我这个sql语句会产生阻塞甚至死锁，请高手看看啦，sql2000

select top 1 RelHumi, ydatetime

from [zsqxdb].[dbo].[YCZ_Minutes_Data_New]
where RelHumi =(
SELECT max(RelHumi) FROM [zsqxdb].[dbo].[YCZ_Minutes_Data_New]
where (year(ydatetime)=year(getdate()))
and (month(ydatetime)=month(getdate()))
and (day(ydatetime)=day(getdate()))
and (datename(HH,ydatetime)=datename(HH,getdate()))
)
and (year(ydatetime)=year(getdate()))
and (month(ydatetime)=month(getdate()))
and (day(ydatetime)=day(getdate()))
and (datename(HH,ydatetime)=datename(HH,getdate()))

就是查询RelHumi在这个小时最大的那个数据和时间，最近老是有死锁，不知道为什么，如何修改

SELECT top 1 max(RelHumi) as RelHumi, ydatetime FROM [zsqxdb].[dbo].[YCZ_Minutes_Data_New]
where (year(ydatetime)=year(getdate()))
and (month(ydatetime)=month(getdate()))
and (day(ydatetime)=day(getdate()))
and (datename(HH,ydatetime)=datename(HH,getdate()))