MYSQL 每个商店按五个字段加入和分组

Question

我试图获得一个复杂的（至少对我而言）MySQL 查询，但我无法获得我想要的结果。

我有一个 DB 和 2 个表：

店铺

id, name

产品

id, store_id, hardware, name, price, url, notify

我希望每个 store_id 获得 3 件产品，通知 = 1，硬件 = 'gpu' 并按价格递增订购。

所以如果我启动这个 SQL 句子：

SELECT s.name as store, p.id as id, p.name as name, p.hardware as hw, p.price as price, p.url as url, p.notify as notify
FROM products p JOIN stores s
ON p.store_id = s.id
AND p.hardware='gpu'
AND p.notify = 1
GROUP BY store
ORDER BY p.price asc;

我每个 store_id 只得到一个产品，我想每个 store_id 得到（最大）树元素。类似于下一个示例：

store	id	name	hw	price	url	notify
store1	1	name1	gpu	price	url	1
store1	2	name2	gpu	price	url	1
store1	3	name3	gpu	price	url	1
store2	8	name8	gpu	price	url	1
store2	12	name12	gpu	price	url	1
store3	22	name22	gpu	price	url	1

等等...

我该怎么做？

示例数据

店铺

CREATE TABLE `stores` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` char(50) NOT NULL,
  `afiliate` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=18 DEFAULT CHARSET=utf8;

产品

CREATE TABLE `products` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `store_id` int(11) NOT NULL,
  `hardware` char(50) COLLATE utf8mb4_unicode_ci NOT NULL,
  `name` varchar(255) COLLATE utf8mb4_unicode_ci NOT NULL,
  `price` decimal(10,2) NOT NULL,
  `notify` tinyint(4) NOT NULL
  PRIMARY KEY (`id`),
  KEY `Store_id_to_products` (`store_id`),
  CONSTRAINT `Store_id_to_products` FOREIGN KEY (`store_id`) REFERENCES `stores` (`id`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB AUTO_INCREMENT=1961 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;

select id, name from stores;

结果

id	name
1	Amazon
2	Ebay
3	BestBuy
4	Target

select * from products;

结果

id	store_id	hardware	name	price	notify
1	3	gpu	EVGA GeForce RTX 3070 FTW3 Ultra Gaming 8GB GDDR6	949.00	1
2	3	gpu	Zotac Gaming GeForce RTX 3090 Trinity OC 24GB GDDR6X	2259.00	1
3	3	gpu	EVGA GeForce RTX 3090 FTW3 Ultra Gaming 24GB GDDR6X	2749.00	1
4	3	gpu	Asus TUF Gaming GeForce RTX 3090 OC Edition 24GB GDDR6X	2549.00	1
5	1	gpu	Gigabyte GTX 1660 Super OC 6G	489.00	1
6	1	gpu	Asus TUF GTX 1660 Super OC 6GB	428.99	1
8	1	gpu	GIGABYTE RTX 3060 GAMING OC 12GB	689.00	1
9	1	gpu	Gigabyte RTX 3080 Aorus Master 10GB	1398.99	1
10	2	gpu	Asus ROG Strix RTX 3080 OC 10GB Blanca	1312.00	1
11	2	gpu	Gigabyte RTX 3080 Gaming OC 10GB	1258.99	1
12	2	gpu	Asus ROG Strix RTX 3090 OC Gaming 24GB	2599.00	1
13	4	gpu	Asus TUF Gaming Radeon RX 6800 OC 16GB	1078.99	1
14	4	gpu	GIGABYTE RX6800XT GAMING OC 16GB	450.00	1
15	4	gpu	Gigabyte GeForce GTX 1660 Ti OC 6G	499.95	1
16	4	gpu	ZOTAC GeForce GTX 1660 SUPER Twin Fan	529.95	1

我正在尝试做一个 SQL 句子，让每个商店获得 3 种最便宜的产品。这是我想要的结果：

id	store_id	hardware	name	price	notify
1	3	gpu	EVGA GeForce RTX 3070 FTW3 Ultra Gaming 8GB GDDR6	949.00	1
2	3	gpu	Zotac Gaming GeForce RTX 3090 Trinity OC 24GB GDDR6X	2259.00	1
4	3	gpu	Asus TUF Gaming GeForce RTX 3090 OC Edition 24GB GDDR6X	2549.00	1
5	1	gpu	Gigabyte GTX 1660 Super OC 6G	489.00	1
6	1	gpu	Asus TUF GTX 1660 Super OC 6GB	428.99	1
8	1	gpu	GIGABYTE RTX 3060 GAMING OC 12GB	689.00	1
10	2	gpu	Asus ROG Strix RTX 3080 OC 10GB Blanca	1312.00	1
11	2	gpu	Gigabyte RTX 3080 Gaming OC 10GB	1258.99	1
12	2	gpu	Asus ROG Strix RTX 3090 OC Gaming 24GB	2599.00	1
14	4	gpu	GIGABYTE RX6800XT GAMING OC 16GB	450.00	1
15	4	gpu	Gigabyte GeForce GTX 1660 Ti OC 6G	499.95	1
16	4	gpu	ZOTAC GeForce GTX 1660 SUPER Twin Fan	529.95	1

提前致谢！！

Answer 1

如果您的 MySQL 版本低于 8+，您可以使用：

SELECT
      t1.id,
      name,
      hardware,
      price,
      notify
FROM (
        SELECT
              id,
              store_id,
              hardware,
              notify,
              price,
              @rn := IF(@prev = store_id, @rn + 1, 1) AS rn,
              @prev := store_id
        FROM products
        JOIN ( SELECT @prev := NULL, @rn := 0) AS vars
        where hardware='gpu' and notify=1
        ORDER BY  price ASC
    ) AS t1
INNER JOIN   stores st on  t1.store_id=st.id
WHERE rn <= 5
ORDER BY   id asc ;

Demo

在MySQL8+

WITH my_table  AS (
  SELECT *, ROW_NUMBER() OVER (PARTITION BY store_id ORDER BY  price ASC ) AS rownum
  FROM products
)
SELECT my_table.id,st.name,hardware,my_table.name,price,notify
FROM my_table 
INNER JOIN  stores st on  my_table.store_id=st.id
WHERE  rownum <= 5
order by my_table.id asc;

Demo

MYSQL 每个商店按五个字段加入和分组

MYSQL join and group by five field per store

mysql

join

示例数据