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我需要建立友谊关系.我有一个友谊类,有两个主键,每个主键都是一个成员类.我收到以下异常:

org.hibernate.MappingException: Foreign key (FK_8ynretl1yt1xe3gcvfytrvpq:Friendship [])) must have same number of columns as the referenced primary key (Member [username])

友谊

@Entity
public class Friendship implements Serializable {
    /**
     * 
     */
    private static final long serialVersionUID = -1234656876554786549L;
    @Id
    @ManyToOne
    Member requester;
    @Id
    @ManyToOne
    Member friend;
    @Temporal(javax.persistence.TemporalType.DATE)
Date date;

会员

@Entity
public class Member {
    @Id
    @MapsId
    @OneToOne(cascade = CascadeType.ALL)
    @JoinColumn(name = "username")
    Credential credential;
    @Column(nullable = false)
    String fname;
    @Column(nullable = false)
    String lname;
    @Column(nullable = false)
    short gender;

凭据 …