使用Hibernate将许多表连接到一个[多对多和额外的列]

Question

Could you help me please, using hibernate and annotations I want to join 4 tables (prof, salle , groupe, cours) with another one (creneau). the 4 of them have a many-to-many relationship with the 5th table.

I googled it, I know that with many-to-many relationship (I found only the case of 2 tables ) will create a link table to join them, it contains their keys (in my case there will be extra columns also)

This is the best link I found Join Tutorial . The solution that I found more appropriate to the problem would be to repeat that tutorial for the 4 tables (prof-creneau)/(salle/creneau) .... and with the same link table.

Is it the best way to achieve it (for me it seems repetitive) ?

Answer 1

Classic @ManyToMany relationship refers between TWO entities.

If you want many-to-many table relationship, with extra column you need join table.

Here is useful example:

http://www.mkyong.com/hibernate/hibernate-many-to-many-example-join-table-extra-column-annotation/

Answer 2

As I mentioned in my comment on your answers, I'm not 100% clear, but I'm guessing you have four distinct many-to-many relationships:

1. prof-creneau
2. salle-creneau
3. groupe-creneau
4. cours-creneau

If that is the case, then your guess is correct. The best way to achieve it is to have four separate many-to-many relationships. This means you will have four join tables (one for each relationship, each one has two columns; a foreign key for creneau and a foreign key for the other table in the relationship).

In Hibernate you would specify all of these mappings separately.

Your DAO classes could look something like:

public class Prof {
    private Set<Creneau> creneaus = ...;
}

public class Salle {
    private Set<Creneau> creneaus = ...;
}

public class Groupe {
    private Set<Creneau> creneaus = ...;
}

public class Cours {
    private Set<Creneau> creneaus = ...;
}

public class Creneau {
    private Set<Prof> profs = ...;
    private Set<Salle> salles = ...;
    private Set<Groupe> groupes = ...;
    private Set<Cours> courss = ...;
}

It may seem repetitive, but you do have four separate relationships here.