mysql - 删除记录时 SQL 触发器不起作用

Question

我有以下触发器:

CREATE TRIGGER `delete_scores_trigger` AFTER DELETE ON `scores`
   FOR EACH ROW BEGIN
UPDATE `users` 
   SET `darts_thrown` = ((SELECT `darts_thrown` 
                            FROM (SELECT * FROM users) as utable 
                           WHERE `id` = old.user_id) - old.darts_thrown) 
 WHERE `users`.`id` = old.user_id;
   END

“分数”表有两个外键，如下所示:

ALTER TABLE `scores`
  ADD CONSTRAINT `scores_game_id_foreign` FOREIGN KEY (`game_id`) 
    REFERENCES `games` (`id`) ON DELETE CASCADE ON UPDATE CASCADE,
  ADD CONSTRAINT `scores_user_id_foreign` FOREIGN KEY (`user_id`) 
    REFERENCES `users` (`id`) ON DELETE CASCADE ON UPDATE CASCADE;
COMMIT;

我想在删除 SCORE 后更新“用户”上的“darts_ thrown”字段。由于外键的存在，每当删除“游戏”时，相应的“分数”记录也会被删除。在那一刻之后或之前，应使用触发器更新 'user'.'darts_thron'。

Answer 1

https://dev.mysql.com/doc/refman/5.7/en/create-table-foreign-keys.html引用操作部分中有一条注释级联外键操作不会激活触发器。