查询或删除重复的记录

DELETE a FROM transaction_records a WHERE  EXISTS(SELECT 1 FROM transaction_records WHERE inpdate='20171224' AND primary_info=a.primary_info AND ID<a.ID);

 

--其他參考以下:

--处理表重复记录(查询和删除)

/******************************************************************************************

 

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1、Num、Name相同的重复值记录,没有大小关系只保留一条

2、Name相同,ID有大小关系时,保留大或小其中一个记录

 

 

日期:2008.06.06

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***********************************************************/

 

--1、用于查询重复处理记录(如果列没有大小关系时2000用生成自增列和临时表处理,SQL2005用

 

row_number函数处理)

 

--> --> (Roy)生成測試數據

  

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),方法3在SQl05时，效率高于1、2

方法1:

Select * from user a where not exists(select 1 from user where Name=a.Name and ID<a.ID)

 

方法2:

select a.* from user a join (select min(ID)ID,Name from user group by Name) b on 

 

a.Name=b.Name and a.ID=b.ID

 

方法3:

select * from user a where ID=(select min(ID) from user where Name=a.Name)

 

方法4:

select a.* from user a join user 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 user a group by ID,Name,Memo having ID=(select min(ID)from user where 

 

Name=a.Name)

 

方法6:

select * from user a where (select count(1) from user where Name=a.Name and ID<a.ID)=0

 

方法7:

select * from user a where ID=(select top 1 ID from user where Name=a.name order by ID)

 

方法8:

select * from user a where ID!>all(select ID from user where Name=a.Name)

 

方法9(注:ID为唯一时可用):

select * from user a where ID in(select min(ID) from user group by Name)

 

--SQL2005:

 

方法10:

select ID,Name,Memo from (select *,min(ID)over(partition by Name) as MinID from user 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 user a)T where MinID=1

 

生成结果:

/*

ID          Name Memo

----------- ---- ----

1           A    A1

4           B    B1

 

(2 行受影响)

*/

 

 

--II、Name相同ID最大的记录,与min相反:

方法1:

Select * from user a where not exists(select 1 from user where Name=a.Name and ID>a.ID)

 

方法2:

select a.* from user a join (select max(ID)ID,Name from user group by Name) b on 

 

a.Name=b.Name and a.ID=b.ID order by ID

 

方法3:

select * from user a where ID=(select max(ID) from user where Name=a.Name) order by ID

 

方法4:

select a.* from user a join user 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 user a group by ID,Name,Memo having ID=(select max(ID)from user where 

 

Name=a.Name)

 

方法6:

select * from user a where (select count(1) from user where Name=a.Name and ID>a.ID)=0

 

方法7:

select * from user a where ID=(select top 1 ID from user where Name=a.name order by ID 

 

desc)

 

方法8:

select * from user a where ID!<all(select ID from user where Name=a.Name)

 

方法9(注:ID为唯一时可用):

select * from user a where ID in(select max(ID) from user group by Name)

 

--SQL2005:

 

方法10:

select ID,Name,Memo from (select *,max(ID)over(partition by Name) as MinID from user 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 user a)T where MinID=1

 

生成结果2:

/*

ID          Name Memo

----------- ---- ----

3           A    A3

5           B    B2

 

(2 行受影响)

*/

 

 

 

--2、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..user') is null

    drop table user

Go

Create table user([ID] int,[Name] nvarchar(1),[Memo] nvarchar(2))

Insert user

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 user a where  exists(select 1 from user where Name=a.Name and ID<a.ID)

 

方法2:

delete a  from user a left join (select min(ID)ID,Name from user 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 user a where ID not in (select min(ID) from user where Name=a.Name)

 

方法4(注:ID为唯一时可用):

delete a from user a where ID not in(select min(ID)from user group by Name)

 

方法5:

delete a from user a where (select count(1) from user where Name=a.Name and ID<a.ID)>0

 

方法6:

delete a from user a where ID<>(select top 1 ID from user where Name=a.name order by ID)

 

方法7:

delete a from user a where ID>any(select ID from user where Name=a.Name)

 

 

 

select * from user

 

生成结果:

/*

ID          Name Memo

----------- ---- ----

1           A    A1

4           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 user a where  exists(select 1 from user where Name=a.Name and ID>a.ID)

 

方法2:

delete a  from user a left join (select max(ID)ID,Name from user 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 user a where ID not in (select max(ID) from user where Name=a.Name)

 

方法4(注:ID为唯一时可用):

delete a from user a where ID not in(select max(ID)from user group by Name)

 

方法5:

delete a from user a where (select count(1) from user where Name=a.Name and ID>a.ID)>0

 

方法6:

delete a from user a where ID<>(select top 1 ID from user where Name=a.name order by ID 

 

desc)

 

方法7:

delete a from user a where ID<any(select ID from user where Name=a.Name)

 

 

select * from user

/*

ID          Name Memo

----------- ---- ----

3           A    A3

5           B    B2

 

(2 行受影响)

*/

 

 

 

 

 

--3、删除重复记录没有大小关系时，处理重复值

 

 

--> --> (Roy)生成測試數據

  

if not object_id('Tempdb..user') is null

    drop table user

Go

Create table user([Num] int,[Name] nvarchar(1))

Insert user

select 1,N'A' union all

select 1,N'A' union all

select 1,N'A' union all

select 2,N'B' union all

select 2,N'B'

Go

 

方法1:

if object_id('Tempdb..#') is not null

    drop table #

Select distinct * into # from user--排除重复记录结果集生成临时表#

 

truncate table user--清空表

 

insert user select * from #    --把临时表#插入到表user中

 

--查看结果

select * from user

 

/*

Num         Name

----------- ----

1           A

2           B

 

(2 行受影响)

*/

 

--重新执行测试数据后用方法2

方法2:

 

alter table user add ID int identity--新增标识列

go

delete a from  user a where  exists(select 1 from user where Num=a.Num and Name=a.Name and 

 

ID>a.ID)--只保留一条记录

go

alter table user drop column ID--删除标识列

 

--查看结果

select * from user

 

/*

Num         Name

----------- ----

1           A

2           B

 

(2 行受影响)

 

*/

 

--重新执行测试数据后用方法3

方法3:

declare Roy_Cursor cursor local for

select count(1)-1,Num,Name from user group by Num,Name having count(1)>1

declare @con int,@Num int,@Name nvarchar(1)

open Roy_Cursor

fetch next from Roy_Cursor into @con,@Num,@Name

while @@Fetch_status=0

begin 

    set rowcount @con;

    delete user where Num=@Num and Name=@Name

    set rowcount 0;

    fetch next from Roy_Cursor into @con,@Num,@Name

end

close Roy_Cursor

deallocate Roy_Cursor

 

--查看结果

select * from user

/*

Num         Name

----------- ----

1           A

2           B

 

(2 行受影响)

 

 

#方法1:

  SELECT * FROM customer a WHERE a.customer_realname='李海锋' AND NOT EXISTS(SELECT 1 FROM 

 

customer WHERE customer_realname=a.customer_realname AND customer_id>a.customer_id AND 

 

customer_realname='李海锋')

 

#方法2:

  SELECT a.* FROM customer a JOIN (SELECT MAX(customer_id) AS customer_id FROM customer 

 

WHERE customer_realname='李海锋'GROUP BY customer_realname) b ON 

 

a.customer_id=b.customer_id  ORDER BY customer_id

 

#方法3:

  SELECT a.* FROM customer a WHERE a.customer_realname='李海锋' AND  a.customer_id=(SELECT 

 

MAX(b.customer_id) FROM customer b WHERE b.customer_realname=a.custo