class problem in php
<?php

  try {

    require_once('./lib/testdb.php');

    $login = new Login();

  }

  catch(Exception $error) {

    print $error->getMessage();

  }



  /* Include the HTML for the form */

  require_once('./lib/form.php');

?>

<?php
  define("DB_HOST", "localhost");

  define("DB_USER", "root");

  define("DB_PASS", "root");
  class Login{
    private $username;
    private $password;
    public function getUsername() {

      return $this->username;

    }

    public function getPassword() {

      return $this->password;

    }

    public function getEncryptedPassword() {

      return sha1($this->password);

    }

   public function connectToMySQL() {

      @mysql_connect(DB_HOST, DB_USER, DB_PASS) OR die("Cannot connect to MySQL server!");

      mysql_select_db("dd") OR die("Cannot select database!");

    }


    public function verifyLogin($username, $password) {

      $this->username = $username;

      if(empty($username) || empty($password)) {

        throw new Exception(Login::ERROR_EMPTY_LOGIN);

      }

      else {

      $query = sprintf("SELECT * FROM 'users' WHERE username = '%s' AND

            userpass = sha1('%s') ");

            $this->clean($username),

            $this->clean($password));



      $result = mysql_query($query) OR die('Cannot perform query!');
        while($info = mysql_fetch_array( $result ))
      {
          echo $info['username'];
      }
}
?>

--
-- Database: `login`
--

-- --------------------------------------------------------

--
-- Table structure for table `login`
--

CREATE TABLE IF NOT EXISTS `login` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `username` varchar(80) NOT NULL,
  `password` varchar(80) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=MyISAM  DEFAULT CHARSET=latin1 AUTO_INCREMENT=2 ;

--
-- Dumping data for table `login`
--

INSERT INTO `login` (`id`, `username`, `password`) VALUES
(1, 'ajay', 'password');

$query = sprintf("SELECT * FROM 'users' WHERE username = '%s' AND
        userpass = sha1('%s') ");    // here
        $this->clean($username),
        $this->clean($password));

$query = sprintf("SELECT * FROM 'users' WHERE username = '%s' AND
        userpass = sha1('%s') ",    // corrected
        $this->clean($username),
        $this->clean($password));

<?php

  try {

    require_once('./lib/testdb.php');

    $login = new Login();

  }

$result = mysql_query($query) OR die('Cannot perform query: ' . mysql_error());

echo $query;