Pembangunan PHP: Bagaimana untuk melaksanakan fungsi klasifikasi artikel

CREATE TABLE articles (
    id INT AUTO_INCREMENT PRIMARY KEY,
    title VARCHAR(255) NOT NULL,
    content TEXT NOT NULL,
    category_id INT NOT NULL,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

CREATE TABLE categories (
    id INT AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(255) NOT NULL
);

<?php
// 连接数据库
$mysqli = new mysqli("localhost", "root", "password", "database");
if ($mysqli->connect_errno) {
    die("连接数据库失败: " . $mysqli->connect_error);
}

// 查询分类列表
$result = $mysqli->query("SELECT * FROM categories");
if ($result->num_rows > 0) {
    while ($row = $result->fetch_assoc()) {
        echo "<a href='category.php?id=".$row["id"]."'>".$row["name"]."</a><br>";
    }
}

// 关闭数据库连接
$mysqli->close();
?>

<?php
// 连接数据库
$mysqli = new mysqli("localhost", "root", "password", "database");
if ($mysqli->connect_errno) {
    die("连接数据库失败: " . $mysqli->connect_error);
}

// 获取分类ID
$category_id = $_GET["id"];

// 查询分类信息
$category_result = $mysqli->query("SELECT * FROM categories WHERE id = ".$category_id);
if ($category_result->num_rows > 0) {
    $category = $category_result->fetch_assoc();
    echo "<h1>".$category["name"]."</h1>";
} else {
    die("分类不存在");
}

// 查询分类下的文章列表
$articles_result = $mysqli->query("SELECT * FROM articles WHERE category_id = ".$category_id);
if ($articles_result->num_rows > 0) {
    while ($row = $articles_result->fetch_assoc()) {
        echo "<h2>".$row["title"]."</h2>";
        echo "<p>".$row["content"]."</p>";
        echo "<hr>";
    }
} else {
    echo "该分类下暂无文章";
}

// 关闭数据库连接
$mysqli->close();
?>

<?php
// 连接数据库
$mysqli = new mysqli("localhost", "root", "password", "database");
if ($mysqli->connect_errno) {
    die("连接数据库失败: " . $mysqli->connect_error);
}

// 获取表单提交的信息
$title = $_POST["title"];
$content = $_POST["content"];
$category_id = $_POST["category_id"];

// 插入文章
$insert_result = $mysqli->query("INSERT INTO articles (title, content, category_id) VALUES ('".$title."', '".$content."', ".$category_id.")");
if ($insert_result === true) {
    echo "文章创建成功";
} else {
    echo "创建文章失败: ".$mysqli->error;
}

// 关闭数据库连接
$mysqli->close();
?>