Function try_equijoin_pair

nodedb-sql/src/planner/dml_update_delete.rs:225–269

Try to extract `(target_col, source_col)` from an equality expression where one side is `target_ref.col` and the other is `source_ref.col`. Also handles unqualified names by assuming they belong to the target.

(
    expr: &ast::Expr,
    target_ref: &str,
    source_ref: &str,
)

/// where one side is `target_ref.col` and the other is `source_ref.col`.
/// Also handles unqualified names by assuming they belong to the target.
fn try_equijoin_pair(
    expr: &ast::Expr,
    target_ref: &str,
    source_ref: &str,
) -> Option<(String, String)> {
    let ast::Expr::BinaryOp {
        left,
        op: ast::BinaryOperator::Eq,
        right,
    } = expr
    else {
        return None;
    };

    let lhs = qualified_ident_pair(left);
    let rhs = qualified_ident_pair(right);

    match (lhs, rhs) {
        (Some((lt, lc)), Some((rt, rc))) => {
            if lt == target_ref && rt == source_ref {
                Some((lc, rc))
            } else if lt == source_ref && rt == target_ref {
                Some((rc, lc))
            } else {
                None
            }
        }
        // One side is unqualified — treat it as belonging to target.
        (Some((t, c)), None) if t == source_ref => {
            if let ast::Expr::Identifier(ident) = right.as_ref() {
                Some((normalize_ident(ident), c))
            } else {
                None
            }
        }
        (None, Some((t, c))) if t == source_ref => {
            if let ast::Expr::Identifier(ident) = left.as_ref() {
                Some((normalize_ident(ident), c))
            } else {
                None
            }
        }
        _ => None,
    }
}

/// Convert `update.assignments` into `Vec<(col, SqlExpr)>`.
fn convert_assignments(assignments: &[ast::Assignment]) -> Result<Vec<(String, SqlExpr)>> {