Fatal error: Cannot declare class database, because the name is already in
 use
 in C:OSPaneldomainsphploglibrariesdatabase.php on line 2

<?php
class database{
public $host = db_host;
public $username = db_user;
public $password = db_pass;
public $db_name = db_name;

public $link;
public $error;

/*
 * Class Constructor
 */
public function __construct(){
    //Call Connect Function
    $this->connect();
}

/*
 * Connector
 */
private function connect() {
    $this->link = new mysqli($this->host, $this->username, $this->password,
$this->db_name);

    if(!$this->link) {
        $this->error = "Connection Failed: ".$this->link->connect_error;
        return false;
    }
}

/*
 * Select
 */
public function select($query) {
    $result = $this->link->query($query) or die($this->link-
>error.__LINE__);
    if($result->num_rows > 0){
        return $result;
    } else {
        return false;
    }
}

/*
 * Insert
 */
public function insert($query) {
    $insert_row = $this->link->query($query) or die($this->link-
>error.__LINE__);

    //Validate Insert
    if($insert_row) {
        header("Location: index.php?msq=".urlencode('Record insert'));
        exit();
    }
}

/*
 * Update
 */
public function update($query) {
    $update_row = $this->link->query($query) or die($this->link-
>error.__LINE__);

    //Validate update
    if($update_row) {
        header("Location: index.php?msq=".urlencode('Record update'));
    }
}
}
?>

<?php include 'includes/header.php'; ?>
<?php
$id = $_GET['id'];

//Create DB Object
$db = new database();

//Create Query
$query = "SELECT * FROM posts WHERE id = ".$id;
//Run Query
$post = $db->select($query)->fetch_assoc();

//Create Query
$query = "SELECT * FROM categories";
//Run Query
$categories = $db->select($query);

?>
<?php include 'includes/header.php'; ?>
<div class="blog-post">
        <h2 class="blog-post-title"><?php echo $post['title']; ?></h2>
        <p class="blog-post-meta"><?php echo formatDate($post['date']); ?>
by <?php echo $post['author']; ?></p>
            <?php echo shortenText($post['body']); ?>
        <a class="readmore" href="post.php?id=<?php echo
urlencode($post['id']); ?>">Read more</a>
    </div><!-- /.blog-post -->
<?php include 'includes/footer.php'; ?>