Nhibernate map multiple tables to a same list - mysql

Question

I have multiple objects meaning various steps (each object is a step) from a flux, they are to be persisted in the DB.
I was thinking on creating a relational table, where I would have each association, only one relation per row. something like, per example:
Steps: Id, Course_Id, Evaluation_Id, ProcessEvaluation_Id
and to clarify:
StepsForClass: id, class_id, steps_id
Course:id, someMoreinfo
Evaluation: id, someOtherinfo
and so on...
to be referenced in the table:
Class: Id, StepsForClass_id, someInfo
How could I map this into something like:
public class Klass
{
public uint Id { get; set; }
public IList<Step> Steps { get; set; }
}
public abstract class Step
{
public uint Id { get; set; }
public abstract void Apply();
}
public class Course : Step
{
//( some more fields )
public override void Apply() { /* ... */ }
}
public class Evaluation : Step
{
//( some other more fields )
public override void Apply() { /* ... */ }
}

Answer 1

You can use inheritence mapping like this:
<class name="Step" table="STEP">
<id name="Id" type="Int64" column="STEP_ID">
<generator class="native"/>
</id>
<property name="Amount" column="AMOUNT"/>
...
<joined-subclass name="Course" table="COURSE">
<key column="STEP_ID"/>
...
</joined-subclass>
<joined-subclass name="Evaluation" table="EVALUATION">
<key column="STEP_ID"/>
...
</joined-subclass>
</class>
For further reading: inheritance mapping