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首先创建一个表：
CREATE TABLE `t1` ( `id` INT(11) NULL DEFAULT NULL, `name` VARCHAR(20) NULL DEFAULT NULL )
插入几条数据：
mysql> select * from t1; +------+------+ | id | name | +------+------+ | 1 | chen | | 2 | li | | 3 | huan | +------+------+ 3 rows in set (0.00 sec)
需求1：删除最大id的那条记录，于是我们会大约写出如下的语句：
mysql> delete from t1 where id=(select max(id) from t1); ERROR 1093 (HY000): You can‘t specify target table ‘t1‘ for update in FROM clause
很不幸，它报错了.
可以修改成如下语句：
mysql> delete a from t1 a,(select max(id) maxid from t1) b where a.id=b.maxid; Query OK, 1 row affected (0.01 sec) mysql> select * from t1; +------+------+ | id | name | +------+------+ | 1 | chen | | 2 | li | +------+------+ 2 rows in set (0.00 sec)
也可以是如下语句：
mysql> delete from t1 where id in ( select a.maxid from (select max(id) maxid from t1) a); Query OK, 1 row affected (0.01 sec) mysql> select * from t1; +------+------+ | id | name | +------+------+ | 1 | chen | +------+------+ 1 row in set (0.00 sec)
需求2：插入一条记录，并且id值是之前该表最大值加1，于是我们会大约写出如下的语句：
mysql> insert into t1 values( (select max(id)+1 from t1),‘you‘); ERROR 1093 (HY000): You can‘t specify target table ‘t1‘ for update in FROM clause
依旧报了同样的错误
可以改写如下：
mysql> insert into t1 select (select max(id)+1 maxid from t1 ) , ‘you‘; Query OK, 1 row affected (0.06 sec) Records: 1 Duplicates: 0 Warnings: 0 mysql> select * from t1; +------+------+ | id | name | +------+------+ | 1 | chen | | 2 | you | +------+------+ 2 rows in set (0.00 sec)
需求3：我们要更新一条语句，id需要变为之前最大值加1，于是我们会大约写出如下的语句：
mysql> update t1 set id=(select max(id)+1 from t1) where id=1; ERROR 1093 (HY000): You can‘t specify target table ‘t1‘ for update in FROM clause
错误如初
我们可以改写为如下语句：
mysql> update t1,(select max(id)+1 as maxid from t1 ) a set id=a.maxid where id=1; Query OK, 1 row affected (0.00 sec) Rows matched: 1 Changed: 1 Warnings: 0 mysql> select * from t1; +------+------+ | id | name | +------+------+ | 3 | chen | | 2 | you | +------+------+ 2 rows in set (0.00 sec)
也可以改成如下语句：
mysql> update t1 set id=(select a.maxid from (select max(id)+1 maxid from t1) a) where id=3; Query OK, 1 row affected (0.01 sec) Rows matched: 1 Changed: 1 Warnings: 0 mysql> select * from t1; +------+------+ | id | name | +------+------+ | 4 | chen | | 2 | you | +------+------+ 2 rows in set (0.00 sec)
总的思路是：把查询的最大值语句转为subquery或derived。
mysql: you can't specify target table 问题解决
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原文地址：http://www.cnblogs.com/zejin2008/p/4974166.html
