mysql - SQL error: DELETE and SELECT FROM conflict

Question

I've a problem with the following SQL query:

DELETE FROM table1 WHERE uid =
(SELECT table1.uid from table1 INNER JOIN table2 ON table2.user = table1.uid
INNER JOIN table3 ON table3.uid = table2.seminar WHERE table3.end_date < CURDATE()))

The error is: You can't specify target table 'table1' for update in FROM clause

Does anybody have an idea how to fix that?

Answer 1

这可能不是最优雅的方式，但您可以将您的条件选择到临时表中，然后从 #MyTempTable 中的位置删除

SELECT table1.uid 
INTO #MyTemp
from table1 INNER JOIN table2 ON table2.user = table1.uid
INNER JOIN table3 ON table3.uid = table2.seminar WHERE table3.end_date < CURDATE())


DELETE FROM table1 
WHERE uid IN
(SELECT uid from #MyTemp)

DROP TABLE #MyTemp

Answer 2

您可以选择加入表格。

DELETE  table1
FROM    table1 
        INNER JOIN table2 
            ON table2.user = table1.uid
        INNER JOIN table3 
            ON table3.uid = table2.seminar
WHERE   table3.end_date < CURDATE()

Answer 3

尝试这个：-

DELETE  table1 FROM    table1 INNER JOIN table2 ON table2.user = table1.uid
        INNER JOIN table3 ON table3.uid = table2.seminar
WHERE   table3.end_date < CURDATE()

Answer 4

我的首选语法是：

Delete deleteAlias
/* Select *         */
from table1 deleteAlias
where exists ( select null from table1 innerTable1 INNER JOIN table2 ON table2.user = innerTable1.uid
INNER JOIN table3 ON table3.uid = table2.seminar WHERE table3.end_date < CURDATE())   

AND deleteAlias.uid = innerTable1.uid

   )

如果这种方法的微妙好处是您可以替换一个简单的“select *”来查看在运行删除之前将删除的内容。

/* Delete deleteAlias */
Select *
from table1 deleteAlias
where exists ( select null from table1 innerTable1 INNER JOIN table2 ON table2.user = innerTable1.uid
INNER JOIN table3 ON table3.uid = table2.seminar WHERE table3.end_date < CURDATE())   

AND deleteAlias.uid = innerTable1.uid

   )

Answer 5

您不能在 select 子句中以临时模式修改或删除正在使用的表。您可以在这里看到解释和替代方案： MySQL 错误 1093 - 无法在 FROM 子句中指定要更新的目标表