public void connectToDatabase(String user, String password)
    {
        Properties connectionProps = new Properties();
        connectionProps.put("user", user);
        connectionProps.put("password", password);
        try
        {
            this.conn = DriverManager.getConnection("jdbc:oracle:thin:@//admlab2.cs.put.poznan.pl:1521/"
                 + "dblab02_students.cs.put.poznan.pl", connectionProps);
            System.out.println("Connection established");
        }
        catch(SQLException ex)
        {
            Logger.getLogger(Main.class.getName()).log(Level.SEVERE,
                    "Could not establish connection to database", ex);
            System.exit(-1);
        }
    }