Question

我正在尝试删除joins tables的记录，但它无效。

我的查询是：

DELETE FROM category
WHERE  catid NOT IN(SELECT av.catid
                    FROM   category av
                           JOIN rel
                             ON rel.catid = av.catid
                           JOIN main_list
                             ON rel.webid = main_list.mainid
                    GROUP  BY av.catid)

为什么此查询不起作用？它引发了以下错误：

#1093 - You can't specify target table 'category' for update in FROM clause

我该如何解决这个问题？我不确定错误是我做错了什么。

Answer 1

尝试使用LEFT JOIN。

DELETE  av
FROM    category av
        LEFT JOIN rel ON rel.catid = av.catid
        LEFT JOIN main_list ON rel.webid = main_list.mainid 
WHERE   rel.catid IS NULL

^{请在执行此查询之前备份您的数据库。}

Answer 2

试试这个::

DELETE c from  category c
LEFT join rel  ON rel.catid = av.catid
LEFT JOIN main_list  ON rel.webid = main_list.mainid
where rel.catid is null

或

DELETE FROM category
WHERE  catid NOT IN(
Select catid from 
(SELECT av.catid as catid
                    FROM   category av
                           JOIN rel
                             ON rel.catid = av.catid
                           JOIN main_list
                             ON rel.webid = main_list.mainid
                    GROUP  BY av.catid)  as tempCat)

删除不使用连接的查询

2 个答案: