题解 | 返回顾客名称和相关订单号以及每个订单的总价

with t3 as(
  select
cust_id,
t1.order_num order_num,
sum(quantity*item_price) OrderTotal
from
Orders t1 left join OrderItems t2 on t1.order_num=t2.order_num
group by cust_id,order_num  
)
select
cust_name,
order_num,
OrderTotal
from 
t3 inner join Customers t4 on t3.cust_id=t4.cust_id
order by cust_name,order_num