Question

I have a many to many mapping between book and author

@Enity
public class Book{

    private Long id;
    private String name;
    ...

    @Id
    @Column(name="book_id")
    public getId(){
    ...
    }
    @ManyToMany(
    @JoinTable(name="book_author",
        joinColumns = @JoinColumn(name="book_id"),
        inverseJoinColumns = @JoinColumn(name="????")
    )
    public List<Author> getAuthors(){
    ...
    }
}

@Enity
public class Author{
    @EmbeddedId;
    private AuthorPk authorPk;
    ...

}

How can i do a many to many mapping on inverseJoinColumn as it is a composite key?

Answer 1

inverseJoinColumns = {@JoinColumn(name = "theFirstColumnInTheJoinTable", 
                                  referencedColumnName = "theFirstColumnInTheTargetTable"),
                      @JoinColumn(name = "theSecondColumnInTheJoinTable", 
                                  referencedColumnName = "theSecondColumnInTheTargetTable")}

But I would definitely avoid composite PKs: they make life much more complicated, and performance worse.