如何去掉数据库重复记录而且只保留一条记录

时间 2019-11-13

标签如何去掉数据库重复记录而且保留一条栏目 SQL 繁體版

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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？方法以下：code

单个字段

一、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it

select * from people  
where peopleId in (select  peopleId  from  people  group  by  peopleId  having  count(peopleId) > 1)

二、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select

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)

多个字段

三、查找表中多余的重复记录（多个字段）方法

select * from vitae a  
where (a.peopleId,a.seq) in  (select peopleId,seq from vitae group by peopleId,seq  having count(*) > 1)

四、删除表中多余的重复记录（多个字段），只留有rowid最小的记录vi

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)

五、查找表中多余的重复记录（多个字段），不包含rowid最小的记录co

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)