题解 | #确定最佳顾客的另一种方式（二）#

select cust_name,total_price from Orders t1 join Customers t2 on t1.cust_id = t2.cust_id  //  使用cust_id 连接 Orders表 与 Customers表
join (select order_num,sum(item_price*quantity) total_price from OrderItems  
     group by order_num) t3  // 使用分组聚合函数求得各订单的订单总额
on t1.order_num = t3.order_num  //  使用 order_num 连接OrderItems 表与上述两表
where total_price >= 1000
order by total_price asc  //  按总价升序排列