如何在java jframe表中插入递增的主键和外键？

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class Main {
    private static final String DB_URL = "jdbc:mysql://localhost:3306/mydatabase";
    private static final String DB_USER = "username";
    private static final String DB_PASSWORD = "password";

    public static void main(String[] args) {
        Connection conn = null;
        PreparedStatement stmt = null;
        ResultSet rs = null;

        try {
            // 连接数据库
            conn = DriverManager.getConnection(DB_URL, DB_USER, DB_PASSWORD);

            // 插入主表数据
            String insertMainTableSql = "INSERT INTO main_table (column1, column2) VALUES (?, ?)";
            stmt = conn.prepareStatement(insertMainTableSql, PreparedStatement.RETURN_GENERATED_KEYS);
            stmt.setString(1, "value1");
            stmt.setString(2, "value2");
            stmt.executeUpdate();

            // 获取插入的主键值
            rs = stmt.getGeneratedKeys();
            int mainId = 0;
            if (rs.next()) {
                mainId = rs.getInt(1);
            }

            // 插入从表数据
            String insertSubTableSql = "INSERT INTO sub_table (main_id, column3) VALUES (?, ?)";
            stmt = conn.prepareStatement(insertSubTableSql);
            stmt.setInt(1, mainId);
            stmt.setString(2, "value3");
            stmt.executeUpdate();

            System.out.println("数据插入成功！");
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            // 关闭连接和资源
            try {
                if (rs != null) {
                    rs.close();
                }
                if (stmt != null) {
                    stmt.close();
                }
                if (conn != null) {
                    conn.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}