MySQL DELETE FROM 以子查询为条件

2021-11-20 00:00:00 sql subquery mysql sql-delete in-subquery

我正在尝试进行这样的查询:

I am trying to do a query like this:

DELETE FROM term_hierarchy AS th
WHERE th.parent = 1015 AND th.tid IN (
    SELECT DISTINCT(th1.tid)
    FROM term_hierarchy AS th1
    INNER JOIN term_hierarchy AS th2 ON (th1.tid = th2.tid AND th2.parent != 1015)
    WHERE th1.parent = 1015
);

如您所知，如果同一个 tid 有其他父级，我想删除与 1015 的父级关系.但是，这给我带来了语法错误:

As you can probably tell, I want to delete the parent relation to 1015 if the same tid has other parents. However, that yields me a syntax error:

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'AS th
WHERE th.parent = 1015 AND th.tid IN (
  SELECT DISTINCT(th1.tid)
  FROM ter' at line 1

我已经检查了文档，并自行运行了子查询，一切似乎都已检查完毕.谁能弄清楚这里出了什么问题?

I have checked the documentation, and run the subquery by itself, and it all seems to check out. Can anyone figure out what's wrong here?

更新:如下所述，MySQL 不允许您删除的表用于条件的子查询.

Update: As answered below, MySQL does not allow the table you're deleting from be used in a subquery for the condition.

推荐答案

不能指定要删除的目标表.

You cannot specify target table for delete.

解决方法

create table term_hierarchy_backup (tid int(10)); <- check data type

insert into term_hierarchy_backup 
SELECT DISTINCT(th1.tid)
FROM term_hierarchy AS th1
INNER JOIN term_hierarchy AS th2 ON (th1.tid = th2.tid AND th2.parent != 1015)
WHERE th1.parent = 1015;

DELETE FROM term_hierarchy AS th
WHERE th.parent = 1015 AND th.tid IN (select tid from term_hierarchy_backup);

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