求助，使用SQL汇总某一列的数据

php_

写了个存储过程，这样应该可以实现了，不知道效率如何？

CREATE OR REPLACE FUNCTION stubfun()
  RETURNS SETOF record AS
$BODY$
declare
        ref refcursor;
        a integer;
        b integer;
        c integer;
        d integer;
BEGIN
        create temp table sum_tmp (uid integer, bid integer, sz integer, ct integer)
        on commit drop;

        insert into sum_tmp
                select uid, bid, sum(sz) as sz, sum(ct) as ct
                from stub2
                group by uid,bid
                order by uid,bid;

        --合并数据
        update stub
                set sz=stub.sz+sum_tmp.sz,ct=stub.ct+sum_tmp.ct
                from sum_tmp
                where stub.uid=sum_tmp.uid and stub.bid=sum_tmp.bid;

        open ref for        
        (
                select * from sum_tmp
        );


        --循环检查是否有新数据需要插入
loop
        fetch ref into a, b, c, d;
        if (found)
        then
                if not exists
                        (select * from stub where uid = a and bid = b)
                then
                        insert into stub values (a,b,c,d);
--                else
--                        update stub set sz=sz+c, ct=ct+d where uid = a and bid = b;
                end if;
        else
                exit;
        end if;
end loop;

   RETURN ;
END;
$BODY$
  LANGUAGE plpgsql VOLATILE
  COST 100;
ALTER FUNCTION stubfun() OWNER TO postgres;