MYSQL: "Cannot add foreign key constraint"

Question

我尝试创建链接到两个表的表。
链接表:

CREATE TABLE `cartsitems` (
    `id` INT NOT NULL AUTO_INCREMENT,
    `cart_id` INT NOT NULL,
    `product_id` INT NOT NULL,
    `price` DOUBLE(6,2) NOT NULL,
    PRIMARY KEY (`id`),
    FOREIGN KEY (`cart_id`) REFERENCES `carts`(`id`),
    FOREIGN KEY (`product_id`) REFERENCES `products`(`id`)
)

产品表:

CREATE TABLE `products` (
  `id` INT AUTO_INCREMENT,
  `category_id` INT,
  `description` VARCHAR(255),
  `price` DOUBLE(6,2),
  PRIMARY KEY (`id`),
  FOREIGN KEY (`id`) REFERENCES `categories`(`id`)
)

购物车表:

 CREATE TABLE `carts` (
    `id` INT NOT NULL AUTO_INCREMENT,
    `users_id` INT NOT NULL,
    PRIMARY KEY (`id`),
    FOREIGN KEY (`users_id`) REFERENCES `users`(`id`)
 )

我搜索并找到了这个答案:MySQL Cannot Add Foreign Key Constraint
我检查引擎是否相同(因为我没有设置其他内容)，还有集合 类型相同(都是int)
及其唯一性(主键)
有什么问题吗？

Answer 1

您在产品表中缺少 id 字段。

CREATE TABLE `products` (
    `id` INT NOT NULL AUTO_INCREMENT,
    `category_id` INT,
    `description` VARCHAR(255),
    `price` DOUBLE(6,2),
    PRIMARY KEY (`id`),
    FOREIGN KEY (`id`) REFERENCES `categories`(`id`)
);