当前位置:Gxlcms > mysql > 如何去掉数据库重复记录并且只保留一条记录

如何去掉数据库重复记录并且只保留一条记录

时间:2021-07-01 10:21:17 帮助过:2人阅读

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 hav

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 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)

人气教程排行