select cust_email
from Customers
where cust_id in
(select cust_id from Orders od
inner join OrderItems odi
on od.order_num = odi.order_num
and odi.prod_id = 'BR01')

/*
题目解析:题意很好理解但又暗藏了很多信息,
这题涉及到三个表查询。首先捋一捋三个表的关系,
仔细理解后发现Customers表通过cust_id和Orders表的cust_id实现两个表的联系,
Orders表通过order_num和OrderItems表的order_num实现两个表的联系,
最后将三个表的关系整合起来查询即可。我个人的理解是这样解题的,
如有不对还请大佬指点。

*/