Hello,

I'm new to Hibernate and working my way through the documentation.

In chapter seven its says a unidirectional 1..m relationship on a foreign key is not recommended and that a join table is the preferred way to go.

Why is that preferred? Poking the 'one's FK into the 'many' table seemed simple and straightforward, but unfortunately the authors don't explain their reasoning for preferring the join table. Are the authors recommending join tables for most relationships?

Thanks,
Greg

I think its because you can not navigate form the 'many-side' (Adress) to the 'one-side' (Person) of the association, but looking at the database structure you have a reference (forign key) from the 'one-side' to the many side. This is quite the other way round as the intended association...

Join tables for one-to-many associations are good for optional associations, e.g. if you have EMP and DEPT tables, you would need a nullable DEBT_ID column in the EMP table if there can be employees who are not assigned to a particular department. A separate EMP_DEPT table would avoid this nullable column (use Google to find out why SQL NULLs are evil), because you simply wouldn't have a record for this EMP in the join table, if it doesn't have a department.