JBoss 4.0.5 - EJB3 - Entity Beans ** The problem is - the foreign key column is not set on the newInstance Row. thus the inserted value is NULL. There is an new instance of a class that is being worked on as follows: aggregate = // retrieve / find in database - ie: already persisted | newInstance = new NewInstance(); | newinstance.setValue(aggregate) | em.persist(newInstance) newInstance is saved, as a new row, in the RDBMS just fine; however, the aggregate_fk (see below for table) is set to null - actually I think it is not even in the insert statement. NewInstance.get/setValue are defined below: @OneToOne(cascade=CascadeType.ALL) | @JoinColumn(name="aggregate_fk", insertable=false, updatable=false, referencedColumnName="pk") | public Aggregate getValue() { return aggregate; } NewInstance Table (Pseudo Notation for sql) integer pk | char(10) column1 | integer aggregate_fk -- foreign key reference to aggregate table Aggregate is actually a lookup table as below integer pk | char(15) key | varchar(64) value *Note: this table is referenced by many other tables in the system; therefore, it cannot contain annotations of OneToMany (etc..) to a specific other table. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4025431#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...