Here is a code of creating form on jinternalframe and connect to mysql.

import java.io.*;
import java.sql.*;
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;

public class JInternalFormDemo extends JDesktopPane {

    public static void main(final String[] args) throws IOException {
        final JInternalFormDemo desktop = new JInternalFormDemo();
        desktop.addForm();
        final JFrame frame = new JFrame("Show Image");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(BorderLayout.CENTER, desktop);
        frame.setSize(600, 100);
        frame.setVisible(true);
    }

    public void addForm() {
        add(createFrame());
    }

    private static int frames;

    private JInternalFrame createFrame() {
       final JInternalFrame frame = new JInternalFrame("Form ");
        JButton ADD=new JButton("Submit");
     JPanel panel=new JPanel(new GridLayout(3,2));
     JLabel label1=new JLabel("Name");
     JLabel label2=new JLabel("Address");
     final JTextField text1=new JTextField(20);
     final JTextField text2=new JTextField(20);
      panel.add(label1);
      panel.add(text1);
      panel.add(label2);
      panel.add(text2);
      panel.add(ADD);
      frame.add(panel);
      ADD.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent ae){
        String value1=text1.getText();
        String value2=text2.getText();
        try{
        Class.forName("com.mysql.jdbc.Driver").newInstance();
                Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/test", "root", "root" );
                Statement st=conn.createStatement();

                     st.executeUpdate("insert into data(name,address) values('"+value1+"','"+value2+"')");
                    JOptionPane.showMessageDialog(null,"Inserted Successfully!");
                    text1.setText(" ");
                    text2.setText(" ");
                }
        catch(Exception e){}

  }
});
        frame.pack();
        frame.setVisible(true);
        frame.setLocation(40 * frames, 40 * frames);
        return frame;
    }
}