        // Check for SERDEPROPERTIES keyword
        if !self.match_token(TokenType::SerdeProperties) {
            self.current = start_index;
            return Ok(None);
        }

        // Parse wrapped properties manually since parse_property doesn't handle 'key'='value' syntax
        let mut expressions = Vec::new();
        if self.match_token(TokenType::LParen) {
            loop {
                if self.check(TokenType::RParen) {
                    break;
                }
                // Parse 'key'='value' or key=value
                let key = self.parse_primary()?;
                if self.match_token(TokenType::Eq) {
                    let value = self.parse_primary()?;
                    expressions.push(Expression::Eq(Box::new(BinaryOp::new(key, value))));
                } else {
                    expressions.push(key);
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            self.expect(TokenType::RParen)?;
        }

        Ok(Some(Expression::SerdeProperties(Box::new(
            SerdeProperties {
                expressions,
                with_: if has_with {
                    Some(Box::new(Expression::Boolean(BooleanLiteral {
                        value: true,
                    })))
                } else {
                    None
                },
            },
        ))))
    }

    /// parse_session_parameter - Ported from Python _parse_session_parameter
    #[allow(unused_variables, unused_mut)]
    /// parse_session_parameter - Parses session parameters (@@var or @@session.var)
    /// Example: @@session.sql_mode, @@global.autocommit
    pub fn parse_session_parameter(&mut self) -> Result<Option<Expression>> {
        // Parse the first identifier or primary
        let first = if let Some(id) = self.parse_id_var()? {
            id
        } else if let Some(primary) = self.parse_primary_or_var()? {
            primary
        } else {
            return Ok(None);
        };

        // Check for dot notation (kind.name)
        let (kind, this) = if self.match_token(TokenType::Dot) {
            // kind is the first part, parse the second
            let kind_name = match &first {
                Expression::Identifier(id) => Some(id.name.clone()),
                _ => None,
            };
            let second = self
                .parse_var()?
                .or_else(|| self.parse_primary_or_var().ok().flatten());
            (kind_name, second.unwrap_or(first))
        } else {
            (None, first)
        };

        Ok(Some(Expression::SessionParameter(Box::new(
            SessionParameter {
                this: Box::new(this),
                kind,
            },
        ))))
    }

    /// parse_set_item - Ported from Python _parse_set_item
    /// Parses an item in a SET statement (GLOBAL, LOCAL, SESSION prefixes, or assignment)
    #[allow(unused_variables, unused_mut)]
    pub fn parse_set_item(&mut self) -> Result<Option<Expression>> {
        // Check for specific prefixes
        let kind = if self.match_text_seq(&["GLOBAL"]) {
            Some("GLOBAL".to_string())
        } else if self.match_text_seq(&["LOCAL"]) {
            Some("LOCAL".to_string())
        } else if self.match_text_seq(&["SESSION"]) {
            Some("SESSION".to_string())
        } else {
            None
        };

        // Delegate to set_item_assignment
        self.parse_set_item_assignment()
    }

    /// parse_set_item_assignment - Implemented from Python _parse_set_item_assignment
    /// Parses SET variable = value assignments
    pub fn parse_set_item_assignment(&mut self) -> Result<Option<Expression>> {
        let start_index = self.current;

        // Try to parse as TRANSACTION
        if self.match_text_seq(&["TRANSACTION"]) {
            // This is handled by parse_set_transaction
            return Ok(Some(Expression::SetItem(Box::new(SetItem {
                name: Expression::Var(Box::new(Var {
                    this: "TRANSACTION".to_string(),
                })),
                value: Expression::Null(Null),
                kind: None,
                no_equals: false,
            }))));
        }

        // Parse left side: primary or column
        let left = self
            .parse_primary_or_var()?
            .or_else(|| self.parse_column().ok().flatten());

        if left.is_none() {
            self.current = start_index;
            return Ok(None);
        }

        // Check for assignment delimiter (= or TO or :=)
        if !self.match_texts(&["=", "TO", ":="]) {
            self.current = start_index;
            return Ok(None);
        }

        // Parse right side: value
        // First try string literals (preserve quoting), then booleans/numbers, then identifiers
        let right_val = if self.check(TokenType::String) {
            let text = self.advance().text.clone();
            Expression::Literal(Literal::String(text))
        } else if self.check(TokenType::False) {
            self.advance();
            Expression::Boolean(BooleanLiteral { value: false })
        } else if self.check(TokenType::True) {
            self.advance();
            Expression::Boolean(BooleanLiteral { value: true })
        } else {
            let right = self
                .parse_id_var()?
                .or_else(|| self.parse_primary_or_var().ok().flatten());
            // Convert Column/Identifier to Var
            match right {
                Some(Expression::Column(col)) => Expression::Var(Box::new(Var {
                    this: col.name.name.clone(),
                })),
                Some(Expression::Identifier(id)) => Expression::Var(Box::new(Var {
                    this: id.name.clone(),
                })),
                Some(other) => other,
                None => Expression::Null(Null),
            }
        };

        Ok(Some(Expression::SetItem(Box::new(SetItem {
            name: left
                .ok_or_else(|| self.parse_error("Expected variable name in SET statement"))?,
            value: right_val,
            kind: None,
            no_equals: false,
        }))))
    }

    /// parse_set_operations - Parses UNION/INTERSECT/EXCEPT operations
    /// This version parses from current position (expects to be at set operator)
    /// Python: _parse_set_operations
    pub fn parse_set_operations(&mut self) -> Result<Option<Expression>> {
        // Parse a SELECT or subquery first
        let left = if self.check(TokenType::Select) {
            Some(self.parse_select()?)
        } else if self.match_token(TokenType::LParen) {
            let inner = self.parse_select()?;
            self.match_token(TokenType::RParen);
            Some(inner)
        } else {
            None
        };

        if left.is_none() {
            return Ok(None);
        }

        self.parse_set_operations_with_expr(left)
    }

    /// parse_set_operations_with_expr - Parses set operations with a left expression
    pub fn parse_set_operations_with_expr(
        &mut self,
        this: Option<Expression>,
    ) -> Result<Option<Expression>> {
        let mut result = this;

        while result.is_some() {
            if let Some(setop) = self.parse_set_operation_with_expr(result.clone())? {
                result = Some(setop);
            } else {
                break;
            }
        }

        Ok(result)
    }

    /// parse_set_operation_with_expr - Parses a single set operation (UNION, INTERSECT, EXCEPT)
    fn parse_set_operation_with_expr(
        &mut self,
        left: Option<Expression>,
    ) -> Result<Option<Expression>> {
        let left_expr = match left {
            Some(e) => e,
            None => return Ok(None),
        };

        // Check for UNION, INTERSECT, EXCEPT
        let op_type = if self.match_token(TokenType::Union) {
            "UNION"
        } else if self.match_token(TokenType::Intersect) {
            "INTERSECT"
        } else if self.match_token(TokenType::Except) {
            "EXCEPT"
        } else {
            return Ok(Some(left_expr));
        };

        // Check for ALL or DISTINCT
        let (all, distinct) = if self.match_token(TokenType::All) {
            (true, false)
        } else {
            let d = self.match_token(TokenType::Distinct);
            (false, d)
        };

        // DuckDB: UNION [ALL] BY NAME SELECT ...
        let by_name = self.match_token(TokenType::By) && self.match_identifier("NAME");

        // Parse the right side (SELECT or subquery)
        let right = if self.check(TokenType::Select) {
            self.parse_select()?
        } else if self.match_token(TokenType::LParen) {
            let inner = self.parse_select()?;
            self.match_token(TokenType::RParen);
            inner
        } else {
            return Ok(Some(left_expr));
        };

        // Create the appropriate set operation expression
        match op_type {
            "UNION" => Ok(Some(Expression::Union(Box::new(Union {
                left: left_expr,
                right,
                all,
                distinct,
                with: None,
                order_by: None,
                limit: None,
                offset: None,
                distribute_by: None,
                sort_by: None,
                cluster_by: None,
                by_name,
                side: None,
                kind: None,
                corresponding: false,
                strict: false,
                on_columns: Vec::new(),
            })))),
            "INTERSECT" => Ok(Some(Expression::Intersect(Box::new(Intersect {
                left: left_expr,
                right,
                all,
                distinct,
                with: None,
                order_by: None,
                limit: None,
                offset: None,
                distribute_by: None,
                sort_by: None,
                cluster_by: None,
                by_name,
                side: None,
                kind: None,
                corresponding: false,
                strict: false,
                on_columns: Vec::new(),
            })))),
            "EXCEPT" => Ok(Some(Expression::Except(Box::new(Except {
                left: left_expr,
                right,
                all,
                distinct,
                with: None,
                order_by: None,
                limit: None,
                offset: None,
                distribute_by: None,
                sort_by: None,
                cluster_by: None,
                by_name,
                side: None,
                kind: None,
                corresponding: false,
                strict: false,
                on_columns: Vec::new(),
            })))),
            _ => Ok(Some(left_expr)),
        }
    }

    /// parse_set_transaction - Implemented from Python _parse_set_transaction
    #[allow(unused_variables, unused_mut)]
    pub fn parse_set_transaction(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["TRANSACTION"]) {
            // Matched: TRANSACTION
            return Ok(None);
        }
        Ok(None)
    }

    /// Helper to consume an optional ClickHouse SETTINGS clause
    /// Used in SHOW, CHECK TABLE, and other ClickHouse statements
    fn parse_clickhouse_settings_clause(&mut self) -> Result<()> {
        if self.match_token(TokenType::Settings) {
            let _ = self.parse_settings_property()?;
        }
        Ok(())
    }

    /// parse_settings_property - Parses SETTINGS property (ClickHouse)
    /// Python: _parse_settings_property
    /// Format: SETTINGS key=value, key=value, ...
    pub fn parse_settings_property(&mut self) -> Result<Option<Expression>> {
        // Parse comma-separated assignment expressions
        let mut expressions = Vec::new();
        loop {
            if let Some(assignment) = self.parse_assignment()? {
                expressions.push(assignment);
            } else {
                break;
            }
            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        Ok(Some(Expression::SettingsProperty(Box::new(
            SettingsProperty { expressions },
        ))))
    }

    /// parse_simplified_pivot - Ported from Python _parse_simplified_pivot
    /// Handles DuckDB simplified PIVOT/UNPIVOT syntax:
    ///   PIVOT table ON columns [IN (...)] USING agg_func [AS alias], ... [GROUP BY ...]
    ///   UNPIVOT table ON columns [INTO NAME col VALUE col, ...]
    #[allow(unused_variables, unused_mut)]
    pub fn parse_simplified_pivot(&mut self, is_unpivot: bool) -> Result<Option<Expression>> {
        // Parse the source table (can be a subquery like (SELECT 1 AS col1, 2 AS col2))
        let this = if self.check(TokenType::LParen) {
            // Could be parenthesized subquery
            self.advance(); // consume (
            if self.check(TokenType::Select) || self.check(TokenType::With) {
                let inner = self.parse_statement()?;
                self.expect(TokenType::RParen)?;
                Some(Expression::Subquery(Box::new(Subquery {
                    this: inner,
                    alias: None,
                    column_aliases: Vec::new(),
                    order_by: None,
                    limit: None,
                    offset: None,
                    lateral: false,
                    modifiers_inside: false,
                    trailing_comments: Vec::new(),
                    distribute_by: None,
                    sort_by: None,
                    cluster_by: None,
                    inferred_type: None,
                })))
            } else {
                // Not a subquery, retreat and parse as expression in parens
                self.current -= 1; // un-consume the (
                Some(self.parse_primary()?)
            }
        } else {
            // Parse table reference (e.g., Cities, schema.table, duckdb_functions())
            Some(self.parse_primary()?)
        };

        // Parse ON columns
        let expressions = if self.match_text_seq(&["ON"]) {
            let mut on_exprs = Vec::new();
            loop {
                // Parse ON expression - use parse_bitwise to handle complex expressions like Country || '_' || Name
                let on_expr = self.parse_bitwise()?;
                if on_expr.is_none() {
                    break;
                }
                let mut expr = on_expr.unwrap();

                // Check for IN clause on this column
                if self.match_token(TokenType::In) {
                    if self.match_token(TokenType::LParen) {
                        let mut in_exprs = Vec::new();
                        loop {
                            if self.check(TokenType::RParen) {
                                break;
                            }
                            if let Some(val) = self.parse_select_or_expression()? {
                                in_exprs.push(val);
                            }
                            if !self.match_token(TokenType::Comma) {
                                break;
                            }
                        }
                        self.expect(TokenType::RParen)?;
                        expr = Expression::In(Box::new(In {
                            this: expr,
                            expressions: in_exprs,
                            query: None,
                            not: false,
                            global: false,
                            unnest: None,
                            is_field: false,
                        }));
                    }
                }
                // Check for alias (UNPIVOT ON (jan, feb, mar) AS q1, ...)
                else if self.match_token(TokenType::As) {
                    let alias_name = self.expect_identifier()?;
                    expr =
                        Expression::Alias(Box::new(Alias::new(expr, Identifier::new(alias_name))));
                }

                on_exprs.push(expr);

                // Continue if comma
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            on_exprs
        } else {
            Vec::new()
        };

        // Parse INTO for UNPIVOT columns (INTO NAME col VALUE col, ...)
        let into = self.parse_unpivot_columns()?;

        // Parse USING clause (aggregation functions with optional aliases)
        // e.g., USING SUM(Population), USING SUM(Population) AS total, MAX(Population) AS max
        // e.g., USING CAST(AVG(LENGTH(function_name)) AS INT)
        let using = if self.match_text_seq(&["USING"]) {
            let mut using_exprs = Vec::new();
            loop {
                // Stop if we hit GROUP BY or end of input
                if self.is_at_end() || self.check(TokenType::Group) || self.check(TokenType::RParen)
                {
                    break;
                }
                // Parse the primary expression (function call, possibly with cast :: operator)
                let func = self.parse_primary()?;
                // Check for :: cast operator (e.g., SUM(Population)::INTEGER)
                let expr = if self.match_token(TokenType::DColon) {
                    let data_type = self.parse_data_type()?;
                    Expression::Cast(Box::new(Cast {
                        this: func,
                        to: data_type,
                        trailing_comments: Vec::new(),
                        double_colon_syntax: true,
                        format: None,
                        default: None,
                        inferred_type: None,
                    }))
                } else {
                    func
                };
                // Try to parse alias (AS alias)
                if self.match_token(TokenType::As) {
                    let alias_name = self.expect_identifier()?;
                    using_exprs.push(Expression::Alias(Box::new(Alias::new(
                        expr,
                        Identifier::new(alias_name),
                    ))));
                } else {
                    using_exprs.push(expr);
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            using_exprs
        } else {
            Vec::new()
        };

        // Parse optional GROUP BY
        let group = self.parse_group()?;

        let source = this.unwrap();

        Ok(Some(Expression::Pivot(Box::new(Pivot {
            this: source,
            expressions,
            fields: Vec::new(),
            using,
            group: group.map(Box::new),
            unpivot: is_unpivot,
            into: into.map(Box::new),
            alias: None,
            include_nulls: None,
            default_on_null: None,
            with: None,
        }))))
    }

    /// parse_slice - Parses array slice syntax [start:end:step]
    /// Python: _parse_slice
    /// Takes an optional 'this' expression (the start of the slice)
    pub fn parse_slice(&mut self) -> Result<Option<Expression>> {
        self.parse_slice_with_this(None)
    }

    /// Implementation of parse_slice with 'this' parameter
    pub fn parse_slice_with_this(
        &mut self,
        this: Option<Expression>,
    ) -> Result<Option<Expression>> {
        // Check for colon - if not found, return this as-is
        if !self.match_token(TokenType::Colon) {
            return Ok(this);
        }

        // Parse end expression
        // Handle special case: -: which means -1 (from end)
        let end = if self.check(TokenType::Dash) && self.check_next(TokenType::Colon) {
            // -: pattern means -1 (from end)
            self.advance(); // consume dash
            Some(Expression::Neg(Box::new(UnaryOp::new(
                Expression::Literal(Literal::Number("1".to_string())),
            ))))
        } else if self.check(TokenType::Colon) || self.check(TokenType::RBracket) {
            // Empty end like [start::step] or [start:]
            None
        } else {
            Some(self.parse_unary()?)
        };

        // Parse optional step expression after second colon
        let step = if self.match_token(TokenType::Colon) {
            if self.check(TokenType::RBracket) {
                None
            } else {
                Some(self.parse_unary()?)
            }
        } else {
            None
        };

        Ok(Some(Expression::Slice(Box::new(Slice {
            this: this.map(Box::new),
            expression: end.map(Box::new),
            step: step.map(Box::new),
        }))))
    }

    /// Parse a slice element (start, end, or step in array slicing)
    /// This uses parse_unary to avoid interpreting : as parameter syntax
    /// Returns None for empty elements (e.g., [:] or [::step])
    fn parse_slice_element(&mut self) -> Result<Option<Expression>> {
        // Check for empty element (next is : or ])
        if self.check(TokenType::Colon) || self.check(TokenType::RBracket) {
            return Ok(None);
        }
        // Handle special case: -: means -1 (from the end)
        // This is used in slicing like [:-:-1] where the first -: means end=-1
        if self.check(TokenType::Dash) && self.check_next(TokenType::Colon) {
            self.advance(); // consume dash
                            // Don't consume the colon - let the caller handle it
            return Ok(Some(Expression::Neg(Box::new(UnaryOp::new(
                Expression::Literal(Literal::Number("1".to_string())),
            )))));
        }
        // Parse full expression (including binary ops like y - 1) but stop at : or ]
        let expr = self.parse_disjunction()?;
        Ok(expr)
    }

    /// parse_sort - Ported from Python _parse_sort
    /// Parses SORT BY clause (Hive/Spark)
    #[allow(unused_variables, unused_mut)]
    pub fn parse_sort(&mut self) -> Result<Option<Expression>> {
        // Check for SORT BY token
        if !self.match_keywords(&[TokenType::Sort, TokenType::By]) {
            return Ok(None);
        }

        // Parse comma-separated ordered expressions
        let mut expressions = Vec::new();
        loop {
            if let Some(ordered) = self.parse_ordered_item()? {
                expressions.push(ordered);
            } else {
                break;
            }
            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        Ok(Some(Expression::SortBy(Box::new(SortBy { expressions }))))
    }

    /// parse_cluster_by_clause - Parses CLUSTER BY clause (Hive/Spark)
    #[allow(unused_variables, unused_mut)]
    pub fn parse_cluster_by_clause(&mut self) -> Result<Option<Expression>> {
        if !self.match_keywords(&[TokenType::Cluster, TokenType::By]) {
            return Ok(None);
        }

        // Parse comma-separated ordered expressions
        let mut expressions: Vec<Ordered> = Vec::new();
        loop {
            if let Some(ordered) = self.parse_ordered_item()? {
                expressions.push(ordered);
            } else {
                break;
            }
            if !self.match_token(TokenType::Comma) {
                break;
            }
        }
        Ok(Some(Expression::ClusterBy(Box::new(ClusterBy {
            expressions,
        }))))
    }

    /// parse_distribute_by_clause - Parses DISTRIBUTE BY clause (Hive/Spark)
    #[allow(unused_variables, unused_mut)]
    pub fn parse_distribute_by_clause(&mut self) -> Result<Option<Expression>> {
        if !self.match_keywords(&[TokenType::Distribute, TokenType::By]) {
            return Ok(None);
        }

        let expressions = self.parse_expression_list()?;
        Ok(Some(Expression::DistributeBy(Box::new(DistributeBy {
            expressions,
        }))))
    }

    /// parse_sortkey - Redshift/PostgreSQL SORTKEY property
    /// Parses SORTKEY(column1, column2, ...) with optional COMPOUND modifier
    #[allow(unused_variables, unused_mut)]
    pub fn parse_sortkey(&mut self) -> Result<Option<Expression>> {
        // Parse the wrapped list of columns/identifiers
        let this = if self.match_token(TokenType::LParen) {
            let mut columns = Vec::new();
            loop {
                if let Some(id) = self.parse_id_var()? {
                    columns.push(id);
                } else {
                    break;
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            self.match_token(TokenType::RParen);

            if columns.is_empty() {
                return Ok(None);
            }

            if columns.len() == 1 {
                columns.into_iter().next().unwrap()
            } else {
                Expression::Tuple(Box::new(Tuple {
                    expressions: columns,
                }))
            }
        } else {
            // Single column without parens
            if let Some(id) = self.parse_id_var()? {
                id
            } else {
                return Ok(None);
            }
        };

        Ok(Some(Expression::SortKeyProperty(Box::new(
            SortKeyProperty {
                this: Box::new(this),
                compound: None, // compound is set by caller if COMPOUND keyword was matched
            },
        ))))
    }

    /// parse_star - Parse STAR (*) token with optional EXCEPT/REPLACE/RENAME
    /// Python: if self._match(TokenType.STAR): return self._parse_star_ops()
    pub fn parse_star(&mut self) -> Result<Option<Expression>> {
        if !self.match_token(TokenType::Star) {
            return Ok(None);
        }

        // Parse optional EXCEPT/EXCLUDE columns
        let except = self.parse_star_except()?;

        // Parse optional REPLACE expressions
        let replace = self.parse_star_replace()?;

        // Parse optional RENAME columns
        let rename = self.parse_star_rename()?;

        Ok(Some(Expression::Star(Star {
            table: None,
            except,
            replace,
            rename,
            trailing_comments: Vec::new(),
            span: None,
        })))
    }

    /// try_parse_identifier - Try to parse an identifier, returning None if not found
    fn try_parse_identifier(&mut self) -> Option<Identifier> {
        if self.is_identifier_token() {
            let token = self.advance();
            let quoted = token.token_type == TokenType::QuotedIdentifier;
            Some(Identifier {
                name: token.text,
                quoted,
                trailing_comments: Vec::new(),
                span: None,
            })
        } else {
            None
        }
    }

    /// parse_star_except - Parse EXCEPT/EXCLUDE clause for Star
    /// Example: * EXCEPT (col1, col2)
    fn parse_star_except(&mut self) -> Result<Option<Vec<Identifier>>> {
        if !self.match_texts(&["EXCEPT", "EXCLUDE"]) {
            return Ok(None);
        }

        // Parse (col1, col2, ...)
        if self.match_token(TokenType::LParen) {
            let mut columns = Vec::new();
            loop {
                if let Some(id) = self.try_parse_identifier() {
                    columns.push(id);
                } else if self.is_safe_keyword_as_identifier() {
                    // ClickHouse: allow keywords like 'key' as column names in EXCEPT
                    let token = self.advance();
                    columns.push(Identifier {
                        name: token.text,
                        quoted: false,
                        trailing_comments: Vec::new(),
                        span: None,
                    });
                } else {
                    break;
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            self.match_token(TokenType::RParen);
            return Ok(Some(columns));
        }

        // Single column without parens
        if let Some(id) = self.try_parse_identifier() {
            return Ok(Some(vec![id]));
        }

        Ok(None)
    }

    /// parse_star_replace - Parse REPLACE clause for Star
    /// Example: * REPLACE (col1 AS alias1, col2 AS alias2)
    fn parse_star_replace(&mut self) -> Result<Option<Vec<Alias>>> {
        if !self.match_texts(&["REPLACE"]) {
            return Ok(None);
        }

        if self.match_token(TokenType::LParen) {
            let mut aliases = Vec::new();
            loop {
                // Parse expression AS alias
                if let Some(expr) = self.parse_disjunction()? {
                    let alias_name = if self.match_token(TokenType::As) {
                        self.try_parse_identifier()
                    } else {
                        None
                    };

                    aliases.push(Alias {
                        this: expr,
                        alias: alias_name.unwrap_or_else(|| Identifier::new("")),
                        column_aliases: Vec::new(),
                        pre_alias_comments: Vec::new(),
                        trailing_comments: Vec::new(),
                        inferred_type: None,
                    });
                } else {
                    break;
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            self.match_token(TokenType::RParen);
            return Ok(Some(aliases));
        }

        Ok(None)
    }

    /// parse_star_rename - Parse RENAME clause for Star
    /// Example: * RENAME (old_col AS new_col, ...)
    fn parse_star_rename(&mut self) -> Result<Option<Vec<(Identifier, Identifier)>>> {
        if !self.match_texts(&["RENAME"]) {
            return Ok(None);
        }

        if self.match_token(TokenType::LParen) {
            let mut renames = Vec::new();
            loop {
                // Parse old_name AS new_name
                if let Some(old_name) = self.try_parse_identifier() {
                    if self.match_token(TokenType::As) {
                        if let Some(new_name) = self.try_parse_identifier() {
                            renames.push((old_name, new_name));
                        }
                    }
                } else {
                    break;
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            self.match_token(TokenType::RParen);
            return Ok(Some(renames));
        }

        Ok(None)
    }

    /// parse_star_op - Helper to parse EXCEPT/REPLACE/RENAME with keywords
    /// Returns list of expressions if keywords match
    pub fn parse_star_op(&mut self, keywords: &[&str]) -> Result<Option<Vec<Expression>>> {
        if !self.match_texts(keywords) {
            return Ok(None);
        }

        // If followed by paren, parse wrapped CSV
        if self.match_token(TokenType::LParen) {
            let expressions = self.parse_expression_list()?;
            self.match_token(TokenType::RParen);
            return Ok(Some(expressions));
        }

        // Otherwise parse single aliased expression
        if let Some(expr) = self.parse_disjunction()? {
            // Try to parse explicit alias
            let result = if self.match_token(TokenType::As) {
                if let Some(alias_name) = self.try_parse_identifier() {
                    Expression::Alias(Box::new(Alias {
                        this: expr,
                        alias: alias_name,
                        column_aliases: Vec::new(),
                        pre_alias_comments: Vec::new(),
                        trailing_comments: Vec::new(),
                        inferred_type: None,
                    }))
                } else {
                    expr
                }
            } else {
                expr
            };
            return Ok(Some(vec![result]));
        }

        Ok(None)
    }

    /// parse_star_ops - Implemented from Python _parse_star_ops
    /// Creates a Star expression with EXCEPT/REPLACE/RENAME clauses
    /// Also handles * COLUMNS(pattern) syntax for DuckDB column selection
    pub fn parse_star_ops(&mut self) -> Result<Option<Expression>> {
        // Handle * COLUMNS(pattern) function (DuckDB)
        // This parses patterns like: * COLUMNS(c ILIKE '%suffix')
        if self.match_text_seq(&["COLUMNS"]) && self.check(TokenType::LParen) {
            // Parse the COLUMNS function arguments
            self.expect(TokenType::LParen)?;
            let this = self.parse_expression()?;
            self.expect(TokenType::RParen)?;

            // Return a Columns expression with unpack=true (since it came from * COLUMNS())
            return Ok(Some(Expression::Columns(Box::new(Columns {
                this: Box::new(this),
                unpack: Some(Box::new(Expression::Boolean(BooleanLiteral {
                    value: true,
                }))),
            }))));
        }

        // Parse EXCEPT/EXCLUDE
        let except_exprs = self.parse_star_op(&["EXCEPT", "EXCLUDE"])?;
        let except = except_exprs.map(|exprs| {
            exprs
                .into_iter()
                .filter_map(|e| match e {
                    Expression::Identifier(id) => Some(id),
                    Expression::Column(col) => Some(col.name),
                    _ => None,
                })
                .collect()
        });

        // Parse REPLACE
        let replace_exprs = self.parse_star_op(&["REPLACE"])?;
        let replace = replace_exprs.map(|exprs| {
            exprs
                .into_iter()
                .filter_map(|e| match e {
                    Expression::Alias(a) => Some(*a),
                    _ => None,
                })
                .collect()
        });

        // Parse RENAME
        let _rename_exprs = self.parse_star_op(&["RENAME"])?;
        let rename: Option<Vec<(Identifier, Identifier)>> = None; // Complex to extract from expressions

        Ok(Some(Expression::Star(Star {
            table: None,
            except,
            replace,
            rename,
            trailing_comments: Vec::new(),
            span: None,
        })))
    }

    /// parse_stored - Implemented from Python _parse_stored
    #[allow(unused_variables, unused_mut)]
    pub fn parse_stored(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["BY"]) {
            return Ok(Some(Expression::InputOutputFormat(Box::new(
                InputOutputFormat {
                    input_format: None,
                    output_format: None,
                },
            ))));
        }
        if self.match_text_seq(&["INPUTFORMAT"]) {
            // Matched: INPUTFORMAT
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_stream - Implemented from Python _parse_stream
    #[allow(unused_variables, unused_mut)]
    pub fn parse_stream(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["STREAM"]) {
            // Matched: STREAM
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_string - Parse string literal
    /// Python: if self._match_set(self.STRING_PARSERS): return STRING_PARSERS[token_type](...)
    pub fn parse_string(&mut self) -> Result<Option<Expression>> {
        // Regular string literal
        if self.match_token(TokenType::String) {
            let text = self.previous().text.clone();
            return Ok(Some(Expression::Literal(Literal::String(text))));
        }
        // National string (N'...')
        if self.match_token(TokenType::NationalString) {
            let text = self.previous().text.clone();
            return Ok(Some(Expression::Literal(Literal::NationalString(text))));
        }
        // Raw string (r"..." or r'...')
        if self.match_token(TokenType::RawString) {
            let text = self.previous().text.clone();
            return Ok(Some(Expression::Literal(Literal::RawString(text))));
        }
        // Heredoc string
        if self.match_token(TokenType::HeredocString) {
            let text = self.previous().text.clone();
            return Ok(Some(Expression::Literal(Literal::String(text))));
        }
        // Hex string (X'...' or 0x...)
        if self.match_token(TokenType::HexString) {
            let text = self.previous().text.clone();
            return Ok(Some(Expression::Literal(Literal::HexString(text))));
        }
        // Bit string (B'...')
        if self.match_token(TokenType::BitString) {
            let text = self.previous().text.clone();
            return Ok(Some(Expression::Literal(Literal::BitString(text))));
        }
        // Byte string (b"..." - BigQuery style)
        if self.match_token(TokenType::ByteString) {
            let text = self.previous().text.clone();
            return Ok(Some(Expression::Literal(Literal::ByteString(text))));
        }
        Ok(None)
    }

    /// parse_string_agg - Parses STRING_AGG function arguments
    /// Python: parser.py:6849-6899
    /// Handles DISTINCT, separator, ORDER BY, ON OVERFLOW, WITHIN GROUP
    #[allow(unused_variables, unused_mut)]
    pub fn parse_string_agg(&mut self) -> Result<Option<Expression>> {
        // Check for DISTINCT
        let distinct = self.match_token(TokenType::Distinct);

        // Parse main expression
        let this = self.parse_disjunction()?;
        if this.is_none() {
            return Ok(None);
        }

        // Parse optional separator
        let separator = if self.match_token(TokenType::Comma) {
            self.parse_disjunction()?
        } else {
            None
        };

        // Parse ON OVERFLOW clause
        let on_overflow = if self.match_text_seq(&["ON", "OVERFLOW"]) {
            if self.match_text_seq(&["ERROR"]) {
                Some(Box::new(Expression::Var(Box::new(Var {
                    this: "ERROR".to_string(),
                }))))
            } else {
                self.match_text_seq(&["TRUNCATE"]);
                let truncate_str = self.parse_string()?;
                let with_count = if self.match_text_seq(&["WITH", "COUNT"]) {
                    Some(true)
                } else if self.match_text_seq(&["WITHOUT", "COUNT"]) {
                    Some(false)
                } else {
                    None
                };
                Some(Box::new(Expression::OverflowTruncateBehavior(Box::new(
                    OverflowTruncateBehavior {
                        this: truncate_str.map(Box::new),
                        with_count: with_count
                            .map(|c| Box::new(Expression::Boolean(BooleanLiteral { value: c }))),
                    },
                ))))
            }
        } else {
            None
        };

        // Parse ORDER BY or WITHIN GROUP
        let order_by = if self.match_token(TokenType::OrderBy) {
            Some(self.parse_expression_list()?)
        } else if self.match_text_seq(&["WITHIN", "GROUP"]) {
            self.match_token(TokenType::LParen);
            let order = self.parse_order()?;
            self.match_token(TokenType::RParen);
            order.map(|o| vec![o])
        } else {
            None
        };

        // Return as GroupConcat (which is the canonical form for STRING_AGG)
        Ok(Some(Expression::GroupConcat(Box::new(GroupConcatFunc {
            this: this.unwrap(),
            separator: separator,
            order_by: None,
            distinct,
            filter: None,
            inferred_type: None,
        }))))
    }

    /// parse_string_as_identifier - Parses a string literal as a quoted identifier
    /// Python: _parse_string_as_identifier
    /// Used for cases where a string can be used as an identifier (e.g., MySQL)
    pub fn parse_string_as_identifier(&mut self) -> Result<Option<Expression>> {
        if self.match_token(TokenType::String) {
            let text = self.previous().text.clone();
            // Remove quotes if present
            let name = if text.starts_with('\'') && text.ends_with('\'') && text.len() >= 2 {
                text[1..text.len() - 1].to_string()
            } else if text.starts_with('"') && text.ends_with('"') && text.len() >= 2 {
                text[1..text.len() - 1].to_string()
            } else {
                text
            };

            Ok(Some(Expression::Identifier(Identifier {
                name,
                quoted: true,
                trailing_comments: Vec::new(),
                span: None,
            })))
        } else {
            Ok(None)
        }
    }

    /// parse_struct_types - Delegates to parse_types
    #[allow(unused_variables, unused_mut)]
    pub fn parse_struct_types(&mut self) -> Result<Option<Expression>> {
        self.parse_types()
    }

    /// parse_subquery - Ported from Python _parse_subquery
    /// Parses a parenthesized SELECT as subquery: (SELECT ...)
    #[allow(unused_variables, unused_mut)]
    pub fn parse_subquery(&mut self) -> Result<Option<Expression>> {
        // Check for opening paren
        if !self.match_token(TokenType::LParen) {
            return Ok(None);
        }

        // Check if it's a SELECT or WITH statement
        if !self.check(TokenType::Select) && !self.check(TokenType::With) {
            // Not a subquery, retreat
            self.current -= 1;
            return Ok(None);
        }

        // Parse the query
        let query = self.parse_statement()?;
        self.expect(TokenType::RParen)?;

        // Parse optional table alias
        let alias = self.parse_table_alias_if_present()?;

        Ok(Some(Expression::Subquery(Box::new(Subquery {
            this: query,
            alias,
            column_aliases: Vec::new(),
            order_by: None,
            limit: None,
            offset: None,
            lateral: false,
            modifiers_inside: false,
            trailing_comments: Vec::new(),
            distribute_by: None,
            sort_by: None,
            cluster_by: None,
            inferred_type: None,
        }))))
    }

    /// Helper to parse table alias if present
    fn parse_table_alias_if_present(&mut self) -> Result<Option<Identifier>> {
        // Check for AS keyword
        let explicit_as = self.match_token(TokenType::As);

        // ClickHouse: keywords can be used as table aliases when AS is explicit
        let is_keyword_alias = explicit_as
            && matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            )
            && self.peek().token_type.is_keyword();

        // Try to parse identifier
        if self.check(TokenType::Identifier)
            || self.check(TokenType::QuotedIdentifier)
            || is_keyword_alias
        {
            if is_keyword_alias
                && !self.check(TokenType::Identifier)
                && !self.check(TokenType::QuotedIdentifier)
            {
                let token = self.advance();
                return Ok(Some(Identifier::new(token.text)));
            }
            if let Some(Expression::Identifier(id)) = self.parse_identifier()? {
                return Ok(Some(id));
            }
        } else if explicit_as {
            // AS was present but no identifier follows - this is an error
            return Err(self.parse_error("Expected identifier after AS"));
        }

        Ok(None)
    }

    /// parse_substring - Ported from Python _parse_substring
    /// Parses SUBSTRING function with two syntax variants:
    /// 1. Standard SQL: SUBSTRING(str FROM start [FOR length])
    /// 2. Function style: SUBSTRING(str, start, length)
    #[allow(unused_variables, unused_mut)]
    pub fn parse_substring(&mut self) -> Result<Option<Expression>> {
        // Parse initial comma-separated arguments
        let mut args: Vec<Expression> = Vec::new();

        // Parse first argument (the string)
        match self.parse_bitwise() {
            Ok(Some(expr)) => {
                let expr = self.try_clickhouse_func_arg_alias(expr);
                args.push(expr);
            }
            Ok(None) => return Ok(None),
            Err(e) => return Err(e),
        }

        // Check for comma-separated additional arguments
        while self.match_token(TokenType::Comma) {
            match self.parse_bitwise() {
                Ok(Some(expr)) => {
                    let expr = self.try_clickhouse_func_arg_alias(expr);
                    args.push(expr);
                }
                Ok(None) => break,
                Err(e) => return Err(e),
            }
        }

        // Check for FROM/FOR syntax (SQL standard)
        let mut start: Option<Expression> = None;
        let mut length: Option<Expression> = None;
        let mut from_for_syntax = false;

        loop {
            if self.match_token(TokenType::From) {
                from_for_syntax = true;
                match self.parse_bitwise() {
                    Ok(Some(expr)) => {
                        let expr = self.try_clickhouse_func_arg_alias(expr);
                        start = Some(expr);
                    }
                    Ok(None) => {}
                    Err(e) => return Err(e),
                }
            } else if self.match_token(TokenType::For) {
                from_for_syntax = true;
                // If no start specified yet, default to 1
                if start.is_none() {
                    start = Some(Expression::Literal(Literal::Number("1".to_string())));
                }
                match self.parse_bitwise() {
                    Ok(Some(expr)) => {
                        let expr = self.try_clickhouse_func_arg_alias(expr);
                        length = Some(expr);
                    }
                    Ok(None) => {}
                    Err(e) => return Err(e),
                }
            } else {
                break;
            }
        }

        // Build the substring expression
        if args.is_empty() {
            return Ok(None);
        }

        let this = args.remove(0);

        // Determine start and length
        let final_start = if let Some(s) = start {
            s
        } else if !args.is_empty() {
            args.remove(0)
        } else {
            Expression::Literal(Literal::Number("1".to_string()))
        };

        let final_length = if length.is_some() {
            length
        } else if !args.is_empty() {
            Some(args.remove(0))
        } else {
            None
        };

        Ok(Some(Expression::Substring(Box::new(SubstringFunc {
            this,
            start: final_start,
            length: final_length,
            from_for_syntax,
        }))))
    }

    /// parse_system_versioning_property - Implemented from Python _parse_system_versioning_property
    /// Calls: parse_table_parts, parse_retention_period
    #[allow(unused_variables, unused_mut)]
    pub fn parse_system_versioning_property(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["OFF"]) {
            return Ok(Some(Expression::WithSystemVersioningProperty(Box::new(
                WithSystemVersioningProperty {
                    on: None,
                    this: None,
                    data_consistency: None,
                    retention_period: None,
                    with_: None,
                },
            ))));
        }
        if self.match_text_seq(&["HISTORY_TABLE", "="]) {
            // Matched: HISTORY_TABLE =
            return Ok(None);
        }
        if self.match_text_seq(&["DATA_CONSISTENCY_CHECK", "="]) {
            // Matched: DATA_CONSISTENCY_CHECK =
            return Ok(None);
        }
        Ok(None)
    }

    /// Parse PostgreSQL ROWS FROM syntax:
    /// ROWS FROM (func1(args) AS alias1(col1 type1, col2 type2), func2(...) AS alias2(...)) [WITH ORDINALITY] [AS outer_alias(...)]
    fn parse_rows_from(&mut self) -> Result<Expression> {
        // Expect opening paren
        self.expect(TokenType::LParen)?;

        let mut expressions = Vec::new();

        loop {
            // Parse each function expression inside ROWS FROM
            // Each element is: func_name(args) [AS alias(col1 type1, col2 type2, ...)]
            let func_expr = self.parse_rows_from_function()?;
            expressions.push(func_expr);

            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        self.expect(TokenType::RParen)?;

        // Check for WITH ORDINALITY
        let ordinality =
            if self.match_token(TokenType::With) && self.match_token(TokenType::Ordinality) {
                true
            } else {
                false
            };

        // Check for outer alias: AS alias(col1 type1, col2 type2, ...)
        let alias = if self.match_token(TokenType::As) {
            Some(Box::new(self.parse_rows_from_alias()?))
        } else {
            None
        };

        Ok(Expression::RowsFrom(Box::new(RowsFrom {
            expressions,
            ordinality,
            alias,
        })))
    }

    /// Parse a single function in ROWS FROM: func_name(args) [AS alias(col1 type1, ...)]
    fn parse_rows_from_function(&mut self) -> Result<Expression> {
        // Parse function name
        let func_name = self.expect_identifier_or_keyword()?;

        // Parse function arguments
        self.expect(TokenType::LParen)?;
        let args = if self.check(TokenType::RParen) {
            Vec::new()
        } else {
            self.parse_function_arguments()?
        };
        self.expect(TokenType::RParen)?;

        let func_expr = Expression::Function(Box::new(Function {
            name: func_name,
            args,
            distinct: false,
            trailing_comments: Vec::new(),
            use_bracket_syntax: false,
            no_parens: false,
            quoted: false,
            span: None,
            inferred_type: None,
        }));

        // Check for AS alias(col1 type1, col2 type2, ...)
        // Return a Tuple(function, TableAlias) so the generator can output: FUNC() AS alias(col type)
        if self.match_token(TokenType::As) {
            let alias_expr = self.parse_rows_from_alias()?;
            Ok(Expression::Tuple(Box::new(Tuple {
                expressions: vec![func_expr, alias_expr],
            })))
        } else {
            Ok(func_expr)
        }
    }

    /// Parse ROWS FROM alias with typed columns: alias_name(col1 type1, col2 type2, ...)
    fn parse_rows_from_alias(&mut self) -> Result<Expression> {
        let alias_name = self.expect_identifier_or_keyword_with_quoted()?;

        // Check for column definitions: (col1 type1, col2 type2, ...)
        let columns = if self.match_token(TokenType::LParen) {
            let mut cols = Vec::new();
            loop {
                if self.check(TokenType::RParen) {
                    break;
                }
                // Parse column name (can be quoted)
                let col_name = self.expect_identifier_or_keyword_with_quoted()?;
                // Parse column type
                let col_type = self.parse_data_type()?;
                // Create ColumnDef expression, preserving the quoted status
                let mut col_def = ColumnDef::new(col_name.name.clone(), col_type);
                col_def.name = col_name; // Preserve the full identifier with quoted flag
                cols.push(Expression::ColumnDef(Box::new(col_def)));

                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            self.expect(TokenType::RParen)?;
            cols
        } else {
            Vec::new()
        };

        Ok(Expression::TableAlias(Box::new(TableAlias {
            this: Some(Box::new(Expression::Identifier(alias_name))),
            columns,
        })))
    }

    /// parse_table - Implemented from Python _parse_table
    /// Calls: parse_table_hints, parse_unnest, parse_partition
    #[allow(unused_variables, unused_mut)]
    pub fn parse_table(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["ROWS", "FROM"]) {
            // ROWS FROM is handled by parse_rows_from() in parse_table_expression()
            return Ok(None);
        }
        if self.match_text_seq(&["*"]) {
            // Matched: *
            return Ok(None);
        }
        if self.match_text_seq(&["NOT", "INDEXED"]) {
            // Matched: NOT INDEXED
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_table_alias - Ported from Python _parse_table_alias
    /// Parses table alias: AS alias [(col1, col2, ...)]
    #[allow(unused_variables, unused_mut)]
    pub fn parse_table_alias(&mut self) -> Result<Option<Expression>> {
        // Check for AS keyword (optional in most dialects)
        let has_as = self.match_token(TokenType::As);

        // Handle AS (col1, col2) - no alias name, just column aliases
        if has_as && self.check(TokenType::LParen) {
            // Parse (col1, col2, ...)
            self.advance(); // consume LParen
            let mut cols = Vec::new();
            loop {
                if self.check(TokenType::RParen) {
                    break;
                }
                if let Ok(Some(col)) = self.parse_id_var() {
                    cols.push(col);
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            self.expect(TokenType::RParen)?;
            return Ok(Some(Expression::TableAlias(Box::new(TableAlias {
                this: None,
                columns: cols,
            }))));
        }

        // Parse the alias identifier
        // ClickHouse: keywords can be used as table aliases (e.g., AS select, AS from)
        let is_keyword_alias = has_as
            && matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::ClickHouse)
            )
            && self.peek().token_type.is_keyword();
        if !self.check(TokenType::Identifier)
            && !self.check(TokenType::QuotedIdentifier)
            && !self.check(TokenType::Var)
            && !is_keyword_alias
        {
            if has_as {
                return Err(self.parse_error("Expected identifier after AS"));
            }
            return Ok(None);
        }

        let alias_token = self.advance();
        let is_quoted = alias_token.token_type == TokenType::QuotedIdentifier;
        let mut alias_ident = Identifier::new(alias_token.text.clone());
        if is_quoted {
            alias_ident.quoted = true;
        }
        let alias = Expression::Identifier(alias_ident);

        // Check for column list: (col1, col2, ...)
        let columns = if self.match_token(TokenType::LParen) {
            let mut cols = Vec::new();
            loop {
                if self.check(TokenType::RParen) {
                    break;
                }
                if let Ok(Some(col)) = self.parse_id_var() {
                    cols.push(col);
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            self.expect(TokenType::RParen)?;
            cols
        } else {
            Vec::new()
        };

        Ok(Some(Expression::TableAlias(Box::new(TableAlias {
            this: Some(Box::new(alias)),
            columns,
        }))))
    }

    /// parse_table_hints - Ported from Python _parse_table_hints
    /// Parses table hints (SQL Server WITH (...) or MySQL USE/IGNORE/FORCE INDEX)
    #[allow(unused_variables, unused_mut)]
    pub fn parse_table_hints(&mut self) -> Result<Option<Expression>> {
        let mut hints = Vec::new();

        // SQL Server style: WITH (hint1, hint2, ...)
        if self.match_text_seq(&["WITH"]) && self.match_token(TokenType::LParen) {
            let mut expressions = Vec::new();
            loop {
                // Parse function or variable as hint
                if let Some(func) = self.parse_function()? {
                    expressions.push(func);
                } else if let Some(var) = self.parse_var()? {
                    expressions.push(var);
                } else {
                    break;
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            self.match_token(TokenType::RParen);

            if !expressions.is_empty() {
                hints.push(Expression::WithTableHint(Box::new(WithTableHint {
                    expressions,
                })));
            }
        } else {
            // MySQL style: USE INDEX, IGNORE INDEX, FORCE INDEX
            while self.match_texts(&["USE", "IGNORE", "FORCE"]) {
                let hint_type = self.previous().text.to_uppercase();

                // Match INDEX or KEY
                let _ = self.match_texts(&["INDEX", "KEY"]);

                // Check for optional FOR clause: FOR JOIN, FOR ORDER BY, FOR GROUP BY
                let target = if self.match_text_seq(&["FOR"]) {
                    let target_token = self.advance();
                    let target_text = target_token.text.to_uppercase();
                    // For ORDER BY and GROUP BY, combine into a single target name
                    let full_target = if (target_text == "ORDER" || target_text == "GROUP")
                        && self.check(TokenType::By)
                    {
                        self.advance(); // consume BY
                        format!("{} BY", target_text)
                    } else {
                        target_text
                    };
                    Some(Box::new(Expression::Identifier(Identifier {
                        name: full_target,
                        quoted: false,
                        trailing_comments: Vec::new(),
                        span: None,
                    })))
                } else {
                    None
                };

                // Parse wrapped identifiers (index names)
                let expressions = if self.match_token(TokenType::LParen) {
                    let mut ids = Vec::new();
                    loop {
                        if let Some(id) = self.parse_id_var()? {
                            ids.push(id);
                        }
                        if !self.match_token(TokenType::Comma) {
                            break;
                        }
                    }
                    self.match_token(TokenType::RParen);
                    ids
                } else {
                    Vec::new()
                };

                hints.push(Expression::IndexTableHint(Box::new(IndexTableHint {
                    this: Box::new(Expression::Identifier(Identifier {
                        name: hint_type,
                        quoted: false,
                        trailing_comments: Vec::new(),
                        span: None,
                    })),
                    expressions,
                    target,
                })));
            }
        }

        if hints.is_empty() {
            return Ok(None);
        }

        // Return as a Tuple containing hints
        Ok(Some(Expression::Tuple(Box::new(Tuple {
            expressions: hints,
        }))))
    }

    /// Parse TSQL TRUNCATE table hints: WITH (PARTITIONS(1, 2 TO 5, 10 TO 20, 84))
    /// Unlike regular table hints, PARTITIONS arguments can contain TO ranges.
    pub fn parse_truncate_table_hints(&mut self) -> Result<Option<Expression>> {
        if !self.match_text_seq(&["WITH"]) || !self.match_token(TokenType::LParen) {
            return Ok(None);
        }

        let mut hints = Vec::new();

        // Check for PARTITIONS specifically
        if self.check_identifier("PARTITIONS") {
            self.advance(); // consume PARTITIONS
            self.expect(TokenType::LParen)?;

            // Parse partition ranges: 1, 2 TO 5, 10 TO 20, 84
            let mut parts = Vec::new();
            loop {
                if self.check(TokenType::RParen) {
                    break;
                }
                let low = self.parse_primary()?;
                if self.match_text_seq(&["TO"]) {
                    let high = self.parse_primary()?;
                    parts.push(Expression::PartitionRange(Box::new(PartitionRange {
                        this: Box::new(low),
                        expression: Some(Box::new(high)),
                        expressions: Vec::new(),
                    })));
                } else {
                    parts.push(low);
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            self.expect(TokenType::RParen)?; // close PARTITIONS(...)

            // Create an Anonymous function for PARTITIONS(...)
            hints.push(Expression::Anonymous(Box::new(Anonymous {
                this: Box::new(Expression::Identifier(Identifier {
                    name: "PARTITIONS".to_string(),
                    quoted: false,
                    trailing_comments: Vec::new(),
                    span: None,
                })),
                expressions: parts,
            })));
        } else {
            // Fall back to regular hint parsing (function or var)
            loop {
                if let Some(func) = self.parse_function()? {
                    hints.push(func);
                } else if let Some(var) = self.parse_var()? {
                    hints.push(var);
                } else {
                    break;
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
        }

        self.expect(TokenType::RParen)?; // close WITH(...)

        if hints.is_empty() {
            return Ok(None);
        }

        // Wrap in WithTableHint then Tuple (same as parse_table_hints)
        let hint = Expression::WithTableHint(Box::new(WithTableHint { expressions: hints }));

        Ok(Some(Expression::Tuple(Box::new(Tuple {
            expressions: vec![hint],
        }))))
    }

    /// parse_table_part - Parse a single part of a table reference
    /// Tries: identifier, string as identifier, placeholder
    #[allow(unused_variables, unused_mut)]
    pub fn parse_table_part(&mut self) -> Result<Option<Expression>> {
        // Try to parse an identifier
        if let Some(id) = self.parse_id_var()? {
            return Ok(Some(id));
        }

        // Try to parse a string as identifier
        if let Some(str_id) = self.parse_string_as_identifier()? {
            return Ok(Some(str_id));
        }

        // Try to parse a placeholder
        if let Some(placeholder) = self.parse_placeholder()? {
            return Ok(Some(placeholder));
        }

        // Accept keywords as identifiers in table part context (e.g., db.cluster where "cluster" is a keyword)
        // This mirrors Python sqlglot's ID_VAR_TOKENS which includes many keyword types
        if self.check_keyword_as_identifier() {
            let text = self.peek().text.clone();
            self.advance();
            return Ok(Some(Expression::Identifier(Identifier {
                name: text,
                quoted: false,
                trailing_comments: Vec::new(),
                span: None,
            })));
        }

        Ok(None)
    }

    /// Check if the current token is a keyword that can be used as an identifier in certain contexts
    /// This includes many SQL keywords like CLUSTER, TABLE, INDEX, etc.
    fn check_keyword_as_identifier(&self) -> bool {
        if self.is_at_end() {
            return false;
        }
        let token_type = self.peek().token_type;
        // Keywords that can be used as identifiers (similar to Python's ID_VAR_TOKENS)
        matches!(
            token_type,
            TokenType::Cluster
                | TokenType::Table
                | TokenType::Index
                | TokenType::View
                | TokenType::Database
                | TokenType::Schema
                | TokenType::Column
                | TokenType::Function
                | TokenType::Procedure
                | TokenType::Constraint
                | TokenType::Sequence
                | TokenType::Type
                | TokenType::Partition
                | TokenType::Comment
                | TokenType::Cache
                | TokenType::Commit
                | TokenType::Begin
                | TokenType::End
                | TokenType::Set
                | TokenType::Show
                | TokenType::Describe
                | TokenType::Use
                | TokenType::Execute
                | TokenType::Delete
                | TokenType::Update
                | TokenType::Merge
                | TokenType::Load
                | TokenType::Copy
                | TokenType::Truncate
                | TokenType::Replace
                | TokenType::Refresh
                | TokenType::Rename
                | TokenType::Filter
                | TokenType::Format
                | TokenType::First
                | TokenType::Next
                | TokenType::Last
                | TokenType::Keep
                | TokenType::Match
                | TokenType::Over
                | TokenType::Range
                | TokenType::Rows
                | TokenType::Row
                | TokenType::Offset
                | TokenType::Limit
                | TokenType::Top
                | TokenType::Cube
                | TokenType::Rollup
                | TokenType::Pivot
                | TokenType::Unpivot
                | TokenType::Window
                | TokenType::Recursive
                | TokenType::Unique
                | TokenType::Temporary
                | TokenType::Volatile
                | TokenType::References
                | TokenType::Natural
                | TokenType::Left
                | TokenType::Right
                | TokenType::Full
                | TokenType::Semi
                | TokenType::Anti
                | TokenType::Apply
                | TokenType::All
                | TokenType::Asc
                | TokenType::Desc
                | TokenType::Analyze
        )
    }

    /// parse_table_parts - Parse catalog.schema.table or schema.table or table
    /// Returns a Table expression with all parts
    #[allow(unused_variables, unused_mut)]
    pub fn parse_table_parts(&mut self) -> Result<Option<Expression>> {
        // Parse the first part
        let first = self.parse_table_part()?;
        if first.is_none() {
            return Ok(None);
        }

        let mut parts = vec![first.unwrap()];

        // Parse additional dot-separated parts
        while self.match_token(TokenType::Dot) {
            if let Some(part) = self.parse_table_part()? {
                parts.push(part);
            } else {
                break;
            }
        }

        // Convert parts to Table expression
        // Last part is table name, second-to-last is schema, third-to-last is catalog
        let (catalog, schema, name) = match parts.len() {
            1 => (None, None, parts.pop().unwrap()),
            2 => {
                let table = parts.pop().unwrap();
                let schema = parts.pop().unwrap();
                (None, Some(schema), table)
            }
            _ => {
                let table = parts.pop().unwrap();
                let schema = parts.pop().unwrap();
                let catalog = parts.pop();
                (catalog, Some(schema), table)
            }
        };

        // Extract identifier from Expression
        let name_ident = match name {
            Expression::Identifier(id) => id,
            _ => Identifier::new(String::new()),
        };
        let schema_ident = schema.map(|s| match s {
            Expression::Identifier(id) => id,
            _ => Identifier::new(String::new()),
        });
        let catalog_ident = catalog.map(|c| match c {
            Expression::Identifier(id) => id,
            _ => Identifier::new(String::new()),
        });

        Ok(Some(Expression::Table(TableRef {
            name: name_ident,
            schema: schema_ident,
            catalog: catalog_ident,
            alias: None,
            alias_explicit_as: false,
            column_aliases: Vec::new(),
            trailing_comments: Vec::new(),
            when: None,
            only: false,
            final_: false,
            table_sample: None,
            hints: Vec::new(),
            system_time: None,
            partitions: Vec::new(),
            identifier_func: None,
            changes: None,
            version: None,
            span: None,
        })))
    }

    /// parse_table_sample - Implemented from Python _parse_table_sample
    /// Calls: parse_number, parse_factor, parse_placeholder
    #[allow(unused_variables, unused_mut)]
    pub fn parse_table_sample(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["USING", "SAMPLE"]) {
            return Ok(Some(Expression::TableSample(Box::new(TableSample {
                this: None,
                sample: None,
                expressions: Vec::new(),
                method: None,
                bucket_numerator: None,
                bucket_denominator: None,
                bucket_field: None,
                percent: None,
                rows: None,
                size: None,
                seed: None,
            }))));
        }
        if self.match_text_seq(&["BUCKET"]) {
            // Matched: BUCKET
            return Ok(None);
        }
        if self.match_text_seq(&["OUT", "OF"]) {
            // Matched: OUT OF
            return Ok(None);
        }
        if self.match_texts(&["SEED", "REPEATABLE"]) {
            // Matched one of: SEED, REPEATABLE
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_term - Parses addition/subtraction expressions (+ - operators)
    /// Python: _parse_term
    /// Delegates to the existing parse_addition in the operator precedence chain
    pub fn parse_term(&mut self) -> Result<Option<Expression>> {
        // Delegate to the existing addition parsing
        match self.parse_addition() {
            Ok(expr) => Ok(Some(expr)),
            Err(_) => Ok(None),
        }
    }

    /// parse_to_table - ClickHouse TO table property
    /// Parses: TO table_name
    #[allow(unused_variables, unused_mut)]
    pub fn parse_to_table(&mut self) -> Result<Option<Expression>> {
        // Parse the table reference
        let table = self.parse_table_parts()?;
        if table.is_none() {
            return Ok(None);
        }

        Ok(Some(Expression::ToTableProperty(Box::new(
            ToTableProperty {
                this: Box::new(table.unwrap()),
            },
        ))))
    }

    /// parse_tokens - Operator precedence parser
    #[allow(unused_variables, unused_mut)]
    pub fn parse_tokens(&mut self) -> Result<Option<Expression>> {
        // Uses operator precedence parsing pattern
        Ok(None)
    }

    /// parse_trim - Ported from Python _parse_trim
    /// Parses TRIM function: TRIM([BOTH|LEADING|TRAILING] chars FROM str) or TRIM(str, chars)
    #[allow(unused_variables, unused_mut)]
    pub fn parse_trim(&mut self) -> Result<Option<Expression>> {
        // Check for position keyword (BOTH, LEADING, TRAILING)
        let (position, position_explicit) = if self.match_texts(&["BOTH"]) {
            (TrimPosition::Both, true)
        } else if self.match_texts(&["LEADING"]) {
            (TrimPosition::Leading, true)
        } else if self.match_texts(&["TRAILING"]) {
            (TrimPosition::Trailing, true)
        } else {
            (TrimPosition::Both, false)
        };

        // Parse first expression
        let first = match self.parse_bitwise() {
            Ok(Some(expr)) => self.try_clickhouse_func_arg_alias(expr),
            Ok(None) => return Ok(None),
            Err(e) => return Err(e),
        };

        // Check for FROM or comma to see if there's a second expression
        let (this, characters, sql_standard_syntax) = if self.match_token(TokenType::From) {
            // SQL standard syntax: TRIM([position] chars FROM str)
            let second = match self.parse_bitwise() {
                Ok(Some(expr)) => self.try_clickhouse_func_arg_alias(expr),
                Ok(None) => return Err(self.parse_error("Expected expression after FROM in TRIM")),
                Err(e) => return Err(e),
            };
            // In SQL standard syntax: first is characters, second is the string
            (second, Some(first), true)
        } else if self.match_token(TokenType::Comma) {
            // Function syntax: TRIM(a, b)
            let second = match self.parse_bitwise() {
                Ok(Some(expr)) => Some(expr),
                Ok(None) => None,
                Err(e) => return Err(e),
            };
            // In Spark, comma syntax is TRIM(chars, str) - pattern first
            // In other dialects, comma syntax is TRIM(str, chars) - string first
            let trim_pattern_first = matches!(
                self.config.dialect,
                Some(crate::dialects::DialectType::Spark)
            );
            if trim_pattern_first && second.is_some() {
                // first=chars, second=str
                (second.unwrap(), Some(first), false)
            } else {
                (first, second, false)
            }
        } else {
            // Single argument: TRIM(str)
            (first, None, false)
        };

        Ok(Some(Expression::Trim(Box::new(TrimFunc {
            this,
            characters,
            position,
            sql_standard_syntax,
            position_explicit,
        }))))
    }

    /// parse_truncate_table - Implemented from Python _parse_truncate_table
    /// Calls: parse_on_property, parse_partition, parse_function
    #[allow(unused_variables, unused_mut)]
    pub fn parse_truncate_table(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["RESTART", "IDENTITY"]) {
            return Ok(Some(Expression::TruncateTable(Box::new(TruncateTable {
                expressions: Vec::new(),
                is_database: None,
                exists: false,
                only: None,
                cluster: None,
                identity: None,
                option: None,
                partition: None,
            }))));
        }
        if self.match_text_seq(&["CONTINUE", "IDENTITY"]) {
            // Matched: CONTINUE IDENTITY
            return Ok(None);
        }
        if self.match_text_seq(&["CASCADE"]) {
            // Matched: CASCADE
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_ttl - Implemented from Python _parse_ttl
    /// Parses ClickHouse TTL expression with optional DELETE, RECOMPRESS, TO DISK/VOLUME
    pub fn parse_ttl(&mut self) -> Result<Option<Expression>> {
        // Parse CSV of TTL actions
        let mut expressions = Vec::new();

        loop {
            // Parse the base expression
            let base_start = self.current;
            let this = match self.parse_bitwise() {
                Ok(Some(expr)) => expr,
                _ => {
                    self.current = base_start;
                    let mut paren_depth = 0usize;
                    while !self.is_at_end() {
                        if paren_depth == 0
                            && (self.check(TokenType::Comma)
                                || self.peek().text.eq_ignore_ascii_case("DELETE")
                                || self.peek().text.eq_ignore_ascii_case("RECOMPRESS")
                                || self.peek().text.eq_ignore_ascii_case("TO")
                                || self.peek().text.eq_ignore_ascii_case("WHERE")
                                || self.peek().text.eq_ignore_ascii_case("GROUP")
                                || self.peek().text.eq_ignore_ascii_case("SET"))
                        {
                            break;
                        }
                        if self.check(TokenType::LParen) {
                            paren_depth += 1;
                        } else if self.check(TokenType::RParen) {
                            if paren_depth == 0 {
                                break;
                            }
                            paren_depth -= 1;
                        }
                        self.advance();
                    }
                    if self.current == base_start {
                        break;
                    }
                    let raw = self
                        .tokens_to_sql(base_start, self.current)
                        .trim()
                        .to_string();
                    Expression::Var(Box::new(Var { this: raw }))
                }
            };

            // Check for TTL action
            let action = if self.match_text_seq(&["DELETE"]) {
                Expression::MergeTreeTTLAction(Box::new(MergeTreeTTLAction {
                    this: Box::new(this),
                    delete: Some(Box::new(Expression::Boolean(BooleanLiteral {
                        value: true,
                    }))),
                    recompress: None,
                    to_disk: None,
                    to_volume: None,
                }))
            } else if self.match_text_seq(&["RECOMPRESS"]) {
                let recompress = if self.match_identifier("CODEC") {
                    self.expect(TokenType::LParen)?;
                    let mut args = Vec::new();
                    if !self.check(TokenType::RParen) {
                        args.push(self.parse_expression()?);
                        while self.match_token(TokenType::Comma) {
                            args.push(self.parse_expression()?);
                        }
                    }
                    self.expect(TokenType::RParen)?;
                    Some(Box::new(Expression::Function(Box::new(Function::new(
                        "CODEC".to_string(),
                        args,
                    )))))
                } else {
                    self.parse_bitwise()?.map(Box::new)
                };
                Expression::MergeTreeTTLAction(Box::new(MergeTreeTTLAction {
                    this: Box::new(this),
                    delete: None,
                    recompress,
                    to_disk: None,
                    to_volume: None,
                }))
            } else if self.match_text_seq(&["TO", "DISK"]) {
                let to_disk = self.parse_string()?.map(Box::new);
                Expression::MergeTreeTTLAction(Box::new(MergeTreeTTLAction {
                    this: Box::new(this),
                    delete: None,
                    recompress: None,
                    to_disk,
                    to_volume: None,
                }))
            } else if self.match_text_seq(&["TO", "VOLUME"]) {
                let to_volume = self.parse_string()?.map(Box::new);
                Expression::MergeTreeTTLAction(Box::new(MergeTreeTTLAction {
                    this: Box::new(this),
                    delete: None,
                    recompress: None,
                    to_disk: None,
                    to_volume,
                }))
            } else {
                this
            };

            expressions.push(action);

            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        // Parse optional top-level WHERE clause (for backwards compatibility)
        let where_ = self.parse_where()?.map(Box::new);

        // Parse optional GROUP BY
        let group = if self.match_token(TokenType::Group) {
            self.expect(TokenType::By)?;
            let mut exprs = Vec::new();
            exprs.push(self.parse_expression()?);
            while self.match_token(TokenType::Comma) {
                exprs.push(self.parse_expression()?);
            }
            Some(Box::new(Expression::Group(Box::new(Group {
                expressions: exprs,
                grouping_sets: None,
                cube: None,
                rollup: None,
                totals: None,
                all: None,
            }))))
        } else {
            None
        };

        // Parse optional SET (aggregates) after GROUP BY
        let aggregates = if group.is_some() && self.match_token(TokenType::Set) {
            let mut aggs = Vec::new();
            loop {
                aggs.push(self.parse_expression()?);
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            if aggs.is_empty() {
                None
            } else {
                Some(Box::new(Expression::Tuple(Box::new(Tuple {
                    expressions: aggs,
                }))))
            }
        } else {
            None
        };

        Ok(Some(Expression::MergeTreeTTL(Box::new(MergeTreeTTL {
            expressions,
            where_,
            group,
            aggregates,
        }))))
    }

    /// parse_type - Parses a data type expression
    /// Python: _parse_type
    pub fn parse_type(&mut self) -> Result<Option<Expression>> {
        // First try to parse an interval
        if let Some(interval) = self.parse_interval()? {
            return self.parse_column_ops_with_expr(Some(interval));
        }

        // Try to parse a data type
        let data_type = self.parse_types()?;

        if let Some(dt) = data_type {
            // If it's a Cast (BigQuery inline constructor), apply column ops
            if matches!(dt, Expression::Cast(_)) {
                return self.parse_column_ops_with_expr(Some(dt));
            }

            // Try to parse a primary expression after the type
            let start_pos = self.current;
            if let Some(primary) = self.parse_primary_or_var()? {
                // If it's a literal, this might be a type cast like DATE '2020-01-01'
                if let Expression::Literal(_) = &primary {
                    let result = self.parse_column_ops_with_expr(Some(primary))?;
                    if let Some(value) = result {
                        // Create a Cast expression
                        if let Expression::DataType(data_type_struct) = dt {
                            return Ok(Some(Expression::Cast(Box::new(Cast {
                                this: value,
                                to: data_type_struct,
                                trailing_comments: Vec::new(),
                                double_colon_syntax: false,
                                format: None,
                                default: None,
                                inferred_type: None,
                            }))));
                        }
                    }
                }
                // Backtrack if not a type-literal pattern
                self.current = start_pos;
            }

            return Ok(Some(dt));
        }

        Ok(None)
    }

    /// parse_type_size - Ported from Python _parse_type_size
    /// Parses type size parameters like 10 in VARCHAR(10) or 10, 2 in DECIMAL(10, 2)
    #[allow(unused_variables, unused_mut)]
    pub fn parse_type_size(&mut self) -> Result<Option<Expression>> {
        // First try to parse a type - this handles both numeric literals and type names
        let this = self.parse_type()?;

        if this.is_none() {
            return Ok(None);
        }

        let mut result = this.unwrap();

        // If it's a Column with no table, convert it to an Identifier (var)
        // This handles cases like CHAR in VARCHAR(100 CHAR)
        if let Expression::Column(ref col) = result {
            if col.table.is_none() {
                result = Expression::Identifier(col.name.clone());
            }
        }

        // Check for optional expression after the type (e.g., "CHAR" in "100 CHAR")
        // This is for byte/char length specifiers in some dialects
        if let Some(var_token) = self.parse_var()? {
            // We have an additional specifier, combine them
            // For now, just return the original result since Rust doesn't have DataTypeParam
            // The var expression would be attached as an expression in Python
        }

        Ok(Some(result))
    }

    /// parse_types - Implemented from Python _parse_types
    /// Calls: parse_string
    #[allow(unused_variables, unused_mut)]
    pub fn parse_types(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["SYSUDTLIB", "."]) {
            return Ok(Some(Expression::Identifier(Identifier {
                name: String::new(),
                quoted: false,
                trailing_comments: Vec::new(),
                span: None,
            })));
        }
        if self.match_text_seq(&["WITH", "TIME", "ZONE"]) {
            // Matched: WITH TIME ZONE
            return Ok(None);
        }
        if self.match_text_seq(&["WITH", "LOCAL", "TIME", "ZONE"]) {
            // Matched: WITH LOCAL TIME ZONE
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_unique - Implemented from Python _parse_unique
    /// Parses UNIQUE [KEY|INDEX] [NULLS NOT DISTINCT] [(columns)] [USING index_type]
    #[allow(unused_variables, unused_mut)]
    pub fn parse_unique(&mut self) -> Result<Option<Expression>> {
        // Check for optional KEY/INDEX
        let _ = self.match_texts(&["KEY", "INDEX"]);

        // Check for NULLS NOT DISTINCT (PostgreSQL 15+ feature)
        let nulls = if self.match_text_seq(&["NULLS", "NOT", "DISTINCT"]) {
            Some(Box::new(Expression::Boolean(BooleanLiteral {
                value: true,
            })))
        } else {
            None
        };

        // Parse the optional key name and schema (column list)
        let unique_key = self.parse_unique_key()?;
        let this = self.parse_schema_with_this(unique_key)?;

        // Parse optional USING index_type
        let index_type = if self.match_token(TokenType::Using) {
            self.advance();
            Some(Box::new(Expression::Var(Box::new(Var {
                this: self.previous().text.clone(),
            }))))
        } else {
            None
        };

        Ok(Some(Expression::UniqueColumnConstraint(Box::new(
            UniqueColumnConstraint {
                this: this.map(Box::new),
                index_type,
                on_conflict: None,
                nulls,
                options: Vec::new(),
            },
        ))))
    }

    /// parse_unique_key - Parse the key/index name for UNIQUE constraint
    /// Simply parses an identifier
    #[allow(unused_variables, unused_mut)]
    pub fn parse_unique_key(&mut self) -> Result<Option<Expression>> {
        self.parse_id_var()
    }

    /// parse_unnest - Ported from Python _parse_unnest
    /// Parses UNNEST(array_expr) [WITH ORDINALITY] [AS alias]
    #[allow(unused_variables, unused_mut)]
    pub fn parse_unnest(&mut self) -> Result<Option<Expression>> {
        // Check for UNNEST keyword
        if !self.match_texts(&["UNNEST"]) {
            return Ok(None);
        }

        // Expect opening parenthesis
        if !self.match_token(TokenType::LParen) {
            return Ok(None);
        }

        // Parse comma-separated array expression(s): UNNEST(arr1, arr2, ...)
        let this = match self.parse_expression() {
            Ok(expr) => expr,
            Err(e) => return Err(e),
        };

        let mut extra_expressions = Vec::new();
        while self.match_token(TokenType::Comma) {
            let expr = self.parse_expression()?;
            extra_expressions.push(expr);
        }

        // Expect closing parenthesis
        self.expect(TokenType::RParen)?;

        // Check for WITH ORDINALITY
        let with_ordinality = self.match_text_seq(&["WITH", "ORDINALITY"]);

        // Parse optional alias
        let alias = if self.match_token(TokenType::As)
            || self.check(TokenType::Identifier)
            || self.check(TokenType::QuotedIdentifier)
        {
            if self.check(TokenType::Identifier) || self.check(TokenType::QuotedIdentifier) {
                let is_quoted = self.check(TokenType::QuotedIdentifier);
                let token = self.advance();
                let mut ident = Identifier::new(token.text.clone());
                if is_quoted {
                    ident.quoted = true;
                }
                Some(ident)
            } else {
                None
            }
        } else {
            None
        };

        Ok(Some(Expression::Unnest(Box::new(UnnestFunc {
            this,
            expressions: extra_expressions,
            with_ordinality,
            alias,
            offset_alias: None,
        }))))
    }

    /// parse_unpivot_columns - Implemented from Python _parse_unpivot_columns
    /// Python: parser.py:4454-4462
    /// Parses INTO NAME column VALUE col1, col2, ...
    #[allow(unused_variables, unused_mut)]
    pub fn parse_unpivot_columns(&mut self) -> Result<Option<Expression>> {
        // Must match INTO keyword
        if !self.match_token(TokenType::Into) {
            return Ok(None);
        }

        // Parse NAME column
        let this = if self.match_text_seq(&["NAME"]) {
            self.parse_column()?
        } else {
            None
        };

        // Parse VALUE columns
        let expressions = if self.match_text_seq(&["VALUE"]) {
            let mut cols = Vec::new();
            loop {
                if let Some(col) = self.parse_column()? {
                    cols.push(col);
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            cols
        } else {
            Vec::new()
        };

        // If we have either this or expressions, return an UnpivotColumns
        if this.is_some() || !expressions.is_empty() {
            Ok(Some(Expression::UnpivotColumns(Box::new(UnpivotColumns {
                this: Box::new(this.unwrap_or(Expression::Null(Null))),
                expressions,
            }))))
        } else {
            Ok(None)
        }
    }

    /// parse_unquoted_field - Parses a field and converts unquoted identifiers to Var
    /// Python: _parse_unquoted_field
    pub fn parse_unquoted_field(&mut self) -> Result<Option<Expression>> {
        let field = self.parse_field()?;

        // If field is an unquoted identifier, convert it to a Var
        match field {
            Some(Expression::Identifier(id)) if !id.quoted => {
                Ok(Some(Expression::Var(Box::new(Var { this: id.name }))))
            }
            other => Ok(other),
        }
    }

    /// parse_user_defined_function - Parses user-defined function call
    /// Python: _parse_user_defined_function
    /// Parses: schema.function_name(param1, param2, ...)
    pub fn parse_user_defined_function(&mut self) -> Result<Option<Expression>> {
        // Parse table parts (potentially schema-qualified function name)
        let this = self.parse_table_parts()?;
        if this.is_none() {
            return Ok(None);
        }

        // If no L_PAREN, return just the table parts (not a function call)
        if !self.match_token(TokenType::LParen) {
            return Ok(this);
        }

        // Parse function parameters
        let mut expressions = Vec::new();
        if !self.check(TokenType::RParen) {
            loop {
                if let Some(param) = self.parse_function_parameter()? {
                    expressions.push(param);
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
        }

        self.match_token(TokenType::RParen);

        Ok(Some(Expression::UserDefinedFunction(Box::new(
            UserDefinedFunction {
                this: Box::new(this.unwrap()),
                expressions,
                wrapped: Some(Box::new(Expression::Boolean(BooleanLiteral {
                    value: true,
                }))),
            },
        ))))
    }

    /// parse_user_defined_function_expression - Parse user-defined function expression
    #[allow(unused_variables, unused_mut)]
    pub fn parse_user_defined_function_expression(&mut self) -> Result<Option<Expression>> {
        // Parse a statement and wrap in Some if successful
        match self.parse_statement() {
            Ok(stmt) => Ok(Some(stmt)),
            Err(_) => Ok(None),
        }
    }

    /// parse_user_defined_type - Parses a user-defined type reference
    /// Python: _parse_user_defined_type
    /// Format: schema.type_name or just type_name
    pub fn parse_user_defined_type(
        &mut self,
        identifier: Identifier,
    ) -> Result<Option<Expression>> {
        let mut type_name = identifier.name.clone();

        // Handle dotted names (schema.type_name)
        while self.match_token(TokenType::Dot) {
            if !self.is_at_end() {
                let token = self.advance();
                type_name = format!("{}.{}", type_name, token.text);
            } else {
                break;
            }
        }

        // Return as a custom data type
        Ok(Some(Expression::DataType(DataType::Custom {
            name: type_name,
        })))
    }

    /// parse_using_identifiers - Ported from Python _parse_using_identifiers
    /// Parses (col1, col2, ...) for JOIN USING clause
    #[allow(unused_variables, unused_mut)]
    pub fn parse_using_identifiers(&mut self) -> Result<Option<Expression>> {
        // Optionally expect opening paren
        let has_paren = self.match_token(TokenType::LParen);

        let mut identifiers = Vec::new();
        loop {
            // Parse column as identifier
            if let Some(expr) = self.parse_identifier()? {
                identifiers.push(expr);
            } else {
                break;
            }
            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        // Match closing paren if we matched opening
        if has_paren {
            self.expect(TokenType::RParen)?;
        }

        if identifiers.is_empty() {
            Ok(None)
        } else {
            Ok(Some(Expression::Tuple(Box::new(Tuple {
                expressions: identifiers,
            }))))
        }
    }

    /// parse_value - Parses a value tuple for INSERT VALUES clause
    /// Python: _parse_value
    /// Syntax: (expr1, expr2, ...) or just expr (single value)
    pub fn parse_value(&mut self) -> Result<Option<Expression>> {
        // Check for parenthesized list of expressions
        if self.match_token(TokenType::LParen) {
            let mut expressions = Vec::new();

            if !self.check(TokenType::RParen) {
                loop {
                    // Support DEFAULT keyword in VALUES
                    if self.match_texts(&["DEFAULT"]) {
                        let text = self.previous().text.to_uppercase();
                        expressions.push(Expression::Var(Box::new(Var { this: text })));
                    } else {
                        // Try to parse an expression
                        let saved_pos = self.current;
                        match self.parse_expression() {
                            Ok(expr) => expressions.push(expr),
                            Err(_) => {
                                self.current = saved_pos;
                            }
                        }
                    }

                    if !self.match_token(TokenType::Comma) {
                        break;
                    }
                }
            }

            self.match_token(TokenType::RParen);
            return Ok(Some(Expression::Tuple(Box::new(Tuple { expressions }))));
        }

        // Single value without parentheses (some dialects support VALUES 1, 2)
        let saved_pos = self.current;
        match self.parse_expression() {
            Ok(expr) => {
                return Ok(Some(Expression::Tuple(Box::new(Tuple {
                    expressions: vec![expr],
                }))));
            }
            Err(_) => {
                self.current = saved_pos;
            }
        }

        Ok(None)
    }

    /// parse_var - Parse variable reference (unquoted identifier)
    /// Python: if self._match(TokenType.VAR): return exp.Var(this=self._prev.text)
    pub fn parse_var(&mut self) -> Result<Option<Expression>> {
        if self.match_token(TokenType::Var) {
            let text = self.previous().text.clone();
            return Ok(Some(Expression::Var(Box::new(Var { this: text }))));
        }
        // Fall back to placeholder parsing
        self.parse_placeholder()
    }

    /// parse_var_from_options - Ported from Python _parse_var_from_options
    /// Parses a variable/identifier from a predefined set of options
    #[allow(unused_variables, unused_mut)]
    pub fn parse_var_from_options(&mut self) -> Result<Option<Expression>> {
        // Without the options dict, we just try to parse an identifier
        if self.is_at_end() {
            return Ok(None);
        }

        // Get current token text as the option
        let token = self.peek().clone();
        if token.token_type == TokenType::Identifier || token.token_type == TokenType::Var {
            self.advance();
            return Ok(Some(Expression::Var(Box::new(Var {
                this: token.text.to_uppercase(),
            }))));
        }

        Ok(None)
    }

    /// parse_var_or_string - Delegates to parse_string
    #[allow(unused_variables, unused_mut)]
    /// parse_var_or_string - Parses a string literal or a variable
    /// Python: parser.py:7506-7507
    pub fn parse_var_or_string(&mut self) -> Result<Option<Expression>> {
        // Try string first, then var
        if let Some(s) = self.parse_string()? {
            return Ok(Some(s));
        }
        self.parse_var_any_token()
    }

    /// parse_vector_expressions - Transforms vector type parameters
    /// Python: _parse_vector_expressions
    /// In Python, this transforms a list of expressions where the first element (identifier)
    /// is converted to a DataType. In Rust, since VECTOR type parsing is handled inline in
    /// parse_data_type, this method parses vector expressions (element_type, dimension) from
    /// the current position and returns them as a Tuple.
    pub fn parse_vector_expressions(&mut self) -> Result<Option<Expression>> {
        let mut expressions = Vec::new();

        // Parse element type - convert identifier to DataType
        if let Some(type_expr) = self.parse_type()? {
            expressions.push(type_expr);
        } else {
            return Ok(None);
        }

        // Parse optional dimension or additional parameters
        while self.match_token(TokenType::Comma) {
            if let Some(expr) = self.parse_primary_or_var()? {
                expressions.push(expr);
            }
        }

        if expressions.is_empty() {
            return Ok(None);
        }

        Ok(Some(Expression::Tuple(Box::new(Tuple { expressions }))))
    }

    /// parse_version - Implemented from Python _parse_version
    /// Python: parser.py:4266-4295
    /// Parses FOR SYSTEM_TIME AS OF, VERSIONS BETWEEN, etc.
    #[allow(unused_variables, unused_mut)]
    pub fn parse_version(&mut self) -> Result<Option<Expression>> {
        // Check for TIMESTAMP or VERSION snapshot token
        let this = if self.match_token(TokenType::TimestampSnapshot) {
            "TIMESTAMP".to_string()
        } else if self.match_token(TokenType::VersionSnapshot) {
            "VERSION".to_string()
        } else {
            return Ok(None);
        };

        // Parse the kind and expression
        let (kind, expression) = if self.match_texts(&["FROM", "BETWEEN"]) {
            // FROM start TO end or BETWEEN start AND end
            let kind_str = self.previous().text.to_uppercase();
            let start = self.parse_bitwise()?;
            self.match_texts(&["TO", "AND"]);
            let end = self.parse_bitwise()?;
            let tuple = Expression::Tuple(Box::new(Tuple {
                expressions: vec![
                    start.unwrap_or(Expression::Null(Null)),
                    end.unwrap_or(Expression::Null(Null)),
                ],
            }));
            (kind_str, Some(Box::new(tuple)))
        } else if self.match_text_seq(&["CONTAINED", "IN"]) {
            // CONTAINED IN (values)
            let expressions = if self.match_token(TokenType::LParen) {
                let exprs = self.parse_expression_list()?;
                self.expect(TokenType::RParen)?;
                exprs
            } else {
                Vec::new()
            };
            (
                "CONTAINED IN".to_string(),
                Some(Box::new(Expression::Tuple(Box::new(Tuple { expressions })))),
            )
        } else if self.match_token(TokenType::All) {
            // ALL
            ("ALL".to_string(), None)
        } else {
            // AS OF
            self.match_text_seq(&["AS", "OF"]);
            let type_expr = self.parse_type()?;
            ("AS OF".to_string(), type_expr.map(Box::new))
        };

        Ok(Some(Expression::Version(Box::new(Version {
            this: Box::new(Expression::Var(Box::new(Var { this }))),
            kind,
            expression,
        }))))
    }

    /// parse_volatile_property - Parses VOLATILE property
    /// Python: _parse_volatile_property
    /// Returns VolatileProperty for table volatility or StabilityProperty for function stability
    pub fn parse_volatile_property(&mut self) -> Result<Option<Expression>> {
        // Check the token before VOLATILE to determine context
        // In SQL, VOLATILE can mean:
        // 1. Table volatility (CREATE VOLATILE TABLE)
        // 2. Function stability (CREATE FUNCTION ... VOLATILE)

        // Look back to see if this is in a table context
        // PRE_VOLATILE_TOKENS typically include: CREATE, REPLACE, GLOBAL, etc.
        let is_table_context = if self.current >= 2 {
            let pre_token = &self.tokens[self.current - 2];
            matches!(
                pre_token.token_type,
                TokenType::Create | TokenType::Global | TokenType::Temporary | TokenType::Replace
            )
        } else {
            false
        };

        if is_table_context {
            Ok(Some(Expression::VolatileProperty(Box::new(
                VolatileProperty { this: None },
            ))))
        } else {
            // Function stability - return StabilityProperty with "VOLATILE" literal
            Ok(Some(Expression::StabilityProperty(Box::new(
                StabilityProperty {
                    this: Box::new(Expression::Literal(Literal::String("VOLATILE".to_string()))),
                },
            ))))
        }
    }

    /// parse_when_matched - Implemented from Python _parse_when_matched
    /// Calls: parse_disjunction, parse_star, parse_value
    #[allow(unused_variables, unused_mut)]
    /// Parse WHEN [NOT] MATCHED clauses for MERGE statements
    /// This is the public entry point that calls parse_when_matched_clauses
    pub fn parse_when_matched(&mut self) -> Result<Option<Expression>> {
        self.parse_when_matched_clauses()
    }

    /// parse_where - Parse WHERE clause
    /// Python: if not self._match(TokenType.WHERE): return None; return exp.Where(this=self._parse_disjunction())
    pub fn parse_where(&mut self) -> Result<Option<Expression>> {
        if !self.match_token(TokenType::Where) {
            return Ok(None);
        }
        // Parse the condition expression
        let condition = self.parse_expression()?;
        Ok(Some(Expression::Where(Box::new(Where { this: condition }))))
    }

    /// parse_window - Implemented from Python _parse_window
    /// Calls: parse_window_spec, parse_partition_and_order
    #[allow(unused_variables, unused_mut)]
    pub fn parse_window(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["WITHIN", "GROUP"]) {
            return Ok(Some(Expression::WindowSpec(Box::new(WindowSpec {
                partition_by: Vec::new(),
                order_by: Vec::new(),
                frame: None,
            }))));
        }
        if self.match_text_seq(&["LAST"]) {
            // Matched: LAST
            return Ok(None);
        }
        if self.match_text_seq(&["EXCLUDE"]) {
            // Matched: EXCLUDE
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_window_clause - Ported from Python _parse_window_clause
    /// Parses WINDOW named_window_definition [, named_window_definition, ...]
    #[allow(unused_variables, unused_mut)]
    pub fn parse_window_clause(&mut self) -> Result<Option<Expression>> {
        if !self.match_token(TokenType::Window) {
            return Ok(None);
        }

        // Parse comma-separated named window definitions
        let mut windows = Vec::new();
        loop {
            // Parse window name
            let name = self.parse_identifier()?;
            if name.is_none() {
                break;
            }

            // Expect AS
            self.expect(TokenType::As)?;

            // Parse window specification (parenthesized)
            self.expect(TokenType::LParen)?;
            let spec = self.parse_window_spec_inner()?;
            self.expect(TokenType::RParen)?;

            if let (Some(name_expr), Some(spec_expr)) = (name, spec) {
                // Create an Alias expression wrapping the spec with the name
                let alias_ident = if let Expression::Identifier(id) = name_expr {
                    id
                } else {
                    Identifier::new("window")
                };
                windows.push(Expression::Alias(Box::new(Alias {
                    this: spec_expr,
                    alias: alias_ident,
                    column_aliases: Vec::new(),
                    pre_alias_comments: Vec::new(),
                    trailing_comments: Vec::new(),
                    inferred_type: None,
                })));
            }

            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        if windows.is_empty() {
            Ok(None)
        } else {
            Ok(Some(Expression::Tuple(Box::new(Tuple {
                expressions: windows,
            }))))
        }
    }

    /// Parse window spec inner (without parentheses)
    fn parse_window_spec_inner(&mut self) -> Result<Option<Expression>> {
        // Parse optional base window name (identifier not followed by PARTITION or ORDER or DISTRIBUTE or SORT)
        let _base = if (self.check(TokenType::Identifier)
            || self.check(TokenType::QuotedIdentifier))
            && !self.check(TokenType::Partition)
            && !self.check(TokenType::Order)
            && !self.check(TokenType::Distribute)
            && !self.check(TokenType::Sort)
        {
            self.parse_identifier()?
        } else {
            None
        };

        // Parse PARTITION BY or DISTRIBUTE BY (Hive uses DISTRIBUTE BY in window specs)
        let partition_by = if self.match_keywords(&[TokenType::Partition, TokenType::By]) {
            self.parse_expression_list()?
        } else if self.match_keywords(&[TokenType::Distribute, TokenType::By]) {
            // Hive: DISTRIBUTE BY is equivalent to PARTITION BY in window specs
            self.parse_expression_list()?
        } else {
            Vec::new()
        };

        // Parse ORDER BY or SORT BY (Hive uses SORT BY in window specs)
        let order_by = if self.match_token(TokenType::Order) {
            self.match_token(TokenType::By);
            let mut orders = Vec::new();
            loop {
                if let Some(ordered) = self.parse_ordered_item()? {
                    orders.push(ordered);
                } else {
                    break;
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            orders
        } else if self.match_token(TokenType::Sort) {
            // Hive: SORT BY is equivalent to ORDER BY in window specs
            self.match_token(TokenType::By);
            let mut orders = Vec::new();
            loop {
                if let Some(ordered) = self.parse_ordered_item()? {
                    orders.push(ordered);
                } else {
                    break;
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            orders
        } else {
            Vec::new()
        };

        // Parse frame specification (ROWS/RANGE/GROUPS BETWEEN ... AND ...)
        let frame = self.parse_window_frame()?;

        Ok(Some(Expression::WindowSpec(Box::new(WindowSpec {
            partition_by,
            order_by,
            frame,
        }))))
    }

    /// parse_window_spec - Implemented from Python _parse_window_spec
    #[allow(unused_variables, unused_mut)]
    pub fn parse_window_spec(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["UNBOUNDED"]) {
            // Matched: UNBOUNDED
            return Ok(None);
        }
        if self.match_text_seq(&["CURRENT", "ROW"]) {
            // Matched: CURRENT ROW
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_with_operator - Parse column with operator class (PostgreSQL)
    /// Parses: ordered_expression [WITH operator]
    #[allow(unused_variables, unused_mut)]
    pub fn parse_with_operator(&mut self) -> Result<Option<Expression>> {
        // First parse an ordered expression with optional operator class
        let this = if let Some(opclass) = self.parse_opclass()? {
            opclass
        } else if let Some(ordered) = self.parse_ordered()? {
            ordered
        } else {
            return Ok(None);
        };

        // Check for WITH operator
        if !self.match_token(TokenType::With) {
            return Ok(Some(this));
        }

        // Parse the operator
        let op = self.parse_var()?;
        let op_str = match op {
            Some(Expression::Identifier(id)) => id.name,
            Some(Expression::Var(v)) => v.this.clone(),
            _ => String::new(),
        };

        Ok(Some(Expression::WithOperator(Box::new(WithOperator {
            this: Box::new(this),
            op: op_str,
        }))))
    }

    /// parse_with_property - Implemented from Python _parse_with_property
    /// Calls: parse_withjournaltable, parse_withisolatedloading, parse_wrapped_properties
    #[allow(unused_variables, unused_mut)]
    pub fn parse_with_property(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["(", "SYSTEM_VERSIONING"]) {
            return Ok(Some(Expression::WithProcedureOptions(Box::new(
                WithProcedureOptions {
                    expressions: Vec::new(),
                },
            ))));
        }
        if self.match_text_seq(&["JOURNAL"]) {
            // Matched: JOURNAL
            return Ok(None);
        }
        if self.match_text_seq(&["DATA"]) {
            // Matched: DATA
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_withdata - Implemented from Python _parse_withdata
    #[allow(unused_variables, unused_mut)]
    pub fn parse_withdata(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["AND", "STATISTICS"]) {
            return Ok(Some(Expression::WithDataProperty(Box::new(
                WithDataProperty {
                    no: None,
                    statistics: None,
                },
            ))));
        }
        if self.match_text_seq(&["AND", "NO", "STATISTICS"]) {
            // Matched: AND NO STATISTICS
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_withisolatedloading - Implemented from Python _parse_withisolatedloading
    #[allow(unused_variables, unused_mut)]
    pub fn parse_withisolatedloading(&mut self) -> Result<Option<Expression>> {
        if self.match_text_seq(&["NO"]) {
            return Ok(Some(Expression::IsolatedLoadingProperty(Box::new(
                IsolatedLoadingProperty {
                    no: None,
                    concurrent: None,
                    target: None,
                },
            ))));
        }
        if self.match_text_seq(&["CONCURRENT"]) {
            // Matched: CONCURRENT
            return Ok(None);
        }
        Ok(None)
    }

    /// parse_withjournaltable - Teradata WITH JOURNAL TABLE property
    /// Parses: WITH JOURNAL TABLE = table_name
    #[allow(unused_variables, unused_mut)]
    pub fn parse_withjournaltable(&mut self) -> Result<Option<Expression>> {
        // Optionally consume TABLE keyword
        self.match_token(TokenType::Table);

        // Optionally consume = sign
        self.match_token(TokenType::Eq);

        // Parse the table reference
        let table = self.parse_table_parts()?;
        if table.is_none() {
            return Ok(None);
        }

        Ok(Some(Expression::WithJournalTableProperty(Box::new(
            WithJournalTableProperty {
                this: Box::new(table.unwrap()),
            },
        ))))
    }

    /// parse_wrapped - Parses an expression wrapped in parentheses
    /// Python: _parse_wrapped(parse_method)
    /// This version parses a disjunction (expression) inside parentheses
    pub fn parse_wrapped(&mut self) -> Result<Option<Expression>> {
        if !self.match_token(TokenType::LParen) {
            return Ok(None);
        }

        let result = self.parse_disjunction()?;
        self.match_token(TokenType::RParen);

        Ok(result)
    }

    /// parse_wrapped_csv - Parses comma-separated expressions wrapped in parentheses
    /// Python: _parse_wrapped_csv(parse_method)
    pub fn parse_wrapped_csv(&mut self) -> Result<Option<Expression>> {
        if !self.match_token(TokenType::LParen) {
            return Ok(None);
        }

        let expressions = self.parse_expression_list()?;
        self.match_token(TokenType::RParen);

        if expressions.is_empty() {
            return Ok(None);
        }

        Ok(Some(Expression::Tuple(Box::new(Tuple { expressions }))))
    }

    /// parse_wrapped_id_vars - Parses comma-separated identifiers wrapped in parentheses
    /// Python: _parse_wrapped_id_vars
    pub fn parse_wrapped_id_vars(&mut self) -> Result<Option<Expression>> {
        if !self.match_token(TokenType::LParen) {
            return Ok(None);
        }

        let mut identifiers = Vec::new();
        loop {
            if let Some(id) = self.parse_id_var()? {
                identifiers.push(id);
            } else {
                break;
            }
            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        self.match_token(TokenType::RParen);

        if identifiers.is_empty() {
            return Ok(None);
        }

        Ok(Some(Expression::Tuple(Box::new(Tuple {
            expressions: identifiers,
        }))))
    }

    /// parse_wrapped_options - Implemented from Python _parse_wrapped_options
    /// Parses space-separated properties wrapped in parentheses (for Snowflake STAGE_FILE_FORMAT, etc.)
    /// Format: = (KEY=VALUE KEY2=VALUE2 ...)
    pub fn parse_wrapped_options(&mut self) -> Result<Option<Expression>> {
        // Match optional = before opening paren
        self.match_token(TokenType::Eq);

        // Expect opening paren
        if !self.match_token(TokenType::LParen) {
            return Ok(None);
        }

        // Parse space-separated properties (no comma required between them)
        let mut properties = Vec::new();
        while !self.check(TokenType::RParen) && !self.is_at_end() {
            // Try to parse a property: KEY=VALUE
            if let Some(prop) = self.parse_option_property()? {
                properties.push(prop);
            } else {
                break;
            }
        }

        // Expect closing paren
        self.match_token(TokenType::RParen);

        if properties.is_empty() {
            Ok(None)
        } else {
            Ok(Some(Expression::Tuple(Box::new(Tuple {
                expressions: properties,
            }))))
        }
    }

    /// Parse a single option property: KEY=VALUE
    /// Handles various value types: identifiers, strings, numbers, nested parens like ('') or (val1, val2)
    fn parse_option_property(&mut self) -> Result<Option<Expression>> {
        // Save position to retreat if this isn't a property
        let index = self.current;

        // Parse the key (identifier/column name)
        // For Snowflake options, keys are identifiers like TYPE, FIELD_DELIMITER, NULL_IF, etc.
        let key = if self.check(TokenType::Identifier)
            || self.check(TokenType::Var)
            || self
                .peek()
                .text
                .chars()
                .all(|c| c.is_ascii_alphanumeric() || c == '_')
        {
            let name = self.peek().text.clone();
            self.advance();
            Some(Expression::Var(Box::new(Var { this: name })))
        } else {
            None
        };

        let key = match key {
            Some(k) => k,
            None => {
                self.current = index;
                return Ok(None);
            }
        };

        // Expect =
        if !self.match_token(TokenType::Eq) {
            self.current = index;
            return Ok(None);
        }

        // Parse the value - can be:
        // - Simple identifier: CSV, SKIP_FILE, BASE64, TRUE, FALSE, CASE_SENSITIVE
        // - String literal: '|', '"', 'TZHTZM YYYY-MM-DD HH24:MI:SS.FF9'
        // - Number: 5
        // - Nested parens for tuple: ('')
        let value = if self.check(TokenType::LParen) {
            // Parse nested parenthesized value like NULL_IF=('')
            self.advance(); // consume (
            let mut inner_exprs = Vec::new();
            while !self.check(TokenType::RParen) && !self.is_at_end() {
                if let Some(expr) = self.parse_primary_for_option()? {
                    inner_exprs.push(expr);
                }
                // Allow comma between nested values
                self.match_token(TokenType::Comma);
            }
            self.match_token(TokenType::RParen);
            Expression::Tuple(Box::new(Tuple {
                expressions: inner_exprs,
            }))
        } else if let Some(primary) = self.parse_primary_for_option()? {
            primary
        } else {
            // Fallback: try to parse as a var
            let text = self.peek().text.clone();
            self.advance();
            Expression::Var(Box::new(Var { this: text }))
        };

        // Return as a Property expression (KEY=VALUE)
        Ok(Some(Expression::Property(Box::new(Property {
            this: Box::new(key),
            value: Some(Box::new(value)),
        }))))
    }

    /// Parse a primary value for option properties
    /// Handles strings, numbers, identifiers, TRUE/FALSE
    fn parse_primary_for_option(&mut self) -> Result<Option<Expression>> {
        // String literal
        if self.check(TokenType::String) {
            let text = self.peek().text.clone();
            self.advance();
            return Ok(Some(Expression::Literal(Literal::String(text))));
        }

        // Number
        if self.check(TokenType::Number) {
            let text = self.peek().text.clone();
            self.advance();
            return Ok(Some(Expression::Literal(Literal::Number(text))));
        }

        // TRUE/FALSE
        if self.check(TokenType::True) {
            self.advance();
            return Ok(Some(Expression::Boolean(BooleanLiteral { value: true })));
        }
        if self.check(TokenType::False) {
            self.advance();
            return Ok(Some(Expression::Boolean(BooleanLiteral { value: false })));
        }

        // Identifier or keyword used as value (CSV, SKIP_FILE, BASE64, etc.)
        if self.check(TokenType::Identifier)
            || self.check(TokenType::Var)
            || (!self.check(TokenType::RParen)
                && !self.check(TokenType::Comma)
                && !self.check(TokenType::Eq)
                && !self.is_at_end())
        {
            let text = self.peek().text.clone();
            // Don't consume if it's a closing paren or could be the next property key followed by =
            if self.check(TokenType::RParen) {
                return Ok(None);
            }
            // Check if this is the start of next property (followed by =)
            if self.check_next(TokenType::Eq) {
                return Ok(None);
            }
            self.advance();
            return Ok(Some(Expression::Var(Box::new(Var { this: text }))));
        }

        Ok(None)
    }

    /// parse_options_list - Parses BigQuery-style OPTIONS list: (key=value, key=value, ...)
    /// Parses key=value assignments where values can be complex expressions
    pub fn parse_options_list(&mut self) -> Result<Vec<Expression>> {
        // Expect opening paren
        if !self.match_token(TokenType::LParen) {
            return Ok(Vec::new());
        }

        // Parse comma-separated key=value pairs
        let mut options = Vec::new();
        loop {
            // Check for empty OPTIONS () or end of list
            if self.check(TokenType::RParen) {
                break;
            }

            // Parse key=value using parse_assignment which handles EQ operations
            if let Some(opt) = self.parse_assignment()? {
                options.push(opt);
            } else {
                break;
            }

            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        // Expect closing paren
        self.expect(TokenType::RParen)?;

        Ok(options)
    }

    /// Parse BigQuery PARTITION BY property and return a typed AST node.
    fn parse_bigquery_partition_by_property(&mut self) -> Result<Option<Expression>> {
        let start = self.current;
        let matched_partition = if self.match_token(TokenType::PartitionBy) {
            true
        } else if self.match_token(TokenType::Partition) {
            self.match_token(TokenType::By)
        } else {
            false
        };

        if !matched_partition {
            self.current = start;
            return Ok(None);
        }

        let mut expressions = Vec::new();
        while !self.is_at_end()
            && !self.check(TokenType::Cluster)
            && !self.check(TokenType::As)
            && !self.check(TokenType::Semicolon)
            && !self.check(TokenType::RParen)
            && !self.check_identifier("OPTIONS")
        {
            match self.parse_expression() {
                Ok(expr) => expressions.push(expr),
                Err(_) => {
                    // Fall back to generic/raw parsing if typed parsing can't consume this form.
                    self.current = start;
                    return Ok(None);
                }
            }

            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        if expressions.is_empty() {
            self.current = start;
            return Ok(None);
        }

        Ok(Some(Expression::PartitionByProperty(Box::new(
            PartitionByProperty { expressions },
        ))))
    }

    /// Parse BigQuery CLUSTER BY property and return a typed AST node.
    fn parse_bigquery_cluster_by_property(&mut self) -> Result<Option<Expression>> {
        let start = self.current;
        if !self.match_keywords(&[TokenType::Cluster, TokenType::By]) {
            self.current = start;
            return Ok(None);
        }

        let mut columns = Vec::new();
        loop {
            if let Some(Expression::Identifier(id)) = self.parse_identifier()? {
                columns.push(id);
            } else if self.is_identifier_or_keyword_token() {
                let name = self.advance().text;
                columns.push(Identifier {
                    name,
                    quoted: false,
                    trailing_comments: Vec::new(),
                    span: None,
                });
            } else {
                // Fall back to generic/raw parsing if typed parsing can't consume this form.
                self.current = start;
                return Ok(None);
            }

            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        if columns.is_empty() {
            self.current = start;
            return Ok(None);
        }

        Ok(Some(Expression::ClusterByColumnsProperty(Box::new(
            ClusterByColumnsProperty { columns },
        ))))
    }

    /// Parse BigQuery OPTIONS (...) clause into typed entries when possible.
    /// Falls back to generic `Properties` when options are not simple key/value assignments.
    fn parse_bigquery_options_property(&mut self) -> Result<Option<Expression>> {
        let start = self.current;
        if !self.match_identifier("OPTIONS") {
            self.current = start;
            return Ok(None);
        }

        let options = self.parse_options_list()?;
        if options.is_empty() {
            return Ok(Some(Expression::OptionsProperty(Box::new(
                OptionsProperty {
                    entries: Vec::new(),
                },
            ))));
        }

        let mut entries = Vec::new();
        for option_expr in &options {
            let Some(entry) = Self::option_entry_from_expression(option_expr) else {
                return Ok(Some(Expression::Properties(Box::new(Properties {
                    expressions: options,
                }))));
            };
            entries.push(entry);
        }

        Ok(Some(Expression::OptionsProperty(Box::new(
            OptionsProperty { entries },
        ))))
    }

    fn option_entry_from_expression(expr: &Expression) -> Option<OptionEntry> {
        let Expression::Eq(eq) = expr else {
            return None;
        };

        let key = match &eq.left {
            Expression::Column(col) if col.table.is_none() => col.name.clone(),
            Expression::Identifier(id) => id.clone(),
            Expression::Var(var) => Identifier {
                name: var.this.clone(),
                quoted: false,
                trailing_comments: Vec::new(),
                span: None,
            },
            _ => return None,
        };

        Some(OptionEntry {
            key,
            value: eq.right.clone(),
        })
    }

    /// parse_environment_list - Parses Databricks ENVIRONMENT list: (dependencies = '...', environment_version = '...')
    /// Parses key=value assignments where values can be string literals
    pub fn parse_environment_list(&mut self) -> Result<Vec<Expression>> {
        // Expect opening paren
        if !self.match_token(TokenType::LParen) {
            return Ok(Vec::new());
        }

        // Parse comma-separated key=value pairs
        let mut env_items = Vec::new();
        loop {
            // Check for empty ENVIRONMENT () or end of list
            if self.check(TokenType::RParen) {
                break;
            }

            // Parse key=value using parse_assignment which handles EQ operations
            if let Some(opt) = self.parse_assignment()? {
                env_items.push(opt);
            } else {
                break;
            }

            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        // Expect closing paren
        self.expect(TokenType::RParen)?;

        Ok(env_items)
    }

    /// parse_wrapped_properties - Ported from Python _parse_wrapped_properties
    /// Parses properties wrapped in parentheses
    #[allow(unused_variables, unused_mut)]
    pub fn parse_wrapped_properties(&mut self) -> Result<Option<Expression>> {
        // Parse wrapped list of properties: (prop1, prop2, ...)
        if !self.match_token(TokenType::LParen) {
            return Ok(None);
        }

        let mut props = Vec::new();
        loop {
            if let Some(prop) = self.parse_property()? {
                props.push(prop);
            }
            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        self.match_token(TokenType::RParen);

        if props.is_empty() {
            return Ok(None);
        }

        // Return as a Properties expression
        Ok(Some(Expression::Properties(Box::new(Properties {
            expressions: props,
        }))))
    }

    /// parse_wrapped_select - Ported from Python _parse_wrapped_select
    /// Parses wrapped select statements including PIVOT/UNPIVOT and FROM-first syntax
    #[allow(unused_variables, unused_mut)]
    pub fn parse_wrapped_select(&mut self, table: bool) -> Result<Option<Expression>> {
        // Check for PIVOT/UNPIVOT
        let is_unpivot = self.check(TokenType::Unpivot);
        if self.match_token(TokenType::Pivot) || self.match_token(TokenType::Unpivot) {
            // Call simplified pivot parser
            return self.parse_simplified_pivot(is_unpivot);
        }

        // Check for FROM (DuckDB FROM-first syntax)
        if self.match_token(TokenType::From) {
            // Parse the FROM clause (table reference)
            let from_expr = self.parse_table()?;

            // Try to parse a full SELECT
            let select = self.parse_select_query()?;

            if let Some(sel) = select {
                // Apply set operations and query modifiers
                let with_ops = self.parse_set_operations_with_expr(Some(sel))?;
                return Ok(with_ops);
            } else if let Some(from_table) = from_expr {
                // Create a SELECT * FROM <table>
                let mut select_struct = Select::new();
                select_struct.expressions = vec![Expression::Star(Star {
                    table: None,
                    except: None,
                    replace: None,
                    rename: None,
                    trailing_comments: Vec::new(),
                    span: None,
                })];
                select_struct.from = Some(From {
                    expressions: vec![from_table],
                });
                let select_all = Expression::Select(Box::new(select_struct));
                let with_ops = self.parse_set_operations_with_expr(Some(select_all))?;
                return Ok(with_ops);
            }
            return Ok(None);
        }

        // Regular case: parse table or nested select
        let this = if table {
            self.parse_table()?
        } else {
            // Parse nested select without set operations
            self.parse_select_query()?
        };

        if this.is_none() {
            return Ok(None);
        }

        // Apply set operations and query modifiers
        let with_ops = self.parse_set_operations_with_expr(this)?;
        Ok(with_ops)
    }

    /// Helper for parse_wrapped_select with default table=false
    pub fn parse_wrapped_select_default(&mut self) -> Result<Option<Expression>> {
        self.parse_wrapped_select(false)
    }

    /// parse_xml_element - Implemented from Python _parse_xml_element
    /// Python: parser.py:6917-6931
    /// Parses XMLELEMENT(NAME name [, expr, ...]) or XMLELEMENT(EVALNAME expr [, expr, ...])
    #[allow(unused_variables, unused_mut)]
    pub fn parse_xml_element(&mut self) -> Result<Option<Expression>> {
        let (this, evalname) = if self.match_text_seq(&["EVALNAME"]) {
            // EVALNAME - parse expression for dynamic element name
            let expr = self.parse_bitwise()?;
            (
                expr,
                Some(Box::new(Expression::Boolean(BooleanLiteral {
                    value: true,
                }))),
            )
        } else {
            // NAME - parse static element name
            self.match_text_seq(&["NAME"]);
            let id = self.parse_id_var()?;
            (id, None)
        };

        // Parse optional expressions (comma-separated content/attributes)
        let expressions = if self.match_token(TokenType::Comma) {
            self.parse_expression_list()?
        } else {
            Vec::new()
        };

        match this {
            Some(t) => Ok(Some(Expression::XMLElement(Box::new(XMLElement {
                this: Box::new(t),
                expressions,
                evalname,
            })))),
            None => Ok(None),
        }
    }

    /// parse_xml_namespace - Ported from Python _parse_xml_namespace
    /// Parses XML namespace declarations
    #[allow(unused_variables, unused_mut)]
    pub fn parse_xml_namespace(&mut self) -> Result<Option<Expression>> {
        let mut namespaces = Vec::new();

        loop {
            // Check for DEFAULT namespace
            let is_default = self.match_text_seq(&["DEFAULT"]);

            // Parse the URI string
            let uri = if is_default {
                self.parse_string()?
            } else {
                // Parse URI with optional alias (AS name)
                let uri_expr = self.parse_string()?;
                if let Some(u) = uri_expr {
                    self.parse_alias_with_expr(Some(u))?
                } else {
                    None
                }
            };

            if let Some(u) = uri {
                namespaces.push(u);
            }

            // Continue if comma
            if !self.match_token(TokenType::Comma) {
                break;
            }
        }

        if namespaces.is_empty() {
            return Ok(None);
        }

        // Return as a Tuple (list of namespaces)
        Ok(Some(Expression::Tuple(Box::new(Tuple {
            expressions: namespaces,
        }))))
    }

    /// parse_xml_table - Implemented from Python _parse_xml_table
    /// Python: parser.py:6933-6961
    /// Parses XMLTABLE(xpath_expr PASSING xml_doc COLUMNS ...)
    #[allow(unused_variables, unused_mut)]
    pub fn parse_xml_table(&mut self) -> Result<Option<Expression>> {
        // Parse optional XMLNAMESPACES clause
        let namespaces = if self.match_text_seq(&["XMLNAMESPACES", "("]) {
            let ns = self.parse_xml_namespace()?;
            self.match_text_seq(&[")", ","]);
            ns.map(Box::new)
        } else {
            None
        };

        // Parse XPath expression (string)
        let this = self.parse_string()?;
        if this.is_none() {
            return Ok(None);
        }

        // Parse PASSING clause
        let passing = if self.match_text_seq(&["PASSING"]) {
            // BY VALUE is optional
            self.match_text_seq(&["BY", "VALUE"]);
            // Parse comma-separated expressions.
            // Oracle XMLTABLE PASSING accepts full expressions (including function calls),
            // not just column references.
            // We need to stop before COLUMNS, RETURNING, or )
            let mut cols = Vec::new();
            loop {
                // Check for stop keywords before parsing a column
                if !self.is_at_end() {
                    let next_text = self.peek().text.to_uppercase();
                    if next_text == "COLUMNS" || next_text == "RETURNING" {
                        break;
                    }
                    if self.check(TokenType::RParen) {
                        break;
                    }
                }
                if let Some(col) = self.parse_assignment()? {
                    cols.push(col);
                } else {
                    break;
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            if cols.is_empty() {
                None
            } else {
                Some(Box::new(Expression::Tuple(Box::new(Tuple {
                    expressions: cols,
                }))))
            }
        } else {
            None
        };

        // Parse optional RETURNING SEQUENCE BY REF
        let by_ref = if self.match_text_seq(&["RETURNING", "SEQUENCE", "BY", "REF"]) {
            Some(Box::new(Expression::Boolean(BooleanLiteral {
                value: true,
            })))
        } else {
            None
        };

        // Parse COLUMNS clause
        let columns = if self.match_text_seq(&["COLUMNS"]) {
            let mut cols = Vec::new();
            loop {
                // Stop if we hit the closing paren
                if self.check(TokenType::RParen) {
                    break;
                }
                // Be permissive with leading commas in multiline XMLTABLE COLUMNS lists.
                if self.match_token(TokenType::Comma) {
                    continue;
                }
                if let Some(col_def) = self.parse_field_def()? {
                    cols.push(col_def);
                } else {
                    break;
                }
                if !self.match_token(TokenType::Comma) {
                    break;
                }
            }
            cols
        } else {
            Vec::new()
        };

        Ok(Some(Expression::XMLTable(Box::new(XMLTable {
            this: Box::new(this.unwrap()),
            namespaces,
            passing,
            columns,
            by_ref,
        }))))
    }

    /// Parse UNLOAD statement (Athena/Presto/Redshift)
    /// UNLOAD (SELECT ...) TO 'location' WITH (options)
    fn parse_unload(&mut self) -> Result<Expression> {
        // Collect entire statement as a Command
        let mut parts = Vec::new();
        parts.push(self.advance().text.clone()); // consume UNLOAD
        parts.push(" ".to_string()); // space after UNLOAD

        while !self.is_at_end() && !self.check(TokenType::Semicolon) {
            let token_type = self.peek().token_type;
            let token_text = self.peek().text.clone();

            // Track string literals
            if token_type == TokenType::String {
                parts.push(format!("'{}'", token_text.replace('\'', "''")));
                self.advance();
                // Add space after string unless followed by punctuation
                if !self.is_at_end() {
                    let next_type = self.peek().token_type;
                    if !matches!(
                        next_type,
                        TokenType::Comma | TokenType::RParen | TokenType::Semicolon
                    ) {
                        parts.push(" ".to_string());
                    }
                }
                continue;
            }

            // Handle ARRAY[...] syntax - no space between ARRAY and [
            if token_text.eq_ignore_ascii_case("ARRAY")
                && self
                    .peek_nth(1)
                    .is_some_and(|t| t.token_type == TokenType::LBracket)
            {
                parts.push(token_text);
                self.advance();
                // Consume [
                parts.push("[".to_string());
                self.advance();
                // Collect until RBracket
                while !self.is_at_end() && !self.check(TokenType::RBracket) {
                    let inner_type = self.peek().token_type;
                    let inner_text = self.peek().text.clone();
                    if inner_type == TokenType::String {
                        parts.push(format!("'{}'", inner_text.replace('\'', "''")));
                    } else {
                        parts.push(inner_text);
                    }
                    self.advance();
                    if self.check(TokenType::Comma) {
                        parts.push(", ".to_string());
                        self.advance();
                    }
                }
                if self.check(TokenType::RBracket) {
                    parts.push("]".to_string());
                    self.advance();
                }
                continue;
            }

            parts.push(token_text);
            self.advance();

            // Add space after most tokens except punctuation
            if !self.is_at_end() {
                let next_type = self.peek().token_type;
                let no_space_before = matches!(
                    next_type,
                    TokenType::Comma
                        | TokenType::RParen
                        | TokenType::RBracket
                        | TokenType::Semicolon
                        | TokenType::LBracket
                );
                let no_space_after = matches!(token_type, TokenType::LParen | TokenType::LBracket);
                if !no_space_before && !no_space_after {
                    parts.push(" ".to_string());
                }
            }
        }

        Ok(Expression::Command(Box::new(Command {
            this: parts.join(""),
        })))
    }

    /// Parse USING EXTERNAL FUNCTION statement (Athena)
    /// USING EXTERNAL FUNCTION name(params) RETURNS type LAMBDA 'arn' SELECT ...
    fn parse_using_external_function(&mut self) -> Result<Expression> {
        // Record start position
        let start_pos = self.peek().span.start;

        // Advance through all tokens until end or semicolon
        while !self.is_at_end() && !self.check(TokenType::Semicolon) {
            self.advance();
        }

        // Get end position from the last consumed token
        let end_pos = if self.current > 0 {
            self.tokens[self.current - 1].span.end
        } else {
            start_pos
        };

        // Extract exact text from source if available
        let command_text = if let Some(ref source) = self.source {
            source[start_pos..end_pos].to_string()
        } else {
            // Fallback: reconstruct from tokens (loses whitespace)
            let mut parts = Vec::new();
            for i in 0..self.current {
                if self.tokens[i].span.start >= start_pos && self.tokens[i].span.end <= end_pos {
                    if self.tokens[i].token_type == TokenType::String {
                        parts.push(format!("'{}'", self.tokens[i].text.replace('\'', "''")));
                    } else {
                        parts.push(self.tokens[i].text.clone());
                    }
                    if i + 1 < self.current {
                        parts.push(" ".to_string());
                    }
                }
            }
            parts.join("")
        };

        Ok(Expression::Command(Box::new(Command {
            this: command_text,
        })))
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::traversal::ExpressionWalk;

    #[test]
    fn test_comment_before_limit() {
        let sql = "SELECT a FROM b WHERE foo AND bla\n-- comment 3\nLIMIT 10";
        let result = Parser::parse_sql(sql).unwrap();
        let output = crate::Generator::sql(&result[0]).unwrap();
        assert_eq!(
            output,
            "SELECT a FROM b WHERE foo AND bla LIMIT 10 /* comment 3 */"
        );
    }

    #[test]
    fn test_variadic_array_postgres() {
        use crate::dialects::DialectType;
        use crate::transpile;

        // Test: ARRAY[10, -1, 5, 4.4] should parse correctly in Postgres
        let sql = "SELECT ARRAY[10, -1, 5, 4.4]";
        let result = transpile(sql, DialectType::PostgreSQL, DialectType::PostgreSQL).unwrap();
        eprintln!("Array test: {} -> {}", sql, result[0]);

        // Test: VARIADIC ARRAY[10, -1, 5, 4.4] in function call
        let sql2 = "SELECT MLEAST(VARIADIC ARRAY[10, -1, 5, 4.4])";
        let result2 = transpile(sql2, DialectType::PostgreSQL, DialectType::PostgreSQL).unwrap();
        eprintln!("VARIADIC test: {} -> {}", sql2, result2[0]);
        assert_eq!(result2[0], sql2);
    }

    #[test]
    fn test_parse_simple_select() {
        let result = Parser::parse_sql("SELECT 1").unwrap();
        assert_eq!(result.len(), 1);
        assert!(result[0].is_select());
    }

    #[test]
    fn test_parse_select_from() {
        let result = Parser::parse_sql("SELECT a, b FROM t").unwrap();
        assert_eq!(result.len(), 1);

        let select = result[0].as_select().unwrap();
        assert_eq!(select.expressions.len(), 2);
        assert!(select.from.is_some());
    }

    #[test]
    fn test_parse_select_where() {
        let result = Parser::parse_sql("SELECT * FROM t WHERE x = 1").unwrap();
        let select = result[0].as_select().unwrap();
        assert!(select.where_clause.is_some());
    }

    #[test]
    fn test_parse_balances_large_and_chain_depth() {
        let mut sql = String::from("SELECT 1 WHERE c0 = 0");
        for i in 1..4096 {
            sql.push_str(&format!(" AND c{i} = {i}"));
        }

        let result = Parser::parse_sql(&sql).unwrap();
        let select = result[0].as_select().unwrap();
        let where_clause = select.where_clause.as_ref().expect("WHERE clause missing");
        let depth = where_clause.this.tree_depth();
        assert!(
            depth < 128,
            "Expected balanced boolean tree depth, got {}",
            depth
        );
    }

    #[test]
    fn test_parse_balances_large_or_chain_depth() {
        let mut sql = String::from("SELECT 1 WHERE c0 = 0");
        for i in 1..4096 {
            sql.push_str(&format!(" OR c{i} = {i}"));
        }

        let result = Parser::parse_sql(&sql).unwrap();
        let select = result[0].as_select().unwrap();
        let where_clause = select.where_clause.as_ref().expect("WHERE clause missing");
        let depth = where_clause.this.tree_depth();
        assert!(
            depth < 128,
            "Expected balanced boolean tree depth, got {}",
            depth
        );
    }

    #[test]
    fn test_parse_select_join() {
        let result = Parser::parse_sql("SELECT * FROM a JOIN b ON a.id = b.id").unwrap();
        let select = result[0].as_select().unwrap();
        assert_eq!(select.joins.len(), 1);
        assert_eq!(select.joins[0].kind, JoinKind::Inner);
    }

    #[test]
    fn test_parse_expression_precedence() {
        let result = Parser::parse_sql("SELECT 1 + 2 * 3").unwrap();
        let select = result[0].as_select().unwrap();
        // Should parse as 1 + (2 * 3) due to precedence
        assert!(matches!(select.expressions[0], Expression::Add(_)));
    }

    #[test]
    fn test_parse_function() {
        // COUNT(*) is now a typed Count expression
        let result = Parser::parse_sql("SELECT COUNT(*)").unwrap();
        let select = result[0].as_select().unwrap();
        assert!(matches!(select.expressions[0], Expression::Count(_)));

        // Unknown functions stay as generic Function
        let result = Parser::parse_sql("SELECT MY_CUSTOM_FUNC(name)").unwrap();
        let select = result[0].as_select().unwrap();
        assert!(matches!(select.expressions[0], Expression::Function(_)));

        // Known aggregate functions are now typed
        let result = Parser::parse_sql("SELECT SUM(amount)").unwrap();
        let select = result[0].as_select().unwrap();
        assert!(matches!(select.expressions[0], Expression::Sum(_)));
    }

    #[test]
    fn test_parse_window_function() {
        let result =
            Parser::parse_sql("SELECT ROW_NUMBER() OVER (PARTITION BY category ORDER BY id)")
                .unwrap();
        let select = result[0].as_select().unwrap();
        assert!(matches!(
            select.expressions[0],
            Expression::WindowFunction(_)
        ));
    }

    #[test]
    fn test_parse_window_function_with_frame() {
        let result = Parser::parse_sql("SELECT SUM(amount) OVER (ORDER BY date ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW)").unwrap();
        let select = result[0].as_select().unwrap();
        assert!(matches!(
            select.expressions[0],
            Expression::WindowFunction(_)
        ));
    }

    #[test]
    fn test_parse_subscript() {
        // Array subscript
        let result = Parser::parse_sql("SELECT arr[0]").unwrap();
        let select = result[0].as_select().unwrap();
        assert!(matches!(select.expressions[0], Expression::Subscript(_)));

        // Function result subscript
        let result = Parser::parse_sql("SELECT SPLIT(name, ',')[0]").unwrap();
        let select = result[0].as_select().unwrap();
        assert!(matches!(select.expressions[0], Expression::Subscript(_)));
    }

    #[test]
    fn test_parse_case() {
        let result = Parser::parse_sql("SELECT CASE WHEN x = 1 THEN 'a' ELSE 'b' END").unwrap();
        let select = result[0].as_select().unwrap();
        assert!(matches!(select.expressions[0], Expression::Case(_)));
    }

    #[test]
    fn test_parse_insert() {
        let result = Parser::parse_sql("INSERT INTO t (a, b) VALUES (1, 2)").unwrap();
        assert!(matches!(result[0], Expression::Insert(_)));
    }

    #[test]
    fn test_parse_template_variable() {
        // Test Databricks/Hive ${variable} syntax
        let result = Parser::parse_sql("SELECT ${x} FROM ${y} WHERE ${z} > 1").unwrap();
        let select = result[0].as_select().unwrap();
        // The expression should be a Parameter with DollarBrace style
        assert!(
            matches!(&select.expressions[0], Expression::Parameter(p) if p.name == Some("x".to_string()))
        );
        // Check the style is DollarBrace
        if let Expression::Parameter(p) = &select.expressions[0] {
            assert_eq!(p.style, ParameterStyle::DollarBrace);
        }
    }

    #[test]
    fn test_parse_update() {
        let result = Parser::parse_sql("UPDATE t SET a = 1 WHERE b = 2").unwrap();
        assert!(matches!(result[0], Expression::Update(_)));
    }

    #[test]
    fn test_parse_delete() {
        let result = Parser::parse_sql("DELETE FROM t WHERE a = 1").unwrap();
        assert!(matches!(result[0], Expression::Delete(_)));
    }

    // DDL tests
    #[test]
    fn test_parse_create_table() {
        let result = Parser::parse_sql(
            "CREATE TABLE users (id INT PRIMARY KEY, name VARCHAR(100) NOT NULL)",
        )
        .unwrap();
        assert!(matches!(result[0], Expression::CreateTable(_)));

        if let Expression::CreateTable(ct) = &result[0] {
            assert_eq!(ct.name.name.name, "users");
            assert_eq!(ct.columns.len(), 2);
            assert!(ct.columns[0].primary_key);
            assert_eq!(ct.columns[1].nullable, Some(false));
        }
    }

    #[test]
    fn test_parse_create_table_if_not_exists() {
        let result = Parser::parse_sql("CREATE TABLE IF NOT EXISTS t (id INT)").unwrap();
        if let Expression::CreateTable(ct) = &result[0] {
            assert!(ct.if_not_exists);
        }
    }

    #[test]
    fn test_parse_create_temporary_table() {
        let result = Parser::parse_sql("CREATE TEMPORARY TABLE t (id INT)").unwrap();
        if let Expression::CreateTable(ct) = &result[0] {
            assert!(ct.temporary);
        }
    }

    #[test]
    fn test_bigquery_create_table_properties_are_typed() {
        use crate::DialectType;

        let sql = "CREATE OR REPLACE TABLE `p1`.`d1`.`t1` PARTITION BY DATE_TRUNC(day, month) CLUSTER BY some_cluster_column OPTIONS(description='', labels=[('l1', 'v1'), ('l2', 'v2')]) AS SELECT CURRENT_DATE AS day, DATE_TRUNC(CURRENT_DATE(), month) AS month, 'c' AS some_cluster_column";
        let parsed = crate::parse(sql, DialectType::BigQuery).unwrap();

        let create = match &parsed[0] {
            Expression::CreateTable(ct) => ct,
            other => panic!(
                "Expected CreateTable, got {:?}",
                std::mem::discriminant(other)
            ),
        };

        assert!(
            create
                .properties
                .iter()
                .any(|p| matches!(p, Expression::PartitionByProperty(_))),
            "Expected typed PARTITION BY property"
        );
        assert!(
            create
                .properties
                .iter()
                .any(|p| matches!(p, Expression::ClusterByColumnsProperty(_))),
            "Expected typed CLUSTER BY property"
        );
        assert!(
            create
                .properties
                .iter()
                .any(|p| matches!(p, Expression::OptionsProperty(_))),
            "Expected typed OPTIONS property"
        );
        assert!(
            !create
                .properties
                .iter()
                .any(|p| matches!(p, Expression::Raw(_))),
            "BigQuery table properties should not fall back to Raw"
        );

        let options = create
            .properties
            .iter()
            .find_map(|p| match p {
                Expression::OptionsProperty(o) => Some(o),
                _ => None,
            })
            .expect("Expected OptionsProperty");
        assert_eq!(options.entries.len(), 2);
        assert_eq!(options.entries[0].key.name, "description");
        assert_eq!(options.entries[1].key.name, "labels");
    }

    #[test]
    fn test_bigquery_create_table_properties_roundtrip() {
        use crate::DialectType;

        let sql = "CREATE TABLE t1 PARTITION BY DATE_TRUNC(day, month) CLUSTER BY some_cluster_column OPTIONS(description='', labels=[('l1', 'v1')]) AS SELECT 1 AS day, 1 AS month, 'c' AS some_cluster_column";
        let expected = "CREATE TABLE t1 PARTITION BY DATE_TRUNC(day, month) CLUSTER BY some_cluster_column OPTIONS (description='', labels=[('l1', 'v1')]) AS SELECT 1 AS day, 1 AS month, 'c' AS some_cluster_column";
        let parsed = crate::parse(sql, DialectType::BigQuery).unwrap();
        let generated = crate::generate(&parsed[0], DialectType::BigQuery).unwrap();
        assert_eq!(generated, expected);
    }

    #[test]
    fn test_parse_drop_table() {
        let result = Parser::parse_sql("DROP TABLE IF EXISTS users CASCADE").unwrap();
        assert!(matches!(result[0], Expression::DropTable(_)));

        if let Expression::DropTable(dt) = &result[0] {
            assert!(dt.if_exists);
            assert!(dt.cascade);
            assert_eq!(dt.names.len(), 1);
        }
    }

    #[test]
    fn test_parse_alter_table_add_column() {
        let result = Parser::parse_sql("ALTER TABLE users ADD COLUMN email VARCHAR(255)").unwrap();
        assert!(matches!(result[0], Expression::AlterTable(_)));

        if let Expression::AlterTable(at) = &result[0] {
            assert_eq!(at.actions.len(), 1);
            assert!(matches!(at.actions[0], AlterTableAction::AddColumn { .. }));
        }
    }

    #[test]
    fn test_parse_alter_table_drop_column() {
        let result = Parser::parse_sql("ALTER TABLE users DROP COLUMN email").unwrap();
        if let Expression::AlterTable(at) = &result[0] {
            assert!(matches!(at.actions[0], AlterTableAction::DropColumn { .. }));
        }
    }

    #[test]
    fn test_tsql_alter_table_set_options() {
        use crate::{transpile, DialectType};
        let tests = vec![
            "ALTER TABLE tbl SET (SYSTEM_VERSIONING=OFF)",
            "ALTER TABLE tbl SET (FILESTREAM_ON = 'test')",
            "ALTER TABLE tbl SET (DATA_DELETION=ON)",
            "ALTER TABLE tbl SET (DATA_DELETION=OFF)",
            "ALTER TABLE tbl SET (SYSTEM_VERSIONING=ON(HISTORY_TABLE=db.tbl, DATA_CONSISTENCY_CHECK=OFF, HISTORY_RETENTION_PERIOD=5 DAYS))",
            "ALTER TABLE tbl SET (SYSTEM_VERSIONING=ON(HISTORY_TABLE=db.tbl, HISTORY_RETENTION_PERIOD=INFINITE))",
            "ALTER TABLE tbl SET (DATA_DELETION=ON(FILTER_COLUMN=col, RETENTION_PERIOD=5 MONTHS))",
        ];
        for sql in tests {
            let result = transpile(sql, DialectType::TSQL, DialectType::TSQL);
            match result {
                Ok(output) => {
                    assert_eq!(output[0].trim(), sql, "Identity failed for: {}", sql);
                }
                Err(e) => {
                    panic!("Parse/generate failed for: {} -- {:?}", sql, e);
                }
            }
        }
    }

    #[test]
    fn test_parse_create_index() {
        let result = Parser::parse_sql("CREATE UNIQUE INDEX idx_email ON users (email)").unwrap();
        assert!(matches!(result[0], Expression::CreateIndex(_)));

        if let Expression::CreateIndex(ci) = &result[0] {
            assert!(ci.unique);
            assert_eq!(ci.name.name, "idx_email");
            assert_eq!(ci.table.name.name, "users");
            assert_eq!(ci.columns.len(), 1);
        }
    }

    #[test]
    fn test_parse_drop_index() {
        let result = Parser::parse_sql("DROP INDEX IF EXISTS idx_email ON users").unwrap();
        assert!(matches!(result[0], Expression::DropIndex(_)));

        if let Expression::DropIndex(di) = &result[0] {
            assert!(di.if_exists);
            assert!(di.table.is_some());
        }
    }

    #[test]
    fn test_parse_create_view() {
        let result =
            Parser::parse_sql("CREATE VIEW active_users AS SELECT * FROM users WHERE active = 1")
                .unwrap();
        assert!(matches!(result[0], Expression::CreateView(_)));
    }

    #[test]
    fn test_parse_create_materialized_view() {
        let result =
            Parser::parse_sql("CREATE MATERIALIZED VIEW stats AS SELECT COUNT(*) FROM users")
                .unwrap();
        if let Expression::CreateView(cv) = &result[0] {
            assert!(cv.materialized);
        }
    }

    #[test]
    fn test_hive_stored_by() {
        use crate::{transpile, DialectType};
        let sql = "CREATE EXTERNAL TABLE X (y INT) STORED BY 'x'";
        let result = transpile(sql, DialectType::Hive, DialectType::Hive);
        match result {
            Ok(output) => {
                assert_eq!(output[0].trim(), sql, "Identity failed for: {}", sql);
            }
            Err(e) => {
                panic!("Parse/generate failed for: {} -- {:?}", sql, e);
            }
        }
    }

    #[test]
    fn test_hive_row_format_serde() {
        use crate::{transpile, DialectType};

        // Test various Hive CREATE TABLE syntax
        let test_cases = vec![
            (
                "CREATE TABLE my_table (a7 ARRAY<DATE>)",
                "CREATE TABLE my_table (a7 ARRAY<DATE>)",
            ),
            (
                "CREATE EXTERNAL TABLE my_table (x INT) ROW FORMAT SERDE 'a'",
                "CREATE EXTERNAL TABLE my_table (x INT) ROW FORMAT SERDE 'a'",
            ),
            (
                "CREATE EXTERNAL TABLE my_table (x INT) STORED AS INPUTFORMAT 'b' OUTPUTFORMAT 'c'",
                "CREATE EXTERNAL TABLE my_table (x INT) STORED AS INPUTFORMAT 'b' OUTPUTFORMAT 'c'",
            ),
            (
                "CREATE EXTERNAL TABLE my_table (x INT) LOCATION 'd'",
                "CREATE EXTERNAL TABLE my_table (x INT) LOCATION 'd'",
            ),
            (
                "CREATE EXTERNAL TABLE my_table (x INT) TBLPROPERTIES ('e'='f')",
                "CREATE EXTERNAL TABLE my_table (x INT) TBLPROPERTIES ('e'='f')",
            ),
            (
                "CREATE EXTERNAL TABLE X (y INT) STORED BY 'x'",
                "CREATE EXTERNAL TABLE X (y INT) STORED BY 'x'",
            ),
        ];

        for (sql, expected) in &test_cases {
            let result = transpile(sql, DialectType::Hive, DialectType::Hive);
            match result {
                Ok(output) => {
                    assert_eq!(output[0].trim(), *expected, "Identity failed for: {}", sql);
                }
                Err(e) => {
                    panic!("Parse/generate failed for: {} -- {:?}", sql, e);
                }
            }
        }

        // Test full case with all Hive table properties
        let sql = "CREATE EXTERNAL TABLE `my_table` (`a7` ARRAY<DATE>) ROW FORMAT SERDE 'a' STORED AS INPUTFORMAT 'b' OUTPUTFORMAT 'c' LOCATION 'd' TBLPROPERTIES ('e'='f')";
        let result = transpile(sql, DialectType::Hive, DialectType::Hive);
        match result {
            Ok(output) => {
                assert_eq!(output[0].trim(), sql, "Identity failed for: {}", sql);
            }
            Err(e) => {
                panic!("Parse/generate failed for: {} -- {:?}", sql, e);
            }
        }
    }

    #[test]
    fn test_parse_drop_view() {
        let result = Parser::parse_sql("DROP VIEW IF EXISTS active_users").unwrap();
        assert!(matches!(result[0], Expression::DropView(_)));
    }

    #[test]
    fn test_parse_truncate() {
        let result = Parser::parse_sql("TRUNCATE TABLE users CASCADE").unwrap();
        assert!(matches!(result[0], Expression::Truncate(_)));

        if let Expression::Truncate(tr) = &result[0] {
            assert!(tr.cascade);
        }
    }

    // Tests for typed aggregate functions
    #[test]
    fn test_parse_typed_aggregates() {
        // COUNT with DISTINCT
        let result = Parser::parse_sql("SELECT COUNT(DISTINCT user_id)").unwrap();
        let select = result[0].as_select().unwrap();
        if let Expression::Count(c) = &select.expressions[0] {
            assert!(c.distinct);
            assert!(!c.star);
        } else {
            panic!("Expected Count expression");
        }

        // AVG
        let result = Parser::parse_sql("SELECT AVG(price)").unwrap();
        let select = result[0].as_select().unwrap();
        assert!(matches!(select.expressions[0], Expression::Avg(_)));

        // MIN/MAX
        let result = Parser::parse_sql("SELECT MIN(a), MAX(b)").unwrap();
        let select = result[0].as_select().unwrap();
        assert!(matches!(select.expressions[0], Expression::Min(_)));
        assert!(matches!(select.expressions[1], Expression::Max(_)));

        // STDDEV/VARIANCE
        let result = Parser::parse_sql("SELECT STDDEV(x), VARIANCE(y)").unwrap();
        let select = result[0].as_select().unwrap();
        assert!(matches!(select.expressions[0], Expression::Stddev(_)));
        assert!(matches!(select.expressions[1], Expression::Variance(_)));
    }

    #[test]
    fn test_parse_typed_window_functions() {
        // ROW_NUMBER
        let result = Parser::parse_sql("SELECT ROW_NUMBER() OVER (ORDER BY id)").unwrap();
        let select = result[0].as_select().unwrap();
        if let Expression::WindowFunction(wf) = &select.expressions[0] {
            assert!(matches!(wf.this, Expression::RowNumber(_)));
        } else {
            panic!("Expected WindowFunction");
        }

        // RANK and DENSE_RANK
        let result = Parser::parse_sql("SELECT RANK() OVER (), DENSE_RANK() OVER ()").unwrap();
        let select = result[0].as_select().unwrap();
        if let Expression::WindowFunction(wf) = &select.expressions[0] {
            assert!(matches!(wf.this, Expression::Rank(_)));
        }
        if let Expression::WindowFunction(wf) = &select.expressions[1] {
            assert!(matches!(wf.this, Expression::DenseRank(_)));
        }

        // LEAD/LAG
        let result = Parser::parse_sql("SELECT LEAD(val, 1, 0) OVER (ORDER BY id)").unwrap();
        let select = result[0].as_select().unwrap();
        if let Expression::WindowFunction(wf) = &select.expressions[0] {
            if let Expression::Lead(f) = &wf.this {
                assert!(f.offset.is_some());
                assert!(f.default.is_some());
            } else {
                panic!("Expected Lead");
            }
        }

        // NTILE
        let result = Parser::parse_sql("SELECT NTILE(4) OVER (ORDER BY score)").unwrap();
        let select = result[0].as_select().unwrap();
        if let Expression::WindowFunction(wf) = &select.expressions[0] {
            assert!(matches!(wf.this, Expression::NTile(_)));
        }
    }

    #[test]
    fn test_parse_string_functions() {
        // CONTAINS, STARTS_WITH, ENDS_WITH
        let result = Parser::parse_sql("SELECT CONTAINS(name, 'test')").unwrap();
        let select = result[0].as_select().unwrap();
        assert!(matches!(select.expressions[0], Expression::Contains(_)));

        let result = Parser::parse_sql("SELECT STARTS_WITH(name, 'A')").unwrap();
        let select = result[0].as_select().unwrap();
        assert!(matches!(select.expressions[0], Expression::StartsWith(_)));

        let result = Parser::parse_sql("SELECT ENDS_WITH(name, 'z')").unwrap();
        let select = result[0].as_select().unwrap();
        assert!(matches!(select.expressions[0], Expression::EndsWith(_)));
    }

    #[test]
    fn test_parse_math_functions() {
        // MOD function
        let result = Parser::parse_sql("SELECT MOD(10, 3)").unwrap();
        let select = result[0].as_select().unwrap();
        assert!(matches!(select.expressions[0], Expression::ModFunc(_)));

        // RANDOM and RAND
        let result = Parser::parse_sql("SELECT RANDOM()").unwrap();
        let select = result[0].as_select().unwrap();
        assert!(matches!(select.expressions[0], Expression::Random(_)));

        let result = Parser::parse_sql("SELECT RAND(42)").unwrap();
        let select = result[0].as_select().unwrap();
        assert!(matches!(select.expressions[0], Expression::Rand(_)));

        // Trigonometric functions
        let result = Parser::parse_sql("SELECT SIN(x), COS(x), TAN(x)").unwrap();
        let select = result[0].as_select().unwrap();
        assert!(matches!(select.expressions[0], Expression::Sin(_)));
        assert!(matches!(select.expressions[1], Expression::Cos(_)));
        assert!(matches!(select.expressions[2], Expression::Tan(_)));
    }

    #[test]
    fn test_parse_date_functions() {
        // Date part extraction functions
        let result =
            Parser::parse_sql("SELECT YEAR(date_col), MONTH(date_col), DAY(date_col)").unwrap();
        let select = result[0].as_select().unwrap();
        assert!(matches!(select.expressions[0], Expression::Year(_)));
        assert!(matches!(select.expressions[1], Expression::Month(_)));
        assert!(matches!(select.expressions[2], Expression::Day(_)));

        // EPOCH and EPOCH_MS
        let result = Parser::parse_sql("SELECT EPOCH(ts), EPOCH_MS(ts)").unwrap();
        let select = result[0].as_select().unwrap();
        assert!(matches!(select.expressions[0], Expression::Epoch(_)));
        assert!(matches!(select.expressions[1], Expression::EpochMs(_)));
    }

    #[test]
    fn test_parse_array_functions() {
        // ARRAY_LENGTH
        let result = Parser::parse_sql("SELECT ARRAY_LENGTH(arr)").unwrap();
        let select = result[0].as_select().unwrap();
        assert!(matches!(select.expressions[0], Expression::ArrayLength(_)));

        // ARRAY_CONTAINS
        let result = Parser::parse_sql("SELECT ARRAY_CONTAINS(arr, 1)").unwrap();
        let select = result[0].as_select().unwrap();
        assert!(matches!(
            select.expressions[0],
            Expression::ArrayContains(_)
        ));

        // EXPLODE
        let result = Parser::parse_sql("SELECT EXPLODE(arr)").unwrap();
        let select = result[0].as_select().unwrap();
        assert!(matches!(select.expressions[0], Expression::Explode(_)));
    }

    #[test]
    fn test_parse_json_functions() {
        // JSON_EXTRACT
        let result = Parser::parse_sql("SELECT JSON_EXTRACT(data, '$.name')").unwrap();
        let select = result[0].as_select().unwrap();
        assert!(matches!(select.expressions[0], Expression::JsonExtract(_)));

        // JSON_ARRAY_LENGTH
        let result = Parser::parse_sql("SELECT JSON_ARRAY_LENGTH(arr)").unwrap();
        let select = result[0].as_select().unwrap();
        assert!(matches!(
            select.expressions[0],
            Expression::JsonArrayLength(_)
        ));

        // TO_JSON and PARSE_JSON
        let result = Parser::parse_sql("SELECT TO_JSON(obj), PARSE_JSON(str)").unwrap();
        let select = result[0].as_select().unwrap();
        assert!(matches!(select.expressions[0], Expression::ToJson(_)));
        assert!(matches!(select.expressions[1], Expression::ParseJson(_)));

        // JSON literal: JSON '"foo"' -> ParseJson
        let result = Parser::parse_sql("SELECT JSON '\"foo\"'").unwrap();
        let select = result[0].as_select().unwrap();
        assert!(
            matches!(select.expressions[0], Expression::ParseJson(_)),
            "Expected ParseJson, got: {:?}",
            select.expressions[0]
        );
    }

    #[test]
    fn test_parse_map_functions() {
        // MAP_KEYS and MAP_VALUES
        let result = Parser::parse_sql("SELECT MAP_KEYS(m), MAP_VALUES(m)").unwrap();
        let select = result[0].as_select().unwrap();
        assert!(matches!(select.expressions[0], Expression::MapKeys(_)));
        assert!(matches!(select.expressions[1], Expression::MapValues(_)));

        // ELEMENT_AT
        let result = Parser::parse_sql("SELECT ELEMENT_AT(m, 'key')").unwrap();
        let select = result[0].as_select().unwrap();
        assert!(matches!(select.expressions[0], Expression::ElementAt(_)));
    }

    #[test]
    fn test_parse_date_literals() {
        // DATE literal (generic mode normalizes to CAST)
        let result = Parser::parse_sql("SELECT DATE '2024-01-15'").unwrap();
        let select = result[0].as_select().unwrap();
        match &select.expressions[0] {
            Expression::Cast(cast) => {
                match &cast.this {
                    Expression::Literal(Literal::String(s)) => assert_eq!(s, "2024-01-15"),
                    other => panic!("Expected String literal in Cast, got {:?}", other),
                }
                assert!(matches!(cast.to, DataType::Date));
            }
            other => panic!("Expected Cast expression, got {:?}", other),
        }

        // TIME literal
        let result = Parser::parse_sql("SELECT TIME '10:30:00'").unwrap();
        let select = result[0].as_select().unwrap();
        match &select.expressions[0] {
            Expression::Literal(Literal::Time(t)) => {
                assert_eq!(t, "10:30:00");
            }
            _ => panic!("Expected Time literal"),
        }

        // TIMESTAMP literal -> CAST in generic mode
        let result = Parser::parse_sql("SELECT TIMESTAMP '2024-01-15 10:30:00'").unwrap();
        let select = result[0].as_select().unwrap();
        match &select.expressions[0] {
            Expression::Cast(cast) => {
                match &cast.this {
                    Expression::Literal(Literal::String(s)) => assert_eq!(s, "2024-01-15 10:30:00"),
                    other => panic!("Expected String literal inside Cast, got {:?}", other),
                }
                assert!(matches!(
                    &cast.to,
                    DataType::Timestamp {
                        precision: None,
                        timezone: false
                    }
                ));
            }
            _ => panic!("Expected Cast expression for TIMESTAMP literal"),
        }
    }

    #[test]
    fn test_parse_star_exclude() {
        // EXCLUDE with multiple columns
        let result = Parser::parse_sql("SELECT * EXCLUDE (col1, col2) FROM t").unwrap();
        let select = result[0].as_select().unwrap();
        if let Expression::Star(star) = &select.expressions[0] {
            assert!(star.except.is_some());
            let except = star.except.as_ref().unwrap();
            assert_eq!(except.len(), 2);
            assert_eq!(except[0].name, "col1");
            assert_eq!(except[1].name, "col2");
        } else {
            panic!("Expected Star expression");
        }

        // EXCEPT (BigQuery syntax)
        let result = Parser::parse_sql("SELECT * EXCEPT (id, created_at) FROM t").unwrap();
        let select = result[0].as_select().unwrap();
        if let Expression::Star(star) = &select.expressions[0] {
            assert!(star.except.is_some());
        } else {
            panic!("Expected Star expression");
        }

        // table.* with EXCLUDE
        let result = Parser::parse_sql("SELECT t.* EXCLUDE (col1) FROM t").unwrap();
        let select = result[0].as_select().unwrap();
        if let Expression::Star(star) = &select.expressions[0] {
            assert!(star.table.is_some());
            assert_eq!(star.table.as_ref().unwrap().name, "t");
            assert!(star.except.is_some());
        } else {
            panic!("Expected Star expression");
        }
    }

    #[test]
    fn test_parse_star_replace() {
        // REPLACE with single expression
        let result = Parser::parse_sql("SELECT * REPLACE (UPPER(name) AS name) FROM t").unwrap();
        let select = result[0].as_select().unwrap();
        if let Expression::Star(star) = &select.expressions[0] {
            assert!(star.replace.is_some());
            let replace = star.replace.as_ref().unwrap();
            assert_eq!(replace.len(), 1);
            assert_eq!(replace[0].alias.name, "name");
        } else {
            panic!("Expected Star expression");
        }

        // REPLACE with multiple expressions
        let result = Parser::parse_sql("SELECT * REPLACE (a + 1 AS a, b * 2 AS b) FROM t").unwrap();
        let select = result[0].as_select().unwrap();
        if let Expression::Star(star) = &select.expressions[0] {
            let replace = star.replace.as_ref().unwrap();
            assert_eq!(replace.len(), 2);
        } else {
            panic!("Expected Star expression");
        }
    }

    #[test]
    fn test_parse_star_rename() {
        // RENAME with multiple columns
        let result =
            Parser::parse_sql("SELECT * RENAME (old_col AS new_col, x AS y) FROM t").unwrap();
        let select = result[0].as_select().unwrap();
        if let Expression::Star(star) = &select.expressions[0] {
            assert!(star.rename.is_some());
            let rename = star.rename.as_ref().unwrap();
            assert_eq!(rename.len(), 2);
            assert_eq!(rename[0].0.name, "old_col");
            assert_eq!(rename[0].1.name, "new_col");
        } else {
            panic!("Expected Star expression");
        }
    }

    #[test]
    fn test_parse_star_combined() {
        // EXCLUDE + REPLACE combined
        let result =
            Parser::parse_sql("SELECT * EXCLUDE (id) REPLACE (name || '!' AS name) FROM t")
                .unwrap();
        let select = result[0].as_select().unwrap();
        if let Expression::Star(star) = &select.expressions[0] {
            assert!(star.except.is_some());
            assert!(star.replace.is_some());
        } else {
            panic!("Expected Star expression");
        }
    }

    #[test]
    fn test_parse_spatial_types() {
        // GEOMETRY with subtype and SRID (PostgreSQL syntax)
        let result = Parser::parse_sql("CREATE TABLE t (geom GEOMETRY(Point, 4326))").unwrap();
        if let Expression::CreateTable(ct) = &result[0] {
            assert_eq!(ct.columns.len(), 1);
            match &ct.columns[0].data_type {
                DataType::Geometry { subtype, srid } => {
                    assert_eq!(subtype.as_deref(), Some("POINT"));
                    assert_eq!(*srid, Some(4326));
                }
                _ => panic!("Expected Geometry type"),
            }
        }

        // GEOGRAPHY without parameters
        let result = Parser::parse_sql("CREATE TABLE t (loc GEOGRAPHY)").unwrap();
        if let Expression::CreateTable(ct) = &result[0] {
            match &ct.columns[0].data_type {
                DataType::Geography { subtype, srid } => {
                    assert!(subtype.is_none());
                    assert!(srid.is_none());
                }
                _ => panic!("Expected Geography type"),
            }
        }

        // GEOMETRY subtype only (no SRID)
        let result = Parser::parse_sql("CREATE TABLE t (geom GEOMETRY(LineString))").unwrap();
        if let Expression::CreateTable(ct) = &result[0] {
            match &ct.columns[0].data_type {
                DataType::Geometry { subtype, srid } => {
                    assert_eq!(subtype.as_deref(), Some("LINESTRING"));
                    assert!(srid.is_none());
                }
                _ => panic!("Expected Geometry type"),
            }
        }

        // Simple POINT type (MySQL-style without SRID)
        let result = Parser::parse_sql("CREATE TABLE t (pt POINT)").unwrap();
        if let Expression::CreateTable(ct) = &result[0] {
            match &ct.columns[0].data_type {
                DataType::Geometry { subtype, srid } => {
                    assert_eq!(subtype.as_deref(), Some("POINT"));
                    assert!(srid.is_none());
                }
                _ => panic!("Expected Geometry type"),
            }
        }
    }

    #[test]
    fn test_parse_duckdb_pivot_simple() {
        let sql = "PIVOT Cities ON Year USING SUM(Population)";
        let result = Parser::parse_sql(sql);
        assert!(
            result.is_ok(),
            "Failed to parse: {} - {:?}",
            sql,
            result.err()
        );
        let stmts = result.unwrap();
        assert_eq!(
            stmts.len(),
            1,
            "Expected 1 statement, got {}: {:?}",
            stmts.len(),
            stmts
        );
        match &stmts[0] {
            Expression::Pivot(p) => {
                assert!(!p.unpivot);
                assert!(!p.expressions.is_empty(), "Should have ON expressions");
                assert!(!p.using.is_empty(), "Should have USING expressions");
            }
            other => panic!("Expected Pivot, got {:?}", other),
        }
    }

    #[test]
    fn test_parse_duckdb_pivot_with_group_by() {
        let sql = "PIVOT Cities ON Year USING SUM(Population) GROUP BY Country";
        let result = Parser::parse_sql(sql);
        assert!(
            result.is_ok(),
            "Failed to parse: {} - {:?}",
            sql,
            result.err()
        );
    }

    #[test]
    fn test_parse_duckdb_unpivot() {
        let sql = "UNPIVOT monthly_sales ON jan, feb, mar INTO NAME month VALUE sales";
        let result = Parser::parse_sql(sql);
        assert!(
            result.is_ok(),
            "Failed to parse: {} - {:?}",
            sql,
            result.err()
        );
    }

    #[test]
    fn test_parse_standard_pivot_in_from() {
        let sql = "SELECT * FROM cities PIVOT(SUM(population) FOR year IN (2000, 2010, 2020))";
        let result = Parser::parse_sql(sql);
        assert!(
            result.is_ok(),
            "Failed to parse: {} - {:?}",
            sql,
            result.err()
        );
    }

    fn assert_pivot_roundtrip(sql: &str) {
        let parsed = crate::parse(sql, crate::DialectType::DuckDB);
        assert!(
            parsed.is_ok(),
            "Failed to parse: {} - {:?}",
            sql,
            parsed.err()
        );
        let stmts = parsed.unwrap();
        assert_eq!(stmts.len(), 1, "Expected 1 statement for: {}", sql);
        let generated = crate::generate(&stmts[0], crate::DialectType::DuckDB);
        assert!(
            generated.is_ok(),
            "Failed to generate: {} - {:?}",
            sql,
            generated.err()
        );
        let result = generated.unwrap();
        assert_eq!(result.trim(), sql, "Round-trip mismatch for: {}", sql);
    }

    fn assert_pivot_roundtrip_bq(sql: &str) {
        let parsed = crate::parse(sql, crate::DialectType::BigQuery);
        assert!(
            parsed.is_ok(),
            "Failed to parse: {} - {:?}",
            sql,
            parsed.err()
        );
        let stmts = parsed.unwrap();
        assert_eq!(stmts.len(), 1, "Expected 1 statement for: {}", sql);
        let generated = crate::generate(&stmts[0], crate::DialectType::BigQuery);
        assert!(
            generated.is_ok(),
            "Failed to generate: {} - {:?}",
            sql,
            generated.err()
        );
        let result = generated.unwrap();
        assert_eq!(result.trim(), sql, "Round-trip mismatch for: {}", sql);
    }

    #[test]
    fn test_pivot_roundtrip_duckdb_simple() {
        assert_pivot_roundtrip("PIVOT Cities ON Year USING SUM(Population)");
    }

    #[test]
    fn test_pivot_roundtrip_duckdb_group_by() {
        assert_pivot_roundtrip("PIVOT Cities ON Year USING SUM(Population) GROUP BY Country");
    }

    #[test]
    fn test_pivot_roundtrip_duckdb_in_clause() {
        assert_pivot_roundtrip(
            "PIVOT Cities ON Year IN (2000, 2010) USING SUM(Population) GROUP BY Country",
        );
    }

    #[test]
    fn test_pivot_roundtrip_duckdb_multiple_using() {
        assert_pivot_roundtrip("PIVOT Cities ON Year USING SUM(Population) AS total, MAX(Population) AS max GROUP BY Country");
    }

    #[test]
    fn test_pivot_roundtrip_duckdb_multiple_on() {
        assert_pivot_roundtrip("PIVOT Cities ON Country, Name USING SUM(Population)");
    }

    #[test]
    fn test_pivot_roundtrip_duckdb_concat_on() {
        assert_pivot_roundtrip("PIVOT Cities ON Country || '_' || Name USING SUM(Population)");
    }

    #[test]
    fn test_pivot_roundtrip_duckdb_multiple_group_by() {
        assert_pivot_roundtrip("PIVOT Cities ON Year USING SUM(Population) GROUP BY Country, Name");
    }

    #[test]
    fn test_pivot_roundtrip_duckdb_first() {
        assert_pivot_roundtrip("PIVOT Cities ON Year USING FIRST(Population)");
    }

    #[test]
    fn test_unpivot_roundtrip_duckdb_basic() {
        assert_pivot_roundtrip(
            "UNPIVOT monthly_sales ON jan, feb, mar, apr, may, jun INTO NAME month VALUE sales",
        );
    }

    #[test]
    fn test_unpivot_roundtrip_duckdb_subquery() {
        assert_pivot_roundtrip("UNPIVOT (SELECT 1 AS col1, 2 AS col2) ON foo, bar");
    }

    #[test]
    fn test_pivot_roundtrip_duckdb_cte() {
        assert_pivot_roundtrip("WITH pivot_alias AS (PIVOT Cities ON Year USING SUM(Population) GROUP BY Country) SELECT * FROM pivot_alias");
    }

    #[test]
    fn test_pivot_roundtrip_duckdb_subquery() {
        assert_pivot_roundtrip("SELECT * FROM (PIVOT Cities ON Year USING SUM(Population) GROUP BY Country) AS pivot_alias");
    }

    #[test]
    fn test_pivot_roundtrip_standard_from() {
        assert_pivot_roundtrip("SELECT * FROM cities PIVOT(SUM(population) FOR year IN (2000, 2010, 2020) GROUP BY country)");
    }

    #[test]
    fn test_pivot_roundtrip_standard_bare_in() {
        assert_pivot_roundtrip("SELECT * FROM t PIVOT(SUM(y) FOR foo IN y_enum)");
    }

    #[test]
    fn test_unpivot_roundtrip_bigquery() {
        assert_pivot_roundtrip_bq("SELECT * FROM q UNPIVOT(values FOR quarter IN (b, c))");
    }

    #[test]
    fn test_pivot_roundtrip_bigquery_aliases() {
        assert_pivot_roundtrip_bq("SELECT cars, apples FROM some_table PIVOT(SUM(total_counts) FOR products IN ('general.cars' AS cars, 'food.apples' AS apples))");
    }

    #[test]
    fn test_unpivot_roundtrip_bigquery_parens() {
        assert_pivot_roundtrip_bq(
            "SELECT * FROM (SELECT * FROM `t`) AS a UNPIVOT((c) FOR c_name IN (v1, v2))",
        );
    }

    #[test]
    fn test_pivot_roundtrip_bigquery_multi_agg() {
        // Note: BigQuery fixture expects implicit aliases to become explicit AS
        let sql = "SELECT * FROM (SELECT a, b, c FROM test) PIVOT(SUM(b) AS d, COUNT(*) AS e FOR c IN ('x', 'y'))";
        assert_pivot_roundtrip_bq(sql);
    }

    // Additional fixture tests for UNPIVOT with COLUMNS and grouped ON
    #[test]
    fn test_unpivot_roundtrip_duckdb_columns_exclude() {
        assert_pivot_roundtrip(
            "UNPIVOT monthly_sales ON COLUMNS(* EXCLUDE (empid, dept)) INTO NAME month VALUE sales",
        );
    }

    #[test]
    fn test_unpivot_roundtrip_duckdb_grouped_columns() {
        assert_pivot_roundtrip("UNPIVOT monthly_sales ON (jan, feb, mar) AS q1, (apr, may, jun) AS q2 INTO NAME quarter VALUE month_1_sales, month_2_sales, month_3_sales");
    }

    #[test]
    fn test_unpivot_roundtrip_duckdb_cte_columns() {
        assert_pivot_roundtrip("WITH unpivot_alias AS (UNPIVOT monthly_sales ON COLUMNS(* EXCLUDE (empid, dept)) INTO NAME month VALUE sales) SELECT * FROM unpivot_alias");
    }

    #[test]
    fn test_unpivot_roundtrip_duckdb_subquery_columns() {
        assert_pivot_roundtrip("SELECT * FROM (UNPIVOT monthly_sales ON COLUMNS(* EXCLUDE (empid, dept)) INTO NAME month VALUE sales) AS unpivot_alias");
    }

    #[test]
    fn test_pivot_roundtrip_duckdb_cte_with_columns() {
        assert_pivot_roundtrip("WITH cities(country, name, year, population) AS (SELECT 'NL', 'Amsterdam', 2000, 1005 UNION ALL SELECT 'US', 'Seattle', 2020, 738) PIVOT cities ON year USING SUM(population)");
    }

    #[test]
    fn test_pivot_roundtrip_standard_first_with_alias() {
        // DuckDB fixture #73: comma before FOR is dropped in expected output
        let sql = "SELECT * FROM t PIVOT(FIRST(t) AS t, FOR quarter IN ('Q1', 'Q2'))";
        let expected = "SELECT * FROM t PIVOT(FIRST(t) AS t FOR quarter IN ('Q1', 'Q2'))";
        let parsed = crate::parse(sql, crate::DialectType::DuckDB);
        assert!(
            parsed.is_ok(),
            "Failed to parse: {} - {:?}",
            sql,
            parsed.err()
        );
        let stmts = parsed.unwrap();
        assert_eq!(stmts.len(), 1);
        let generated = crate::generate(&stmts[0], crate::DialectType::DuckDB);
        assert!(
            generated.is_ok(),
            "Failed to generate: {} - {:?}",
            sql,
            generated.err()
        );
        let result = generated.unwrap();
        assert_eq!(result.trim(), expected, "Round-trip mismatch");
    }

    #[test]
    fn test_pivot_roundtrip_bigquery_implicit_alias() {
        // BigQuery fixture #134: implicit aliases become explicit AS
        let sql = "SELECT * FROM (SELECT a, b, c FROM test) PIVOT(SUM(b) d, COUNT(*) e FOR c IN ('x', 'y'))";
        let expected = "SELECT * FROM (SELECT a, b, c FROM test) PIVOT(SUM(b) AS d, COUNT(*) AS e FOR c IN ('x', 'y'))";
        let parsed = crate::parse(sql, crate::DialectType::BigQuery);
        assert!(
            parsed.is_ok(),
            "Failed to parse: {} - {:?}",
            sql,
            parsed.err()
        );
        let stmts = parsed.unwrap();
        assert_eq!(stmts.len(), 1);
        let generated = crate::generate(&stmts[0], crate::DialectType::BigQuery);
        assert!(
            generated.is_ok(),
            "Failed to generate: {} - {:?}",
            sql,
            generated.err()
        );
        let result = generated.unwrap();
        assert_eq!(result.trim(), expected, "Round-trip mismatch");
    }

    #[test]
    fn test_duckdb_struct_enum_union_row_types() {
        use crate::DialectType;

        // Helper to test roundtrip with DuckDB dialect - runs in a thread with larger stack
        fn check(sql: &str, expected: Option<&str>) {
            let sql = sql.to_string();
            let expected = expected.map(|s| s.to_string());
            let result = std::thread::Builder::new()
                .stack_size(16 * 1024 * 1024) // 16MB stack
                .spawn(move || {
                    let expected_out = expected.as_deref().unwrap_or(&sql);
                    let parsed = crate::parse(&sql, DialectType::DuckDB);
                    assert!(
                        parsed.is_ok(),
                        "Failed to parse: {} - {:?}",
                        sql,
                        parsed.err()
                    );
                    let stmts = parsed.unwrap();
                    assert!(!stmts.is_empty(), "No statements parsed: {}", sql);
                    let generated = crate::generate(&stmts[0], DialectType::DuckDB);
                    assert!(
                        generated.is_ok(),
                        "Failed to generate: {} - {:?}",
                        sql,
                        generated.err()
                    );
                    let result = generated.unwrap();
                    assert_eq!(result.trim(), expected_out, "Mismatch for: {}", sql);
                })
                .expect("Failed to spawn test thread")
                .join();
            assert!(result.is_ok(), "Test thread panicked");
        }

        // UNION type
        check("CREATE TABLE tbl1 (u UNION(num INT, str TEXT))", None);
        // ENUM type
        check(
            "CREATE TABLE color (name ENUM('RED', 'GREEN', 'BLUE'))",
            None,
        );
        // ROW type -> STRUCT
        check(
            "SELECT CAST(ROW(1, 2) AS ROW(a INTEGER, b INTEGER))",
            Some("SELECT CAST(ROW(1, 2) AS STRUCT(a INT, b INT))"),
        );
        // STRUCT with parens
        check("CAST(x AS STRUCT(number BIGINT))", None);
        // STRUCT with quoted field names
        check(
            "CAST({'i': 1, 's': 'foo'} AS STRUCT(\"s\" TEXT, \"i\" INT))",
            None,
        );
        // Nested STRUCT
        check(
            "CAST(ROW(1, ROW(1)) AS STRUCT(number BIGINT, row STRUCT(number BIGINT)))",
            None,
        );
        // STRUCT with array suffix - test just the type parsing part
        // Note: STRUCT_PACK -> struct literal transform is a separate feature
        check("CAST(x AS STRUCT(a BIGINT)[][])", None);
        check("CAST(x AS STRUCT(a BIGINT)[])", None);
        // Double-colon cast with STRUCT type
        check("CAST({'a': 'b'} AS STRUCT(a TEXT))", None);
    }

    // Helper for roundtrip identity tests
    fn roundtrip(sql: &str) -> String {
        let ast =
            Parser::parse_sql(sql).unwrap_or_else(|e| panic!("Parse error for '{}': {}", sql, e));
        crate::generator::Generator::sql(&ast[0])
            .unwrap_or_else(|e| panic!("Generate error for '{}': {}", sql, e))
    }

    fn assert_roundtrip(sql: &str) {
        let result = roundtrip(sql);
        assert_eq!(result, sql, "\n  Input:    {}\n  Output:   {}", sql, result);
    }

    fn assert_roundtrip_expected(sql: &str, expected: &str) {
        let result = roundtrip(sql);
        assert_eq!(
            result, expected,
            "\n  Input:    {}\n  Expected: {}\n  Output:   {}",
            sql, expected, result
        );
    }

    #[test]
    fn test_xmlelement_basic() {
        assert_roundtrip("SELECT XMLELEMENT(NAME foo)");
    }

    #[test]
    fn test_xmlelement_with_xmlattributes() {
        assert_roundtrip("SELECT XMLELEMENT(NAME foo, XMLATTRIBUTES('xyz' AS bar))");
    }

    #[test]
    fn test_xmlelement_with_multiple_attrs() {
        assert_roundtrip("SELECT XMLELEMENT(NAME test, XMLATTRIBUTES(a, b)) FROM test");
    }

    #[test]
    fn test_xmlelement_with_content() {
        assert_roundtrip(
            "SELECT XMLELEMENT(NAME foo, XMLATTRIBUTES(CURRENT_DATE AS bar), 'cont', 'ent')",
        );
    }

    #[test]
    fn test_xmlelement_nested() {
        assert_roundtrip("SELECT XMLELEMENT(NAME foo, XMLATTRIBUTES('xyz' AS bar), XMLELEMENT(NAME abc), XMLCOMMENT('test'), XMLELEMENT(NAME xyz))");
    }

    #[test]
    fn test_on_conflict_do_update() {
        assert_roundtrip("INSERT INTO newtable AS t(a, b, c) VALUES (1, 2, 3) ON CONFLICT(c) DO UPDATE SET a = t.a + 1 WHERE t.a < 1");
    }

    #[test]
    fn test_on_conflict_do_nothing() {
        // ON CONFLICT(id) is the canonical form (no space before paren)
        assert_roundtrip_expected(
            "INSERT INTO test (id, name) VALUES (1, 'test') ON CONFLICT (id) DO NOTHING",
            "INSERT INTO test (id, name) VALUES (1, 'test') ON CONFLICT(id) DO NOTHING",
        );
    }

    #[test]
    fn test_truncate_restart_identity() {
        assert_roundtrip("TRUNCATE TABLE t1 RESTART IDENTITY");
    }

    #[test]
    fn test_truncate_restart_identity_restrict() {
        assert_roundtrip("TRUNCATE TABLE t1 RESTART IDENTITY RESTRICT");
    }

    #[test]
    fn test_insert_by_name() {
        assert_roundtrip("INSERT INTO x BY NAME SELECT 1 AS y");
    }

    #[test]
    fn test_insert_default_values_returning() {
        assert_roundtrip("INSERT INTO t DEFAULT VALUES RETURNING (c1)");
    }

    #[test]
    fn test_union_all_by_name() {
        assert_roundtrip("SELECT 1 AS x UNION ALL BY NAME SELECT 2 AS x");
    }

    #[test]
    fn test_minus_as_except() {
        // MINUS is Oracle/Redshift syntax for EXCEPT
        assert_roundtrip_expected(
            "SELECT foo, bar FROM table_1 MINUS SELECT foo, bar FROM table_2",
            "SELECT foo, bar FROM table_1 EXCEPT SELECT foo, bar FROM table_2",
        );
    }

    #[test]
    fn test_filter_without_where() {
        assert_roundtrip_expected(
            "SELECT SUM(x) FILTER (x = 1)",
            "SELECT SUM(x) FILTER(WHERE x = 1)",
        );
    }

    #[test]
    fn test_comment_on_materialized_view() {
        assert_roundtrip("COMMENT ON MATERIALIZED VIEW my_view IS 'this'");
    }

    #[test]
    fn test_create_index_concurrently() {
        assert_roundtrip("CREATE INDEX CONCURRENTLY idx ON t(c)");
    }

    #[test]
    fn test_create_index_if_not_exists() {
        assert_roundtrip("CREATE INDEX IF NOT EXISTS idx ON t(c)");
    }

    #[test]
    fn test_alter_table_partition_hive() {
        // Hive: ALTER TABLE x PARTITION(y=z) ADD COLUMN a VARCHAR(10)
        assert_roundtrip("ALTER TABLE x PARTITION(y = z) ADD COLUMN a VARCHAR(10)");
    }

    #[test]
    fn test_alter_table_change_column_hive() {
        // Hive/MySQL: CHANGE COLUMN old_name new_name data_type
        assert_roundtrip("ALTER TABLE x CHANGE COLUMN a a VARCHAR(10)");
    }

    #[test]
    fn test_alter_table_add_columns_hive() {
        // Hive/Spark: ADD COLUMNS (col1 TYPE, col2 TYPE)
        assert_roundtrip("ALTER TABLE X ADD COLUMNS (y INT, z STRING)");
    }

    #[test]
    fn test_alter_table_add_columns_cascade_hive() {
        // Hive/Spark: ADD COLUMNS (col1 TYPE, col2 TYPE) CASCADE
        assert_roundtrip("ALTER TABLE X ADD COLUMNS (y INT, z STRING) CASCADE");
    }

    #[test]
    fn test_group_by_with_cube() {
        // Hive/MySQL: GROUP BY ... WITH CUBE
        let sql = "SELECT key, value FROM T1 GROUP BY key, value WITH CUBE";
        let result = Parser::parse_sql(sql).unwrap();
        let select = result[0].as_select().unwrap();

        if let Some(group_by) = &select.group_by {
            // Debug: print the expressions
            eprintln!("GROUP BY expressions: {:?}", group_by.expressions);

            // Check if there's a Cube expression with empty expressions
            let has_cube = group_by.expressions.iter().any(|e| {
                if let Expression::Cube(c) = e {
                    c.expressions.is_empty()
                } else {
                    false
                }
            });
            assert!(
                has_cube,
                "Should have a Cube expression with empty expressions in GROUP BY"
            );
        } else {
            panic!("Should have GROUP BY clause");
        }
    }

    #[test]
    fn test_group_by_with_rollup() {
        // Hive/MySQL: GROUP BY ... WITH ROLLUP
        let sql = "SELECT key, value FROM T1 GROUP BY key, value WITH ROLLUP";
        let result = Parser::parse_sql(sql).unwrap();
        let select = result[0].as_select().unwrap();

        if let Some(group_by) = &select.group_by {
            // Check if there's a Rollup expression with empty expressions
            let has_rollup = group_by.expressions.iter().any(|e| {
                if let Expression::Rollup(r) = e {
                    r.expressions.is_empty()
                } else {
                    false
                }
            });
            assert!(
                has_rollup,
                "Should have a Rollup expression with empty expressions in GROUP BY"
            );
        } else {
            panic!("Should have GROUP BY clause");
        }
    }
}

#[cfg(test)]
mod join_marker_tests {
    use super::*;
    use crate::dialects::DialectType;

    #[test]
    fn test_oracle_join_marker_simple() {
        let sql = "select a.baz from a where a.baz = b.baz (+)";
        let result = Parser::parse_sql(sql);
        println!("Result: {:?}", result);
        assert!(result.is_ok(), "Parse error: {:?}", result.err());
    }

    #[test]
    fn test_oracle_join_marker_with_comma_join_and_aliases() {
        let sql = "SELECT e1.x, e2.x FROM e e1, e e2 WHERE e1.y = e2.y (+)";
        let result = crate::dialects::Dialect::get(DialectType::Oracle).parse(sql);
        println!("Result: {:?}", result);
        assert!(result.is_ok(), "Parse error: {:?}", result.err());
    }

    #[test]
    fn test_oracle_xmltable_with_quoted_dot_columns() {
        let sql = "SELECT warehouse_name warehouse,\n   warehouse2.\"Water\", warehouse2.\"Rail\"\n   FROM warehouses,\n   XMLTABLE('/Warehouse'\n      PASSING warehouses.warehouse_spec\n      COLUMNS\n         \"Water\" varchar2(6) PATH 'WaterAccess',\n         \"Rail\" varchar2(6) PATH 'RailAccess')\n      warehouse2";
        let result = crate::dialects::Dialect::get(DialectType::Oracle).parse(sql);
        println!("Result: {:?}", result);
        assert!(result.is_ok(), "Parse error: {:?}", result.err());
    }

    #[test]
    fn test_oracle_quoted_dot_projection() {
        let sql = "SELECT warehouse2.\"Water\", warehouse2.\"Rail\" FROM warehouses warehouse2";
        let result = crate::dialects::Dialect::get(DialectType::Oracle).parse(sql);
        println!("Result: {:?}", result);
        assert!(result.is_ok(), "Parse error: {:?}", result.err());
    }

    #[test]
    fn test_oracle_xmltable_columns_only() {
        let sql = "SELECT * FROM XMLTABLE('/Warehouse' PASSING warehouses.warehouse_spec COLUMNS \"Water\" varchar2(6) PATH 'WaterAccess', \"Rail\" varchar2(6) PATH 'RailAccess') warehouse2";
        let result = crate::dialects::Dialect::get(DialectType::Oracle).parse(sql);
        println!("Result: {:?}", result);
        assert!(result.is_ok(), "Parse error: {:?}", result.err());
    }

    #[test]
    fn test_oracle_projection_alias_then_quoted_dot() {
        let sql =
            "SELECT warehouse_name warehouse, warehouse2.\"Water\" FROM warehouses warehouse2";
        let result = crate::dialects::Dialect::get(DialectType::Oracle).parse(sql);
        println!("Result: {:?}", result);
        assert!(result.is_ok(), "Parse error: {:?}", result.err());
    }
}

#[cfg(test)]
mod clickhouse_parser_regression_tests {
    use crate::dialects::DialectType;

    #[test]
    fn test_clickhouse_select_format_clause_not_alias() {
        let sql = "SELECT 1 FORMAT TabSeparated";
        let result = crate::dialects::Dialect::get(DialectType::ClickHouse).parse(sql);
        assert!(result.is_ok(), "Parse error: {:?}", result.err());
    }

    #[test]
    fn test_clickhouse_projection_select_group_by_parses() {
        let sql = "CREATE TABLE t (a String, b String, c UInt64, PROJECTION p1 (SELECT a, sum(c) GROUP BY a, b), PROJECTION p2 (SELECT b, sum(c) GROUP BY b)) ENGINE=MergeTree()";
        let result = crate::dialects::Dialect::get(DialectType::ClickHouse).parse(sql);
        assert!(result.is_ok(), "Parse error: {:?}", result.err());
    }

    /// ClickHouse ternary operator AST structure tests.
    /// Ported from Python sqlglot: tests/dialects/test_clickhouse.py::test_ternary (lines 765-778).
    /// Verifies that `x ? (y ? 1 : 2) : 3` parses into nested IfFunc nodes
    /// with the correct AST shape.
    #[test]
    fn test_clickhouse_ternary_ast_structure() {
        use crate::expressions::Expression;

        let result = crate::parse_one("x ? (y ? 1 : 2) : 3", DialectType::ClickHouse);
        assert!(result.is_ok(), "Parse error: {:?}", result.err());
        let ternary = result.unwrap();

        // Root should be IfFunc
        let if_func = match &ternary {
            Expression::IfFunc(f) => f,
            other => panic!("Expected IfFunc, got {:?}", std::mem::discriminant(other)),
        };

        // this (condition) should be Column "x"
        assert!(
            matches!(&if_func.condition, Expression::Column(_)),
            "Expected condition to be Column, got {:?}",
            std::mem::discriminant(&if_func.condition)
        );

        // true branch should be Paren
        assert!(
            matches!(&if_func.true_value, Expression::Paren(_)),
            "Expected true_value to be Paren, got {:?}",
            std::mem::discriminant(&if_func.true_value)
        );

        // false branch should be Literal
        let false_value = if_func.false_value.as_ref().expect("Expected false_value");
        assert!(
            matches!(false_value, Expression::Literal(_)),
            "Expected false_value to be Literal, got {:?}",
            std::mem::discriminant(false_value)
        );

        // Inside the Paren, the nested ternary should also be IfFunc
        let inner_paren = match &if_func.true_value {
            Expression::Paren(p) => p,
            _ => unreachable!(),
        };
        let nested_if = match &inner_paren.this {
            Expression::IfFunc(f) => f,
            other => panic!(
                "Expected nested IfFunc, got {:?}",
                std::mem::discriminant(other)
            ),
        };

        // Nested condition should be Column "y"
        assert!(
            matches!(&nested_if.condition, Expression::Column(_)),
            "Expected nested condition to be Column, got {:?}",
            std::mem::discriminant(&nested_if.condition)
        );

        // Nested true should be Literal 1
        assert!(
            matches!(&nested_if.true_value, Expression::Literal(_)),
            "Expected nested true_value to be Literal, got {:?}",
            std::mem::discriminant(&nested_if.true_value)
        );

        // Nested false should be Literal 2
        let nested_false = nested_if
            .false_value
            .as_ref()
            .expect("Expected nested false_value");
        assert!(
            matches!(nested_false, Expression::Literal(_)),
            "Expected nested false_value to be Literal, got {:?}",
            std::mem::discriminant(nested_false)
        );
    }

    /// Verify that `a AND b ? 1 : 2` has And as the ternary condition
    /// (AND binds tighter than ?).
    /// Ported from Python sqlglot: test_clickhouse.py line 778.
    #[test]
    fn test_clickhouse_ternary_and_precedence() {
        use crate::expressions::Expression;

        let result = crate::parse_one("a and b ? 1 : 2", DialectType::ClickHouse);
        assert!(result.is_ok(), "Parse error: {:?}", result.err());
        let ternary = result.unwrap();

        let if_func = match &ternary {
            Expression::IfFunc(f) => f,
            other => panic!("Expected IfFunc, got {:?}", std::mem::discriminant(other)),
        };

        // The condition should be And (not just Column "b")
        assert!(
            matches!(&if_func.condition, Expression::And(_)),
            "Expected condition to be And, got {:?}",
            std::mem::discriminant(&if_func.condition)
        );
    }

    #[test]
    fn test_parse_interval_bare_number_duckdb() {
        use crate::dialects::{Dialect, DialectType};
        let sql = "SELECT CAST('2018-01-01 00:00:00' AS DATE) + INTERVAL 3 DAY";
        let d = Dialect::get(DialectType::DuckDB);
        match d.parse(sql) {
            Ok(result) => {
                assert!(!result.is_empty(), "Should parse to at least one statement");
                // Test transpilation to DuckDB target - should normalize number to quoted string
                let output_duckdb = d.transpile_to(sql, DialectType::DuckDB).unwrap();
                assert_eq!(
                    output_duckdb[0],
                    "SELECT CAST('2018-01-01 00:00:00' AS DATE) + INTERVAL '3' DAY",
                    "DuckDB output should have quoted interval value"
                );
                // Test transpilation to Hive target
                let output_hive = d.transpile_to(sql, DialectType::Hive).unwrap();
                assert_eq!(
                    output_hive[0],
                    "SELECT CAST('2018-01-01 00:00:00' AS DATE) + INTERVAL '3' DAY",
                    "Hive output should have quoted interval value"
                );
            }
            Err(e) => panic!("Failed to parse DuckDB INTERVAL 3 DAY: {}", e),
        }
    }
}