[PHP e Mysql]mysql_fetch_object

[neida]

include 'include/conf.inc.php';

$sql = "SELECT c.categorie,
      GROUP_CONCAT(p.name ORDER BY p.name SEPARATOR ', ') prodotti
       FROM tbl_prodotti p
      LEFT JOIN tbl_categorie c ON p.id_categorie = c.ID_categorie
      GROUP BY p.id_categorie
      ORDER BY c.categorie";

$ris = mysql_query($sql) or die(mysql_error());

while($riga = mysql_fetch_object($ris))
{
    echo "$riga->categorie - $riga->prodotti 
";
}