There two types of user in my domain model: OrdinaryUser and AdminUser. I use the "TABLE Per Hierarchy" stategy to mapping these two types of user as subclasses of User with a discriminator column called "user_type".

And now I want to promote an ordinary user to an admin user without changing his id (which is generated by the sequence generator.), and name.

How can I do that in Hibernate?

I have searched this topic in Google for a long time and can't find an answer.

Thanks very much.

Whether an object's discriminator value can be changed after it has been saved into database?[/code]

How are you planning to do the "promotion" in java?
if you have 2 seperate classes for the user types -
you're going to have to :

//write a constructor that does the data copying and instantiation
//for the AdvancedUser class
AdvancedUser au = new AvancedUser(simpleUser);
Hibernate.delete(simpleUser);

//exit session here !!! very important!!!

au.setId(simpleUser.getId())
Hibernate.save(au);
//preferably force flush() here too...

Thank you for your reply.

I have try it and it does not work. The exception is as follows:

2007-07-31 22:57:17,546 ERROR [org.hibernate.jdbc.AbstractBatcher] - Exception executing batch:
org.hibernate.StaleStateException: Batch update returned unexpected row count from update [0]; actual row count: 0; expected: 1

intuition - you didn't exit the session before trying to create the AdvancedUser.

please post full stack trace.

(and don't forget to rate...:-)

since I use the sequence ID generator and when I save an object with explicitly setting id, it would throw exception:

org.hibernate.StaleStateException: Batch update returned unexpected row count from update [0]; actual row count: 0; expected: 1