where 简单联结: select c.cust_email from OrderItems a,Orders b,Customers c where c.cust_id=b.cust_id and a.order_num=b.order_num and a.prod_id ='BR01' inner join 内联结: select c.cust_email from Orders b #注意以下两条件中b是公共的 inner join OrderItems a on a.order_num=b.order_num inner join Customers c on c.cus...