清除Mysql重复数据，一条SQL语句删除Mysql数据库重复数据

问题：

需要删除数据库中重复的QQ号，使用什么SQL语句呢？

按照SQL语句构造思想，可以写成这样：
delete from qq where id not in (select min(id) from qq group by qq)

但在运行时提示：
SQL执行错误 # 1093.从数据库的响应：
You can't specify target table 'qq' for update in FROM dause

这是神马意思？

1093错误为：在修改（删除）一个数据表的时候子查询不能是同一个表

既然知道了问题的原因，我们就能想到解决的办法。

解决办法：把子查询再套一层，变成原来表的孙子查询就可以了，例如：

delete from qq where id not in (select qq.id from (select min(id) as id from qq group by qq) as qq)

总结：

delete from qq where id not in (select qq.id from (select min(id) as id from qq group by qq) as qq) 这是对的
但是 delete from qq where id not in (select min(id) from qq group by qq) 就会报1093错误