求一条关于时间条件的语句
大家好！
          我有一个表TableTime如下：
    Barcode                 Createdate                               Result
      KK1           2007-09-23   01:21:33                           NG
      KK1           2007-09-23   02:22:33                           NG
      KK1           2007-09-23   04:36:21                           NG
      KK2           2007-09-23   05:36:21                           OK
      KK2           2007-09-23   06:36:21                           OK
      KK3           2007-09-23   04:34:21                           NG
      KK1           2007-09-23   04:58:21                           OK
      KK3           2007-09-23   08:34:21                           NG
........
我想找出数据库中同一条码的时间最后的记录，
如表中的结果就应该是：
KK1           2007-09-23   04:58:21                           OK
KK2           2007-09-23   06:36:21                           OK
KK3           2007-09-23   08:34:21                           NG

请问这个语句该怎么写？




------解决方案--------------------
select * from TableTime
where Barcode,Createdate in (
select Barcode ,max(Createdate)
from TableTime
group by Barcode )

------解决方案--------------------
select a.*
from
tabletime a,
(select Barcode ,max(Createdate) creatdate
from TableTime
group by Barcode
) b
where
a.Barcode=b.Barcode
and a.Createdate=b.Createdate
------解决方案--------------------

select *
from (
select tt.*,
row_number() over(partition by Barcode order by Createdate desc) as rn
from TableTime tt
)zz
where rn = 1;

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

如果是NG的情况:

select *
from (
select tt.*,
row_number() over(partition by Barcode order by Createdate desc) as rn
from TableTime tt
)zz
where rn = 1
and tt.Result = 'NG ';

------解决方案--------------------
create table TableTime(Barcode varchar2(10), Createdate varchar2(50), Result varc