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 , t.order_num, t.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) t on o.order_num =t.order_num order by c.cust_name,t.order_num #考察多表连接，我在做题的时候实在太粗心了，导致一直出现 "Unknown column order_num in 'field list'" 的情况，实际是我在子查询（select order_num ,sum( quantity *item_price ) as OrderTotal from OrderItems ）忘记写from了，唉，还是要细心的