SQL 优化求助

请帮忙看看怎么优化一下，该表数据约为66万，运行时间要19秒,SQL如下：

select DATEPART (hh ,Date_time ) as Hours ,
sum(Counts)*100.0/(Select sum(Counts) as total
                          from APP_MR_UL_L_TA b
                          where BSC_NO = 'BSC0121401' and DATEPART (hh ,a.Date_time ) = DATEPART (hh ,b.Date_time ) ) as PerValues
from APP_MR_UL_L_TA a
where 1 = 1 and BSC_NO = 'BSC0121401' and DL_L < -90 and TA <2
group by DATEPART (hh ,Date_time )
order by DATEPART (hh ,Date_time ) asc

注：环境
SQL Server 2005
CPU:T2300 2*@1.66GHZ
RAM:1.5GB

不胜感激。

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8分太少了

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不会 学习

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1:加索引
2：升级硬件
3：优化SQL语句

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偶对钱感兴趣，对感激没兴趣，呵