PHP开发：如何实现文章标签功能

// 数据库连接
$conn = mysqli_connect("localhost", "username", "password", "dbname");

if(!$conn){
    die("数据库连接失败：" . mysqli_connect_error());
}

// 获取文章ID和标签名称
$article_id = $_POST['article_id'];
$tag_name = $_POST['tag_name'];

// 将标签插入标签表
$sql = "INSERT INTO tag (tag_name) VALUES ('$tag_name')";
if(mysqli_query($conn, $sql)){
    // 获取插入的标签ID
    $tag_id = mysqli_insert_id($conn);

    // 将文章ID和标签ID插入文章标签关系表
    $sql = "INSERT INTO article_tag (article_id, tag_id) VALUES ('$article_id', '$tag_id')";
    if(mysqli_query($conn, $sql)){
        echo "标签添加成功";
    }
    else{
        echo "添加标签失败：" . mysqli_error($conn);
    }
}
else{
    echo "添加标签失败：" . mysqli_error($conn);
}

// 关闭数据库连接
mysqli_close($conn);

// 数据库连接
$conn = mysqli_connect("localhost", "username", "password", "dbname");

if(!$conn){
    die("数据库连接失败：" . mysqli_connect_error());
}

// 获取标签名称
$tag_name = $_GET['tag_name'];

// 根据标签名称查询对应的文章
$sql = "SELECT a.article_id, a.title, a.content FROM article a 
        INNER JOIN article_tag at ON a.article_id = at.article_id 
        INNER JOIN tag t ON at.tag_id = t.tag_id 
        WHERE t.tag_name = '$tag_name'";
$result = mysqli_query($conn, $sql);

if(mysqli_num_rows($result) > 0){
    // 输出查询结果
    while($row = mysqli_fetch_assoc($result)){
        echo "文章ID：" . $row['article_id'] . "<br>";
        echo "标题：" . $row['title'] . "<br>";
        echo "内容：" . $row['content'] . "<br>";
        echo "<br>";
    }
}
else{
    echo "没有找到对应的文章";
}

// 关闭数据库连接
mysqli_close($conn);