update t_mrp_planorderentry set fentrydroprequireqty =(
(select pl1.fdropqty from t_mrp_planorder pl1 where pl1.fid=t_mrp_planorderentry.fid) * frequireqty / 
(select pl2.forderqty from t_mrp_planorder pl2 where pl2.fid=t_mrp_planorderentry.fid))
where fid in (select fid from t_mrp_planorder where fbillstatus in ('C','D') and fdropqty>0) and fentrydroprequireqty=0;