--------------------------------- -- 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 * FROM Prudocts AS T WHERE (SELECT COUNT(*) FROM Prudocts WHERE categoryId=T.categoryId AND ProductId>T.ProductId)<4 and exists (select 1 from Category where Depth=1 and categoryId=T.categoryId)
修改一下~SELECT * FROM Prudocts AS T WHERE (SELECT COUNT(*) FROM Prudocts WHERE categoryId=T.categoryId AND ProductId<T.ProductId)<4 and exists (select 1 from Category where Depth=1 and categoryId=T.categoryId)不过我觉得你原来的语句也没什么不对.贴点数据出来
select top 4 *
from products
where exists(
select 1
from category
where categoryId=products.categoryId
and depth=1
)
比如:
CategoryId ProductId ProductName
1 11 商品1
1 12 商品2
2 21 商品3
2 22 商品4
3 31 商品5
3 32 商品6
就是得出这样的结果,前4个太多了,我就举个前2项的例by~~~谢谢帮忙
-- 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)
*/
是这样子的,如果我只操作一张表,比如Products表,我是可以得出每个类型前几项的数据的,但是如果我操作两张表的时候,一直都得不到结果,直接就把Products这表里面的数据全输出出来了。我写的SQL在楼顶。。
FROM Prudocts AS T
WHERE (SELECT COUNT(*) FROM Prudocts WHERE categoryId=T.categoryId AND ProductId>T.ProductId)<4
and exists (select 1 from Category where Depth=1 and categoryId=T.categoryId)
FROM Prudocts AS T
WHERE (SELECT COUNT(*) FROM Prudocts WHERE categoryId=T.categoryId AND ProductId<T.ProductId)<4
and exists (select 1 from Category where Depth=1 and categoryId=T.categoryId)不过我觉得你原来的语句也没什么不对.贴点数据出来