--批量对符合条件的表记录进行更新
--aa代表查询出的符合条件数据的别名
--aa后的表示需要符合的条件
--loop后开始写更新操作
begin
  for aa in (select a.objectid
               from geographic_info a, geographic_info_bf b
              where a.objectid = b.objectid
                and b.pgeocode = 'xxx') loop
    update geographic_info
       set qxcode = 'xxx', pgeocode = 'xxx'
     where objectid = aa.objectid;
  end loop;
end;