1DROP TRIGGER task_tr_delete; 2 3CREATE TRIGGER task_tr_delete 4 DELETE ON task 5BEGIN 6 UPDATE thread 7 SET task_count = task_count - 1 8 WHERE id = old.thread_id; 9 10 UPDATE thread 11 SET task_sum_cost = task_sum_cost - coalesce(old.cost, 0) 12 WHERE id = old.thread_id; 13 14 DELETE FROM task_comment WHERE task_id=old.id; 15 16 UPDATE thread_comment 17 SET task_count = task_count - 1 18 WHERE id = old.thread_comment_id; 19END;