题解 | #返回顾客名称和相关订单号以及每个订单的总价#

select c.cust_name,a.order_num, a.OrderTotal
from Customers c
join Orders o 
on c.cust_id = o.cust_id
join
(
    select order_num,sum(quantity*item_price) as OrderTotal
    from OrderItems 
    group by order_num
)a
on o.order_num = a.order_num
order by c.cust_name,a.order_num