@prefix dc: <http://purl.org/dc/elements/1.1/> .
@prefix dcterms: <http://purl.org/dc/terms/> .
@prefix ex: <https://sparql.uniprot.org/.well-known/sparql-examples/> .
@prefix idr: <https://idr.openmicroscopy.org/> .
@prefix kv: <http://www.openmicroscopy.org/ns/default/> .
@prefix obda: <https://w3id.org/obda/vocabulary#> .
@prefix omecore: <https://ld.openmicroscopy.org/core/> .
@prefix omekg: <https://ld.openmicroscopy.org/omekg#> .
@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 schema: <https://schema.org/> .
@prefix sh: <http://www.w3.org/ns/shacl#> .
@prefix xml: <http://www.w3.org/XML/1998/namespace/> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .

ex:003 a sh:SPARQLExecutable, sh:SPARQLSelectExecutable ;
    rdfs:comment "Count the number of unique image map annotation keys"^^rdf:HTML ;
    sh:prefixes _:sparql_example_prefixes ;
    schema:keywords "image, mapAnnotation, key, unique, count" ;
    schema:target <http://idr-sparql.uni-muenster.de/qlever/sparql> ;
    sh:select """
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 dcterms: <http://purl.org/dc/terms/>
PREFIX dc: <http://purl.org/dc/elements/1.1/>
PREFIX omecore: <https://ld.openmicroscopy.org/core/>
PREFIX omekg: <https://ld.openmicroscopy.org/omekg#>
PREFIX obda: <https://w3id.org/obda/vocabulary#>
PREFIX xml: <http://www.w3.org/XML/1998/namespace/>
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
PREFIX kv: <http://www.openmicroscopy.org/ns/default/>
PREFIX idr: <https://idr.openmicroscopy.org/>
PREFIX up: <http://purl.uniprot.org/core/>
PREFIX skos: <http://www.w3.org/2004/02/skos/core#>

select (count(distinct ?key) as ?nkey) where {
  ?img a omecore:Image;
       omecore:hasAnnotation/omecore:mapEntry/omecore:key ?key .
  }
""" .