在MySQL中联接三个表，并获得每个ID一行（第一个表中的每个实体一行）

Question

i have three table for products, product configs(eg iPhone x 64 black, iPhone x 64 red) and product inventories; I want to select all products and sort by price (in config table) and availability (in inventory table) but get only one row per product; how can id do this? below is my mysql table structure

CREATE TABLE `product_inventories` (
  `inventory_id` bigint(20) NOT NULL,
  `quantity` int(11) NOT NULL,
  `warehouse_id` bigint(20) DEFAULT NULL,
  `config_id` bigint(20) NOT NULL
) ENGINE=MyISAM DEFAULT CHARSET=utf8;

CREATE TABLE `product_configs` (
  `config_id` bigint(20) NOT NULL,
  `product_id` bigint(20) DEFAULT NULL,
  `price` decimal(12,3) DEFAULT NULL,
  `discount_percent` int(11) DEFAULT NULL,
  `sku` varchar(30) DEFAULT NULL
) ENGINE=MyISAM DEFAULT CHARSET=utf8 ROW_FORMAT=FIXED;

CREATE TABLE `products` (
  `id` bigint(20) NOT NULL,
  `title` varchar(255) DEFAULT NULL,
  `category_id` bigint(20) NOT NULL,
) ENGINE=MyISAM DEFAULT CHARSET=utf8 ROW_FORMAT=DYNAMIC;

i tried this query :

SELECT * 
FROM products 
    LEFT JOIN product_configs ON products.id = product_configs.product_id 
    LEFT JOIN product_inventories inventories ON inventories.inventory_id =
         (SELECT product_inventories.inventory_id from product_inventories
          WHERE product_inventories.config_id = product_configs.config_id
          ORDER by product_inventories.quantity DESC LIMIT 1 ) 
ORDER BY product_configs.price ASC, inventories.quantity DESC

edit: with this query:

SELECT *
FROM products 
    LEFT JOIN product_configs ON products.id = product_configs.product_id 
    LEFT JOIN product_inventories inventories ON inventories.inventory_id =
         (SELECT product_inventories.inventory_id from product_inventories
          WHERE product_inventories.config_idd = product_configs.config_id
          ORDER by product_inventories.quantity DESC LIMIT 1 ) 

ORDER BY product_configs.price is null, product_configs.price ASC, inventories.quantity DESC

i have below result; but i want one product per config with min price and max quantity

Answer 1

Try This:

SELECT 
    ...,
    SUM(quantity) AS total_quantity
FROM products AS p
    LEFT JOIN product_configs AS pc ON pc.product_id = p.id
    LEFT JOIN product_inventories AS pi ON pi.config_id = pc.config_id
GROUP BY p.id
ORDER BY pc.price ASC, pi.quantity DESC

Answer 2

Try this one, see if it will work:

SELECT *,MIN(price),MAX(quantity) FROM products LEFT JOIN product_configs ON products.id = product_configs.product_id LEFT JOIN product_inventories inventories ON inventories.inventory_id = (SELECT product_inventories.inventory_id FROM product_inventories INNER JOIN product_configs ON product_inventories.config_id = product_configs.config_id ORDER BY product_inventories.quantity DESC LIMIT 1 ) GROUP BY sku ORDER BY product_configs.price ASC, inventories.quantity DESC;

Note that I still retain SELECT * and added min(price),max(quantity) at the end so you can do the comparison. If this is not working for you, you may need to provide some data example and an illustration of how your desired output is.