mysql - 连接 MySQL 中的三个表并获取每个 id 一行(第一个表中每个实体一行)

Question

我有三个产品表、产品配置(例如 iPhone x 64 黑色、iPhone x 64 红色)和产品库存；我想选择所有产品并按价格(在配置表中)和可用性(在库存表中)排序，但每个产品只获取一行；我怎么能做到这一点？下面是我的mysql表结构

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;

我尝试了这个查询:

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

编辑:使用此查询:

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

我有以下结果；但我想要每个配置一个产品，具有最低价格和最大数量

Answer 1

试试这个:

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