Mysql 添加外键约束时出错

每次尝试向表插入外键时，我都会收到以下消息：

错误代码：1215。无法添加外键约束0.281秒

我的创建表代码：

CREATE TABLE `test`.`buy`(
    `id` INT NOT NULL AUTO_INCREMENT,
    `id_customer` INT UNSIGNED NOT NULL,
    `code` VARCHAR(45) NOT NULL,
    PRIMARY KEY(`id`),
    UNIQUE INDEX `code_UNIQUE`(`code`),
    CONSTRAINT `id_customer` FOREIGN KEY(`id_customer`) REFERENCES `test`.`customer`(`id_customer`) ON DELETE RESTRICT ON UPDATE CASCADE,
    CONSTRAINT `code` FOREIGN KEY(`code`) REFERENCES `test`.`product`(`code`) ON DELETE RESTRICT ON UPDATE CASCADE
)

---

我该怎么办？

请下次格式化代码，以便阅读

您不需要约束xxx位，请尝试以下操作：

CREATE TABLE test.buy (
  id INT NOT NULL AUTO_INCREMENT,
  id_customer INT UNSIGNED NOT NULL,
  code VARCHAR(45) NOT NULL,
  PRIMARY KEY (id),
  UNIQUE INDEX code_UNIQUE (code),
  FOREIGN KEY (id_customer) 
    REFERENCES test.customer (id_customer) 
    ON DELETE RESTRICT ON UPDATE CASCADE,
  FOREIGN KEY (code) 
    REFERENCES test.product (code) 
    ON DELETE RESTRICT ON UPDATE CASCADE
);

如果仍然不起作用，请确保您引用的其他表（test.customer和test.product）已经存在，并且它们具有相同数据类型的匹配字段

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