如何在jComboBox中显示多个字段，而在数据库中只插入一个字段？

import javax.swing.*;
import java.sql.*;
import java.util.ArrayList;
import java.util.List;

public class ComboBoxExample {
    private JComboBox<DataModel> comboBox;
    private List<DataModel> dataModels;

    public ComboBoxExample() {
        comboBox = new JComboBox<>();
        dataModels = new ArrayList<>();

        // 连接数据库
        try {
            Connection connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/mydatabase", "username", "password");
            Statement statement = connection.createStatement();

            // 查询数据库获取多个字段的数据
            ResultSet resultSet = statement.executeQuery("SELECT field1, field2, field3 FROM mytable");

            while (resultSet.next()) {
                // 创建数据模型对象并添加到列表中
                DataModel dataModel = new DataModel(resultSet.getString("field1"), resultSet.getString("field2"), resultSet.getString("field3"));
                dataModels.add(dataModel);
            }

            // 创建ComboBoxModel对象并设置为jComboBox的数据模型
            ComboBoxModel<DataModel> comboBoxModel = new DefaultComboBoxModel<>(dataModels.toArray(new DataModel[0]));
            comboBox.setModel(comboBoxModel);

            // 添加监听器
            comboBox.addActionListener(e -> {
                // 获取选中项的数据模型对象
                DataModel selectedDataModel = (DataModel) comboBox.getSelectedItem();

                // 获取需要插入数据库的字段值
                String field1Value = selectedDataModel.getField1();

                // 将字段值插入数据库中的相应字段
                // ...
            });

            // 关闭数据库连接
            resultSet.close();
            statement.close();
            connection.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> {
            ComboBoxExample example = new ComboBoxExample();
            JFrame frame = new JFrame();
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            frame.add(example.comboBox);
            frame.pack();
            frame.setVisible(true);
        });
    }

    // 数据模型类
    private static class DataModel {
        private String field1;
        private String field2;
        private String field3;

        public DataModel(String field1, String field2, String field3) {
            this.field1 = field1;
            this.field2 = field2;
            this.field3 = field3;
        }

        public String getField1() {
            return field1;
        }

        public String getField2() {
            return field2;
        }

        public String getField3() {
            return field3;
        }

        @Override
        public String toString() {
            // 返回需要在jComboBox中显示的字段
            return field1 + " - " + field2 + " - " + field3;
        }
    }
}