select copy.nam,                  --부등호 큰 쪽

         copy.val,                     --부등호 큰 쪽

         sum(org.val) "누계"  --부등호 작은 쪽
from   (select nam, val
           from   A
           order by nam) org,
         (select nam, val
          from   A
          order by nam) copy
where  org.nam <= copy.nam --부등호 큰 쪽 기준으로 group by 해야 됨
group by copy.nam, copy.val