在where语句参数

select docket_number,aging from (
    select docket_number, 
        sum(cast(dateDiff(\"mi\",assigned,coalesce(completed,getdate()))/60.00 as decimal(20,2))) aging

    from ft_details_h 

    group by docket_number
)a where aging case  when  @hh <= 72 then  <= @hh else  > @hh end

where 
    (@hh <= 72 and aging <= @hh) or
    (@hh > 72 and aging > @hh)

   where (aging <= @hh And @hh <= 72) Or 
         (aging > @hh And aging > 72)

   where (aging <= @hh And @hh <= 72) Or 
         (aging > @hh  And @hh > 72)