Veritabanından belirli bir kritere göre veri listeletmek?

<?
if ($_GET['sil'])
mysql_query("delete from auth where a_id='".$_GET['sil']."'");
?>

<table width="400" cellspacing="0" cellpadding="2">
<?
$sql=mysql_query("SELECT a_id, user, yetki FROM auth ORDER BY user ASC");
while($data=mysql_fetch_array($sql)) {
?>
<tr><td width="60%"><?=$data['user']?></td>
<td><? if ($data['yetki'] != 1) { ?><a href="bayi_sil.php?sil=<?=$data['a_id']?>" onclick=" if ( !confirm('Bayiyi silmek istediğinizden emin misiniz?') ) return false; ">Sil</a>
<? } else { ?><? } ?>
</td>
</tr>
<? } ?>
</table>

$sql=mysql_query("SELECT a_id, user, yetki FROM auth ORDER BY user ASC");

$sql=mysql_query("SELECT a_id, user, yetki FROM auth WHERE yetkikolonununismi = 9 ORDER BY user ASC");