如下一个表:
a b c d
A 70 WRYR ART
A 50 GHS GHSR
A 10 ATA SH
C 80 ATA SHGS
C 10 PFJAO AT
V 40 QQQQ GJH
V 30 SG AAG
V 20 GHSA GG
V 10 HDG HHb列是数值,是按照a列每个名称来降序排列的,现请教如何能取出按照a列名称,每种就要b列最大的2个值的数据,比如取到的数据如下表:
a b c d
A 70 WRYR ART
A 50 GHS GHSR
C 80 ATA SHGS
C 10 PFJAO AT
V 40 QQQQ GJH
V 30 SG AAG
谢谢大家!!!!!!!
a b c d
A 70 WRYR ART
A 50 GHS GHSR
A 10 ATA SH
C 80 ATA SHGS
C 10 PFJAO AT
V 40 QQQQ GJH
V 30 SG AAG
V 20 GHSA GG
V 10 HDG HHb列是数值,是按照a列每个名称来降序排列的,现请教如何能取出按照a列名称,每种就要b列最大的2个值的数据,比如取到的数据如下表:
a b c d
A 70 WRYR ART
A 50 GHS GHSR
C 80 ATA SHGS
C 10 PFJAO AT
V 40 QQQQ GJH
V 30 SG AAG
谢谢大家!!!!!!!
-- 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)
*/
-- Author :fredrickhu(我是小F,向高手学习)
-- Date :2010-01-25 13:27:39
-- Version:
-- Microsoft SQL Server 2005 - 9.00.4035.00 (Intel X86)
-- Nov 24 2008 13:01:59
-- Copyright (c) 1988-2005 Microsoft Corporation
-- Developer Edition on Windows NT 5.2 (Build 3790: Service Pack 1)
--
----------------------------------------------------------------
--> 测试数据:[tb]
if object_id('[tb]') is not null drop table [tb]
go
create table [tb]([a] varchar(1),[b] int,[c] varchar(5),[d] varchar(4))
insert [tb]
select 'A',70,'WRYR','ART' union all
select 'A',50,'GHS','GHSR' union all
select 'A',10,'ATA','SH' union all
select 'C',80,'ATA','SHGS' union all
select 'C',10,'PFJAO','AT' union all
select 'V',40,'QQQQ','GJH' union all
select 'V',30,'SG','AAG' union all
select 'V',20,'GHSA','GG' union all
select 'V',10,'HDG','HH'
--------------开始查询--------------------------
SELECT * FROM TB AS T WHERE B IN(SELECT TOP 2 B FROM TB WHERE A=T.A ORDER BY B DESC)
----------------结果----------------------------
/* a b c d
---- ----------- ----- ----
A 70 WRYR ART
A 50 GHS GHSR
C 80 ATA SHGS
C 10 PFJAO AT
V 40 QQQQ GJH
V 30 SG AAG(6 行受影响)
*/
from (
select *,rn=ROW_NUMBER()over(partition by a order by b desc) from tb
) z
where rn<=2
go
create table [tb]([a] varchar(1),[b] int,[c] varchar(5),[d] varchar(4))
insert [tb]
select 'A',70,'WRYR','ART' union all
select 'A',50,'GHS','GHSR' union all
select 'A',10,'ATA','SH' union all
select 'C',80,'ATA','SHGS' union all
select 'C',10,'PFJAO','AT' union all
select 'V',40,'QQQQ','GJH' union all
select 'V',30,'SG','AAG' union all
select 'V',20,'GHSA','GG' union all
select 'V',10,'HDG','HH'select a,b,c,d
from (
select *,rn=ROW_NUMBER()over(partition by a order by b desc) from tb
) z
where rn<=2(9 行受影响)
a b c d
---- ----------- ----- ----
A 70 WRYR ART
A 50 GHS GHSR
C 80 ATA SHGS
C 10 PFJAO AT
V 40 QQQQ GJH
V 30 SG AAG(6 行受影响)
go
create table [tb]([a] varchar(1),[b] int,[c] varchar(5),[d] varchar(4))
insert [tb]
select 'A',70,'WRYR','ART' union all
select 'A',50,'GHS','GHSR' union all
select 'A',10,'ATA','SH' union all
select 'C',80,'ATA','SHGS' union all
select 'C',10,'PFJAO','AT' union all
select 'V',40,'QQQQ','GJH' union all
select 'V',30,'SG','AAG' union all
select 'V',20,'GHSA','GG' union all
select 'V',10,'HDG','HH'
自动生成代码的存储过程
楼主可以去看看昨夜小楼的BLOG
from 如下一个表 t
where 2>(select count(*) from 如下一个表 where a=t.a and b>t.b)
order by a,b desc
a b c d
A 70 WRYR ART
A 50 GHS GHSR
A 50 ATA SH
C 80 ATA SHGS
C 10 PFJAO AT
V 40 QQQQ GJH
V 30 SG AAG
V 30 GHSA GG
V 10 HDG HH请教如何能取出按照a列名称,每种就要b列最大的2个值的数据,比如取到的数据如下表: a b c d
A 70 WRYR ART
A 50 GHS GHSR
A 50 ATA SH
C 80 ATA SHGS
C 10 PFJAO AT
V 40 QQQQ GJH
V 30 SG AAG
V 30 GHSA GG
谢谢大家!!!!!!!
-- Author :fredrickhu(我是小F,向高手学习)
-- Date :2010-01-25 15:58:40
-- Version:
-- Microsoft SQL Server 2005 - 9.00.4035.00 (Intel X86)
-- Nov 24 2008 13:01:59
-- Copyright (c) 1988-2005 Microsoft Corporation
-- Developer Edition on Windows NT 5.2 (Build 3790: Service Pack 1)
--
----------------------------------------------------------------
--> 测试数据:[tb]
if object_id('[tb]') is not null drop table [tb]
go
create table [tb]([a] varchar(1),[b] int,[c] varchar(5),[d] varchar(4))
insert [tb]
select 'A',70,'WRYR','ART' union all
select 'A',50,'GHS','GHSR' union all
select 'A',50,'ATA','SH' union all
select 'C',80,'ATA','SHGS' union all
select 'C',10,'PFJAO','AT' union all
select 'V',40,'QQQQ','GJH' union all
select 'V',30,'SG','AAG' union all
select 'V',30,'GHSA','GG' union all
select 'V',10,'HDG','HH'
--------------开始查询--------------------------
SELECT * FROM TB AS T WHERE B IN(SELECT TOP 2 with ties B FROM TB WHERE A=T.A ORDER BY B DESC)
----------------结果----------------------------
/* a b c d
---- ----------- ----- ----
A 70 WRYR ART
A 50 GHS GHSR
A 50 ATA SH
C 80 ATA SHGS
C 10 PFJAO AT
V 40 QQQQ GJH
V 30 SG AAG
V 30 GHSA GG(8 行受影响)
*/