public boolean insertNewUser(String username, String password) throws Exception
    {
        connection.connect();
        connection.executeQuery(USER_LOGIN +"'"+ username.toLowerCase()+"'");
        if(connection.next())
        {
            throw new Exception("Ya existe el usuario que desea agregar");
        }
        return connection.executeNonQuery("INSERT INTO users values (NULL, '"+username.toLowerCase()+"', '"+ password.toLowerCase() +"');");
        
    }