corejava Project help needed

Question

Hi

I'm Riya a B.Tech. student and i have to make a corejava project on the topic COLLEGE MANAGEMENT SYSTEM . I have created the required database using MS Access. I m facing problem in a code which i m attaching here. Actually i want to update a data in the data base so i have made 2 frames in one of them Roll no. is asked when it is entered then the 2nd frame opens and asks Enter Marks to be updated...when i enter the marks to be updated then a dialogue box opens shoing "Marks Updated Successfully". Till here i don't have any problem..the problem is when i open the database i see that actually the Marks is not updated there.So please please please somebody help me solving this problem.

The code is as follows:

1ST FRAME

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;

class MyFrame03 extends JFrame implements ActionListener {
    JLabel l1;
    JTextField t1;
    JPanel p1, p2;
    JButton b1;
    Connection con;
    PreparedStatement pst;
    String s1;

    MyFrame03() {
        setLayout(new GridLayout(4, 1));
        setTitle("Enter Data Required");
        setBackground(Color.blue);
        l1 = new JLabel("Roll no");
        t1 = new JTextField(12);
        p1 = new JPanel();
        p2 = new JPanel();
        b1 = new JButton("SUBMIT");
        p1.add(l1);
        p1.add(t1);
        p2.add(b1);
        add(p1, "Center");
        add(p2, "South");
        b1.addActionListener(this);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setSize(400, 500);
        setVisible(true);
        try {
            Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
            con = DriverManager.getConnection("Jdbc:Odbc:dsn3");
            if (con != null)
                System.out.println("Connection Established");
        }
        catch (Exception e) {
            System.out.println("exception");
        }
    }

    public void actionPerformed(ActionEvent e1) {
        if (e1.getSource() == b1) {
            s1 = t1.getText();
            try {
                pst = con.prepareStatement("insert into stud values(?)");
                pst.setString(1, s1);
                pst.executeUpdate();
                con.commit();
                con.close();
            }
            catch (SQLException e) {
                System.out.println("except1");
            }
            MyFrame04 m1 = new MyFrame04(s1);
            dispose();
        }
    }

    public static void main(String s[]) throws SQLException {
        MyFrame03 m1 = new MyFrame03();
    }
}

2nd FRAME

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;

class MyFrame04 extends JFrame implements ActionListener {
    JLabel l1;
    JTextField t1;
    JPanel p1, p2;
    JButton b1;
    String s1, s2;
    Connection con;
    PreparedStatement pst;

    public MyFrame04(String s1) {
        this.s1 = s1;
        setLayout(new GridLayout(4, 1));
        setTitle("Update Marks");
        setBackground(Color.blue);
        l1 = new JLabel("Enter Marks");
        t1 = new JTextField(12);
        b1 = new JButton("SUBMIT");
        p1 = new JPanel();
        p2 = new JPanel();
        p1.add(l1);
        p1.add(t1);
        p2.add(b1);
        add(p1, "Center");
        add(p2, "South");
        b1.addActionListener(this);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setSize(400, 500);
        setVisible(true);
        try {
            Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
            con = DriverManager.getConnection("Jdbc:Odbc:dsn3");
            if (con != null)
                System.out.println("Connection Established");
        }
        catch (Exception e) {
            System.out.println("exception");
        }
    }

    public void actionPerformed(ActionEvent e1) {
        if (e1.getSource() == b1) {
            s2 = t1.getText();
            try {
                pst = con.prepareStatement("UPDATE stud set Marks=? WHERE Roll no=?");
                pst.setString(1, s2);
                pst.setString(2, s1);
                pst.executeUpdate();
                con.commit();
                con.close();
            }
            catch (SQLException e) {
                System.out.println("except1");
            }
            JOptionPane.showMessageDialog(this, "Marks updated succesfully");
            dispose();
        }
    }
}

Thankyou

Answer 1

Does your database access code work without Swing? The simplest way to see this would be something like:

class HelloDatabase {
  public static void main(String[] args) {
    try {
        Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
        Connection con = DriverManager.getConnection("Jdbc:Odbc:dsn3");
        if (con != null) {
            int marks = 1, roll = 1; // or whatever (your data here)
            System.out.println("Connection Established");
            PreparedStatement pst = con.prepareStatement("UPDATE stud SET marks=? WHERE roll_num=?");
            pst.setString(1, marks);
            pst.setString(2, roll);
            pst.executeUpdate();
            con.commit();
            con.close();
        }
    }
    catch (Exception e) {
        System.out.println("exception");
    }    
  }
}

If this gets a handle and accesses your database properly, you're in luck.

By the way -- and this may actually be your issue -- I noticed that your SQL query from the original post had an ambiguity in it:

UPDATE stud set Marks=? WHERE Roll no=?

"Roll no" would not get recognized a valid SQL field, as far as I understand -- these should be a single 'word' (like 'roll', 'roll_num' or even 'RollNum' -- but I don't think a name like 'Roll no' would work here.)