如何去掉数据库重复记录并且只保留一条记录

来源：互联网发布：娄烨电影知乎编辑：程序博客网时间：2024/06/05 03:12

在n条记录里,存在着些相同的记录,如何能用SQL语句,删除掉重复并保留一条呢？

方法如下：

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 peoplewhere 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 awhere (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 awhere (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 awhere (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)

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