从MYSQL检索数据并保存XML

Question

I am completely new to PHP and I am trying to retrieve data from mysql database and store it in a xml file (and then I will create an automatic download of the file). So I have the first and the last step implemented, but I cannot store the xml data I am getting. Probably I am missing something really simple, but I have tried many things and none of them gave me the result I wanted. This is the code I am using

<?php

$file = new DOMDocument("1.0"); 


$file->formatOutput = true;



//database configuration
$config['host'] = "xxx";
$config['user'] = "xxx";
$config['pass'] = "xxx";
$config['db_name']    = "xxx";
$config['table_name'] = "xxx";


//connect
mysql_connect($config['host'],$config['user'],$config['pass']);

//Select
@mysql_select_db($config['db_name']);


$file          = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>";
$root_element = $config['table_name']."s"; 
$file         .= "<$root_element>";

//All items
$sql = "SELECT * FROM ".$config['table_name'];

$result = mysql_query($sql);
if (!$result) {
    die('Invalid query: ' . mysql_error());
}

if(mysql_num_rows($result)>0)
{
   while($result_array = mysql_fetch_assoc($result))
   {
      $file .= "<".$config['table_name'].">";

      foreach($result_array as $key => $value)
      {
         //$key holds the table column name
         $file .= "<$key>";

         $file .= "<$value>";

         //and close the element
         $file .= "</$key>";
      }

      $file.="</".$config['table_name'].">";
   }
}


$file .= "</$root_element>";

//If I do an echo here with the headers, it is working.

echo $xml->saveXML();

$file->save('example.xml');



?>

Thanks for the help ;)

SOLVED: I wasn't able to make it work on the way I explained here, but I found how to skip the problem. What I did was just to create the xml in one .html/.php document and from another save the file and download using:

$xml = file_get_contents('xxxx.html');
file_put_contents('example.xml', $xml);