SQL查找 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

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) 
--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

-- 更新时间 某日期以后随机

select dateadd(ss,	abs(checksum(newid()) % 31449600),'2014-01-01 ' + CONVERT (VARCHAR, getdate(), 14))