sum(isnull((case when c.mode=0 then c.value end),0)) 為0時合計,
sum(isnull((case when c.mode=1 then c.value end),0)) 為1時合計
from
(select a.id id,a.value value,b.mode mode
from table1 a,table2 b where a.item=b.item) c
group by c.id;