How can I display a specific class for an individual with SPARQL?

Question

I used Protege to create a small ontology.

I start with a class A, a class B, and a class C. Class C contains the subclasses x, y and z. The individuals populating this ontology fall under two classes: the first class is either A or B, the second one is one of the subclasses of C.

I want to retrieve all individuals which have a property H, and which are also either part of class x or y, but not z. I have been able to do that with the following query:

SELECT ?individual
    WHERE {?individual ont:hasH ?individual.
        FILTER(NOT EXISTS { ?individual rdf:type ont:z } )}

(ont is the prefix for my ontology)

This query does what I want. But for these individuals, I would also like to know whether they are part of class x or y. I've tried changing my query to the following, to no avail:

SELECT ?individual ?class
    WHERE {?individual ont:hasH ?individual.
        FILTER(NOT EXISTS { ?individual rdf:type ont:z } ) ?class rdf:type ont:C}

Since x and y belong to class C, what I need to know what the class C of the selected individuals is. How could I do that?

(Please bear in mind that I'm completely new to SPARQL.)

Answer 1

You say a couple of things that make the issue a bit confusing:

I start with a class A, a class B, and a class C. Class C contains the subclasses x, y and z.

…

Since x and y belong to class C,

We don't usually say that a class contains subclasses; we just say that a class has subclasses, or that one class is a subclass of another. When A is a subclass of B, then whenever some i is an A (ie, we have the triple [i rdf:type A]), then i is also a B (ie, we have the triple [i rdf:type B]).

At any rate, you can do the following to find out, for each individual that has an ont:hasH property and is not an instance of ont:z, whether it's an ont:x or an ont:y:

SELECT ?individual ?class WHERE {
  #-- The first part, which you already provided, ensures that 
  #-- ?individual has a value for ont:hasH, and does not have 
  #-- type ont:z .
  ?individual ont:hasH ?individual.
  FILTER( NOT EXISTS { ?individual rdf:type ont:z } )

  #-- Since each of these individuals also has type ont:x or
  #-- ont:y, you can bind a variable to ont:x and ont:y and 
  #-- match against it, too.  For each result, ?xy will be 
  #-- bound to either ont:X or ont:y, depending on what type 
  #-- ?individual has.
  values ?xy { ont:x ont:y }
  ?individual rdf:type ?xy
}