select cust_name,t3.order_num ,sum(quantity*item_price) as OrderTotal
from Customers t1  inner join  Orders t2
on t1.cust_id=t2.cust_id
inner join OrderItems t3
on t2.order_num=t3.order_num
group by cust_name,t3.order_num
order by cust_name,t3.order_num