multi-user login java (admin,user,teacher)

Question

I have three user types in database. http://oi44.tinypic.com/2z8qflw.jpg

And heres my login form http://oi44.tinypic.com/20p5v04.jpg

When i choose admin as usertype, enter the username and password from the database, the admin form shows up. But when i choose teacher and student, and type the username&pass from the database, only the JOptionpane shows up which is the Invalid details.

heres my code for login jframe:

JButton btnLogin = new JButton("Login");
btnLogin.setFont(new Font("Book Antiqua", Font.PLAIN, 18));
btnLogin.addActionListener(new ActionListener() {
  public void actionPerformed(ActionEvent arg0) {
    String sql = "SELECT * FROM useRecords ";
    try {
      ps = conn.prepareStatement(sql);
      rs=ps.executeQuery();
      String user = usern.getText();
      String pwd = new String (passw.getPassword());
      String type =(String)typeUser.getSelectedItem();
      while(rs.next()) { 
        String uname = rs.getString("username");
        String pass = rs.getString("password");
        if ((user.equals(uname)) && (pwd.equals(pass))) { 
          if (type.equals("Admin")) {  // ... admin
            dispose();
            aCai aCai = new aCai();
            aCai.setVisible(true);
            aCai.setExtendedState(Frame.MAXIMIZED_BOTH);
          } else if (type.equals("Teacher")) {  // ... teacher
            dispose();
            tCai tCai = new tCai();
            tCai.setVisible(true);
            tCai.setExtendedState(Frame.MAXIMIZED_BOTH);
          } else {
            dispose();
            sCai sCai = new sCai();
            sCai.setVisible(true);
            sCai.setExtendedState(Frame.MAXIMIZED_BOTH);
          }
        } else {
          JOptionPane.showMessageDialog(null,  "User name and password do"
                                       + " not match!","ALERT!",
                                       JOptionPane.ERROR_MESSAGE); 
          break;
        }
      }
    } catch(Exception e) {
      JOptionPane.showMessageDialog(null, e);
    } finally {
      try{
        rs.close();
        ps.close();
      } catch(Exception e) {
      }
    }
  }
});

Answer 1

The problem is, you are asking for ALL the rows from the useRecord table and looping through the result set. When you fail to find a match for the username or password on the FIRST row, you show the JOptionPane and break out of the loop, preventing any other possible checks

while(rs.next()) { 
        String uname = rs.getString("username");
        String pass = rs.getString("password");
        if ((user.equals(uname)) && (pwd.equals(pass))) { 
            //...
        } else {
          JOptionPane.showMessageDialog(null,  "User name and password do"
                                       + " not match!","ALERT!",
                                       JOptionPane.ERROR_MESSAGE); 
          break;
        }
}

A better approach might be to ask the database for all the results that match the username and password directly, for example...

String user = usern.getText();
String pwd = new String (passw.getPassword());
String type =(String)typeUser.getSelectedItem();
String sql = "SELECT * FROM useRecords where username=? and password=? and type = ?";
try {
    ps = conn.prepareStatement(sql);
    ps.bindString(1, user);
    ps.bindString(2, pwd);
    ps.bindString(3, type);
    rs=ps.executeQuery();

ps- As a side note, you should avoid storing passwords using plain text in this manner (in fact you should avoid storing them in String). Personally, I would use some kind of one-way hash algorithm to store password in the database, this way, if the database is compromised, then it won't matter (alot) if they get the passwords - IMHO