Function resolve_group_by_expr

nodedb-sql/src/planner/aggregate.rs:178–212

Resolve a GROUP BY expression that references a SELECT alias or ordinal. `GROUP BY b` where `b` is an alias → returns the aliased expression. `GROUP BY 1` → returns the 1st SELECT expression (0-indexed).

(
    expr: &ast::Expr,
    select_items: &'a [ast::SelectItem],
)

/// `GROUP BY b` where `b` is an alias → returns the aliased expression.
/// `GROUP BY 1` → returns the 1st SELECT expression (0-indexed).
fn resolve_group_by_expr<'a>(
    expr: &ast::Expr,
    select_items: &'a [ast::SelectItem],
) -> Option<&'a ast::Expr> {
    match expr {
        ast::Expr::Identifier(ident) => {
            let alias_name = normalize_ident(ident);
            select_items.iter().find_map(|item| {
                if let ast::SelectItem::ExprWithAlias { expr, alias } = item
                    && normalize_ident(alias) == alias_name
                {
                    Some(expr)
                } else {
                    None
                }
            })
        }
        ast::Expr::Value(v) => {
            if let ast::Value::Number(n, _) = &v.value
                && let Ok(idx) = n.parse::<usize>()
                && idx >= 1
                && idx <= select_items.len()
            {
                match &select_items[idx - 1] {
                    ast::SelectItem::UnnamedExpr(e) => Some(e),
                    ast::SelectItem::ExprWithAlias { expr, .. } => Some(expr),
                    _ => None,
                }
            } else {
                None
            }
        }
        _ => None,
    }
}

/// Extract the bucket interval from a time_bucket() call.
///