我在事件和用戶之間有多對多的關(guān)系。我通過在 User 模型中聲明mappedby()使 Event 模型成為關(guān)系的所有者。我可以從事件模型變量中刪除用戶，這在調(diào)試時工作正常。事件：@Entitypublic class Event {  @ManyToMany(fetch = FetchType.LAZY,        cascade = {                CascadeType.PERSIST,                CascadeType.MERGE        })  @JoinTable(        name = "event_registrations",        joinColumns = @JoinColumn(name="event_id", referencedColumnName =         "id"),        inverseJoinColumns = @JoinColumn(name = "user_id",         referencedColumnName = "id"))  private List<User> userList;}public void registerUser(User user){    this.userList.add(user);}public void removeUsers(ArrayList<Integer> userIds){    for(int userId: userIds){        this.userList.removeIf(user -> user.getId() == userId);    }}用戶：@Entitypublic class User {  @ManyToMany(fetch = FetchType.LAZY,        cascade = {                CascadeType.PERSIST,                CascadeType.MERGE        },        mappedBy = "userList")  @JsonIgnore  private List<Event> eventRegistrations;  public void addEventRegistration(Event event) {    this.eventRegistrations.add(event);  }  public void removeEventRegistration(long eventId){      this.eventRegistrations.removeIf(event -> event.getId() == eventId);  }}執(zhí)行從事件中刪除用戶的代碼：Event event = eventService.getEventById(id);event.removeUsers(userIds);我目前唯一的問題是這些更改沒有保存到數(shù)據(jù)庫中，即使userList變量得到了更新。任何幫助表示贊賞！