oracle 数据库查询语句答:--正式语句:select a.main_id,a.main_name,max(decode(b.sub_id, 1, b.sub_id)) sub_id_a,max(decode(b.sub_id, 1, b.sub_name)) sub_name_a,max(decode(b.sub_id, 2, b.sub_id)) sub_id_b,max(decode(b.sub_id, 2, b.sub_name)) sub_name_b,max(decode(b.sub_...