Ho risolto così, forse potrà servire a qualcuno:
[PHP]
<?
$query3 = "SELECT *, DATE_FORMAT(data_ins_file, '%d-%m-%Y')AS data_ins_file
FROM c_upload_file, a_admin
WHERE c_upload_file.id_admin_ins_file = a_admin.id_admin ORDER BY c_upload_file.data_ins_file DESC, c_upload_file.ora_ins_file DESC";
$result3 = mysql_query($query3, $conn) or die (mysql_error() );
while ($row = mysql_fetch_array($result3)){?>
<a href="#" onmouseover="ajax_showTooltip('../pann_contr_comune/images_big_file_admin.php?foto=<?=$row[id_upload_file]?>',this);return false" onmouseout="ajax_hideTooltip()">
<img src="../images/icona_obiettivo.gif" width="41" height="41" border="0">
</a>
?>
[/PHP]