1549. 每件商品的最新订单

表: Customers

+---------------+---------+
| Column Name   | Type    |
+---------------+---------+
| customer_id   | int     |
| name          | varchar |
+---------------+---------+
customer_id 是该表主键.
该表包含消费者的信息.

 

表: Orders

+---------------+---------+
| Column Name   | Type    |
+---------------+---------+
| order_id      | int     |
| order_date    | date    |
| customer_id   | int     |
| product_id    | int     |
+---------------+---------+
order_id 是该表主键.
该表包含消费者customer_id产生的订单.
不会有商品被相同的用户在一天内下单超过一次.

 

表: Products

+---------------+---------+
| Column Name   | Type    |
+---------------+---------+
| product_id    | int     |
| product_name  | varchar |
| price         | int     |
+---------------+---------+
product_id 是该表主键.
该表包含所有商品的信息.

 

写一个解决方案, 找到每件商品的最新订单(可能有多个).

返回的结果以 product_name 升序排列, 如果有排序相同, 再以 product_id 升序排列. 如果还有排序相同, 再以 order_id 升序排列.

查询结果格式如下例所示。

 

示例 1：

输入:
Customers表：
+-------------+-----------+
| customer_id | name      |
+-------------+-----------+
| 1           | Winston   |
| 2           | Jonathan  |
| 3           | Annabelle |
| 4           | Marwan    |
| 5           | Khaled    |
+-------------+-----------+
Orders表：
+----------+------------+-------------+------------+
| order_id | order_date | customer_id | product_id |
+----------+------------+-------------+------------+
| 1        | 2020-07-31 | 1           | 1          |
| 2        | 2020-07-30 | 2           | 2          |
| 3        | 2020-08-29 | 3           | 3          |
| 4        | 2020-07-29 | 4           | 1          |
| 5        | 2020-06-10 | 1           | 2          |
| 6        | 2020-08-01 | 2           | 1          |
| 7        | 2020-08-01 | 3           | 1          |
| 8        | 2020-08-03 | 1           | 2          |
| 9        | 2020-08-07 | 2           | 3          |
| 10       | 2020-07-15 | 1           | 2          |
+----------+------------+-------------+------------+
Products表：
+------------+--------------+-------+
| product_id | product_name | price |
+------------+--------------+-------+
| 1          | keyboard     | 120   |
| 2          | mouse        | 80    |
| 3          | screen       | 600   |
| 4          | hard disk    | 450   |
+------------+--------------+-------+
输出：
+--------------+------------+----------+------------+
| product_name | product_id | order_id | order_date |
+--------------+------------+----------+------------+
| keyboard     | 1          | 6        | 2020-08-01 |
| keyboard     | 1          | 7        | 2020-08-01 |
| mouse        | 2          | 8        | 2020-08-03 |
| screen       | 3          | 3        | 2020-08-29 |
+--------------+------------+----------+------------+
解释：
keyboard 的最新订单在2020-08-01, 在这天有两次下单.
mouse 的最新订单在2020-08-03, 在这天只有一次下单.
screen 的最新订单在2020-08-29, 在这天只有一次下单.
hard disk 没有被下单, 我们不把它包含在结果表中.

select p.product_name, t1.product_id, t1.order_id, t1.order_date
from products p join
(select 
    product_id, 
    order_id, 
    order_date, 
-- 这里使用rank或者dense_rank都是可以的
-- partition by是精华
    rank() over (partition by product_id order by order_date desc) as r
from orders o) as t1 on p.product_id=t1.product_id
where t1.r=1
order by p.product_name, t1.product_id, t1.order_id;

SELECT
    t1.product_name,
    t2.product_id,
    t2.order_id,
    t2.order_date
FROM
    Products AS t1
INNER JOIN Orders AS t2 ON t1.product_id = t2.product_id
WHERE (t2.product_id, t2.order_date) IN (
    SELECT
	    product_id,
	    MAX(order_date) AS 'order_date'
    FROM
	    Orders
    GROUP BY product_id
)
ORDER BY t1.product_name, t2.product_id, t2.order_id