Question

我在我的一个数据库的触发器中有这个更新语句：

UPDATE trainees 
SET rsi_total = (
  SELECT SUM(RsiTotal) as RsiTotal 
  FROM (
    SELECT MAX(hours) as RsiTotal 
    FROM courses 
      LEFT JOIN do_not_add ON courses.fk_class_id = do_not_add.fk_class_id 
      INNER JOIN trainees ON courses.FK_TRAINEES_ID = trainees.PK_TRAINEE_ID 
    WHERE do_not_add.fk_class_id IS NULL 
      AND trainees.pk_trainee_id = new.fk_trainees_id 
    GROUP BY courses.FK_CLASS_ID
  ) courses
) 
WHERE trainees.pk_trainee_id = new.fk_trainees_id

并且完全符合我的期望，最近我将我的数据库迁移到另一台机器并移动并重命名了几个表和列。所以我重写了这个触发器：

UPDATE main 
SET rsi_total = (
  SELECT SUM(RsiTotal) as RsiTotal 
  FROM (
    SELECT MAX(completed_hrs) as RsiTotal 
    FROM courses 
      LEFT JOIN jac.do_not_add ON courses.fk_class_id = do_not_add.fk_class_id 
      INNER JOIN main ON courses.fk_main_id = main.pk_main_id 
    WHERE do_not_add.fk_class_id IS NULL 
      AND main.pk_main_id = new.fk_main_id 
    GROUP BY courses.FK_CLASS_ID
  ) courses
) 
WHERE main.pk_main_id = new.fk_main_id

但我收到错误1093？我查看了这个错误，它说我无法更新正在更改的表，我不明白为什么旧的触发器继续工作但不是这个新的？

Answer 1

迁移到另一台计算机，您可能获得了更新版本的MySql，其中优化程序不再接受任何更长的子查询来访问正在更新的同一个表。

请看this detailed answer。

MySQL 5.7更新错误：1093

1 个答案: