處理表重複記錄(查詢和刪除)_整理貼4

處理表重複記錄(查詢和刪除)_整理貼4

--處理表重複記錄(查詢和刪除)/******************************************************************************************************************************************************1、Num、Name相同的重複值記錄,沒有大小關係只保留一條2、Name相同,ID有大小關係時,保留大或小其中一個記錄整理人：中國風(Roy)日期:2008.06.06******************************************************************************************************************************************************/--1、用於查詢重複處理記錄(如果列沒有大小關係時2000用生成自增列和臨時表處理,SQL2005用row_number函數處理)--> --> (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,N"A",N"A1" union allselect 2,N"A",N"A2" union allselect 3,N"A",N"A3" union allselect 4,N"B",N"B1" union allselect 5,N"B",N"B2"Go--I、Name相同ID最小的記錄(推薦用1,2,3),方法3在SQl05時，效率高於1、2方法1:Select * from #T a where not exists(select 1 from #T where Name=a.Name and ID<a.ID)方法2:select a.* from #T a join (select min(ID)ID,Name from #T group by Name) b on a.Name=b.Name and a.ID=b.ID方法3:select * from #T a where ID=(select min(ID) from #T where Name=a.Name)方法4:select a.* from #T a join #T b on a.Name=b.Name and a.ID>=b.ID group by a.ID,a.Name,a.Memo having count(1)=1 方法5:select * from #T a group by ID,Name,Memo having ID=(select min(ID)from #T where Name=a.Name)方法6:select * from #T a where (select count(1) from #T where Name=a.Name and ID<a.ID)=0方法7:select * from #T a where ID=(select top 1 ID from #T where Name=a.name order by ID)方法8:select * from #T a where ID!>all(select ID from #T where Name=a.Name)方法9(注:ID為唯一時可用):select * from #T a where ID in(select min(ID) from #T group by Name)--SQL2005:方法10:select ID,Name,Memo from (select *,min(ID)over(partition by Name) as MinID from #T a)T where ID=MinID方法11:select ID,Name,Memo from (select *,row_number()over(partition by Name order by ID) as MinID from #T a)T where MinID=1生成結果:/*ID Name Memo----------- ---- ----1 A A14 B B1(2 行受影響)*/--II、Name相同ID最大的記錄,與min相反:方法1:Select * from #T a where not exists(select 1 from #T where Name=a.Name and ID>a.ID)方法2:select a.* from #T a join (select max(ID)ID,Name from #T group by Name) b on a.Name=b.Name and a.ID=b.ID order by ID方法3:select * from #T a where ID=(select max(ID) from #T where Name=a.Name) order by ID方法4:select a.* from #T a join #T b on a.Name=b.Name and a.ID<=b.ID group by a.ID,a.Name,a.Memo having count(1)=1 方法5:select * from #T a group by ID,Name,Memo having ID=(select max(ID)from #T where Name=a.Name)方法6:select * from #T a where (select count(1) from #T where Name=a.Name and ID>a.ID)=0方法7:select * from #T a where ID=(select top 1 ID from #T where Name=a.name order by ID desc)方法8:select * from #T a where ID!<all(select ID from #T where Name=a.Name)方法9(注:ID為唯一時可用):select * from #T a where ID in(select max(ID) from #T group by Name)--SQL2005:方法10:select ID,Name,Memo from (select *,max(ID)over(partition by Name) as MinID from #T a)T where ID=MinID方法11:select ID,Name,Memo from (select *,row_number()over(partition by Name order by ID desc) as MinID from #T a)T where MinID=1生成結果2:/*ID Name Memo----------- ---- ----3 A A35 B B2(2 行受影響)*/--2、刪除重複記錄有大小關係時,保留大或小其中一個記錄--> --> (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,N"A",N"A1" union allselect 2,N"A",N"A2" union allselect 3,N"A",N"A3" union allselect 4,N"B",N"B1" union allselect 5,N"B",N"B2"Go--I、Name相同ID最小的記錄(推薦用1,2,3),保留最小一條方法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為唯一時可用):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生成結果:/*ID Name Memo----------- ---- ----1 A A14 B B1(2 行受影響)*/--II、Name相同ID保留最大的一條記錄: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 max(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 max(ID) from #T where Name=a.Name)方法4(注:ID為唯一時可用):delete a from #T a where ID not in(select max(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 desc)方法7:delete a from #T a where ID<any(select ID from #T where Name=a.Name)select * from #T/*ID Name Memo----------- ---- ----3 A A35 B B2(2 行受影響)*/--3、刪除重複記錄沒有大小關係時，處理重複值--> --> (Roy)生成測試數據if not object_id("Tempdb..#T") is null drop table #TGoCreate table #T([Num] int,[Name] nvarchar(1))Insert #Tselect 1,N"A" union allselect 1,N"A" union allselect 1,N"A" union allselect 2,N"B" union allselect 2,N"B"Go方法1:if object_id("Tempdb..#") is not null drop table #Select distinct * into # from #T--排除重複記錄結果集生成臨時表#truncate table #T--清空表insert #T select * from # --把臨時表#插入到表#T中--查看結果select * from #T/*Num Name----------- ----1 A2 B(2 行受影響)*/--重新執行測試數據後用方法2方法2:alter table #T add ID int identity--新增標識列godelete a from #T a where exists(select 1 from #T where Num=a.Num and Name=a.Name and ID>a.ID)--只保留一條記錄goalter table #T drop column ID--刪除標識列--查看結果select * from #T/*Num Name----------- ----1 A2 B(2 行受影響)*/--重新執行測試數據後用方法3方法3:declare Roy_Cursor cursor local forselect count(1)-1,Num,Name from #T group by Num,Name having count(1)>1declare @con int,@Num int,@Name nvarchar(1)open Roy_Cursorfetch next from Roy_Cursor into @con,@Num,@Namewhile @@Fetch_status=0begin set rowcount @con; delete #T where Num=@Num and Name=@Name set rowcount 0; fetch next from Roy_Cursor into @con,@Num,@Nameendclose Roy_Cursordeallocate Roy_Cursor--查看結果select * from #T/*Num Name----------- ----1 A2 B(2 行受影響)*/