#确定哪些订单购买了 prod_id 为 BR01 的产品#

select
    cust_id
    ,order_date
from OrderItems oi , Orders o 
where oi.order_num = o.order_num and prod_id = "BR01"
order by 2

select
    cust_id
    ,order_date
from OrderItems oi 
    join Orders o 
        on oi.order_num = o.order_num 
where prod_id = "BR01"
order by 2

select
    cust_id
    ,order_date
from Orders oi 
where order_num in (select
                    order_num
                  from OrderItems
                  where prod_id ="BR01"
                  )
order by 2

select
    cust_id
    ,order_date
from Orders o 
    join (select
            order_num
          from OrderItems 
          where prod_id ="BR01"
         ) oi
        on oi.order_num = o.order_num
order by 2

select 
    cust_id
    ,order_date
from Orders
    ,(
        select 
            order_num
        from OrderItems
        where prod_id="BR01") t
where t.order_num = Orders.order_num
order by 2;