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SQL语句实现删除重复记录并只保留一条

时间：2020-01-09 15:45 编辑：来源：阅读：
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摘要：SQL语句实现删除重复记录并只保留一条

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 [b]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 [/b]

[u]复制代码[/u] 代码如下:

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

[b]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 [/b]

[u]复制代码[/u] 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)

[b]3、查找表中多余的重复记录（多个字段） [/b]

[u]复制代码[/u] 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)

[b]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 [/b]

[u]复制代码[/u] 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)

[b]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[/b]

[u]复制代码[/u] 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) 

[b]6.消除一个字段的左边的第一位： [/b]

[u]复制代码[/u] 代码如下:

update tableName set [Title]=Right([Title],(len([Title])-1)) where Title like '村%'

[b]7.消除一个字段的右边的第一位：[/b]

[u]复制代码[/u] 代码如下:

update tableName set [Title]=left([Title],(len([Title])-1)) where Title like '%村'

[b]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[/b]

[u]复制代码[/u] 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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