Question

我有下表：

@Entity(name = 'STUDENT')
class Student {
   @Id    
   @Column(name = 'STUDENT_ID')
   String studentId

   @OneToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER, mappedBy = "id.student")
   Set<Disabilities> disabilities = [] 
}


@Entity(name = 'STUDENT_DISABILITY')
class Disability {

    @EmbeddedId
    DisabilityId id

    @Nullable
    @Column(name = 'MOD_DT')
    LocalDateTime modifiedDate
}

@Embeddable
class DisabilityId implements Serializable {

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = 'STUDENT_ID')
    Student student

    @Column(name = 'DISABILITY_CD')
    String disabilityCode
}

这一切都很好，但是我正在尝试将新表'Disability_info'表联接到'Disability'表。这是Disability_info表：

@Entity
@Table(name = 'DISABILITY_INFO')
class DisabilityInfo {

    @Id
    @Column(name = 'DISABILITY_CD')
    String id

    @Column(name = 'DISABILITY_NAME')
    String disabilityName

    @Column(name = 'DISABILITY_DESC')
    String disabilityDesc
}

我遇到的问题是DisabilityInfo的主键是Disability类的复合键的一部分。我想要的就是下面的sql：

SELECT * FROM DISABILITY a INNER JOIN DISABILITY_INFO b on a.DISABILITY_CD = b.DISABILITY_CD

任何人都可以阐明我如何实现这一目标吗？

谢谢。

Answer 1

我知道了。需要多对一的关联。我最初的想法是一个残疾应该有一个描述，因此存在1：1的关系。

但是，实际上，有多个残疾引用相同的描述，这意味着这实际上是多对一的关系！

@Entity(name = 'STUDENT_DISABILITY')
class Disability {

@EmbeddedId
DisabilityId id

@Nullable
@Column(name = 'MOD_DT')
LocalDateTime modifiedDate


@ManyToOne
@JoinColumn(name = 'DISABILITY_ID, insertable = false, updatable = false)
DisabilityInfo disabilityInfo

}

JPA复合键映射的一部分

1 个答案: