这条SQL语句怎么样精简呢

[soyestrellafortuna]

select *
  from prpdexch
 where exchdate = (select max(exchdate)
                     from prpdexch
                    where basecurrency = 'HKD'
                      and exchcurrency = 'CNY'
                      and validstatus = '1')
   and basecurrency = 'HKD'
   and exchcurrency = 'CNY'
   and validstatus = '1'

一张兑换率表，里面存放的是各种货币之间的兑换率关系。我想查离当前时间最近的一条兑换率信息。于是就写了上面的语句。虽然可以查询出来。但是这种写法我自己都觉得纠结。
请问有没有可以精简的写法呢。谢谢各位了！

[xpingping]

select * from
(select *
  from prpdexch
 where basecurrency = 'HKD'
   and exchcurrency = 'CNY'
   and validstatus = '1'
 order by exchdate desc)
where rownum=1

[amdgaming]

2种方法 哪种比较好啊？

藐视第二种需要在时间上建索引啊

[我心飞翔]

建议采用：

SELECT * FROM
(SELECT *  FROM prpdexch
   WHERE basecurrency = 'HKD'
   AND exchcurrency = 'CNY'
   AND validstatus = '1'
   ORDER BY exchdate DESC)
WHERE ROWNUM = 1;

[soyestrellafortuna]

谢谢各位。结贴。见者有分吧。