Sql到NHibernate QueryOver

select k1.Id,k.sm
from tblKarbarg_1 k1
inner join (
            select kd.Karbarg_1_id,SUM(kd.MablaghSanad) as sm 
            from tblKarbarg_1_Detail kd 
            group by kd.Karbarg_1_id
            ) K 
on k.Karbarg_1_id=k1.Id