having count删除重复数据只保留一条

having count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 www.2cto.com 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 select * from people wher

having count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 

  www.2cto.com  

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 

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   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） 

select * from vitae a 

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

  www.2cto.com  

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)   

 

6.消除一个字段的左边的第一位： 

 

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： 

 

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 

update vitae set ispass=-1 

where peopleId in (select peopleId from vitae group by peopleId