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;