Java 删除带有约束的行

我想从实体保留中删除行。 这个实体看起来像

@Entity
@Table(name="reservation")
public class Reservation {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(nullable = false, unique = true)
    private Integer id;

    @ManyToOne(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
    @OnDelete(action = OnDeleteAction.CASCADE)
    @JsonIgnoreProperties({"hibernateLazyInitializer", "handler"})
    private Seance reservationSeance;

    @ManyToOne(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
    @JoinColumn(name = "user_id")
    private User userReservation;

    @OneToMany(orphanRemoval = true)
    private List<Seat> seats = new ArrayList<>();
    ............

}

我在实体关系中使用了ManyToMany和hibernate来创建额外的表曲目

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如何避免从表Seance中删除记录，我只想从Reservation表中删除记录？

您还没有发布

Seance

和

存储库

代码，因此我将填补空白

首先，您需要删除

@OnDelete（action=ondeletection.CASCADE）

注释，因为它实际上是在删除

保留时告诉数据库删除
Seance

然后，您需要在
reservation
表的外键列（@JoinColumn）中允许空值，如下所示：

@Entity
@Table(name="Seance")
public class Seance {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(nullable = false, unique = true)
    private Integer id;

    @OneToMany(fetch = FetchType.LAZY)
    @JoinColumn(name = "reservation_id", nullable = true)
    private Reservation reservation;

    ...
}

public void deleteReservation(int reservationId) {
    Session currentSession = sessionFactory.getCurrentSession();

    // get reservation with primary key
    Reservation reservation = currentSession.get(Reservation.class, reservationId);  
    Seance seance = reservation.getSeance();

    //set reservation_id null
    Seance.setReservation(null);

    //delete the reservation
    currentSession.remove(reservation);
}

最后，在DAO中，您需要为与要删除的
保留相关的
Seance
设置空值，然后才将其删除，如下所示：

@Entity
@Table(name="Seance")
public class Seance {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(nullable = false, unique = true)
    private Integer id;

    @OneToMany(fetch = FetchType.LAZY)
    @JoinColumn(name = "reservation_id", nullable = true)
    private Reservation reservation;

    ...
}

public void deleteReservation(int reservationId) {
    Session currentSession = sessionFactory.getCurrentSession();

    // get reservation with primary key
    Reservation reservation = currentSession.get(Reservation.class, reservationId);  
    Seance seance = reservation.getSeance();

    //set reservation_id null
    Seance.setReservation(null);

    //delete the reservation
    currentSession.remove(reservation);
}