根据最近时间求单价....SQL

CREATE TABLE tb(日期 datetime, 料号 NVARCHAR(30), 单价 int)

INSERT tb SELECT '2008/5/1','AAA',2
UNION ALL SELECT '2008/6/6','BBB',22
UNION ALL SELECT '2008/6/6','CCC ',12
UNION ALL SELECT '2008/7/3','BBB',21
UNION ALL SELECT '2008/7/9','AAA ',1

--select * from tb

--select distinct 料号 FROM TB
--select count (distinct 料号) from tb

--select TOP 1 日期 ,单价 from tb where 料号 ='AAA' order by 日期 DESC

create procedure sp_查询最近单价
WITH ENCRYPTION
AS
begin tran--启动事务
declare @ERROR int
set @ERROR=0
begin
declare @temp table
(
[日期] datetime,
[料号] NVARCHAR(30),
[单价] int
)
declare @tempdb料号 table
(
[id] int identity(1,1),
[料号] NVARCHAR(30)
)
declare @改后temp table
(
[日期] datetime,
[料号] NVARCHAR(30),
[单价] int
)
insert into @temp select * from tb
-- SELECT * FROM @tempdb
SET @ERROR =@ERROR +@@ERROR
IF (@ERROR <>0) GOTO EXT
insert into @tempdb料号 select DISTINCT 料号 from tb
-- SELECT * FROM @tempdb料号
SET @ERROR =@ERROR +@@ERROR
IF (@ERROR <>0) GOTO EXT

declare @temp日期 datetime,@temp料号 varchar(30),@temp单价 INT,@I int
set @i=1
select distinct 料号 FROM @tempdb料号 where id=@i

WHILE @@rowcount<>0
begin
select TOP 1 @temp日期=日期 ,@temp料号=料号,@temp单价=单价 from @temp where 料号 =(select distinct 料号 FROM @tempdb料号 where id=@i )
order by 日期 DESC
SET @ERROR =@ERROR +@@ERROR
IF (@ERROR <>0) GOTO EXT
INSERT INTO @改后temp VALUES(@temp日期,@temp料号,@temp单价)
SET @ERROR =@ERROR +@@ERROR
IF (@ERROR <>0) GOTO EXT
set @i=@i+1
select distinct 料号 FROM @tempdb料号 where id=@i
end

select * from @改后temp

end

--异常出口
EXT:

--判断执行状态
IF (@ERROR =0)
BEGIN
COMMIT
END
ELSE
ROLLBACK

exec sp_查询最近单价

结果:
2008-07-09 00:00:00.000 AAA 1
2008-07-03 00:00:00.000 BBB 21
2008-06-06 00:00:00.000 CCC 12