使用 PHP 开发知识问答网站中的问题频道和专题功能。

CREATE TABLE questions (
  id INT AUTO_INCREMENT PRIMARY KEY,
  title VARCHAR(255) NOT NULL,
  content TEXT NOT NULL,
  created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
  updated_at DATETIME DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
);

CREATE TABLE topics (
  id INT AUTO_INCREMENT PRIMARY KEY,
  name VARCHAR(100) NOT NULL,
  created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
  updated_at DATETIME DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
);

<?php
// 配置数据库连接
$host = 'localhost';
$db = 'qa_db';
$user = 'root';
$password = '';

// 连接数据库
$conn = new PDO("mysql:host=$host;dbname=$db", $user, $password);
$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

// 查询问题列表
$query = "SELECT * FROM questions ORDER BY created_at DESC";
$stmt = $conn->prepare($query);
$stmt->execute();
$questions = $stmt->fetchAll(PDO::FETCH_ASSOC);

// 显示问题列表
foreach ($questions as $question) {
    echo "<h2>{$question['title']}</h2>";
    echo "<p>{$question['content']}</p>";
    echo "<p>发布时间：{$question['created_at']}</p>";
}
?>

<?php
// 创建专题
if (isset($_POST['create_topic'])) {
    $name = $_POST['topic_name'];
    
    // 插入专题到数据库
    $query = "INSERT INTO topics (name) VALUES (:name)";
    $stmt = $conn->prepare($query);
    $stmt->bindParam(':name', $name);
    $stmt->execute();
}

// 查询专题列表
$query = "SELECT * FROM topics ORDER BY created_at DESC";
$stmt = $conn->prepare($query);
$stmt->execute();
$topics = $stmt->fetchAll(PDO::FETCH_ASSOC);

// 显示专题列表
foreach ($topics as $topic) {
    echo "<h3>{$topic['name']}</h3>";
    echo "<a href='edit_topic.php?id={$topic['id']}'>编辑</a> ";
    echo "<a href='delete_topic.php?id={$topic['id']}' onclick='return confirm("确定要删除该专题吗？")'>删除</a>";
}

// 创建专题表单
echo "<form method='post'>";
echo "<input type='text' name='topic_name'>";
echo "<input type='submit' name='create_topic' value='创建专题'>";
echo "</form>";
?>