Реализация регистрации!

<?php
function error($err,$code=1){
 
            $xml = new SimpleXMLElement('<xml/>');
                        $response = $xml->addChild('response');
                        $errors=  $response->addChild('errors', $err);
                        $errors ->addAttribute('code', $code);
                        exit($xml->asXML());
}
function answer($msg,$l,$p){
 
            $xml = new SimpleXMLElement('<xml/>');
                        $response = $xml->addChild('response');
                        $answer=  $response->addChild('answer', $msg);
                        $user  =  $response->addChild('user', $l);
                        $user ->addAttribute('login', $l);
                        $user ->addAttribute('pass', $p);
                        exit($xml->asXML());
}
session_start();
$db = mysql_connect ("localhost","root","passwordsql)");
mysql_select_db ("dexa_db",$db);
mysql_query("CREATE TABLE IF NOT EXISTS `users` (`id` int(11) NOT NULL auto_increment,`login` varchar(15) NOT NULL default '', `password` varchar(15) NOT NULL default '',PRIMARY KEY  (`id`)) TYPE=MyISAM AUTO_INCREMENT=3 ;");
if(isset($_POST['act'])){
switch($_POST['act']){
 
default:
  break;// Нахрен если команда не наша.
  case "login":
if (isset($_POST['login'])) { $login = $_POST['login']; if ($login == '') { unset($login);} } 
if (isset($_POST['password'])) { $password=$_POST['password']; if ($password =='') { unset($password);} }
if (empty($login) or empty($password))
{
error ("You have entered all the information venites back and fill in all fields!","1");
}
$login = stripslashes($login);
$login = htmlspecialchars($login);
 
$password = stripslashes($password);
$password = htmlspecialchars($password);
 
//удаляем лишние пробелы
$login = trim($login);
$password = trim($password);
 
 
// подключаемся к базе
 
 
 
 
$result = mysql_query("SELECT * FROM users WHERE login='$login'",$db);
$myrow = mysql_fetch_array($result);
if (empty($myrow['password']))
{
error ("Sorry, you entered an incorrect username or password.","3");
}
else {
          if ($myrow['password']==$password) {
          $_SESSION['login']=$myrow['login']; 
          $_SESSION['id']=$myrow['id'];
          answer( "You have successfully logged in!",$login,$password);
          }
 
       else {
       error ("Sorry, you entered an incorrect username or password.","3");
       }
}
break;// Вот и залогились
case "rega":
if (isset($_POST['login'])) { $login = $_POST['login']; if ($login == '') { unset($login);} } 
if (isset($_POST['password'])) { $password=$_POST['password']; if ($password =='') { unset($password);} }
if (empty($login) or empty($password))
{
error ("You have entered all the information venites back and fill in all fields!","1");// Код первый
}
$login = stripslashes($login);
$login = htmlspecialchars($login);
 
$password = stripslashes($password);
$password = htmlspecialchars($password);
$login = trim($login);
$password = trim($password);
$result = mysql_query("SELECT id FROM users WHERE login='$login'",$db);
$myrow = mysql_fetch_array($result);
if (!empty($myrow['id'])) {
error ("Sorry, you entered your login is already registered. Please enter a different username.","2");//Код второй
}
$result2 = mysql_query ("INSERT INTO users (login,password) VALUES('$login','$password')");
if ($result2=='TRUE')
{
answer("You have successfully logged in!",$login,$password);
}
 
else {
error("Error! You are not logged. There was some crap.","0"); //Код ноль, какая-то хрень
     }
}
 
 
}
?>