Kijken of user al bestaat

<?        
       	$selectu = mysql_query("SELECT `name` from `users` WHERE `name` = '".$_POST['usern']."'") or die (mysql_error());
       	$usertel = mysql_num_rows($selectu);
       	if ($usertel == 1){
	       	echo "Deze username is al in gebruik, neem een andere.";
       	}
       	else
       	{?>

<?        
       	$selectu = mysql_query("SELECT `name` from `users` WHERE `name` = '".$_POST['usern']."'") or die (mysql_error());
       	$usertel = mysql_num_rows($selectu);
       	if ($usertel == 1){
	       	echo "Deze username is al in gebruik, neem een andere.";
       	}
       	else
       	{?>

<?
require_once ("config.php");

if(isset($_POST['submit']))
{ 
        
        
       	$selectu = mysql_query("SELECT `name` from `users` WHERE `name` = '".$_POST['usern']."'") or die (mysql_error());
       	$usertel = mysql_num_rows($selectu);
       	if ($usertel == 1){
	       	echo "Deze username is al in gebruik, neem een andere.";
       	}
       	else
       	{
		
$password = md5( $_POST['pass'] ); 
$password2 = md5( $_POST['pass2'] );
        
        if( $password == $password2 ) 
        { 
                $query = mysql_query( "INSERT INTO `users` ( `name` , `pass` ) VALUES ( '".$_POST['usern']."', '".$password."')" ) or die ( mysql_error() ); 
                echo "U bent toegevoegd aan de database, u kunt nu inloggen."; 
        } 
        else 
        { 
                echo "De 2 paswoorden komen niet overéén met elkaar, probeer het nog eens."; 
        }
    } 
}
else 
{ 
?> 
<form method="post" action="" name="registreren"> 
<table> 
  <tr> 
    <td>Naam:</td> 
    <td><input type="text" name="usern" maxlength="40"></td> 
  </tr> 
  <tr> 
    <td>Wachtwoord:</td> 
    <td><input type="password" name="pass" maxlength="20"></td> 
  </tr> 
  <tr> 
    <td>Wachtwoord (Ter controle):</td> 
    <td><input type="password" name="pass2" maxlength="20"></td> 
  </tr> 
  <tr> 
    <td>&nbsp;</td> 
    <td><input type="submit" name="submit" value="Registreer"></td> 
  </tr> 
</table> 
</form> 
<?php 
} 
?>  

<?
require_once ("config.php");
 
if(isset($_POST['submit']))
{ 
 
 
       	$selectu = mysql_query("SELECT `name` from `users` WHERE `name` = '".$_POST['usern']."'") or die (mysql_error());
       	$usertel = mysql_num_rows($selectu);
       	if ($usertel == 1){
	       	echo "Deze username is al in gebruik, neem een andere.";
       	}
       	else
       	{
 
$password = md5( $_POST['pass'] ); 
$password2 = md5( $_POST['pass2'] );
 
        if( $password == $password2 ) 
        { 
                $query = mysql_query( "INSERT INTO `users` ( `name` , `pass` ) VALUES ( '".$_POST['usern']."', '".$password."')" ) or die ( mysql_error() ); 
                echo "U bent toegevoegd aan de database, u kunt nu inloggen."; 
        } 
        else 
        { 
                echo "De 2 paswoorden komen niet overéén met elkaar, probeer het nog eens."; 
        }
    } 
}
else 
{ 
?> 
<form method="post" action="" name="registreren"> 
<table> 
  <tr> 
    <td>Naam:</td> 
    <td><input type="text" name="usern" maxlength="40"></td> 
  </tr> 
  <tr> 
    <td>Wachtwoord:</td> 
    <td><input type="password" name="pass" maxlength="20"></td> 
  </tr> 
  <tr> 
    <td>Wachtwoord (Ter controle):</td> 
    <td><input type="password" name="pass2" maxlength="20"></td> 
  </tr> 
  <tr> 
    <td>&nbsp;</td> 
    <td><input type="submit" name="submit" value="Registreer"></td> 
  </tr> 
</table> 
</form> 
<?php 
} 
?>

"SELECT `name` from `users` WHERE `name` = '".$_POST['usern']."'"

"SELECT `name` from `users` WHERE `name` = '".$_POST['usern']."'"