CREATE OR REPLACE FUNCTION delete_product_changes()
RETURNS TRIGGER
LANGUAGE plpgsql
AS $$
BEGIN
    -- Delete all changes associated with the product
    DELETE FROM change
    WHERE product_code = OLD.code;

    RETURN OLD;
END;
$$;


CREATE TRIGGER trg_delete_product_changes
BEFORE DELETE
ON product
FOR EACH ROW
EXECUTE FUNCTION delete_product_changes();