题解 | #返回每个顾客不同订单的总金额#

select
    o.cust_id,
    t.total_ordered
from
    Orders o
    join (
        select
            order_num,
            sum(item_price * quantity) as total_ordered
        from
            OrderItems
        group by
            order_num
    ) t on o.order_num = t.order_num
order by
    t.total_ordered DESC