相关疑难解决方法(0)

我已经能够让JPA/Hibernate ON DELETE CASCADE成功复制功能(看起来像默认行为),但我现在正在尝试复制ON DELETE SET NULL功能,我遇到了问题.

这是我的两个班级:

@Entity
@Table(name = "teacher")
public class Teacher
{
    @Id
    @GeneratedValue
    @Column(name = "id", nullable = false, length = 4)
    private int id;

    @OneToMany(mappedBy = "teacher")
    private List<Student> studentList;

    // ...
}

@Entity
@Table(name = "student")
public class Student
{
    @Id
    @GeneratedValue
    @Column(name = "id", nullable = false, length = 4)
    private int id;

    @ManyToOne(optional = true)
    @JoinColumn(name = "teacher_id", nullable = true)
    private Teacher teacher;

    // ...
}

当我尝试删除教师时,会出现以下错误: …