HELP!! Problem when updating foreign key reference to null.

[Ashraf Moosa]

Hi 

I am a new user to ojb and I have a problem when updating foreign key
reference to null.
I am using ojb version 0.9.8, in a session bean deployed to jboss 3.0.5.
I have marked all my session bean methods as transaction required.
 
I have three tables:
Artist:
ArtistId,              Integer,            PK, AUTO_INCREMENT
            ArtsistName:     VARCHAR        
Gallery
            GalleryId           Integer,             PK, AUTO_INCREMENT
            GalleryName:    VARCHAR
 
Painting:
            PaintingId          Integer,             PK, AUTO_INCREMENT
            PaintingTitle:     VARCHAR
ArtistId              Integer              FK 
            GalleryId           Integer              FK 
            
 
 
I can successfully create a new painting object and persist it to my
database with the foreign keys initially set to null.
I can also successfully update my painting object with different foreign
key values for artist and gallery. However 
When I try to update my painting object to reflect the gallery or artist
foreign key as null as in the following example code:
 
try
{
Painting painting = findPaintingByTitle("SomeTitle");  //This method
successfully returns me a painting object represented by the title
Transaction tx = odmg.currentTransaction();
tx.lock(painting,Transaction.UPGRADE);
painting.setGallery(null);
}
catch(....)
 
my changes are not reflected in the database and I do not get any ojb
errors or warnings.
 
Any suggestions!!
 
Ashraf Moosa