echo "
<select>
<option value=-1>Bir Marka Seçiniz</option>";

$liste = mysql_query("SELECT id,isim FROM kategori");
while($listele = mysql_fetch_array($liste, MYSQL_ASSOC)) {
echo "<option value=\"".$listele['id']."\">".$listele['isim']."</option>";
}
echo"
</select>";