public boolean deleteUser(String userLogin) {
        try {
            Statement deleteUser = waggrConnection.createStatement();
            String del = String.format("DELETE FROM users WHERE login = '%s';", userLogin);
            int res = deleteUser.executeUpdate(del);
            if (res!=0) {
                deleteUser.close();
                return true;
            }
            deleteUser.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return false;
    }