About Question enthuware.oce-jpad.v6.2.432 :

[himaiMinh]

For the second option "a map of employee-project does not make sense at all."
I think the major reason why it does not make sense because Project is an entity.
When an entity is a value of a map, we should use @ManyToMany instead of @ElementCollection.
This point can be added to the explanation if it is correct.

[himaiMinh]

The forth option has this "@JoinTable annotation is used when there is no additional column in the join table. Here, we have startdate, enddate and hoursperweek as well in the same join table. I think this should be the explanation for the third option.

The forth option is wrong because @ElementCollection should be used with @CollectionTable, not @JoinTable.

[admin]

Updated.
thank you for your feedback!
Paul.