public String showMessage() throws Exception {
		Connection conn = null;
		ResultSet rs = null;
		Statement stmt = null;
		try {
			Class.forName("com.mysql.jdbc.Driver");
			conn = DriverManager.getConnection(url, user, psw);
			if (!conn.isClosed())
				System.out.println("Success connecting to the Database!");
			else
				System.out.println("Fail connecting to the Database!");
			stmt = conn.createStatement();
			rs = stmt.executeQuery("select * from message;");
			while(rs.next()) {
				String[] temp = new String[2];
				temp[0] = rs.getString("user_name");
				temp[1] = rs.getString("message");
				res.add(temp);
			} 
			return SUCCESS;
		} catch (Exception e) {
			System.out.print("connection error!");
			e.printStackTrace();
			return ERROR;
		}
	}