题解 | #确定最佳顾客的另一种方式（二）#

难点：关联字段的选择以及子查询和联结的使用

根据题目，分析解题思路：

在OrderItems表，根据订单号，计算出订单总金额 在Orders表，根据订单号，得出是哪一个顾客 用order_num 列 将 Orders表 与 OrderItems表关联 用cust_id 列 将 Customers 表与 Orders表关联 最后添加订单金额筛选条件和排序

select
  a.cust_name,
  c.d as total_price
from
  Customers a,Orders b
  inner join 
  (
    select
      order_num,
      sum(item_price * quantity) as d
    from
      OrderItems
    group by
      order_num
  ) c on b.order_num = c.order_num
where
  a.cust_id = b.cust_id
  and c.d >= 1000
order by
  total_price