JPA/Hibernate ManyToMany 尝试让数据持久化

Question

我有一个任务，我们有一个电视/体育应用程序，用户可以在其中提交赛事、球队和赛事所在的电视频道。我希望如果我删除一个频道，它会更新数据库中的其他事件以删除该频道，但我希望该事件持续存在。

我的讲座告诉我们使用双向多对多，但它有同样的问题，当我删除一个通道时，它会删除具有该通道的所有事件，然后还会删除参与该事件的所有团队。这是可以用下面的代码完成的事情还是我以错误的方式进行？

我使用了通道表中的每个 CascadeType 来查看数据是否会持久存在，但它要么收到 SQL 错误：23503，要么删除通道链接到的所有内容。

事件类

@Entity
@Table(name = "events")
public class Events {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Column(name = "event_name")
    private String eventName;

    @Column(name= "event_date")
    private Date eventDate;

    @ManyToMany(cascade = {
                    CascadeType.PERSIST,
                    CascadeType.MERGE
            })
    @JoinTable(name = "events_channels",
            joinColumns = { @JoinColumn(name = "events_id") },
            inverseJoinColumns = { @JoinColumn(name = "channels_id") })
    private List<Channels> channels;

    @ManyToMany(cascade = {
            CascadeType.PERSIST,
            CascadeType.MERGE
    })
    private List<Teams> homeTeam;

    @ManyToMany(cascade = {
            CascadeType.PERSIST,
            CascadeType.MERGE
    })
    private List<Teams> awayTeam;

    public Events() {}
}

通道类

@Entity
@Table(name="channels")
public class Channels {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Column(name = "channel_name")
    private String channelName;

    @ManyToMany(fetch = FetchType.LAZY,
            cascade = {
                    CascadeType.REMOVE
            },
            mappedBy = "channels")
    @JsonIgnore
    private List<Events> events;

    public Channels() {}
}

I 也有一个 data.sql，我将以下虚拟数据放入 ManyToMany 连接表中。

INSERT INTO events_channels (events_id, channels_id) VALUES (1, 1);
INSERT INTO events_channels (events_id, channels_id) VALUES (1, 3);
INSERT INTO events_channels (events_id, channels_id) VALUES (2, 1);
INSERT INTO events_channels (events_id, channels_id) VALUES (2, 3);
INSERT INTO events_channels (events_id, channels_id) VALUES (3, 1);
INSERT INTO events_channels (events_id, channels_id) VALUES (4, 2);
INSERT INTO events_channels (events_id, channels_id) VALUES (5, 2);
INSERT INTO events_channels (events_id, channels_id) VALUES (4, 3);
INSERT INTO events_channels (events_id, channels_id) VALUES (5, 4);
INSERT INTO events_channels (events_id, channels_id) VALUES (6, 2);
INSERT INTO events_channels (events_id, channels_id) VALUES (7, 1);
INSERT INTO events_channels (events_id, channels_id) VALUES (7, 3);
INSERT INTO events_channels (events_id, channels_id) VALUES (8, 1);
INSERT INTO events_channels (events_id, channels_id) VALUES (8, 3);