public function getRelatedCountries()
    {
        $conn = $this->app->getApplicationBox()->get_connection();

        $sql = 'SELECT DISTINCT Users.country ' . $this->generate_sql_constraints() . ' ORDER BY Users.country';

        $stmt = $conn->prepare($sql);
        $stmt->execute($this->sql_params);
        $rs = $stmt->fetchAll(PDO::FETCH_ASSOC);
        $stmt->closeCursor();

        $countries = [];
        $listCountry = Countries::getCountries($this->app['locale']);
        foreach ($rs as $row) {
            if (trim($row['country']) === '') {
                continue;
            }

            if (isset($listCountry[$row['country']])) {
                $countries[$row['country']] = $listCountry[$row['country']];
            }
        }

        return $countries;
    }