#确定订单购买了 prod_id 为 BR01 的产品#

# 方法一
/*select cust_id,order_date 
from OrderItems oi,Orders o
where oi.order_num=o.order_num and prod_id='BR01'
order by order_date;*/
# 方法二
/*select cust_id,order_date
from OrderItems oi join Orders o on oi.order_num=o.order_num
where prod_id='BR01'
order by order_date;*/
# 方法三
select cust_id,order_date
from Orders o
where order_num in (select order_num
                    from OrderItems oi
                    where prod_id='BR01')
order by order_date;