Function inject_column_aliases

datafusion/sql/src/unparser/rewrite.rs:464–492

Injects column aliases into the projection of a logical plan by wrapping expressions with `Expr::Alias` using the provided list of aliases. Example: - `SELECT col1, col2 FROM table` with aliases `["alias_1", "some_alias_2"]` will be transformed to - `SELECT col1 AS alias_1, col2 AS some_alias_2 FROM table`

(
    projection: &Projection,
    aliases: impl IntoIterator<Item = Ident>,
)

/// - `SELECT col1, col2 FROM table` with aliases `["alias_1", "some_alias_2"]` will be transformed to
/// - `SELECT col1 AS alias_1, col2 AS some_alias_2 FROM table`
pub(super) fn inject_column_aliases(
    projection: &Projection,
    aliases: impl IntoIterator<Item = Ident>,
) -> LogicalPlan {
    let mut updated_projection = projection.clone();

    let new_exprs = updated_projection
        .expr
        .into_iter()
        .zip(aliases)
        .map(|(expr, col_alias)| {
            let relation = match &expr {
                Expr::Column(col) => col.relation.clone(),
                _ => None,
            };

            Expr::Alias(Alias {
                expr: Box::new(expr.clone()),
                relation,
                name: col_alias.value,
                metadata: None,
            })
        })
        .collect::<Vec<_>>();

    updated_projection.expr = new_exprs;

    LogicalPlan::Projection(updated_projection)
}

fn find_projection(logical_plan: &LogicalPlan) -> Option<&Projection> {
    match logical_plan {