三种方法

确定哪些订单购买了 prod_id 为 BR01 的产品(二)

http://www.nowcoder.com/practice/999aa31a9a504c60baa088d90d82e64d

#方法一
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 order_date;
#方法二
select cust_id,order_date
from Orders 
where order_num in 
(select order_num
from OrderItems
where prod_id="BR01")
order by order_date;
#方法三
select cust_id,order_date
from Orders o join OrderItems oi on o.order_num=oi.order_num
where prod_id="BR01"
order by order_date;
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#方法四 select cust_id,order_date from Orders a,OrderItems b where a.order_num =b.order_num and b.prod_id ='BR01' order by order_date
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发布于 2022-04-15 15:06
请问为什么方法三中,cust_id,order_date,以及prod_id前面不用加上所属表的名称?比如oi.prod_id,o.cust_id,o.order_date~
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发布于 2023-02-07 16:23 辽宁

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