删除选择（错误1093）

Question

我需要删除此查询中的结果：

SELECT a.cad_id
FROM `Cad` a
WHERE NOT EXISTS
(
SELECT b.cad_id
FROM `rel` b
WHERE a.cad_id = b.rel
)

我试试：

DELETE FROM `Cad` WHERE cad_id = (
SELECT a.cad_id
FROM `Cad` a
WHERE NOT EXISTS
(
SELECT b.cad_id
FROM `rel` b
WHERE a.cad_id = b.rel
)
)

1093 - 您无法在FROM子句

中指定目标表'Cad'进行更新

我该如何解决？

Answer 1

在临时表中选择内部查询数据。

DELETE FROM `cad` 
WHERE  cad_id IN (SELECT * 
                 FROM  (SELECT a.cad_id 
                        FROM   `cad` a 
                        WHERE  NOT EXISTS (SELECT b.cad_id 
                                           FROM   `rel` b 
                                           WHERE  a.cad_id = b.rel)) AS 
                       tempTable)