CREATE TABLE [dbo].[dianfeijiage](
[id] [int] IDENTITY(1,1) NOT NULL,
[leixing] [nvarchar](50) COLLATE Chinese_PRC_CI_AI NULL,
[jiage] [decimal](18, 4) NULL,
[riqi] [datetime] NULL,
CONSTRAINT [PK_dianfeijiage] PRIMARY KEY CLUSTERED
(
[id] ASC
)WITH (IGNORE_DUP_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY]
21 不收费用电 0.0000 2009-06-01 00:00:00.000
15 动力用电 0.8130 2009-06-01 00:00:00.000
20 农业用电 0.4400 2009-06-01 00:00:00.000
12 生活用电 0.5283 2009-06-01 00:00:00.000
14 营业用电 0.8130 2009-06-01 00:00:00.000
22 营业用电 212.0000 2009-06-05 00:00:00.000
23 营业用电 32.0000 2009-06-22 00:00:00.000查出:取出每种用电最新价格
21 不收费用电 0.0000 2009-06-01 00:00:00.000
15 动力用电 0.8130 2009-06-01 00:00:00.000
20 农业用电 0.4400 2009-06-01 00:00:00.000
12 生活用电 0.5283 2009-06-01 00:00:00.00023 营业用电 32.0000 2009-06-22 00:00:00.000
[id] [int] IDENTITY(1,1) NOT NULL,
[leixing] [nvarchar](50) COLLATE Chinese_PRC_CI_AI NULL,
[jiage] [decimal](18, 4) NULL,
[riqi] [datetime] NULL,
CONSTRAINT [PK_dianfeijiage] PRIMARY KEY CLUSTERED
(
[id] ASC
)WITH (IGNORE_DUP_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY]
21 不收费用电 0.0000 2009-06-01 00:00:00.000
15 动力用电 0.8130 2009-06-01 00:00:00.000
20 农业用电 0.4400 2009-06-01 00:00:00.000
12 生活用电 0.5283 2009-06-01 00:00:00.000
14 营业用电 0.8130 2009-06-01 00:00:00.000
22 营业用电 212.0000 2009-06-05 00:00:00.000
23 营业用电 32.0000 2009-06-22 00:00:00.000查出:取出每种用电最新价格
21 不收费用电 0.0000 2009-06-01 00:00:00.000
15 动力用电 0.8130 2009-06-01 00:00:00.000
20 农业用电 0.4400 2009-06-01 00:00:00.000
12 生活用电 0.5283 2009-06-01 00:00:00.00023 营业用电 32.0000 2009-06-22 00:00:00.000
sqlserver的高手一大堆。。
--处理表重复记录(查询和删除)
/******************************************************************************************************************************************************
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
整理人:中国风(Roy)日期:2008.06.06
******************************************************************************************************************************************************/--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--II、Name相同ID最大的记录,与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为唯一时可用):
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生成结果2:
/*
ID Name Memo
----------- ---- ----
3 A A3
5 B B2(2 行受影响)
*/
*
from
dianfeijiage t
where
not exists(select 1 from dianfeijiage where leixing=t.leixing and riqi>t.riqi)
select * from dianfeijiage a
where not exists(select 1 from dianfeijiage b where a.leixing=b.leixing and a.riqi<b.riqi)
FROM [dianfeijiage] AS T
WHERE NOT EXISTS(SELECT * FROM [dianfeijiage] WHERE [leixing]=T.[leixing] AND [riqi]>T.[riqi])