class db {
    static private $instance;
    private $host = 'host';
    private $user = 'username';
    private $password = 'password';
    private $db = 'database';
    private $mysql;
    static public function getInstance() {
        if (!isset(self::$instance)) {
            self::$instance == new self();
        }
        return self::$instance;
    }
    public function __construct() {
        $mysql = mysql_connect($this->host, $this->user, $this->password);
        if (!$link) {
            die('Could not connect: ' . mysql_error());
        }
        if (!mysql_select_db($this->db,$mysql)) {
            die('Could not connect: ' . mysql_error());
        }
    }
}