Hi everyone:

Is there any benefit if I use the <subclass> ? What situation should I use it? I take a test use it. I found that if I query parent object like , all the object including son object would be query! why it do this in this way? Could someone tell me what time should I use subclass function ? THks!

be sure to understand implicit and explicit polymorphic query...

I see this article http://www.hibernate.org/hib_docs/reference/en/html/queryhql.html.
But I don't know what benefit using subclass. The element decide whether I will use polymorphism. It means that if I set the polymorphism to false, hibernate will query parent object only without children. If I set the plymorphism to true,hibernate will query all the object (parent and children).

But the problem is that I don't know what situation that I need query all parent and children object. Could you give me an example ? Thks!