SPARQL Examples – List Classes

Example SPARQL queries that can help you list the classes in an ontology.

List all classes

PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> SELECT DISTINCT ?type WHERE { ?s a ?type. }

Note: The SPARQL keyword a is a shortcut for the common predicate rdf:type, giving the class of a resource.

List root classes

SELECT ?directSub ?super WHERE { ?directSub rdfs:subClassOf ?super . FILTER NOT EXISTS { ?directSub rdfs:subClassOf ?otherSub . FILTER (?otherSub != ?directSub) } }

List all classes with a given prefix

PREFIX bc: <http://base22.com/ont/bc#> SELECT DISTINCT ?type WHERE { ?subject a ?type. FILTER( STRSTARTS(STR(?type),str(bc:)) ) }

List class hierarchy

PREFIX owl: <http://www.w3.org/2002/07/owl#> PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> SELECT DISTINCT ?subject ?label ?supertype WHERE { { ?subject a owl:Class . } UNION { ?individual a ?subject . } . OPTIONAL { ?subject rdfs:subClassOf ?supertype } . OPTIONAL { ?subject rdfs:label ?label } } ORDER BY ?subject

Note that when a reasoner is enabled classes may typically be inferred to be rdfs:subClassOf themselves and rdfs:subClassOf any parent class, not just the direct parent.

List class hierarchy – filtered

Give a class hierarchy, but filter out several structural elements so that we only end up with the unique classes in our ontology.

PREFIX owl: <http://www.w3.org/2002/07/owl#> PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> SELECT DISTINCT ?subject ?label ?supertype WHERE { { ?subject a owl:Class . } UNION { ?individual a ?subject . } . OPTIONAL { ?subject rdfs:subClassOf ?supertype } . OPTIONAL { ?subject rdfs:label ?label }. FILTER (?subject != owl:Class && ?subject != rdf:List && ?subject != rdf:Property && ?subject != rdfs:Class && ?subject != rdfs:Datatype && ?subject != rdfs:ContainerMembershipProperty && ?subject != owl:DatatypeProperty && ?subject != owl:NamedIndividual && ?subject != owl:Ontology ) } ORDER BY ?subject

Note that when a reasoner is enabled classes may typically be inferred to be rdfs:subClassOf themselves and rdfs:subClassOf any parent class, not just the direct parent.

List class hierarchy with direct subclasses only

This is similar to the query above, but uses the Sesame-specific sesame:directSubClassOf to get only direct subclasses. This would work in any RDF4J (formerly Sesame) system such as Graph DB.

PREFIX owl: <http://www.w3.org/2002/07/owl#> PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> PREFIX : <https://codyburleson.com/hyperg/> SELECT DISTINCT ?subject ?label ?supertype WHERE { { ?subject a owl:Class . OPTIONAL { ?subject sesame:directSubClassOf ?supertype } . OPTIONAL { ?subject rdfs:label ?label }. } FILTER (?subject != owl:Class && ?subject != rdf:List && ?subject != rdf:Property && ?subject != rdfs:Class && ?subject != rdfs:Datatype && ?subject != rdfs:ContainerMembershipProperty && ?subject != owl:DatatypeProperty && ?subject != owl:NamedIndividual && ?subject != owl:Ontology && ?subject != ?supertype) } ORDER BY ?subject