题解 | #确定最佳顾客的另一种方式（二）#

select cust_name,total_price
from 
(
    select order_num,sum(item_price * quantity) total_price
    from OrderItems 
    group by order_num
) oi 
inner join Orders o on oi.order_num = o.order_num
inner join Customers c on c.cust_id = o.cust_id
where total_price>= 1000
order by total_price;

此题目和上一道题的区别是，多了一个聚合函数的使用。

为了思路不混乱，用到聚合函数的表放在第一个，先聚合以后再和其他的表进行联合。三表联合完成，在这里进行筛选就不会出错了