@ManyToMany 额外列

Question

我需要模拟客户和促销之间的关系。 我们需要关于客户促销分数的历史记录 CLIENTS_PROMOTIONS_HISTORY 和当前分数 CLIENTS_PROMOTIONS

DB 建模很好，但我发现很难为实体建模。 我打算仅将 CLIENTS_PROMOTIONS 表用于关系目的，以便客户可以了解他们的促销活动 + 每个促销活动的当前分数。但不知道在哪里存储当前分数。

实体和图表：

@Entity
@Table(name = "CLIENTS")
@SecondaryTable(name = "CLIENTS_PROMOTIONS",
                pkJoinColumns = @PrimaryKeyJoinColumn(name = "ID_CLIENT"))
class Client {

    @Id
    @Column(name = "ID_CLIENT", nullable = false, unique = true)
    Long id;

    @OneToOne(cascade = CascadeType.ALL, optional = false)
    @JoinColumn(name = "ID_USER", nullable = false, unique = true)
    User user;

    @Column(name = "NAME", nullable = false)
    String name;

    @Column(name = "BIRTHDAY", nullable = false)
    Date birthday;

    @Column(name = "EMAIL", nullable = false)
    String email;

    @Column(name = "SEX", nullable = false)
    Character sex;

    @ManyToMany
    @JoinTable(name = "CLIENTS_PROMOTIONS", 
               joinColumns = @JoinColumn(name = "ID_CLIENT"),
               inverseJoinColumns = @JoinColumn(name = "ID_PROMOTION"))
    Set<Promotion> promotions;
}

-

@Entity
@Table(name = "PROMOTIONS")
class Promotion {

    @Id
    @Column(name = "ID_PROMOTION", nullable = false, unique = true)
    Long id;

    @Column(name = "ID_ESTABLISHMENT", nullable = false)
    Long establishmentId;

    @Column(name = "TITLE", nullable = false)
    String title;

    @Column(name = "LIMIT_SCORE", nullable = false)
    Long limitScore;

    @Column(name = "DESCRIPTION", nullable = false)
    String description;

    @Column(name = "REWARD", nullable = false)
    String reward;
}

Answer 1

您需要为 Client_Promotions 创建一个 Entity 并模拟此 Entity 与 Promotion 和 Client 的关系 @ManyToOne > 实体，而不是 @ManyToMany。