求sql语句求和后比较,该怎么处理

求sql语句求和后比较
select sum(raw) as raw from tabData where ID like 'T809' and ObservTime between '2011-06-05 11:52:57' AND '2011-06-06 11:52:57'
想将sum(raw) as raw这点判断一下大于多少

select sum(raw) as raw from tabData where ID like 'T809' and ObservTime between '2011-06-05 11:52:57' AND '2011-06-06 11:52:57' order by raw desc
order by raw desc不起作用了。why？

------解决方案--------------------
select sum(raw) as raw from tabData where ID like 'T809' and ObservTime between '2011-06-05 11:52:57' AND '2011-06-06 11:52:57'
想将sum(raw) as raw这点判断一下大于多少

select sum(raw) as raw from tabData where ID like 'T809' and ObservTime between '2011-06-05 11:52:57' AND '2011-06-06 11:52:57' having sum(raw)>你的值

试试
select sum(raw) as raw from tabData where ID like 'T809' and ObservTime between '2011-06-05 11:52:57' AND '2011-06-06 11:52:57' order by 1 desc
------解决方案--------------------
select sum(raw) as raw 
from tabData 
where ID like 'T809' 
and ObservTime between '2011-06-05 11:52:57' AND '2011-06-06 11:52:57' 
order by sum(raw) desc