@ManyToMany 表之间的关系

Question

我有三个独立的实体dish, kitchen, restaraunt 和链接表many。 我的问题是，如何在我的实体类中定义这种关系？

厨房模型

@Entity
@Table(name = "kitchen")
public class Kitchen {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;
    @Column(name = "kitchen_name")
    private String name;
    @Column(name = "kitchen_photo")
    private Blob photo;
}

碟形模型

@Entity
@Table(name = "dish")
public class Dish {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;
    @Column(name = "dish_name")
    private String dishName;
    @Column(name = "dish_photo")
    private Blob dishPhoto;

餐厅模式

 public class Restaraunt {
        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        private long id;
        @Column(name = "res_name")
        private String name;
        @Column(name = "res_rating")
        private double rating;
        @Column(name = "res_address")
        private String address;
        @Column(name = "res_number")
        private String number;
        @Column(name = "res_site")
        private String site;
        @Column(name = "res_price")
        private String price;
        @Column(name = "res_photo")
        private Blob photo;

链接表 许多模型

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

    @Column(name = "res_id")
    private long res_id;
    @Column(name = "kitchen_id")
    private long kitchen_id;
    @Column(name = "dish_id")
    private long dish_id;
    @Column(name = "many_name")
    private String name;
    @Column(name = "many_rating")
    private double rating;
    @Column(name = "many_address")
    private String address;
    @Column(name = "namy_number")
    private String number;
    @Column(name = "many_site")
    private String site;
    @Column(name = "many_price")
    private String price;
    @Column(name = "many_photo")
    private Blob photo;
    @Column(name = "dish_name")
    private String dishName;
    @Column(name = "kitchen_name")
    private String kitchenName;
    @Column(name = "dish_photo")
    private Blob dishPhoto;
    @Column(name = "kitchen_photo")
    private Blob kitchePhoto;

我知道如何定义两个表之间的这种关系，但对于两个以上我不确定。 我需要创建表Many 吗？

Answer 1

要理解Restaurant 将有许多菜肴 和一个Kitchen

你可以像下面这样定义关系

@Entity
public class Restaraunt {

// all other fields

@OneToMany
private Set<Dish> dishes;

@OneToOne
private Kitchen kitchen;

}

您可以像上面一样从一侧进行映射，也可以从两侧进行映射，即从Dish 和Kitchen 以及Dish 到Restaurant 作为ManyToOne 和Kitchen 到@987654330 @如OneToOne

我看不出有任何理由使用Many 模型。