存储过程查询的一个有关问题 江湖救急了

存储过程查询的一个问题 江湖救急了
查询出一个表里 bookid不重复并且时间是最新的数据 

例如： booksid datetime 
  1 10:00:00 
  1 12:00:00 
  2 07:00:00 
  2 11:00:00 
我只想要 1 12:00:00 和 2 11:00:00 数据 
我该怎么办 各位大神前来帮帮忙
拜托了

[解决办法]

SQL code

select * from tb t where datetime=(select max(datetime) from tb where bookid=t.bookid)
[解决办法]
SQL code
select * from tb t where [datetime]=(select max([datetime]) from tb where bookid=t.bookid)
[解决办法]
SQL code
select A.*from TB Awhere not exists(select 1 from TB B where A.booksid = B.booksid and A.datetime <B.datetime)
[解决办法]
select b.booksid,b.datetime from table as b join
(
select booksid,max(datetime) from table as A group by booksid) as c
on b.booksid=c.booksid and b.datetime=c.datetime

ls几位的也可以的,很多种办法
[解决办法]
select b.booksid,b.datetime from table as b join
(
select booksid,max(datetime)as datetime from table as A group by booksid) as c
on b.booksid=c.booksid and b.datetime=c.datetime
[解决办法]
SQL code
create table ny(booksid int,dt time)  insert into nyselect 1, '10:00:00' union allselect 1, '12:00:00' union allselect 2, '07:00:00' union allselect 2, '11:00:00'select booksid,dtfrom(select *,row_number() over(partition by booksid order by dt desc) rn from ny) ywhere rn=1/*booksid     dt----------- ----------------1           12:00:00.00000002           11:00:00.0000000(2 row(s) affected)*/