如何用PHP实现CMS系统的智能推荐功能

// 获取当前用户的ID
$user_id = $_SESSION['user_id'];

// 查询用户曾经浏览过的文章
$query = "SELECT DISTINCT article_id FROM user_actions WHERE user_id = '$user_id' AND action_type = 'view'";
$result = mysqli_query($conn, $query);

// 构建已浏览文章的数组
$viewed_articles = array();
while ($row = mysqli_fetch_assoc($result)) {
    $viewed_articles[] = $row['article_id'];
}

// 查询与已浏览文章相似的其他用户浏览过的文章
$query = "SELECT DISTINCT article_id FROM user_actions WHERE user_id != '$user_id' AND action_type = 'view' AND article_id IN (SELECT article_id FROM user_actions WHERE user_id = '$user_id' AND action_type = 'view')";
$result = mysqli_query($conn, $query);

// 构建相似文章的数组
$similar_articles = array();
while ($row = mysqli_fetch_assoc($result)) {
    $similar_articles[] = $row['article_id'];
}

// 查询推荐的文章
$query = "SELECT * FROM articles WHERE article_id IN (SELECT DISTINCT article_id FROM user_actions WHERE user_id != '$user_id' AND action_type = 'view' AND article_id NOT IN (" . implode(',', $viewed_articles) .") AND article_id IN (" . implode(',', $similar_articles) . "))";
$result = mysqli_query($conn, $query);

// 输出推荐的文章
while ($row = mysqli_fetch_assoc($result)) {
    echo $row['title'];
    echo $row['content'];
}