User Class

class User
{
    private $conn;
    private $db;
    private $u;
    private $conre;

    function __construct($conn, $db, $u, $conre) {
        $this->conn = $conn;
        $this->db = $db;
        $this->u = $u;
        $this->conre = $conre;
    }

    function getUserNameByID($id)
    {
        $query = $conn->prepare('SELECT '.$u['name'].' FROM '.$tb['user'].' WHERE '.$u['id'].' = :id ');
        $query->execute(array(
            ':id' => $id
        ));
        $result = $query->fetchAll();
        if ( count($result) ){
            $name = "ERROR - user class, function getUserNameByID, line 25, last-change: 14.07.2013";
            foreach($result as $row1)
            {
                $name = $row1[$u['name']];
            }
        }

        return $name;
    }
}