mysql错误: 1215 Cannot add foreign key constraint[ foreign keys same type, innodb]

Question

我需要一双新的眼睛来看看我到底做错了什么。

CREATE TABLE IF NOT EXISTS `spring_normalize`.`users` (
  `username` VARCHAR(60) NOT NULL,
  `password` VARCHAR(80) NULL,
  `authority` VARCHAR(45) NULL,
  `name` VARCHAR(100) NULL,
  `enabled` TINYINT(1) NULL,
  `email` VARCHAR(60) NULL,
PRIMARY KEY (`username`))
ENGINE = InnoDB;

CREATE TABLE IF NOT EXISTS `spring_normalize`.`offers` (
  `id` INT NOT NULL AUTO_INCREMENT,
  `text` VARCHAR(100) NULL,
  `users_username` VARCHAR(60) NOT NULL,
PRIMARY KEY (`id`, `users_username`),
INDEX `fk_offers_users_idx` (`users_username` ASC),
CONSTRAINT `fk_offers_users`
  FOREIGN KEY (`users_username`)
  REFERENCES `spring_normalize`.`users` (`username`)
  ON DELETE NO ACTION
  ON UPDATE NO ACTION)
ENGINE = InnoDB;

来自其他有同样问题的人:

1. Db 是 InnoDB 吗？是的
2. 所有表都是 InnoDB 吗？是的
3. 引用表中是否存在唯一索引？是的
4. 引用列和引用列是否完全属于同一类型？是的

质疑我做错了什么？提前致谢!

Answer 1

正如其他人在评论中所述，您的查询是正确的

您可以尝试一些事情:

---

首先选择您的数据库并将其从您的 2 create table

中删除

USE `spring_normalize`;


CREATE TABLE IF NOT EXISTS `users` (
  `username` VARCHAR(60) NOT NULL,
  `password` VARCHAR(80) NULL,
  `authority` VARCHAR(45) NULL,
  `name` VARCHAR(100) NULL,
  `enabled` TINYINT(1) NULL,
  `email` VARCHAR(60) NULL,
PRIMARY KEY (`username`))
ENGINE = InnoDB;

CREATE TABLE IF NOT EXISTS `offers` (
  `id` INT NOT NULL AUTO_INCREMENT,
  `text` VARCHAR(100) NULL,
  `users_username` VARCHAR(60) NOT NULL,
PRIMARY KEY (`id`, `users_username`),
INDEX `fk_offers_users_idx` (`users_username` ASC),
CONSTRAINT `fk_offers_users`
  FOREIGN KEY (`users_username`)
  REFERENCES `users` (`username`)
  ON DELETE NO ACTION
  ON UPDATE NO ACTION)
ENGINE = InnoDB;

---

尝试在创建表之前指定它，以防引擎会(奇怪地)尝试在 users 之前创建表 offers:

-- Do not check foreign key constraints
SET FOREIGN_KEY_CHECKS = 0;

---

最后，如果没有解决问题，请在收到错误后执行此操作，它将为您提供更多信息

SHOW ENGINE INNODB STATUS;