Oracle多表级联更新详解

用游标实现，我觉得绝对这种方法比较安全的。
--首先定一个游标把需要用到的一些数据存放到游标中:

declare
  cursor d_cursor_cus_info is
    select t3.id_           as id_,
           t3.owe_money_    as owe_money_,
           a.heatingarea    as heating_area_
    from t_cus_owe_money_2 t2
    left join t_cus_owe_money_3 t3 on t2.id_= t3.id_
    left join (select s.bh,  sum(
           case
                 when s.stkbz='0' then nvl(s.mj,0)
                 when s.stkbz='1' then 0-nvl(s.mj,0)
           end
      ) as heatingarea from  sk s  where s.nd = '2008-2009' group by s.bh) a on t2.bh_=a.bh
  where  t3.owe_money_- t2.owe_money_  = a.heatingarea*5 and t3.owe_money_ > 0;

--然后循环游标对数据进行更新：

begin
        for everyrow in d_cursor_cus_info
        loop
         update t_cus_year_status t
             set t.heating_area_ = everyrow.heating_area_,
                 t.owe_money_    = everyrow.owe_money_
             where t.year_ = '2008-2009'
                   and t.id_ = everyrow.id_;
       end loop;
      commit;
end;