Struct SnowflakeDialect 

pub struct SnowflakeDialect;

Snowflake 方言实现（云数仓，独立实现）

支持 Snowflake 特有特性：

• VARIANT/OBJECT/ARRAY 半结构化类型
• COPY INTO 数据加载
• TIME TRAVEL 时间旅行查询

Implementations

impl SnowflakeDialect

Snowflake 特有 SQL 构造方法

pub fn build_copy_into(&self, target: &str, source: &str) -> String

生成 COPY INTO 数据加载语句

COPY INTO target FROM source

pub fn build_time_travel_at(&self, table: &str, timestamp: &str) -> String

生成 TIME TRAVEL AT 查询语句

SELECT * FROM table AT(OBJECT => timestamp)

pub fn build_time_travel_before(&self, table: &str, timestamp: &str) -> String

生成 TIME TRAVEL BEFORE 查询语句

SELECT * FROM table BEFORE(timestamp => timestamp)

Trait Implementations

impl Clone for SnowflakeDialect

fn clone(&self) -> SnowflakeDialect

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for SnowflakeDialect

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Dialect for SnowflakeDialect

Available on crate feature dialect-snowflake only.

fn clone_box(&self) -> Box<dyn Dialect>

克隆为 trait object（用于 QueryBuilder::clone_for_count）。

fn db_type(&self) -> DbType

返回该方言对应的数据库类型

fn quote(&self, identifier: &str) -> String

引用标识符（表名、列名等）

fn escape_string(&self, s: &str) -> String

转义字符串字面量，确保可安全嵌入 SQL

fn supports_returning(&self) -> bool

该方言是否支持 RETURNING 子句

fn build_pagination(&self, sql: &str, page: u64, limit: u64) -> String

生成分页 SQL

fn json_type(&self) -> &'static str

获取 JSON 类型的 SQL 类型名

fn json_extract(&self, column: &str, path: &str) -> String

生成 JSON_EXTRACT 函数调用

fn full_text_search(&self, columns: &[&str], keyword: &str) -> String

生成全文检索 SQL

fn bool_to_int(&self, expr: &str) -> String

将布尔表达式转换为整型存储

fn concat(&self, parts: &[&str]) -> String

生成 CONCAT 函数调用

fn supports_if_exists(&self) -> bool

该方言是否支持 IF EXISTS

fn supports_if_not_exists(&self) -> bool

该方言是否支持 IF NOT EXISTS

fn auto_increment_keyword(&self) -> &'static str

获取自增列关键字

fn last_insert_id_sql(&self) -> Option<&'static str>

获取最近插入 ID 的 SQL（独立可执行语句）

fn build_create_table(&self, table: &str, columns: &[ColumnDef]) -> String

生成 CREATE TABLE 语句

fn build_alter_table(&self, table: &str, changes: &[TableChange]) -> String

生成 ALTER TABLE 语句

fn quote_checked(&self, identifier: &str) -> Result<String, DbError>

L-4 修复：带校验的引用标识符

fn build_drop_table(&self, table: &str, if_exists: bool) -> String

生成 DROP TABLE 语句

fn build_upsert_on_conflict( &self, conflict_columns: &[&str], update_columns: &[&str], all_columns: &[String], ) -> Option<String>

P2-6：生成批量 upsert 的冲突处理子句（ON CONFLICT / ON DUPLICATE KEY UPDATE）

fn build_lock_clause(&self, lock_type: LockType) -> Option<String>

P2-3：生成行锁子句（TASK-025/026）

fn supports_lock_for_update(&self) -> bool

P2-3：该方言是否支持 FOR UPDATE 行锁（TASK-029）

fn supports_lock_shared(&self) -> bool

P2-3：该方言是否支持共享锁（TASK-029）

fn build_insert_or_ignore_prefix(&self, table: &str) -> String

P2-4：生成 INSERT OR IGNORE 前缀（TASK-027）