Enum Projection 

pub enum Projection {
    All(Vec<String>),
    Columns(Vec<ProjectedColumn>),
}

Projection specification for SELECT clauses.

Represents either all columns (after wildcard expansion) or specific columns.

Variants

All(Vec<String>)

All columns (expanded from *). Contains the list of column names in definition order.

Columns(Vec<ProjectedColumn>)

Specific columns/expressions.

Implementations

impl Projection

pub fn len(&self) -> usize

Returns the number of columns in the projection.

pub fn is_empty(&self) -> bool

Returns true if the projection has no columns.

pub fn column_names(&self) -> Vec<Option<&str>>

Returns the column names in the projection.

For Projection::All, all names are present (from the wildcard expansion). For Projection::Columns, names may be None for complex expressions without aliases. See ProjectedColumn::output_name for details.

Trait Implementations

impl Clone for Projection

fn clone(&self) -> Projection

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Projection

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

Formats the value using the given formatter.