prova a modificare in

codice:
$query = mysql_query("SELECT * FROM siti WHERE categoria_siti ='pavimenti' ORDER BY titolo_siti ASC") or die(mysql_error());
$righe=mysql_num_rows($query);
if($righe > 0){
while($result = mysql_fetch_array($query)) {
....
...
..
}
}else{
echo 'no records found';
}