题解 | 返回顾客名称和相关订单号以及每个订单的总价

select cust_name,o1.order_num,(quantity*item_price) as OrderTotal
from Customers c join Orders o1 on c.cust_id = o1.cust_id join OrderItems o2 on o1.order_num = o2.order_num
order by cust_name