PHP und JSON

Daten aus mySQL in eine JSON Datei schreiben

<?php 
$sql=mysql_query("select * from Posts limit 20"); 

$response = array();
$posts = array();
$result=mysql_query($sql);
while($row=mysql_fetch_array($result)) 
{ 
$title=$row['title']; 
$url=$row['url']; 

$posts[] = array('title'=> $title, 'url'=> $url);

} 

$response['posts'] = $posts;

$fp = fopen('results.json', 'w');
fwrite($fp, json_encode($response));
fclose($fp);

?>