hello, thak you for your help,
but i am not confused in inheritance,
User "is a" Collaborator, so i can not simply set it.
so, how i will set it in this situation?
I do not find the way to persist a user entity that belongs to an existing collaborator, I can add a user object and it results to 2 new created rows in the data base but what i want to do is to add only a user object and not a new collaborator.
I can find a collaborator by Collaborator clbr=em.findById(2);
and i want to add a user that its collaborator is clbr but how to associate the new user object to this collaborator object ?
Below my entities
Must I change my strategy to table per class?