无法从本体检索实例

此查询不返回任何内容。

PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> 
PREFIX owl: <http://test.com/my-ontology.owl#> 

SELECT DISTINCT ?class ?birthyear ?gender
WHERE {
  ?class a owl:UserProfile.
  OPTIONAL { ?class owl:birthyear ?birthyear}
  OPTIONAL { ?class owl:gender ?gender}
}
LIMIT 25

但是,如果我放弃 ?class a owl:UserProfile. ,此查询返回正确的结果:

class             birthyear    gender
owl:userProf_ES   1984         male

我也尝试过此查询,但它也返回空结果:

SELECT DISTINCT ?class ?type ?birthyear ?gender
WHERE {
  ?class rdf:type ?type.
  ?type rdfs:subClassOf owl:User.
  OPTIONAL { ?class owl:birthyear ?birthyear}
  OPTIONAL { ?class owl:gender ?gender}
}
LIMIT 25

为什么会这样?

UserProfile 是 User . 我还有以下属性 用户配置文件 在保护中:

PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> 
PREFIX owl: <http://www.test.com/my-ontology.owl#> 
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
PREFIX oo:  <http://www.w3.org/2002/07/owl#> 

INSERT { 
  owl:userProf_ES owl:name 'Roger' . 
  owl:userProf_ES owl:nationalityCode 'ES' . 
  owl:userProf_ES owl:languageCode 'es_ES' . 
  owl:userProf_ES owl:gender 'male' . 
  owl:userProf_ES owl:birthyear 1984 . 
  owl:userProf_ES owl:purchasingPower 'medium' . 
  owl:userProf_ES owl:buyingBehaviour 'bargain' . 
  owl:userProf_ES owl:travelingBehaviour 'traveler' . 
  owl:userProf_ES owl:lblSporty true . 
  owl:userProf_ES owl:lblFamily true . 
  owl:userProf_ES owl:lblWorker false . 
  owl:userProf_ES owl:lblHealthy true . 
  owl:userProf_ES owl:lblGamer false . 
  owl:userProf_ES owl:hasNationality owl:ES . 
  owl:userProf_ES owl:hasSpokenLanguage owl:es_ES . 
  owl:userProf_ES owl:hasTravelingBehaviour owl:traveler . 
  owl:userProf_ES owl:hasBuyingBehaviour owl:bargain . 
  owl:userProf_ES owl:hasPurchasingPower owl:medium . 
} 
WHERE {
  FILTER NOT EXISTS { 
    owl:userProf_ES rdf:type owl:UserProfile . 
  } 
}