sql 查出一张表中重复的所有记录数据

在面试的时候碰到一个问题，就是

写一张表中有id和name 两个字段，查询出name重复的所有数据，现在列下：

select * from xi a where 
(a.username) in  (select username from xi group by username  having count(*) > 1)

• 查询出所有数据进行分组之后，和重复数据的重复次数的查询数据，先列下

select  count(username) as '重复次数',username from xi 
group by username  having count(*)>1 order by username desc

查询及删除重复记录的方法大全

• 查找表中多余的重复记录，重复记录是根据单个字段（peopleId）来判断

select * from people
where peopleId in 
(select  peopleId  from  people  group  by  peopleId  having  count(peopleId) > 1)

• 删除表中多余的重复记录，重复记录是根据单个字段（peopleId）来判断，只留有rowid最小的记录

delete from people 
where peopleId  in (select  peopleId  from people  group  by  peopleId   having  count(peopleId) > 1)
and rowid not in (select min(rowid) from  people  group by peopleId  having count(peopleId )>1)

• 查找表中多余的重复记录（多个字段）

select * from vitae a
where (a.peopleId,a.seq) in  (select peopleId,seq from vitae group by peopleId,seq  having count(*) > 1)

• 删除表中多余的重复记录（多个字段），只留有rowid最小的记录

delete from vitae a
where (a.peopleId,a.seq) in  (select peopleId,seq from vitae group by peopleId,seq having count(*) > 1)
and rowid not in (select min(rowid) from vitae group by peopleId,seq having count(*)>1)

• 查找表中多余的重复记录（多个字段），不包含rowid最小的记录

select * from vitae a
where (a.peopleId,a.seq) in  (select peopleId,seq from vitae group by peopleId,seq having count(*) > 1)
and rowid not in (select min(rowid) from vitae group by peopleId,seq having count(*)>1)