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, ord.order_num, quantity * item_price OrderTotal from Customers cus join Orders ord on cus.cust_id = ord.cust_id join OrderItems ori on ord.order_num = ori.order_num order by cust_name asc, ord.order_num asc