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SQL语句实现删除重复记录并只保留一条

(编辑:jimmy 日期: 2024/6/18 浏览:3 次 )

复制代码 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
复制代码 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
复制代码 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)
复制代码 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
复制代码 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
复制代码 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:
复制代码 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:
复制代码 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
复制代码 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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