mssql sqlserver 三种数据表数据去重方法分享

create table test(keyId int identity,sort varchar(10),
info varchar(20))
go

---方法1 
truncate table test ;

insert into test(sort,info)values(‘A‘,‘maomao365.com‘)--1
insert into test(sort,info)values(‘A‘,‘猫猫小屋‘) --2
insert into test(sort,info)values(‘B‘,‘mssql_blog‘) --3
insert into test(sort,info)values(‘B‘,‘优秀的sql——blog‘) --4
insert into test(sort,info)values(‘B‘,‘maomao365‘) --5
insert into test(sort,info)values(‘C‘,‘sql优化blog‘) --6
go

delete from test where test.keyId = (select max(b.keyId) from test b where test.sort=b.sort);
select * from test 
---方法2:
truncate table test ; 
insert into test(sort,info)values(‘A‘,‘maomao365.com‘)
insert into test(sort,info)values(‘A‘,‘猫猫小屋‘)
insert into test(sort,info)values(‘B‘,‘mssql_blog‘)
insert into test(sort,info)values(‘B‘,‘优秀的sql——blog‘)
insert into test(sort,info)values(‘B‘,‘maomao365‘)
insert into test(sort,info)values(‘C‘,‘sql优化blog‘)
go
delete from test 
where keyid not in(select min(keyId) from test group by sort having count(sort)>=1);
select * from test 
---方法3:
truncate table test ; 
insert into test(sort,info)values(‘A‘,‘maomao365.com‘)
insert into test(sort,info)values(‘A‘,‘猫猫小屋‘)
insert into test(sort,info)values(‘B‘,‘mssql_blog‘)
insert into test(sort,info)values(‘B‘,‘优秀的sql——blog‘)
insert into test(sort,info)values(‘B‘,‘maomao365‘)
insert into test(sort,info)values(‘C‘,‘sql优化blog‘)
go
delete A2 from (
select row_Number() over(partition by sort order by keyid) as keyId_e,* from test 
) as A2 where A2.keyId_e >1

select * from test 
go
drop table test