Method getCountries

public static function getCountries($id = 0)
{
    if ($id > 0) {
        $db = Factory::getDBO();
        $q = ' SELECT a.country_id FROM #__phocacart_zone_countries AS a' . ' WHERE a.zone_id = ' . (int) $id . ' ORDER BY a.zone_id';
        $db->setQuery($q);
        $countries = $db->loadColumn();
        return $countries;
    }
    return false;
}