删除数据库中重复记录的SQL语句（转）

参考URL：http://qinya.iteye.com/blog/677306

 

在几千条记录里,存在着些相同的记录,如何能用SQL语句,删除掉重复的呢? 

思考：如何仅有部分字段重复，如何查找所有记录，重复记录只显示一遍？？

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)