Enum ScanProjection 

pub enum ScanProjection {
    Column(Projection),
    Computed {
        expr: ScalarExpr<FieldId>,
        alias: String,
    },
}

A column or computed expression to include in scan results.

Scans can project either stored columns or expressions computed from them.

Variants

Column(Projection)

Project a stored column directly.

Computed

Compute a value from an expression and return it with an alias.

Fields

expr: ScalarExpr<FieldId>

The expression to evaluate (can reference column field IDs).

alias: String

The name to give the computed column in results.

Implementations

impl ScanProjection

pub fn column<P: Into<Projection>>(proj: P) -> Self

Create a projection for a stored column.

pub fn computed<S: Into<String>>(expr: ScalarExpr<FieldId>, alias: S) -> Self

Create a projection for a computed expression.

Trait Implementations

impl Clone for ScanProjection

fn clone(&self) -> ScanProjection

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for ScanProjection

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

Formats the value using the given formatter.

impl From<&Projection> for ScanProjection

fn from(value: &Projection) -> Self

Converts to this type from the input type.

impl From<&ScanProjection> for ScanProjection

fn from(value: &ScanProjection) -> Self

Converts to this type from the input type.

impl From<Projection> for ScanProjection

fn from(value: Projection) -> Self

Converts to this type from the input type.