MSSQL sql server 2005/2008 row_number()函数应用之–删除表中重复记录,只保留一条不重复数据


row_number函数在数据库中的功能是为每一行 按照一定的规则生成一个编号,
我们常常利用这一属性,对表进行分页操作,下文我们将讲述采用 row_number函数删除表中重复数据行

/*建表*/
create table A(keyId int,info varchar(20))
go 
/*生成数据*/
insert into A(keyId,info)values
(1,'a'),(2,'b'),(3,'C'),(4,'d'),(5,'e'),
(1,'a'),(21,'b1'),(31,'C1'),(4,'d'),(51,'e'),
(1,'a'),(6,'b1'),(7,'C1'),(4,'d000'),(10,'e')
go


/*删除 keyId重复数据 中的另外几条*/
delete [A2] from 
(select row_number() over (Partition By keyId order by keyId) as keyId2,* from A ) as [A2]
where [A2].keyId2  >1 
 

/*
/*删除 所有列都重复数据 中的另外几条*/
delete [A2] from 
(select row_number() over (Partition By keyId,info order by keyId) as keyId2,* from A ) as [A2]
where [A2].keyId2  >1 
 */

/*展示删除后的数据*/

select * from A 
go

truncate table A 
drop table A 
go