SQL40 返回购买 prod_id 为 BR01 的产品的所有顾客的电子邮件(二) 利用inner join将Orders和OrderItems联表,然后通过子查询定位出prod_id等于BR01的顾客邮箱 select cust_email from Customers where cust_id in (select cust_id from Orders inner join OrderItems using(order_num) where prod_id="BR01")