MySQL的DELETE FROM与子查询的条件

Question

我试图做一个查询这样的：

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 
); 

正如你可能会说，我想删除父关系1015是否相同TID有其他家长。但是，我得到一个语法错误：

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 

我已经检查的文件，并通过自身运行子查询，而这一切似乎退房。任何人都可以弄清楚这里有什么问题吗？

更新：如下面的回答，MySQL不允许将您要删除的表用于条件的子查询中。

Answer 1

您不能指定目标表删除。

一种解决方法

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); 

Answer 2

您需要在delete语句中再次引用别名，如：

DELETE th FROM term_hierarchy AS th 
.... 

As outlined here in MySQL docs.

Answer 3

别名应包含在DELETE关键字后：

DELETE th 
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 
); 

Answer 4

对于其他人发现这个问题看，同时使用子查询，删除，我离开你这个例子超过MySQL（即使有些人似乎认为它不能完成）：

DELETE e.* 
FROM tableE e 
WHERE id IN (SELECT id 
      FROM tableE 
      WHERE arg = 1 AND foo = 'bar'); 

会给你一个错误：

ERROR 1093 (HY000): You can't specify target table 'e' for update in FROM clause 

但此查询：

DELETE e.* 
FROM tableE e 
WHERE id IN (SELECT id 
      FROM (SELECT id 
        FROM tableE 
        WHERE arg = 1 AND foo = 'bar') x); 

会工作得很好：

Query OK, 1 row affected (3.91 sec) 

环绕你的子查询了在其他子查询（这里命名为x） MySQL会很乐意做你所要求的。

Answer 5

我以一种稍微不同的方式接近这个，它对我有用;

我需要从我的表中删除secure_links引用conditions表，其中不再有任何条件行左。一个家政脚本基本上。这给了我错误 - 你不能指定目标表进行删除。

所以在这里寻找灵感我想出了下面的查询，它工作得很好。 这是因为它创建了一个用作DELETE参考的临时表sl1。

DELETE FROM `secure_links` WHERE `secure_links`.`link_id` IN 
      (
      SELECT 
       `sl1`.`link_id` 
      FROM 
       (
       SELECT 

        `sl2`.`link_id` 

       FROM 
        `secure_links` AS `sl2` 
        LEFT JOIN `conditions` ON `conditions`.`job` = `sl2`.`job` 

       WHERE 

        `sl2`.`action` = 'something' AND 
        `conditions`.`ref` IS NULL 
       ) AS `sl1` 
      ) 

适合我。

Answer 6

是不是删除中的“in”子句...如果从子查询中返回大量的值，效率极低？不知道为什么你不会为了删除而不是内部（或右边）从子查询中反向删除原始表，而不是我们的“in（subquery）”。

DELETE T FROM Target AS T 
RIGHT JOIN (full subquery already listed for the in() clause in answers above) ` AS TT ON (TT.ID = T.ID) 

也许它是在回答“MySQL不允许它”，但是，它工作正常，我提供的我一定要完全弄清楚删除的内容（DELETE FROM牛逼目标AS T）。 Delete with Join in MySQL阐明DELETE/JOIN问题。

Answer 7

如果你想与2个查询要做到这一点，你总是可以做同样的事情到这一点：

1）抓住IDS从表：

SELECT group_concat(id) as csv_result FROM your_table WHERE whatever = 'test' ... 

然后复制用鼠标/键盘导致或编程语言为XXX：

2) DELETE FROM your_table WHERE id IN (XXX) 

也许你可以在一个查询中做到这一点，但这是我更喜欢的。