blustar angel

how do i increase the quatity of an item when it is added again and again into my shopping cart table.there is only a button add to cart.there is no textfeild for quantitiy.
the code as of now i have retreives the items from database and add it into the shipping cart table. if i clik on it again and again the same item wil be shown again and again.

Java Code:

 DefaultTableModel model = (DefaultTableModel) 
tbl1.getModel();
            DefaultTableModel tm = (DefaultTableModel) 
tbl2.getModel();
            int a = tbl1.getSelectedRow();
            if (a == 0) {
                
                try {
                    Class.forName("java.sql.Driver");
                    Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/album", "root", "123");
                    Statement stm = con.createStatement();
                    String sql = "select ALBUMNAME,PRICE FROM albums WHERE ALBUMNAME='twilight' ;";
                    ResultSet res = stm.executeQuery(sql);
                    while (res.next()) {
                        String ALBUMNAME = res.getString("ALBUMNAME");
                        int PRICE = res.getInt ("PRICE");

                        tm.addRow(new Object[]{ALBUMNAME, PRICE});
                    }
                    res.close();
                    con.close();
                    stm.close();
                    


                } catch (Exception e) {
                    JOptionPane.showMessageDialog(null, "error in connectivity");
                }