create view order_info as 
select 
   v1.order_no
  ,v1.order_date
  ,v1.customer_code
  ,v1.customer_name
  ,v2.seqno
  ,v2.article_code
  ,v2.article_name
  ,v2.qty
  ,v2.price
  ,v2.amount
from
( 
  select 
     r.order_no
    ,r.order_date
    ,r.customer_code
    ,c.customer_name
  from receive_order r inner join customer_master c
  on (r.customer_code = c.customer_code)
)
v1 inner join 
(
  select 
     i.order_no as order_no2
    ,i.seqno
    ,i.article_code
    ,i.qty
    ,a.article_name
    ,a.price
    ,a.price * i.qty as amount
  from order_item i inner join article_master a 
  on (i.article_code = a.article_code)
) 
v2 on (v1.order_no = v2.order_no2)