PHPは知識問答サイトにタグ分類機能を実装しています。

CREATE TABLE `qa_database`.`questions` (
  `id` INT NOT NULL AUTO_INCREMENT,
  `title` VARCHAR(100) NOT NULL,
  `content` TEXT NOT NULL,
  `created_at` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`)
);

CREATE TABLE `qa_database`.`tags` (
  `id` INT NOT NULL AUTO_INCREMENT,
  `name` VARCHAR(50) NOT NULL,
  PRIMARY KEY (`id`)
);

ALTER TABLE `qa_database`.`questions` ADD COLUMN `tag_id` INT NULL AFTER `created_at`;

<?php
$servername = "localhost";
$username = "your_username";
$password = "your_password";
$dbname = "qa_database";

// 创建连接
$conn = new mysqli($servername, $username, $password, $dbname);

// 检查连接是否成功
if ($conn->connect_error) {
    die("连接失败: " . $conn->connect_error);
}

// 设置字符集
$conn->set_charset("utf8");

// 在这里执行其他操作...

// 关闭连接
$conn->close();
?>

<?php
function getAllTags($conn) {
    $sql = "SELECT * FROM tags";
    $result = $conn->query($sql);

    $tags = array();
    if ($result->num_rows > 0) {
        while($row = $result->fetch_assoc()) {
            $tags[] = $row;
        }
    }

    return $tags;
}
?>

<?php
function getQuestionsByTag($conn, $tagId) {
    $sql = "SELECT * FROM questions WHERE tag_id = $tagId";
    $result = $conn->query($sql);

    $questions = array();
    if ($result->num_rows > 0) {
        while($row = $result->fetch_assoc()) {
            $questions[] = $row;
        }
    }

    return $questions;
}
?>

<?php
// 获取所有标签
$tags = getAllTags($conn);

// 获取第一个标签下的问题列表
$tagId = $tags[0]['id'];
$questions = getQuestionsByTag($conn, $tagId);
?>

<h1>标签分类</h1>

<!-- 标签列表 -->
<ul>
    <?php foreach ($tags as $tag): ?>
        <li><a href="?tag=<?php echo $tag['id']; ?>"><?php echo $tag['name']; ?></a></li>
    <?php endforeach; ?>
</ul>

<!-- 问题列表 -->
<ul>
    <?php foreach ($questions as $question): ?>
        <li><?php echo $question['title']; ?></li>
    <?php endforeach; ?>
</ul>