private void openConnection() {
        if (this.dbConnParamUrl == null)
            return;

        try {
            if (this.dbconn != null && !this.dbconn.isClosed())
                this.dbconn.close();

            this.dbconn = DriverManager.getConnection(  dbConnParamUrl,
                                                        dbConnParamUser,
                                                        dbConnParamPassword
                                                     );
        } catch (SQLException e) {
            e.printStackTrace();
            this.dbconn = null;
        }
    }