@OneToMany (bidirectional)

假设现在有 university 和 student 两张表：

university	student
id name	id name university_id

一个大学可以有很多学生，而一个学生只能来自一个大学。学生依赖于大学存在，如果大学不存在，这个大学的学生也不存在。

很明显，在这个情况下，university 是 parent table，student 是 child table。并且，university 是 non-owning side，student 是 owning side。

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

    @OneToMany(mappedBy = "university", cascade = CascadeType.ALL, orphanRemoval = true, fetch = FetchType.LAZY)
    private List<Student> students;

    /* Getters and setters */
}

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

    @ManyToOne
    @JoinColumn(name = "university_id")
    private University university;

    /* Getters and setters */
}