1、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)
2、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)
3、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)
4、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)
5、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)
(二)
比方说
在A表中存在一个字段“name”，
而且不同记录之间的“name”值有可能会相同，
现在就是需要查询出在该表中的各记录之间，“name”值存在重复的项；
Select
Name,Count(*) From A Group By Name Having Count(*) > 1
如果还查性别也相同大则如下:
Select Name,sex,Count(*) From A Group By Name,sex Having
Count(*) > 1
来源： http://www.cnblogs.com/tiasys/archive/2012/09/22/2697728.html