I am new to Hibernate and learning Hibernate using the hibernate documentation (http://docs.jboss.org/hibernate/orm/3.3/reference/en-US/html/associations.html#assoc-unidirectional-12m) and going through the one-to-many and many-to-one associations without using Join tables. The document says that:

Many-to-One

A unidirectional many-to-one association is the most common kind of unidirectional association.

One-to-Many

A unidirectional one-to-many association on a foreign key is an unusual case, and is not recommended.

Why the document recommends not use one-to-many associations? Please help me in understanding this?

Also the document says that the association for many-to-one with join table is used when the association is optional. What does it mean when it says the association is optional?

Many-to-one

A unidirectional many-to-one association on a join table is common when the association is optional.

Please help me in understanding the concepts.

Thanks for your post, I could use assistance here as well. What is the comment that association is optional refer to? I'm lost there. thank you.

Hi, are you asking me the same question back to me which I don't know or you want to give an answer for my post?

"optional" in this context means that the entity might be associated with null.

You have to declare if that is a valid relation or not, as the mapping to the database schema depends on it.