Leetcode力扣 MySQL数据库 1549 每件商品对的最新订单

1549 每件商品对的最新订单

SQL架构

Create table If Not Exists Customers_1549 (customer_id int, name varchar(10));
Create table If Not Exists Orders_1549 (order_id int, order_date date, customer_id int, product_id int);
Create table If Not Exists Products_1549 (product_id int, product_name varchar(20), price int);
Truncate table Customers_1549;
insert into Customers_1549 (customer_id, name) values ('1', 'Winston');
insert into Customers_1549 (customer_id, name) values ('2', 'Jonathan');
insert into Customers_1549 (customer_id, name) values ('3', 'Annabelle');
insert into Customers_1549 (customer_id, name) values ('4', 'Marwan');
insert into Customers_1549 (customer_id, name) values ('5', 'Khaled');
Truncate table Orders_1549;
insert into Orders_1549 (order_id, order_date, customer_id, product_id) values ('1', '2020-07-31', '1', '1');
insert into Orders_1549 (order_id, order_date, customer_id, product_id) values ('2', '2020-7-30', '2', '2');
insert into Orders_1549 (order_id, order_date, customer_id, product_id) values ('3', '2020-08-29', '3', '3');
insert into Orders_1549 (order_id, order_date, customer_id, product_id) values ('4', '2020-07-29', '4', '1');
insert into Orders_1549 (order_id, order_date, customer_id, product_id) values ('5', '2020-06-10', '1', '2');
insert into Orders_1549 (order_id, order_date, customer_id, product_id) values ('6', '2020-08-01', '2', '1');
insert into Orders_1549 (order_id, order_date, customer_id, product_id) values ('7', '2020-08-01', '3', '1');
insert into Orders_1549 (order_id, order_date, customer_id, product_id) values ('8', '2020-08-03', '1', '2');
insert into Orders_1549 (order_id, order_date, customer_id, product_id) values ('9', '2020-08-07', '2', '3');
insert into Orders_1549 (order_id, order_date, customer_id, product_id) values ('10', '2020-07-15', '1', '2');
Truncate table Products_1549;
insert into Products_1549 (product_id, product_name, price) values ('1', 'keyboard', '120');
insert into Products_1549 (product_id, product_name, price) values ('2', 'mouse', '80');
insert into Products_1549 (product_id, product_name, price) values ('3', 'screen', '600');
insert into Products_1549 (product_id, product_name, price) values ('4', 'hard disk', '450');

表: Customers

表: Orders

表: Products

写一个SQL 语句, 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:

Customers
+-------------+-----------+
| customer_id | name |
+-------------+-----------+
| 1 | Winston |
| 2 | Jonathan |
| 3 | Annabelle |
| 4 | Marwan |
| 5 | Khaled |
+-------------+-----------+

Orders
+----------+------------+-------------+------------+
| 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
+------------+--------------+-------+
| product_id | product_name | price |
+------------+--------------+-------+
| 1 | keyboard | 120 |
| 2 | mouse | 80 |
| 3 | screen | 600 |
| 4 | hard disk | 450 |
+------------+--------------+-------+

Result
+--------------+------------+----------+------------+
| 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 |
+--------------+------------+----------+------------+
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.

解题

select product_name, o.product_id, order_id, order_date
from Orders_1549 o left join Products_1549 p
using(product_id)
where (product_id, order_date) in
(select product_id, max(order_date) order_datefrom Orders_1549group by product_id
)
order by product_name, product_id, order_id;