SQL语句实现删除重复记录并只保留一条
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这篇文章主要介绍了SQL语句实现删除重复记录并只保留一条,本文直接给出实现代码,并给出多种查询重复记录的方法,需要的朋友可以参考下
代码如下:
delete WeiBoTopics where Id in(select max(Id) from WeiBoTopics group by WeiBoId,Title having COUNT() > 1);
SQL删除重复数据,只保留一条用SQL语句,删除掉重复项只保留一条在几千条记录里,存在着些相同的记录,如何能用SQL语句,删除掉重复的呢
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
代码如下:
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
代码如下:
delete from people where peopleName in (select peopleName from people group by peopleName having count(peopleName) > 1) and peopleId not in (select min(peopleId) from people group by peopleName having count(peopleName)>1)
3、查找表中多余的重复记录(多个字段)
代码如下:
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
代码如下:
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
代码如下:
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)
6.消除一个字段的左边的第一位
代码如下:
update tableName set [Title]=Right([Title],(len([Title])-1)) where Title like '村%'
7.消除一个字段的右边的第一位
代码如下:
update tableName set [Title]=left([Title],(len([Title])-1)) where Title like '%村'
8.假删除表中多余的重复记录(多个字段),不包含rowid最小的记录
代码如下:
update vitae set ispass=-1 where peopleId in (select peopleId from vitae group by peopleId,seq having count() > 1) and seq in (select 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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