两个实体之间的多个不同类型关联--SpringBoot、PostgreSQL

Question

假设我有2个实体类，User和post。

波纹管示例

@Entity
public class User{

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @OneToMany(mappedBy = "user")
    private Set<Post> posts;

    @ManyToMany
    @JoinTable(
            joinColumns = @JoinColumn(name = "user_id"),
            inverseJoinColumns = @JoinColumn(name = "post_id"))
    private Set<Post> followedPosts;
}

@Entity
public class Post{

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Post id;

    @ManyToOne
    @JoinColumn(name = "id", nullable = false)
    private User user;

    @ManyToMany(mappedBy = "followedPosts")
    private Set<User> users;
}

Answer 1

是的，您可以在相同的2个表之间有许多关联。

一个表甚至可以有多个返回到自身的关联，例如，Person表可以有一个Father_ID列和一个Mother_ID列，这两个外键（一对多关联）都返回到Person表本身。