Mysql利用联表查询和分组来删除重复数据

//删除表中重复的id，保留最大的idmysql> select * from user;+----+------+| id | name |+----+------+|  1 | a    ||  2 | b    ||  3 | c    ||  4 | d    ||  5 | a    ||  6 | a    ||  7 | c    ||  8 | d    |+----+------+8 rows in set (0.08 sec)

mysql> delete a from user a left join (select max(id) as id, name from user group by name having(count(id)) > 1)  b on a.name = b.name where a.id < b.id;Query OK, 4 rows affected (0.13 sec) //删除重复数据成功mysql> select * from user;+----+------+| id | name |+----+------+|  2 | b    ||  6 | a    ||  7 | c    ||  8 | d    |+----+------+