Gegevens exporteren uit mysql in de xml met behulp van php

Probeer deze code:

<?php
$dbh=mysql_connect($localhost, $username, $password) or die ('I cannot connect to the database because: ' . mysql_error());
$result = mysql_query("SELECT * FROM 12345_flv.flv WHERE enabled = '1' ORDER BY id DESC") or die('Could not connect: ' . mysql_error());  

$string = '<videos><updated>2010-07-20T00:00:00Z</updated><video>';

while ($row = mysql_fetch_array($result)) { 
    $id=$row['id'];
    $title=$row['title'];
    $string .='<id>'.$id.'</id>';
    $string .='<title>'.$title.'</title>';
}
$string .='</video></videos>'; 
$xml = new SimpleXMLElement($string);
Header('Content-type: text/xml');
echo $xml->asXML();
?>