题解 | #返回顾客名称和相关订单号以及每个订单的总价#

1、先通过OrderItems计算得到每个订单的汇总表 2、用汇总表和其他三张表相连接，得到最终表

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