I mapped some classes of an hierachy with strategy "TABLE PER CONCRETE CLASS", which also means my superclass Element doens't have its own table. Subclasses of Element are ElementA and ElementB, those have their own tables.

And then in an another entity, i mapped a ONE-TO-MANY Collection like this :


The problem is, i failed to either delete or adding elements into the List. When i tried to delete by using session.saveorUpdate(), it says


And when i tried to add a new Element to the list :



Which is understandable, because there is no such table.

For clarity, my superclass is mapped like this.



Getting elements from the database work completly okay though.
What did i do wrong here ? Thanks for any help.

TABLE_PER_CLASSis not very efficient from a SQL statement perspective.

In your example, I guess it's because the Element class is abstract that you get some of your issues, so you should make the changes like this:

1. Change TABLE_PER_CLASS to JOINED
2. Make the Element non-abstract
3. Remove fetch = FetchType.EAGER from the @OneToMany collection since it's going to cause performance problems
4. Use a ManyToOne association in Element instead of a unidirectional @oneToMany as explained in this article and turn the association into a bidirectional one
5. Once the association is bidirectional, make sure you synchronize both ends of the association as explained in this article

Follow all these steps, and you should be fine.