比如以下表结构
select newsid,ntitle,cid,ndate from newsview
1 AA 1 981101
2 BB 1 981102
3 CC 1 981104
4 ABC 2 981105
5 CCD 2 981106
6 SA 2 981107
7 pab 3 981108
8 aa 1 981109
9 ccd 3 981110
.................
N XXX Ncid为类别如何通过一句查询得到以下结果 1 AA 1 981101
2 BB 1 981102
4 ABC 2 981105
5 CCD 2 981106
7 pab 3 981108
9 ccd 3 981110也就是说查询每个种类按时间排序的前二条信息集合
select newsid,ntitle,cid,ndate from newsview
1 AA 1 981101
2 BB 1 981102
3 CC 1 981104
4 ABC 2 981105
5 CCD 2 981106
6 SA 2 981107
7 pab 3 981108
8 aa 1 981109
9 ccd 3 981110
.................
N XXX Ncid为类别如何通过一句查询得到以下结果 1 AA 1 981101
2 BB 1 981102
4 ABC 2 981105
5 CCD 2 981106
7 pab 3 981108
9 ccd 3 981110也就是说查询每个种类按时间排序的前二条信息集合
-- 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)
*/
from tb t
where
ndate in(select top 2 ndate from tb where cid=t.cid order by ndate desc)
WHERE NDATE
IN(SELECT TOP 2 NDATE FROM TB WHERE CID=T.CID ORDER BY NDTATE DESC)
-- Author :fredrickhu(我是小F,向高手学习)
-- Date :2009-11-12 11:02:12
-- 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]([newsid] int,[ntitle] varchar(3),[cid] int,[ndate] int)
insert [tb]
select 1,'AA',1,981101 union all
select 2,'BB',1,981102 union all
select 3,'CC',1,981104 union all
select 4,'ABC',2,981105 union all
select 5,'CCD',2,981106 union all
select 6,'SA',2,981107 union all
select 7,'pab',3,981108 union all
select 8,'aa',1,981109 union all
select 9,'ccd',3,981110
--------------开始查询--------------------------
SELECT * FROM tb AS T WHERE 2>(SELECT COUNT(*) FROM tb WHERE cID=T.cID AND nDate<T.nDate)----------------结果----------------------------
/* newsid ntitle cid ndate
----------- ------ ----------- -----------
1 AA 1 981101
2 BB 1 981102
4 ABC 2 981105
5 CCD 2 981106
7 pab 3 981108
9 ccd 3 981110(6 行受影响)
*/
WHERE NDATE
IN(SELECT TOP 2 NDATE FROM TB WHERE CID=T.CID ORDER BY NDTATE )
---测试数据---
if object_id('[tb]') is not null drop table [tb]
go
create table [tb]([newsid] int,[ntitle] varchar(3),[cid] int,[ndate] int)
insert [tb]
select 1,'AA',1,981101 union all
select 2,'BB',1,981102 union all
select 3,'CC',1,981104 union all
select 4,'ABC',2,981105 union all
select 5,'CCD',2,981106 union all
select 6,'SA',2,981107 union all
select 7,'pab',3,981108 union all
select 8,'aa',1,981109 union all
select 9,'ccd',3,981110
---查询---
select *
from tb t
where
ndate in(select top 2 ndate from tb where cid=t.cid order by ndate)
order by cid,newsid---结果---
newsid ntitle cid ndate
----------- ------ ----------- -----------
1 AA 1 981101
2 BB 1 981102
4 ABC 2 981105
5 CCD 2 981106
7 pab 3 981108
9 ccd 3 981110(所影响的行数为 6 行)
go
create table [tb]([newsid] int,[ntitle] varchar(3),[cid] int,[ndate] int)
insert [tb]
select 1,'AA',1,981101 union all
select 2,'BB',1,981102 union all
select 3,'CC',1,981104 union all
select 4,'ABC',2,981105 union all
select 5,'CCD',2,981106 union all
select 6,'SA',2,981107 union all
select 7,'pab',3,981108 union all
select 8,'aa',1,981109 union all
select 9,'ccd',3,981110
SELECT * FROM TB T
WHERE ndate
IN(SELECT TOP 2 ndate FROM TB WHERE CID=T.CID ORDER BY ndate )
(所影响的行数为 9 行)newsid ntitle cid ndate
----------- ------ ----------- -----------
1 AA 1 981101
2 BB 1 981102
4 ABC 2 981105
5 CCD 2 981106
7 pab 3 981108
9 ccd 3 981110(所影响的行数为 6 行)
where newsid in (select top 2 newsid from newsview where cid = t.cid order by ndate)
if object_id('[tb]') is not null drop table [tb]
go
create table [tb]([newsid] int,[ntitle] varchar(3),[cid] int,[ndate] int)
insert [tb]
select 1,'AA',1,981101 union all
select 2,'BB',1,981102 union all
select 3,'CC',1,981104 union all
select 4,'ABC',2,981105 union all
select 5,'CCD',2,981106 union all
select 6,'SA',2,981107 union all
select 7,'pab',3,981108 union all
select 8,'aa',1,981109 union all
select 9,'ccd',3,981110select [newsid] ,[ntitle] ,[cid] ,[ndate] from (
select orid= row_number() over(partition by [cid] order by [newsid]),* from [tb])A
where orid < =2
============
newsid ntitle cid ndate
----------- ------ ----------- -----------
1 AA 1 981101
2 BB 1 981102
4 ABC 2 981105
5 CCD 2 981106
7 pab 3 981108
9 ccd 3 981110(6 行受影响)
select [newsid] ,[ntitle] ,[cid] ,[ndate] from (
select orid= row_number() over(partition by [cid] order by [ndate]),* from [tb])A
where orid < =2=========
--按时间排序
表AID 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
表BID GID Author Title Date
---- ----------- ----------------------------- --------------------------------------- -----------------------
033 1 格罗夫Groff.J.R.-B SQL完全手册-B 2009-07-01 11:00:00.000
034 1 KalenDelaney-B SQLServer2005技术内幕存储引擎-B 2008-08-01 11:00:00.000
035 2 Alex.Kriegel.Boris.M.Trukhnov-B SQL宝典-B 2007-10-05 11:00:00.000
037 2 胡百敬-B SQLServer2005数据库开发详解-B 2008-06-15 11:00:00.000
039 3 赵松涛-B SQLServer2005系统管理实录-B 2008-10-01 11:00:00.000
040 3 黄占涛-B SQL技术手册-B 2006-01-01 11:00:00.000
我的表是通过 select * from a union all select * from b 得来的,这样怎么办(不想用视图行吗?)
*
FROM
(select * from a union all select * from b) AS T
WHERE
2>(SELECT COUNT(*) FROM (select * from a union all select * from b) WHERE cID=T.cID AND nDate<T.nDate)
SELECT
*
FROM
(select * from a union all select * from b) AS T
WHERE
2>(SELECT COUNT(*) FROM (select * from a union all select * from b)b WHERE b.cID=T.cID AND b.nDate<T.nDate)
insert into @ls(newsid,ntitle,cid,ndate) values(1,'AA',1,'981101')
insert into @ls(newsid,ntitle,cid,ndate) values(2,'BB',1,'981102')
insert into @ls(newsid,ntitle,cid,ndate) values(3,'CC',1,'981104')
insert into @ls(newsid,ntitle,cid,ndate) values(4,'ABC',2,'981105')
insert into @ls(newsid,ntitle,cid,ndate) values(5,'CCD',2,'981106')
insert into @ls(newsid,ntitle,cid,ndate) values(6,'SA',2,'981107')
insert into @ls(newsid,ntitle,cid,ndate) values(7,'pab',3,'981108')
insert into @ls(newsid,ntitle,cid,ndate) values(8,'aa',1,'981109')
insert into @ls(newsid,ntitle,cid,ndate) values(9,'ccd',3,'981110')
select newsid,ntitle,cid,ndate from (select row_number() over(partition by cid order by ndate) as px,* from @ls) a where px<=2