这是我的密码：

@Entity
public class User {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    private String username;

    private String password;

    @OneToOne(mappedBy = "user", cascade = CascadeType.ALL, fetch = FetchType.EAGER, optional = false)
    private Employee employee;

    public User() {
    }

    //SETTERS AND GETER

}

@Entity
public class Employee {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    private String name;

    @OneToOne(fetch = FetchType.EAGER)
    @JoinColumn(name = "user_id")
    private User user;

    public Employee() {
    }

    //SETTERS AND GETER

}

为了我的服务，我试着这样做：

User user = new User();
    user.setUsername("my_username");
    user.setPassword("12345");

    Employee employee = new Employee();
    employee.setName("My Name");
    employee.setBirth(LocalDate.now());

    user.setEmployee(employee);

    userService.save(user);

应用程序上没有错误，也没有任何问题，但是在我的数据库中，user\u id列是空的，我该怎么做才能用user id自动设置user\u id？提前谢谢！