Не получается зарегистрировать пользователя

 <?php
  $connect = mysql_connect('localhost','root') or die(mysql_error());
  mysql_select_db('tutorials');
  if(isset($_POST[submit])) {
    $username = $_POST[username];
    $login = $_POST[login];
    $password = $_POST[password];
    $r_password = $_POST[r_password];
    if($password == $r_password) {
 
    }
    else {
      die('Password should be the same');
    }
  }
?>
<form action="register.php" method="post">
  <input type="text" name="username" placeholder="username" required>
  <br>
  <input type="text" name="login" placeholder = "login" required>
  <br>
  <input type="password" name ="password" id="lan1" placeholder="password" required>
  <br>
  <input type="password" name = "r_password" id='copy' placeholder ="repeate password" required>
  <input type="submit" name="submit" value="register" onclick="lan()">
  <br>
  </form>