Enum SelectExpr 

pub enum SelectExpr {
    Wildcard(WildcardOptions),
    QualifiedWildcard(TableReference, WildcardOptions),
    Expression(Expr),
}

Represents a SELECT expression in a SQL query.

SelectExpr supports three types of expressions commonly found in the SELECT clause:

• Wildcard (*) - Selects all columns
• Qualified wildcard (table.*) - Selects all columns from a specific table
• Regular expression - Any other expression like columns, functions, literals etc.

This enum is typically used when you need to handle wildcards. After expanding * in the query, you can use Expr for all other expressions.

Examples

use datafusion_expr::col;
use datafusion_expr::expr::WildcardOptions;
use datafusion_expr::select_expr::SelectExpr;

// SELECT *
let wildcard = SelectExpr::Wildcard(WildcardOptions::default());

// SELECT mytable.*
let qualified = SelectExpr::QualifiedWildcard(
    "mytable".into(),
    WildcardOptions::default()
);

// SELECT col1
let expr = SelectExpr::Expression(col("col1").into());

Variants

Wildcard(WildcardOptions)

Represents a wildcard (*) that selects all columns from all tables. The WildcardOptions control additional behavior like exclusions.

QualifiedWildcard(TableReference, WildcardOptions)

Represents a qualified wildcard (table.*) that selects all columns from a specific table. The TableReference specifies the table and WildcardOptions control additional behavior.

Expression(Expr)

Represents any other valid SELECT expression like column references, function calls, literals, etc.

Trait Implementations

impl Clone for SelectExpr

fn clone(&self) -> SelectExpr

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for SelectExpr

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

Formats the value using the given formatter.

impl Display for SelectExpr

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

Formats the value using the given formatter.

impl<'a> From<(Option<&'a TableReference>, &'a Arc<Field>)> for SelectExpr

Create an SelectExpr::Expression from an optional qualifier and a FieldRef. This is useful for creating SelectExpr::Expression from a DFSchema.

See example on Expr

fn from(value: (Option<&'a TableReference>, &'a FieldRef)) -> Self

Converts to this type from the input type.

impl From<Column> for SelectExpr

Create an SelectExpr::Expression from a Column

fn from(value: Column) -> Self

Converts to this type from the input type.

impl From<Expr> for SelectExpr

fn from(expr: Expr) -> Self

Converts to this type from the input type.