select 标题,作者 from (select 标题,作者,id=row_number() over (partition by 作者 order by 标题) from 投稿) t where id<=2
select 标题,作者 from 投稿 T WHERE 标题 IN(SELECT TOP 2 标题 FROM 投稿 WHERE 作者=T.作者 )
select 标题,作者 from 投稿 T WHERE 标题 IN(SELECT TOP 2 标题 FROM 投稿 WHERE 作者=T.作者 ORDER BY NEWID())
select 标题,作者 from 投稿 t where 标题 in (select top(2) 标题 from 投稿 where 作者=t.作者)
SQL2005 select 标题,作者 from ( select 标题,作者,id=row_number() over (partition by 作者 order by 标题) from 投稿 ) t where id <=2 SQL2000 select 标题,作者 from 投稿 T WHERE 标题 IN (SELECT TOP 2 标题 FROM 投稿 WHERE 作者=T.作者 )
--------------------------------- -- 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) */
select K_wz.wzid,K_wz.title,K_wz.txtuserName,K_wz.Price,K_user.txtqq from K_wz INNER JOIN K_user ON K_wz.txtuserName = K_user.txtuserName where K_wz.step<5 and K_wz.leixing=1同理,如何每个用户显示最多2个title?谢谢。多个表查询,不知道名字弄
select wzid,title,txtuserName,Price,txtqq from ( select K_wz.wzid,K_wz.title,K_wz.txtuserName,K_wz.Price,K_user.txtqq, id=row_number() over (partition by K_wz.txtuserName order by K_wz.title) from K_wz INNER JOIN K_user ON K_wz.txtuserName = K_user.txtuserName where K_wz.step <5 and K_wz.leixing=1) T where id<=2
select K_wz.wzid,K_wz.title,K_wz.txtuserName,K_wz.Price,K_user.txtqq from K_user cross apply ( select top 2 * from K_wz where K_wz.txtuserName = K_user.txtuserName and K_wz.step <5 and K_wz.leixing=1 ) K_wz
这语句有问题吧?select top 2只是查询在最前的两行标题,而不是表中任何的两个标题,要是我想要查询最多只能返回表中任何的两个标题呢?我觉得select top 2有问题
(select 标题,作者,id=row_number() over (partition by 作者 order by 标题) from 投稿) t
where id<=2
SQL2005
select 标题,作者
from (
select 标题,作者,id=row_number() over (partition by 作者 order by 标题) from 投稿
) t
where id <=2 SQL2000
select 标题,作者
from 投稿 T
WHERE 标题 IN (SELECT TOP 2 标题 FROM 投稿 WHERE 作者=T.作者 )
-- 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)
*/
select K_wz.wzid,K_wz.title,K_wz.txtuserName,K_wz.Price,K_user.txtqq,
id=row_number() over (partition by K_wz.txtuserName order by K_wz.title)
from K_wz INNER JOIN K_user ON K_wz.txtuserName = K_user.txtuserName
where K_wz.step <5 and K_wz.leixing=1) T
where id<=2
from K_user
cross apply (
select top 2 * from K_wz where K_wz.txtuserName = K_user.txtuserName and
K_wz.step <5 and K_wz.leixing=1 ) K_wz
这语句有问题吧?select top 2只是查询在最前的两行标题,而不是表中任何的两个标题,要是我想要查询最多只能返回表中任何的两个标题呢?我觉得select top 2有问题