select
  b.ITEM_CODE as CODE,
  c.ITEM_NAME as NAME,
  SUM((b.UNITPRICE * b.ORDER_QTY)) as TOTAL_AMT
from
  orders a
  left join orders_dtl b
    on a.ORDER_NO = b.order_no
  left join item c
    on b.item_code = c.item_code
group by
  code,name
order by
  TOTAL_AMT desc, b.item_code limit 5