direx

function getNameFromNumber($num)
    {
        $numeric = $num % 26;
        $letter = chr(65 + $numeric);
        $num2 = intval($num / 26);
        if ($num2 > 0) {
            return getNameFromNumber($num2 - 1) . $letter;
        } else {
            return $letter;
        }
    }