我的数据库中有一个表story_category,其中包含损坏的条目。下一个查询将返回损坏的条目:

SELECT * 
FROM  story_category 
WHERE category_id NOT IN (
    SELECT DISTINCT category.id 
    FROM category INNER JOIN 
       story_category ON category_id=category.id);

我试图删除它们执行:

DELETE FROM story_category 
WHERE category_id NOT IN (
    SELECT DISTINCT category.id 
    FROM category 
      INNER JOIN story_category ON category_id=category.id);

但我得到了下一个错误:

#1093-不能在FROM子句中为更新指定目标表“story_category”

我如何克服这一问题?


当前回答

DELETE FROM story_category
WHERE category_id NOT IN (
    SELECT cid FROM (
        SELECT DISTINCT category.id AS cid FROM category INNER JOIN story_category ON category_id=category.id
    ) AS c
)

其他回答

根据@CheekySoft链接的Mysql UPDATE语法,它就在底部。

当前,无法更新表并从子查询中的同一表中进行选择。

我猜您正在从store_category中删除,同时仍在联盟中从中进行选择。

如果Priority列值在表中大于等于1,并且在WHERE子句中使用同一表上的子查询,以确保至少有一行包含Priority=1(因为这是在执行更新时要检查的条件),则我会这样做:


UPDATE My_Table
SET Priority=Priority + 1
WHERE Priority >= 1
AND (SELECT TRUE FROM (SELECT * FROM My_Table WHERE Priority=1 LIMIT 1) as t);

我知道它有点难看,但它确实很好。

如果你做不到

UPDATE table SET a=value WHERE x IN
    (SELECT x FROM table WHERE condition);

因为它是同一张桌子,所以你可以一边玩一边做:

UPDATE table SET a=value WHERE x IN
    (SELECT * FROM (SELECT x FROM table WHERE condition) as t)

[更新或删除或其他]

最简单的方法是在子查询中引用父查询表时使用表别名。

例子:

insert into xxx_tab (trans_id) values ((select max(trans_id)+1 from xxx_tab));

将其更改为:

insert into xxx_tab (trans_id) values ((select max(P.trans_id)+1 from xxx_tab P));
DELETE FROM story_category
WHERE category_id NOT IN (
    SELECT cid FROM (
        SELECT DISTINCT category.id AS cid FROM category INNER JOIN story_category ON category_id=category.id
    ) AS c
)