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1、sql语句实现根据字段删除重复行代码，删除重复记录有大小关系时,保留大或小其中一个记录- - (Roy)生成測試數據if not object_id(Tempdb.#T) is null drop table #TGoCreate table #T(ID int,Name nvarchar(1),Memo nvarchar(2)Insert #Tselect 1,NA,NA1 union allselect 2,NA,NA2 union allselect 3,NA,NA3 union allselect 4,NB,NB1 union allselect 5,NB,NB2Go-I、Name相同
2、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 IDa.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 w
3、here 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 ID0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 IDany(select ID from #T where Name=a.Name)select * from #T生成结果:/*ID Name Memo- - -1 A A14 B B1(2 行受影响)*/-II、Name相同ID保留最大的一条记录:方法1:delete a from #T a where exists(select 1 from #T where Name=a.Name and IDa.ID)
sql语句实现根据字段删除重复行代码
