I'm looking how to implement 'table-per-subclass' with greater than 2 inheritance. E.g. (C# syntax)

classA{}
classB : ClassA{}
classC : ClassB{}

I've tried something like the following below: (Nested <joined-subclass>
But am having issues with inserts etc. (I'm using SQ 2000 and C#)
A sample app, (preferably C#) would be great!

<class name="MyClass.ClassA, MyNameSpace" table="ClassATable">
<id name="ClassAPrimId" column="ClassAPrimId">
<generator class="native" />
</id>
<property name="...."/>

<joined-subclass name="MyClass.MyClassB, MyNameSpace" table="ClassBTable">
<key column="FK_ClassB_PK_ClassA"/>
<property name="...."/>

<joined-subclass name="ZMyClass.MyClassC, MyNameSpace" table="ClassCTable">
<key column="FK_ClassC_PK_ClassB"/>
<property name="...."/>
</joined-subclass>
</joined-subclass>

</class>

Hi,

The idea of having a table with a discriminator column is the following: each row of the table represents a single class, i.e. one row is either a classB, or a classC; but not both (sure you can do a type cast in your code, but now we are talking only about o/r mapping).
So, I think, the answer to your question is the following: specify all the discriminator values for the bottom levels (classC's and classB's that are not inherited by any of the classC's) in the classA <discriminator> tag. Then, classB's that ARE inherited by classC's should NOT have discriminator-value; instead, hibernate should automagically determine this from the underlying classC's. I haven't tested if this works. But, I think it's worth trying. If I were a hibernate developer, I would've done it this way.

Greetings,
Mitko