Php 将标记添加到blog_标记表时无法添加或更新子行

当我想将标签添加到我的blog_标签表时，我收到以下错误消息：

MySQL said: Documentation

#1452 - Cannot add or update a child row: a foreign key constraint fails (`blog`.`blog_tags`, CONSTRAINT `blog_tags_ibfk_1` FOREIGN KEY (`tid`) REFERENCES `blog_post_tags` (`tag_id`) ON DELETE CASCADE ON UPDATE CASCADE)

这是我的数据库模式：

------------------------------------------------------------
-- Table structure for table `blog_categories`
--

CREATE TABLE `blog_categories` (
  `cid` int(10) UNSIGNED NOT NULL,
  `category` varchar(255) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

-- --------------------------------------------------------

--
-- Table structure for table `blog_post_tags`
--

CREATE TABLE `blog_post_tags` (
  `bpid` int(10) UNSIGNED NOT NULL,
  `post_id` int(10) UNSIGNED NOT NULL,
  `tag_id` int(10) UNSIGNED NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

-- --------------------------------------------------------

--
-- Table structure for table `blog_tags`
--

CREATE TABLE `blog_tags` (
  `tid` int(10) UNSIGNED NOT NULL,
  `tags` varchar(255) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

-- --------------------------------------------------------
CREATE TABLE `posts` (
  `pid` int(10) UNSIGNED NOT NULL,
  `url` varchar(255) NOT NULL,
  `title` varchar(140) NOT NULL,
  `description` varchar(170) NOT NULL,
  `content` text NOT NULL,
  `category_id` int(10) UNSIGNED NOT NULL,
  `image` varchar(255) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

    -- --------------------------------------------------------
--
-- Indexes for table `blog_categories`
--
ALTER TABLE `blog_categories`
  ADD PRIMARY KEY (`cid`);

--
-- Indexes for table `blog_post_tags`
--
ALTER TABLE `blog_post_tags`
  ADD PRIMARY KEY (`bpid`),
  ADD KEY `post_id_index` (`post_id`),
  ADD KEY `tag_id_index` (`tag_id`);

--
-- Indexes for table `blog_tags`
--
ALTER TABLE `blog_tags`
  ADD PRIMARY KEY (`tid`);

--
-- Indexes for table `password_resets`
--
ALTER TABLE `password_resets`
  ADD KEY `password_resets_email_index` (`email`),
  ADD KEY `password_resets_token_index` (`token`);

--
-- Indexes for table `posts`
--
ALTER TABLE `posts`
  ADD PRIMARY KEY (`pid`),
  ADD KEY `category_id_index` (`category_id`);

--
-- Indexes for table `users`
--
ALTER TABLE `users`
  ADD PRIMARY KEY (`id`),
  ADD UNIQUE KEY `users_email_unique` (`email`);

--
-- AUTO_INCREMENT for dumped tables
--

--
-- AUTO_INCREMENT for table `blog_categories`
--
ALTER TABLE `blog_categories`
  MODIFY `cid` int(10) UNSIGNED NOT NULL AUTO_INCREMENT, AUTO_INCREMENT=7;
--
-- AUTO_INCREMENT for table `blog_post_tags`
--
ALTER TABLE `blog_post_tags`
  MODIFY `bpid` int(10) UNSIGNED NOT NULL AUTO_INCREMENT;
--
-- AUTO_INCREMENT for table `blog_tags`
--
ALTER TABLE `blog_tags`
  MODIFY `tid` int(10) UNSIGNED NOT NULL AUTO_INCREMENT, AUTO_INCREMENT=3;
--
-- AUTO_INCREMENT for table `posts`
--
ALTER TABLE `posts`
  MODIFY `pid` int(10) UNSIGNED NOT NULL AUTO_INCREMENT, AUTO_INCREMENT=7;
--
-- AUTO_INCREMENT for table `users`
--
ALTER TABLE `users`
  MODIFY `id` int(10) UNSIGNED NOT NULL AUTO_INCREMENT;
/*!40101 SET CHARACTER_SET_CLIENT=@OLD_CHARACTER_SET_CLIENT */;
/*!40101 SET CHARACTER_SET_RESULTS=@OLD_CHARACTER_SET_RESULTS */;
/*!40101 SET COLLATION_CONNECTION=@OLD_COLLATION_CONNECTION */;

这是

phpmyadmin

中的设计器窗口，其中显示了我的表之间的关系。谢谢你的帮助：D

---

您还没有展示所有内容。还显示您为结果添加的约束hanks@riggsfully。我添加了完整的模式：在您的模式中仍然没有提到

约束

，您还没有显示所有内容。还显示您为结果添加的约束hanks@riggsfully。我添加了完整的模式：在您的模式中仍然没有提到

约束