Enthuware

The 4th option works ok with Hibernate.

Why do You think that "@JoinTable annotation is used when there is no additional column in the join table." ?

As per Section 2.7.2, when the value type of the map is a basic type or an embeddable class, a collection table is used to map the map.

Here, ProjectAllocation is not an entity but an embedded class, that is why CollectionTable is more appropriate.

admin wrote:As per Section 2.7.2, when the value type of the map is a basic type or an embeddable class, a collection table is used to map the map.

Here, ProjectAllocation is not an entity but an embedded class, that is why CollectionTable is more appropriate.

My question is not about @CollectionTable, but rather about Your statement:
"@JoinTable annotation is used when there is no additional column in the join table."

Why do You think so?

Because if there are additional columns, you use the @CollectionTable. It follows from the same statement. If there are no additional columns, you can use @JoinColumns just like you do for any other one to many or many to many relationship.

Hello! Since the joinColumn element of @CollectionTable is not specified, shouldn't the join column name in EMP_PROJECTS table be defaulted to EMPLOYEE_<Name of id attribute> ?

Yes, you are right. Should be fixed.
thank you for your feedback.