-- 表尚未建成时放行。否则要求：列不可空，且无残留 NULL（不可空后必然为 0 行，双保险）。
SELECT
  (SELECT COUNT(*) FROM information_schema.TABLES
    WHERE TABLE_SCHEMA=DATABASE() AND TABLE_NAME='ado_module_dashboard_rebuild_job') = 0
  OR (
    (SELECT IS_NULLABLE FROM information_schema.COLUMNS
      WHERE TABLE_SCHEMA=DATABASE()
        AND TABLE_NAME='ado_module_dashboard_rebuild_job'
        AND COLUMN_NAME='cancel_requested_flag') = 'NO'
    AND
    (SELECT COUNT(*) FROM ado_module_dashboard_rebuild_job
      WHERE cancel_requested_flag IS NULL) = 0
  );