Question

如何去掉数据库重复记录并且只保留一条记录

Answer 1

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)