create table Grade
(
GradeID int identity(1,1) primary key,
SNO int,
CNO int,
Score float
)
insert into Grade(SNO,CNO,Score) values(100,10,100);
insert into Grade(SNO,CNO,Score) values(100,11,45);
insert into Grade(SNO,CNO,Score) values(100,12,30);

insert into Grade(SNO,CNO,Score) values(101,10,87);
insert into Grade(SNO,CNO,Score) values(101,11,100);
insert into Grade(SNO,CNO,Score) values(101,12,87);

insert into Grade(SNO,CNO,Score) values(102,10,87);
insert into Grade(SNO,CNO,Score) values(102,11,45);
insert into Grade(SNO,CNO,Score) values(102,12,100);

insert into Grade(SNO,CNO,Score) values(103,12,50);

create proc [dbo].[Product_Insert]
@ProductCategoryID int,
@ProductName nvarchar(50),
@ProductImage image,
@Description text,
@Price smallmoney
as
--Start the transaction
begin transaction
declare @ProductImageID int
insert into ProductImages(ProductImage) values(@ProductImage)
--Roll back the transaction if there were any error
if @@error<>0
begin
--Roll back the transaction
rollback
--Raise an error and return
raiserror('Error insert into ProductImages.',16,1)
return
end
set @ProductImageID=@@identity

insert into Products(ProductCategoryID,ProductName,ProductImageID,Description,Price) 
values(@ProductCategoryID,@ProductName,@ProductImageID,@Description,@Price)
--Roll back the transaction if there were any error
if @@error<>0
begin
--Roll back the transaction
rollback
--Raise an error and return
raiserror('Error insert into Products.',16,1)
return
end
commit

---------------------------------
--  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
---- ----------- ----------------------------- -------------------------------