更新表（多表相关联）

update f_shortforest forest
   set forest.forestquantity = (select (decode(sum(detail.quantity),
                                               null,
                                               0,
                                               sum(detail.quantity)) * 0.6 +
                                       decode(forest.forestquantity,
                                               null,
                                               0,
                                               forest.forestquantity) * 0.4)
                                  FROM d_salerplan@tpo       master,
                                       d_salerplandetail@tpo detail
                                 where master.sorderid = detail.sorderid
                                   and forest.estimateyear =
                                       substr(master.ordermonth, 1, 4)
                                   and forest.month =
                                       substr(master.ordermonth, 5, 2)
                                   and forest.productid = detail.productid
                                 group by detail.productid)
where exists(select detail.quantity
                                  FROM d_salerplan@tpo       master,
                                       d_salerplandetail@tpo detail
                                 where master.sorderid = detail.sorderid
                                   and forest.estimateyear =
                                       substr(master.ordermonth, 1, 4)
                                   and forest.month =
                                       substr(master.ordermonth, 5, 2)
                                   and forest.productid = detail.productid);