mysql 删除字段内的重复内容只保留一条

delete from 表名 where 字段1 not in (select 字段1 from (select 字段1 from 表名 group by 需要判断的重复的字段) s)

例如有表UserTable 中字段id,name,sex等字段,需要删除name相同的记录,一个name只保留id最大一条记录

delete from UserTable where id not in (select maxid from (select max(id) as maxid from UserTable group by name) s)