Biegral Blog

--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))