题解 prod_id 为 BR01 的产品顾客的电子邮件
返回购买 prod_id 为 BR01 的产品的所有顾客的电子邮件（二）
https://www.nowcoder.com/practice/c7aa73afc41f4dfc925baebdd175c345
select ct.cust_email FROM Customers AS ct JOIN Orders AS od ON od.cust_id = ct.cust_id JOIN OrderItems AS ot ON ot.order_num = od.order_num AND ot.prod_id = 'BR01'
