我正在尝试在Protege 4.3(在Pizza.owl上)运行以下SPARQL查询,但是我得到一个空结果:
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX owl: <http://www.w3.org/2002/07/owl#>
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX : <http://www.co-ode.org/ontologies/pizza/pizza.owl#>
SELECT ?pizzaInstance ?pizzaClass ?toppingInstance
WHERE {
?pizzaClass rdfs:subClassOf :NamedPizza .
?pizzaInstance rdf:type ?pizzaClass .
?pizzaInstance :hasTopping ?toppingInstance .
}
这只发生在我运行涉及属性的查询时。使用相同的前缀,以下查询可以正常工作 - 并返回NamedPizza:
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX owl: <http://www.w3.org/2002/07/owl#>
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX : <http://www.co-ode.org/ontologies/pizza/pizza.owl#>
SELECT ?pizzaInstance
WHERE {
?pizzaInstance rdfs:subClassOf :Pizza .
}
第一个查询有什么问题?
我终于明白我做错了什么。此查询返回pizzaInstance的个人,并且我的本体中的所有个体都没有顶部。当我查询hasCalorificContentValue
而不是hasTopping
时,我得到了预期的结果:
PREFIX pz: <http://www.semanticweb.org/ontologies/2017/11/Ontology1512823737278.owl#>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX owl: <http://www.w3.org/2002/07/owl#>
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
SELECT ?pizzaClass ?pizzaInstance ?calorificInstance
WHERE {
?pizzaClass rdfs:subClassOf pz:NamedPizza .
?pizzaInstance rdf:type ?pizzaClass.
?pizzaInstance pz:hasCalorificContentValue ?calorificInstance.
}
检查原始owl文件时,查询变得有意义(示例-MargheritaPizza属于MargheritaPizza类型,并且涉及数据类型属性hasCalorificValue):
<owl:NamedIndividual rdf:about="&Ontology1512823737278;Example-MargheritaPizza">
<rdf:type rdf:resource="&Ontology1512823737278;MargheritaPizza"/>
<hasCalorificContentValue rdf:datatype="&xsd;int">263</hasCalorificContentValue>
</owl:NamedIndividual>
Here是一个很好的教程,希望这有助于某人。