Hi,
I have one requirement in my project which is that I need to set value of Cascade to "none" when I save the object to the database and I need to set the value of this attribute to "All" when I load the object from the database for the same class. If I do this then I am able to avoid the duplications in the database. So could anybody tell me how to achieve this functionality for Cascade?

You know, I think you might be approaching the problem from the wrong angle.

Why are you getting 'duplicates.' You shouldn't be. The real problem is why is that happening. I think you're trying to work around hibernate, rather than really taking advantage of it, which will cause more problems later down the road.

Hi Cameron,
I will tell you the details about mjy code.

I have two classes:
public class A{
private int id;
private B b;

//and getters and setters for all attributes.

}

public class B{
int id;
//Other attributes and all getter setters
}

Now there are two tables for Class suppose AT and for class B BT.
Table BT contains the static data suppose 8 rows which do not change. Now in table AT for attribute a I want the reference i.e. foreign key from Table BT. Hibernate will do this association using mapping file.

Now consider the following senario:

I create the instance of Class A and saveOrUpdate it using session.saveOrUpdate() method. If the cascades value is "all" then when saving this new instance it will create new id's for Class A as well as B and associate the classes A and B using new ids. So even if the values of columns other than id don't change in Class B the hibernate is going to save this as new instance in the table BT. So this creates the duplications of rows in the database. To avoid this I want the value of cascade ="none" when I will save the instance and it should be "all" when I load the instance of class A so that all associations will be taken care by hibernate.

I think you have understood my problem. If you think I am wrong somewhere with hibernate's persistence logic please clarify me.

Also what reference would you suggest to me for studying persistence logic used by hibernate?

This JavaRanch thread seems to provide a bit more insight on the topic:

http://saloon.javaranch.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic&f=78&t=004209

As far as learning Hibernate, I'd always recommend my own book, Hibernate Made Easy, but I'm biased. :)

Hibernate Made Easy will get you started and up and running very quickly, and you will learn how Hibernate works, and why various things happen when you're working with Hibernate and JPA. But Hibernate Made Easy isn't the reference. You also need Java Persistence with Hibernate by Gaving King by your side at all times. :)

Thanks very much.