SPARQL

Question

我正在尝试在 PROTEGE 2000 中执行此 SPARQL 查询，但 MAX 函数不起作用。就像 Max() 不接受 ?cpt.

的类型

SELECT  ?searcher (COUNT(?publication) AS ?cpt)
WHERE {ont:GradeP ont:isFor ?searcher.
    ?publication ont:isPublishedBy ?searcher.}
GROUP BY ?searcher 
HAVING (MAX(?cpt))

这里是个例外：

SparqlReasonerException: org.openrdf.query.QueryEvaluationException: Unsupported value expr type: class org.openrdf.query.algebra.Max

The request is working without HAVING, so i guess there is no problem with my ontology. So can please anyone tell me where is the issue. Thanks!

Answer 1

我不确定你为什么在这里使用 group by，但也许你有理由。一种方法是使用 order by。我在 dbpedia 上提供了一个示例。

select distinct ?x count(?y) as ?count
where{
    ?x a dbpedia-owl:Person.
    ?x dbpprop:author  ?y
}
order by desc(?count)
limit 1

结果是here。

SPARQL - Max() 不工作

SPARQL - Max() isn't working

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