题解 | #返回每个顾客不同订单的总金额#

with t as(
select order_num,sum(item_price*quantity)'total_order'
from OrderItems 
group by order_num
)
select o.cust_id,t.total_order 
from Orders o left join t
on o.order_num=t.order_num
order by t.total_order desc;