将资料从MySQL载入JComboBox

Question

I have two MySQL tables as image below

movie

movie_title

         JComboBox combo = new JComboBox();
        combo.setBounds(125, 15, 190, 20);
         try {   
            DatabaseConnection db=new DatabaseConnection();
            Connection connect=db.getConnection();
            String sql="Select title FROM movie_title";
            PreparedStatement ps=connect.prepareStatement(sql);
            ResultSet rs = ps.executeQuery();
            while (rs.next()) {
            String name = rs.getString("title");
            combo.addItem(name);            
        }

    } catch (Exception e) {
        System.out.println("null");
    }
         combo.addActionListener(new ActionListener()
        {
    public void actionPerformed(ActionEvent event)
    {
        JComboBox comboBox=(JComboBox) event.getSource();
         Object selected = comboBox.getSelectedItem();
         displayDay(selected);
    }

    private void displayDay(Object selected) {
        // TODO Auto-generated method stub
         try {  
                combo1.removeAllItems();
                DatabaseConnection db=new DatabaseConnection();
                Connection connect=db.getConnection();
                String sql="Select movie_day FROM movie WHERE movie_title = ?";
                PreparedStatement ps=connect.prepareStatement(sql);
                ps.setObject(1, selected);
                ResultSet rs = ps.executeQuery();
                while (rs.next()) {
                String day = rs.getString("movie_day");
                combo1.addItem(day);   
            }

        } catch (Exception e) {
            System.out.println("null");
        }

    }
        });

I have implemented ActionListener in comboBox . When user select movie Marvel's Captain America, it will get the movie_day item from movie and load into combo1. Is there a way I can make the combo1 display the movie_day which is Sunday, 28 Apr 2016 one time only instead of two ?

Edit

private void displayDay(Object selected) {
        // TODO Auto-generated method stub
         try {  
                combo1.removeAllItems();
                DatabaseConnection db=new DatabaseConnection();
                Connection connect=db.getConnection();
                String sql="Select movie_day FROM movie WHERE movie_title = ?";
                PreparedStatement ps=connect.prepareStatement(sql);
                ps.setObject(1, selected);
                ResultSet rs = ps.executeQuery();
                while (rs.next()) {
                String day = rs.getString("movie_day");
                DefaultComboBoxModel model = (DefaultComboBoxModel)combo1.getModel();                
                if (model.getIndexOf(day) == -1)
                {
                    combo1.addItem(day);
                }

            }

        } catch (Exception e) {
            System.out.println("null");
        }

Answer 1

Is there a way I can make the combo1 display the movie_day which is Sunday, 28 Apr 2016 one time only instead of two ?

Before adding the date to the combo box you need to check if the date already exists.

DefaultComboBoxModel model = (DefaultComboBoxModel)comboBox.getModel();

if (model.getIndexOf(theDate) == -1)
{
    comboBox.addItem( theDate );
}

You could also change the SQL statement to only get "unique" dates, but I don't know SQL well enough to give you the actual syntax. Maybe this SQL Tutorial will help, otherwise you need to find a better tutorial.