Updating a database using EJB Inheritance

Question

I am new to EJB's, so please forgive my ignorance. I creating the following classes that inherit from each other along with a method to update my database:
@Entity
@Inheritance(strategy = InheritanceType.JOINED)
@DiscriminatorColumn(name="TYPE", discriminatorType=DiscriminatorType.STRING)
public abstract class ObjectA implements java.io.Serializable {
     protected String name;
     protected String desc;
     protected String type;
@Entity
@DiscriminatorValue("OBJECTB")
public class ObjectB extends ObjectA implements java.io.Serializable {
     protected String str_b;
     public ObjectB(String name, String desc, String type, String str_b) {
          this.name = name;
          this.desc = desc;
          this.type = type;
          this.str_b = str_b;
@Entity
@DiscriminatorValue("OBJECTC")
public class ObjectC extends ObjectB implements java.io.Serializable {
     private String str_c;
     public ObjectC(String name, String desc, String type, String str_b, String str_c) {
          this.name = name;
          this.desc = desc;
          this.type = type;
          this.str_b = str_b;
          this.str_c = str_c;
public class MyFacade implements ServletContextListener {
     @PersistenceUnit(unitName="Pu")
    private EntityManagerFactory emf;
    @Resource
    private UserTransaction utx;
    public MyFacade() { }
    public void contextDestroyed(ServletContextEvent sce) {
        if (emf.isOpen()) emf.close();
    public void contextInitialized(ServletContextEvent sce) {
        ServletContext context = sce.getServletContext();
        context.setAttribute("MyFacade", this);
     public void updateObject(ObjectA obj) {
        EntityManager em = emf.createEntityManager();
        try{
            utx.begin();
            em.merge(obj);
            utx.commit();
        } catch(Exception exe){
            try {
                utx.rollback();
            } catch (Exception e) {}
            throw new RuntimeException("Error updating obj", exe);
        } finally {
            em.close();
}If I do the following:
     String name = "test name";
     String desc = "updating object c";
     String type = "OBJECTC";
     String b = "b";
     String c = "c";
     MyFacade myf = new MyFacade();
     ObjectC objC = new ObjectC(name, desc, type, b, c);
     myf.updateObject(objC);
     .....In my database, only the values associated with ObjectC get updated and nothing from ObjectA or ObjectB get updated in the database. Does the "merge" method not work on inheritance. How do I update my database using inheritance?
Thanks!
Message was edited by:
FourierXForm

Answer 1

did you only have ISQL for testing it?
Can you debug the form and look, if someone happens - exceptions, ... ?
after the update you can use
message (SQL%ROWCOUNT); pause ;
to look, how many records were updated