Spring Boot使用MyBatis进行两个表的关联

CREATE TABLE users (
    id INT AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(100),
    email VARCHAR(100)
);
CREATE TABLE orders (
    id INT AUTO_INCREMENT PRIMARY KEY,
    user_id INT,
    order_name VARCHAR(100),
    FOREIGN KEY (user_id) REFERENCES users(id)
);

public class User {
    private Long id;
    private String name;
    private String email;
    private List<Order> orders;
    // Getters and setters
    // ...
}
public class Order {
    private Long id;
    private Long userId;
    private String orderName;
    // Getters and setters
    // ...
}

@Mapper
public interface UserMapper {
    List<User> getAllUsers();
    User getUserById(Long id);
    List<Order> getOrdersByUserId(Long userId);
    void insertUser(User user);
    void updateUser(User user);
    void deleteUser(Long id);
}

<mapper namespace="com.example.mapper.UserMapper">
    <resultMap id="userResultMap" type="com.example.model.User">
        <id property="id" column="id" />
        <result property="name" column="name" />
        <result property="email" column="email" />
    </resultMap>
    <select id="getAllUsers" resultMap="userResultMap">
        SELECT * FROM users
    </select>
    <select id="getUserById" resultMap="userResultMap">
        SELECT * FROM users WHERE id = #{id}
    </select>
    <select id="getOrdersByUserId" resultType="com.example.model.Order">
        SELECT * FROM orders WHERE user_id = #{userId}
    </select>
    <insert id="insertUser">
        INSERT INTO users (name, email) VALUES (#{name}, #{email})
    </insert>
    <update id="updateUser">
        UPDATE users SET name = #{name}, email = #{email} WHERE id = #{id}
    </update>
    <delete id="deleteUser">
        DELETE FROM users WHERE id = #{id}
    </delete>
</mapper>

@Service
public class UserService {
    private final UserMapper userMapper;
    public UserService(UserMapper userMapper) {
        this.userMapper = userMapper;
    }
    public List<User> getAllUsers() {
        List<User> users = userMapper.getAllUsers();
        for (User user : users) {
            List<Order> orders = userMapper.getOrdersByUserId(user.getId());
            user.setOrders(orders);
        }
        return users;
    }
    // 其他操作方法...
    // ...
}