sql 删除表中多余的重复记录（多个字段），只保留一条记录

1.查询重复记录

select * from 表名

where 重复字段 in (select 重复字段 from 表名 group by
重复字段 having count(重复字段) > 1)

2.删除保留一条重复记录

delete from 表名

where 重复字段 in (select 重复字段 from 表名 group by 重复字段 having count(重复字段) > 1)

and ID not in (select min(ID) from 表名 group by 重复字段 having count(重复字段 )>1)

例子： role表中有两个字段，id,name

delete from role

where name in (select a.name from (select name from role group by name having count(name) > 1) a)

and id not in (select b.id from(select min(id) id from role group by name having count(name)>1) b)