MySQL 数据去重

背景：数据库中存在除主键以外的重复数据。

原理：删除，自连接，查询分组，最大值。

执行SQL：

DELETE a from user as a JOIN(

SELECT name,count(*),MAX(id) as id from user GROUP BY name HAVING count(*)>1

) as b on a.name = b.name where a.id = b.id;