select j.id,j.jobdate,sum(j.total) + jh.histtotal
from job j
inner join (select id,jobdate,sum(total) as histtotal
from jobhistory 
group by id,jobdate)jh
on j.jobdate = jh.jobdate
and j.id = jh.id
group by j.id,j.jobdate,jh.histtotal

select sum(a.total) as total
  from (select sum(total) as total from jobhistory where jobdate = '7/2/2012' and id=35
        union all
        select sum(total) as total from job where jobdate = '7/2/2012' and id=35
       ) as a