Learning SQL Query with JCheckBox and JButton

Question

Hello,
I am learning how to access a very simple Access table. I am able to connect to the database and return a simple query. As I make it more complicated is where I have confused myself. The program is suppose to allow the user to pick any field they want to query using JCheckBox. After they have checked the fields off, the run query button is hit and outputs the results in a JOPtion Pane with a JTable. I am trying to do a test run and I can't make the query at least output something. If I can get any clues to the right direction would be appreciated. Thanks.
package mypackage25;
import java.sql.*;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class QueryAddressBook extends JFrame
    private JLabel selectQueryLabel;
    private JCheckBox firstName, lastName,
                   telephone, addressI, addressII, city,
                   state, zip;
    private JPanel selectQueryPanel, checkBoxPanel, executePanel;
    private JButton runQueryButton, clearSQLButton;
    private Connection connection;
    private Statement statement;
    private ResultSet resultSet;
    public QueryAddressBook()
      super("Query an Address Book");
      //Driver and Connection
      try
      //Driver for MicrosoftAccess
      Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
      //Inform the user that the Driver was loaded successfully
      System.out.println("Driver Loaded");
      //Connect to specific database(i.e. MyAddress3) in Access
      Connection connection=DriverManager.getConnection("jdbc:odbc:MyAddress3");
      //Inform User
      System.out.println("Database connected");
      }//end try
      catch(ClassNotFoundException cnfe)
        cnfe.printStackTrace();
      }//end catch
      catch(SQLException sqle)
        sqle.printStackTrace();
      }//end catch
      //get content pane and set its layout
      Container container=getContentPane();
      container.setLayout(new BorderLayout());
      //GUI Components
      selectQueryLabel=new JLabel("Select Fields to be Queried");
      firstName=new JCheckBox("First Name");
      lastName=new JCheckBox("Last Name");
      telephone=new JCheckBox("Telephone");
      addressI=new JCheckBox("Address I");
      addressII=new JCheckBox("Address II");
      city=new JCheckBox("City");
      state=new JCheckBox("State");
      zip=new JCheckBox("Zipcode");
      //register listeners for JCheckBoxes
      CheckBoxHandler handler=new CheckBoxHandler();
      firstName.addItemListener(handler);
      lastName.addItemListener(handler);
      telephone.addItemListener(handler);
      addressI.addItemListener(handler);
      addressII.addItemListener(handler);
      city.addItemListener(handler);
      state.addItemListener(handler);
      zip.addItemListener(handler);
      //set up selectQueryPanel
      selectQueryPanel=new JPanel();
      selectQueryPanel.setLayout(new FlowLayout());
      selectQueryPanel.add(selectQueryLabel);
      //set up CheckBox Panel
      checkBoxPanel=new JPanel();
      checkBoxPanel.setLayout(new FlowLayout());
      checkBoxPanel.add(firstName);
      checkBoxPanel.add(lastName);
      checkBoxPanel.add(telephone);
      checkBoxPanel.add(addressI);
      checkBoxPanel.add(addressII);
      checkBoxPanel.add(city);
      checkBoxPanel.add(state);
      checkBoxPanel.add(zip);
      //set up execute panel
      executePanel=new JPanel();
      executePanel.setLayout(new FlowLayout());
      //set up buttons
      runQueryButton=new JButton("Run Query");
      clearSQLButton=new JButton("Clear SQL");
      runQueryButton.addActionListener
        new ActionListener()
          public void actionPerformed(ActionEvent event)
            if(event.getSource().equals(runQueryButton))
              runSQLQuery();
      executePanel.add(runQueryButton);
      executePanel.add(clearSQLButton);
      container.add(selectQueryPanel, BorderLayout.NORTH);
      container.add(checkBoxPanel, BorderLayout.CENTER);
      container.add(executePanel, BorderLayout.SOUTH);
      setSize(800,150);
      setVisible(true);
    public static void main(String args[])
      QueryAddressBook dwgui=new QueryAddressBook();
      dwgui.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }//end main
    //private inner class for ItemListener event handling
    private class CheckBoxHandler implements ItemListener
      public void itemStateChanged(ItemEvent event)
      }//end method itemStateChanged
    }//end private inner class CheckBoxHandler
    private void runSQLQuery()
      String output="";
      try
        statement=connection.createStatement();
        resultSet=statement.executeQuery("select firstName from address");
        while(resultSet.next())
          output+=resultSet.getString(1)+"\n";
        JOptionPane.showMessageDialog(null,output);
        System.out.println(output);
      }//end try
      catch(SQLException sqle)
        sqle.printStackTrace();
      }//end catch
    }//end runSQLQuery
}//end class

Answer 1

At present your query string is
"Select firstName from Address"
Instead of using the above hardcoded string, try to build the
query String using logic that checks which check boxes are selected
by the user.
Example..
String query = "SELECT ";
if (firstName.isSelected()) {
query = query + " firstName";
Be sure, you add the comma properly between two fields :-)