[Hibernate Tools] Reverse ing - class hierarchy

ahuut · **Joined:** Mon Jul 30, 2007 1:59 pm **Posts:** 6

Hello,

I would like to use Hibernate Tools for a project and I need to generate the HBM files and java files from an existing Oracle 10g database.

The both generations work, but the HBM files desn't contain any information about the hierarchy. See the SQL code below :

Code:

create table Employe (
    ID integer not null,
    NOM varchar(20)
);
alter table Employe 
    add constraint Employe_pk primary key (ID);
 
create table Note (
    ID integer not null,
    valeur varchar(20)
);
alter table Note
    add constraint Note_pk primary key (ID);
 
create table Ouvrier (
    EMPLOYE_ID integer not null,
    SERVICE varchar(20),
    NOTE_ID integer not null
);
alter table Ouvrier
    add constraint Ouvrier_pk primary key (EMPLOYE_ID);
alter table Ouvrier
    add constraint Employe_fk foreign key (EMPLOYE_ID) references Employe (ID);
alter table Ouvrier
    add constraint Note_fk foreign key (NOTE_ID) references NOTE (ID);

Here I would like to have a class Ouvrier wich extends Employe like it's possible with Hibernate.

Is my SQL code wrong to do that or is my Hibernate Tools configuration wrong or perhaps Hibernate Tools reverse ing cannot do that ?

maitscha · **Joined:** Sat May 20, 2006 3:49 am **Posts:** 78

hi, I'm also using Hibernate Tools with Oracle 10g for a year now, but I never heared something that Hibernate Tools support generation of inheritance structures.

I think a relational database does not really have support for inheritance, you can only emulate it. There are several patterns how to map a object-oriented inheritance structure to a relational database. see the pdf Mapping Objects to Tables for a complete list of all patterns.

I think because of this inheritance is not supported with Hibernate Tools.

ahuut · **Joined:** Mon Jul 30, 2007 1:59 pm **Posts:** 6

In fact I have firstly tested Hibernate Synchronizer wich was able to generate my hierarchy.

That's why I belived that Hibernate Tools was able to do it also.

So, is there a way to implement this hierarchy with a reverse strategy for example, I searched in this way but I didn't found anything about this kind of class manipulation.

max · **Posted:** Tue Jul 31, 2007 9:51 am

hmm interesting that hibernate synchronizer detects this...what rules does it use ?