SQL去除重复记录(七种)
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2022-03-02 23:29:08
话不多说,请看代码:
if not object_id('tempdb..#t') is null
drop table #t
go
create tab...
话不多说,请看代码:
if not object_id('tempdb..#t') is null drop table #t go create table #t([id] int,[name] nvarchar(1),[memo] nvarchar(2)) insert #t select 1,n'a',n'a1' union all select 2,n'a',n'a2' union all select 3,n'a',n'a3' union all select 4,n'b',n'b1' union all select 5,n'b',n'b2' go
--i、name相同id最小的记录(推荐用1,2,3),保留最小一条
方法1:
delete a from #t a where exists(select 1 from #t where name=a.name and id<a.id)
方法2:
delete a from #t a left join (select min(id)id,name from #t group by name) b on a.name=b.name and a.id=b.id where b.id is null
方法3:
delete a from #t a where id not in (select min(id) from #t where name=a.name)
方法4(注:id为唯一时可用):
delete a from #t a where id not in(select min(id)from #t group by name)
方法5:
delete a from #t a where (select count(1) from #t where name=a.name and id<a.id)>0
方法6:
delete a from #t a where id<>(select top 1 id from #t where name=a.name order by id)
方法7:
delete a from #t a where id>any(select id from #t where name=a.name) select * from #t
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