Mysql 外键约束失败-可能对我的关系有误解

我在一些MySQL关系方面遇到了一些问题。我想我的结构中缺少了一些明显的东西。以下是我的SQL：

DROP TABLE IF EXISTS `parentlist_comments`;
CREATE TABLE `parentlist_comments` (
  `id` char(36) NOT NULL,
  `parentlist_id` char(36) NOT NULL,
  `user_id` char(36) NOT NULL,
  `comment` char(50) NOT NULL,
  `accepted` tinyint(1) NOT NULL DEFAULT '0',
  `submitted` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`),
  KEY `fk_parentlist_comments_parentlist` (`parentlist_id`),
  KEY `fk_parentlist_comment_user` (`user_id`),
  CONSTRAINT `fk_parentlist_comments_parentlist` FOREIGN KEY (`parentlist_id`) REFERENCES `parentlists` (`id`) ON DELETE CASCADE ON UPDATE CASCADE,
  CONSTRAINT `fk_parentlist_comment_user` FOREIGN KEY (`user_id`) REFERENCES `users` (`id`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

DROP TABLE IF EXISTS `parentlist_submissions`;
CREATE TABLE `parentlist_submissions` (
  `id` char(36) NOT NULL,
  `parentlist_id` char(36) NOT NULL,
  `type_id` char(36) NOT NULL,
  `name` char(25) NOT NULL,
  `user_id` char(36) NOT NULL,
  `accepted` tinyint(1) NOT NULL DEFAULT '0',
  `submitted` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
  `votes` int(3) NOT NULL DEFAULT '0',
  PRIMARY KEY (`id`),
  KEY `fk_parentlist_submissions_user` (`user_id`),
  KEY `fk_parentlist_submissions_list` (`parentlist_id`),
  KEY `fk_parentlist_submissions_type` (`type_id`),
  CONSTRAINT `fk_parentlist_submissions_list` FOREIGN KEY (`parentlist_id`) REFERENCES `parentlists` (`id`) ON DELETE CASCADE ON UPDATE CASCADE,
  CONSTRAINT `fk_parentlist_submissions_type` FOREIGN KEY (`type_id`) REFERENCES `types` (`id`) ON DELETE CASCADE ON UPDATE CASCADE,
  CONSTRAINT `fk_parentlist_submissions_user` FOREIGN KEY (`user_id`) REFERENCES `users` (`id`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

DROP TABLE IF EXISTS `parentlists`;
CREATE TABLE `parentlists` (
  `id` char(36) NOT NULL,
  `name` char(20) NOT NULL,
  `description` char(50) NOT NULL,
  `user_id` char(36) NOT NULL,
  `max_comments` int(3) NOT NULL DEFAULT '0',
  `max_submissions` int(3) NOT NULL DEFAULT '10',
  `max_votes` int(3) NOT NULL DEFAULT '0',
  PRIMARY KEY (`id`),
  KEY `fk_list_user` (`user_id`),
  CONSTRAINT `fk_list_user` FOREIGN KEY (`user_id`) REFERENCES `users` (`id`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8 ROW_FORMAT=FIXED;

DROP TABLE IF EXISTS `submissions`;
CREATE TABLE `submissions` (
  `id` char(36) NOT NULL,
  `type_id` char(36) NOT NULL,
  `name` char(30) NOT NULL,
  `description` char(50) NOT NULL,
  `embed` char(200) DEFAULT NULL,
  `user_id` char(36) NOT NULL,
  `accepted` tinyint(1) NOT NULL DEFAULT '0',
  `submitted` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
  `votes` int(5) NOT NULL DEFAULT '0',
  PRIMARY KEY (`id`),
  KEY `fk_submission_user` (`user_id`),
  KEY `fk_submission_type` (`type_id`),
  CONSTRAINT `fk_submission_type` FOREIGN KEY (`type_id`) REFERENCES `types` (`id`) ON DELETE CASCADE ON UPDATE CASCADE,
  CONSTRAINT `fk_submission_user` FOREIGN KEY (`user_id`) REFERENCES `users` (`id`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

DROP TABLE IF EXISTS `types`;
CREATE TABLE `types` (
  `id` char(36) NOT NULL,
  `name` char(20) NOT NULL,
  `description` char(20) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

DROP TABLE IF EXISTS `users`;
CREATE TABLE `users` (
  `id` char(36) NOT NULL,
  `name` char(20) NOT NULL,
  `password` char(20) NOT NULL,
  `email` char(50) NOT NULL,
  PRIMARY KEY (`id`)
    ) ENGINE=InnoDB DEFAULT CHARSET=utf8;

我在parentlist\u submissions中创建了一个名为submission\u id的列。我正在尝试在parentlist_submissions.submission_id和submissions.id之间创建外键关系，当我尝试这样做时，我得到一个错误：外键约束失败。无论出于何种原因，我的查询浏览器都不允许复制此内容

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非常感谢您的帮助

您似乎缺少“parentlist\u submissions.submission\u id”列。

该错误通常是由于表中已填充了违反约束的数据造成的。（请注意，如果刚刚添加了列，则空值可能是一个问题。）

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我猜，因为我没有看到您在创建提交索引列或创建外键约束的位置发布了语句。

是的，这是由于空数据不符合约束。非常感谢。家长列表上似乎没有提交id列？