version 3

Is it oky to use HQL?
If yes which situation should we use it ?

or we should always try and fetch objects using traversing ?

which of the 2 ways is efficient ?
whats the advantage of using either of them ?

it depends is the most accurate answer you be able to get with suche generic question. I would recommend you to buy Hibernate In Action (see the top of the screen). It give you a good view and usage of Hibernate