题解 | #返回购买价格为 10 美元或以上产品的顾客列表#
返回购买 prod_id 为 BR01 的产品的所有顾客的电子邮件(一)
http://www.nowcoder.com/practice/962b16554fbf4b99a87f4d68020c5bfb
select cust_email from Customers
where cust_id in (select cust_id from Orders where order_num
in (select order_num from OrderItems
where prod_id='BR01'));