题解 | #返回顾客名称和相关订单号以及每个订单的总价#

                                  from OrderItems as OI
                                  WHERE O.order_num=OI.order_num
                                  group by OI.order_num
                                ) as OrderTotal
from Customers as C INNER JOIN Orders as O 
on C.cust_id= O.cust_id
inner join OrderItems as OI
on O.order_num=OI.order_num
group by C.cust_name, O.order_num
order by C.cust_name, O.order_num;