mysql delete from 限制

mysql进行delete时若子查询中的表为同一张表会出现错误

如：

mysql> DELETE FROM tab1 WHERE col1 = ( SELECT MAX( col1 ) FROM tab1 );

ERROR 1093 (HY000): You can’t specify target table ‘tab1′ for update in FROM clause

我们可以用别名来绕过这个限制

mysql>DELETE FROM tab1 where col1 = (select * from (select id   from tab1) as b)