我有一组数据如下:
A 19
A 18
....
A 1B 19
B 18
....
B 1C 19
C 18
....
C 1我不想使用union
想把每组的前2都给列出来是不是有更直接的办法
结果
A 19
A 18
B 19
B 18
C 19
C 18
A 19
A 18
....
A 1B 19
B 18
....
B 1C 19
C 18
....
C 1我不想使用union
想把每组的前2都给列出来是不是有更直接的办法
结果
A 19
A 18
B 19
B 18
C 19
C 18
-- Author: liangCK 小梁
-- Title : 查每个分组前N条记录
-- Date : 2008-11-13 17:19:23
-----------------------------------> 生成测试数据: #T
IF OBJECT_ID('tempdb.dbo.#T') IS NOT NULL DROP TABLE #T
CREATE TABLE #T (ID VARCHAR(3),GID INT,Author VARCHAR(29),Title VARCHAR(39),Date DATETIME)
INSERT INTO #T
SELECT '001',1,'邹建','深入浅出SQLServer2005开发管理与应用实例','2008-05-10' UNION ALL
SELECT '002',1,'胡百敬','SQLServer2005性能调校','2008-03-22' UNION ALL
SELECT '003',1,'格罗夫Groff.J.R.','SQL完全手册','2009-07-01' UNION ALL
SELECT '004',1,'KalenDelaney','SQLServer2005技术内幕存储引擎','2008-08-01' UNION ALL
SELECT '005',2,'Alex.Kriegel.Boris.M.Trukhnov','SQL宝典','2007-10-05' UNION ALL
SELECT '006',2,'飞思科技产品研发中心','SQLServer2000高级管理与开发','2007-09-10' UNION ALL
SELECT '007',2,'胡百敬','SQLServer2005数据库开发详解','2008-06-15' UNION ALL
SELECT '008',3,'陈浩奎','SQLServer2000存储过程与XML编程','2005-09-01' UNION ALL
SELECT '009',3,'赵松涛','SQLServer2005系统管理实录','2008-10-01' UNION ALL
SELECT '010',3,'黄占涛','SQL技术手册','2006-01-01'--SQL查询如下:--按GID分组,查每个分组中Date最新的前2条记录
--1.字段ID唯一时:
SELECT * FROM #T AS T WHERE ID IN(SELECT TOP 2 ID FROM #T WHERE GID=T.GID ORDER BY Date DESC)--2.如果ID不唯一时:
SELECT * FROM #T AS T WHERE 2>(SELECT COUNT(*) FROM #T WHERE GID=T.GID AND Date>T.Date)--SQL Server 2005 使用新方法--3.使用ROW_NUMBER()进行排位分组
SELECT ID,GID,Author,Title,Date
FROM
(
SELECT rid=ROW_NUMBER() OVER(PARTITION BY GID ORDER BY Date DESC),*
FROM #T
) AS T
WHERE rid<=2--4.使用APPLY
SELECT DISTINCT b.*
FROM #T AS a
CROSS APPLY
(
SELECT TOP(2) * FROM #T WHERE a.GID=GID ORDER BY Date DESC
) AS b
--结果
/*ID GID Author Title Date
---- ----------- ----------------------------- --------------------------------------- -----------------------
003 1 格罗夫Groff.J.R. SQL完全手册 2009-07-01 00:00:00.000
004 1 KalenDelaney SQLServer2005技术内幕存储引擎 2008-08-01 00:00:00.000
005 2 Alex.Kriegel.Boris.M.Trukhnov SQL宝典 2007-10-05 00:00:00.000
007 2 胡百敬 SQLServer2005数据库开发详解 2008-06-15 00:00:00.000
009 3 赵松涛 SQLServer2005系统管理实录 2008-10-01 00:00:00.000
010 3 黄占涛 SQL技术手册 2006-01-01 00:00:00.000(6 行受影响)
*/--得到每组前几条数据
--假設每組Col1中, Col3不會重復--建立測試環境
Create Table TEST
(Col1 Varchar(10),
Col2 Varchar(10),
Col3 Int)
--插入數據
Insert TEST Select 'BD1V','Label', 4
Union All Select 'BD1V', 'BATT', 2
Union All Select 'BD1V', 'ODD', 3
Union All Select 'BD1V', 'HDD', 5
Union All Select 'BD1V', 'LCD', 1
Union All Select 'BD1W','HDD', 3
Union All Select 'BD1W','RAM', 8
Union All Select 'BD1W','TP CABLE', 5
Union All Select 'BD1W','LCD', 6
Union All Select 'BD1W','Label', 2
Union All Select 'BL3', 'LCD CABLE', 7
Union All Select 'BL3', 'LABEL', 6
Union All Select 'BL3', 'LCD', 5
Union All Select 'BL3', 'RAM', 1
Union All Select 'BL3D', 'Label', 4
GO
--測試
--方法一:
Select Col1, Col2, Col3 From TEST A
Where (Select Count(*) From TEST Where Col1 = A.Col1 And Col3 > A.Col3) < 3
Order By Col1, Col3 Desc
--方法二:
Select Col1, Col2, Col3 From TEST A
Where Exists (Select Count(*) From TEST Where Col1 = A.Col1 And Col3 > A.Col3 Having Count(*) < 3)
Order By Col1, Col3 Desc
--方法三:
Select Col1, Col2, Col3 From TEST A
Where Col3 In (Select TOP 3 Col3 From TEST Where Col1 = A.Col1 Order By Col3 Desc)
Order By Col1, Col3 Desc
GO
--刪除測試環境
Drop Table TEST
--結果
/*
Col1 Col2 Col3
BD1V HDD 5
BD1V Label 4
BD1V ODD 3
BD1W RAM 8
BD1W LCD 6
BD1W TP CABLE 5
BL3 LCD CABLE 7
BL3 LABEL 6
BL3 LCD 5
BL3D Label 4
*/
declare @T table (c1 varchar(1),c2 int)
insert into @T
SELECT 'A',10 UNION all
select 'A',18 union all
select 'A',1 union all
select 'B',19 union all
select 'B',18 union all
select 'B',1 union all
select 'C',19 union all
select 'C',18 union all
select 'C',1select * from @T t WHERE c2 IN (SELECT TOP 2 c2 FROM @T WHERE c1=t.c1)/*
c1 c2
---- -----------
A 10
A 18
B 19
B 18
C 19
C 18
*/
select 分类,数量
from(
select 分类,数量,rn=row_number() over (partition by 分类 order by 数量 desc)
from tb
) t
where rid <= 2
order by 分类,数量 desc
select t.* from tb t where col2 in (select top 2 col2 from tb where col1 = t.col1 order by col2 desc)
--小三的partition by order by 之句
select 分类,数量
from(
select 分类,数量,rn=row_number() over (partition by 分类 order by 数量 desc)
from tb
) t
where rid <= 2
order by 分类,数量 desc
一个笨重的方法
SELECT AA.NAME,AA.NUMBER FROM A A1 INNER JOIN
(
SELECT RESULT= ROW_NUMBER()OVER(PARTITION BY NAME ORDER BY NUMBER DESC ) ,A2.NAME,A2.NUMBER FROM A A2) AA
ON A1.NAME=AA.NAME AND A1.NUMBER=AA.NUMBER AND (AA.RESULT=1 OR AA.RESULT=2
)
NAME NUMBER
-------------------------------------------------- -----------
A 18
A 19
B 18
B 19
C 18
C 19(6 行受影响)
一个比较笨重的方法SELECT AA.NAME,AA.NUMBER FROM A A1 INNER JOIN
(
SELECT RESULT= ROW_NUMBER()OVER(PARTITION BY NAME ORDER BY NUMBER DESC ) ,A2.NAME,A2.NUMBER FROM A A2) AA
ON A1.NAME=AA.NAME AND A1.NUMBER=AA.NUMBER AND (AA.RESULT=1 OR AA.RESULT=2
)
/*
NAME NUMBER
-------------------------------------------------- -----------
A 18
A 19
B 18
B 19
C 18
C 19(6 行受影响)
*/