0 to 1 relation

magic · **Posted:** Tue Feb 15, 2005 4:56 pm

Hi,

how map a unidirectionnal '0 to 1' relation between 2 classes ?
I have one class A which can have (or not) an instance of B. So i have, 2 tables: A et B, and B have a foreign key from A. But i don't understand how map this model in hibernate (one-to-one, many-to-one with unique contraint ?)

Regards,

magic · **Posted:** Tue Feb 15, 2005 5:07 pm

Indeed my problem is a bit more complex. I can't store the B data in A (with null columns), because i have a C entity which have a 0 to n relation with B (that's why i have a table for B).

So C has a bag of Bs, but i don't see how link A and B now :-/

mgreer · **Posted:** Wed Feb 16, 2005 2:34 am

magic wrote:

Indeed my problem is a bit more complex. I can't store the B data in A (with null columns), because i have a C entity which have a 0 to n relation with B (that's why i have a table for B).

So C has a bag of Bs, but i don't see how link A and B now :-/

I would suggest not putting a foreign key in B at all, if both A and C can link to B. Use mapping tables.