题解 | #返回每个顾客不同订单的总金额#

SELECT
  o.cust_id as cust_id , tb.total_ordered as total_ordered
from
  (
    select
      a.order_num,
      SUM(a.item_price * a.quantity) as total_ordered
    from
      OrderItems a
    group by
      a.order_num
  ) tb,
  Orders o
where
  tb.order_num = o.order_num
order by
  tb.total_ordered desc