Here is one way of doing it:
select Col1,Col2
from MyTable
where DateCol > dateadd(hh,8,(dateadd(dd,datediff(dd,'20100101',getdate()),'20100101')))
and DateCol < dateadd(hh,10,(dateadd(dd,datediff(dd,'20100101',getdate()),'20100101')))
Adi
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