题解 | #返回每个顾客不同订单的总金额#

select
    t2.cust_id as cust_id,
    t1.total_ordered as total_ordered
from
    (
        select
            order_num,
            sum(item_price * quantity) as total_ordered
        from
            OrderItems
        group by
            order_num
    ) as t1, Orders as t2
    where t1.order_num = t2.order_num
    order by total_ordered desc;