Question

也许,我只能掌握一些基本思想,而这里却提出了我的问题。我试图从卢旺达国防军的储存中提取三倍(使用4个仓库,但也尝试过XMLKnife)和SPARQL的盘问,明确了前线,取得了空洞的结果。

当然,我不像卢旺达国防军的辛塔克斯一号那样做任何事情,而是使用“和解”生成的数据(其范围被缩小到一个适合实例的规模)。

<?xml version="1.0" encoding="UTF-8" ?>
<rdf:RDF
  xml:base = "http://www.lehigh.edu/~zhp2/2004/0401/univ-bench.owl"
  xmlns:rdf = "http://www.w3.org/1999/02/22-rdf-syntax-ns#"
  xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#" 
  xmlns:owl="http://www.w3.org/2002/07/owl#"
  xmlns:ub="univ-bench.owl#"
>

<owl:DatatypeProperty rdf:ID="name">
  <rdfs:label>name</rdfs:label>
</owl:DatatypeProperty>

<owl:Class rdf:ID="Organization">
  <rdfs:label>organization</rdfs:label>
</owl:Class>

<owl:Class rdf:ID="University">
  <rdfs:label>university</rdfs:label>
  <rdfs:subClassOf rdf:resource="#Organization" />
</owl:Class>

<ub:University rdf:about="http://www.University0.edu">
   <ub:name>University0</ub:name>
</ub:University>

</rdf:RDF>

然后,我问,在进口后,我数据库实际包含的三倍:

SELECT * WHERE {?s ?p ?o} ORDERBY ?s

结果是:

<http://www.University0.edu>    <univ-bench.owl#name>   "University0"
<http://www.University0.edu>    <http://www.w3.org/1999/02/22-rdf-syntax-ns#type>       <univ-bench.owl#University>
<http://www.lehigh.edu/~zhp2/2004/0401/univ-bench.owl#Organization>         <http://www.w3.org/2000/01/rdf-schema#label>    "organization"
<http://www.lehigh.edu/~zhp2/2004/0401/univ-bench.owl#Organization>     <http://www.w3.org/1999/02/22-rdf-syntax-ns#type>       <http://www.w3.org/2002/07/owl#Class>
<http://www.lehigh.edu/~zhp2/2004/0401/univ-bench.owl#University>       <http://www.w3.org/2000/01/rdf-schema#subClassOf>       <http://www.lehigh.edu/~zhp2/2004/0401/univ-bench.owl#Organization>
<http://www.lehigh.edu/~zhp2/2004/0401/univ-bench.owl#University>       <http://www.w3.org/2000/01/rdf-schema#label>    "university"
<http://www.lehigh.edu/~zhp2/2004/0401/univ-bench.owl#University>       <http://www.w3.org/1999/02/22-rdf-syntax-ns#type>       <http://www.w3.org/2002/07/owl#Class>
<http://www.lehigh.edu/~zhp2/2004/0401/univ-bench.owl#name>     <http://www.w3.org/2000/01/rdf-schema#label>    "name"
<http://www.lehigh.edu/~zhp2/2004/0401/univ-bench.owl#name>     <http://www.w3.org/1999/02/22-rdf-syntax-ns#type>       <http://www.w3.org/2002/07/owl#DatatypeProperty>

显而易见的是,我有<代码><univ-bench.owl#name>作为头三者的一部分。

Nevertheless following query returns no results:

SELECT * WHERE {?s <univ-bench.owl#name> ?o}

I ve tried dozens of combinations, with namespaces and without, but can t make it work. Can anyone explain why RDF engine doesn t find a predicate that s obviously there?

BTW, extracting the same triple with OBJECT="University0" works OK.

Answer 1

This is invalid:

<代码>xmlns:ub=“univ-bench.owl#”

姓名: URIsmust在RDF/XML中是绝对的。 (在Turtle等其他合成类动物中,可以比较,但在RDF/XML中则不是这样。) 如果你的例子确实是用“互换”直接产生的,那么“互换”就会被打破。这一工作应当:

xmlns:ub=” http://www.lehigh.edu/~zhp2/2004/0401/univ-bench.owl#"

当然,你需要在SPARQL问询中,如@RobV。

Answer 2

I suspect your problem is that you are not trying to match the correct URI in your query:

SELECT * WHERE {?s <univ-bench.owl#name> ?o}

Anything enclosed in angle brackets is treated as a URI and since you ve used a relative URI the SPARQL processor is presumeably resolving it against some arbitrary base resulting in an absolute URI different from the one in your data thus your query won t match anything.

What you need to do is either specify the full URI like so:

SELECT * WHERE {?s <http://www.lehigh.edu/~zhp2/2004/0401/univ-bench.owl#name> ?o}

Or use a prefix like so:

PREFIX ub: <univ-bench.owl#>
SELECT * WHERE { ?s ub:name ?o }

If none of these are working then I suspect it is some issue with relative URIs. My advice would be never use relative URIs, always use absolute URIs wherever possible. If you must use relative URIs always specify a Base URI explicitly i.e. ensure your data used absolute URIs, reload it into your store and try again.

可在以下网站查阅:xml:base=”http://example.org> in RDF/XML或BASE <http://example.org/> in SPARQL。如果使用4个仓库,我认为其进口商的指挥线有可用来确定URI在未指明的情况下的违约基数的论点。

你可能要做的另一件事是试图把你的数据放在另一个三倍的仓库中,如果你这样做的话,你是否经历过同样的行为,就意味着像我所建议的那样,存在相对的绝对的“国际独立”问题。如果其他仓库回答询问的罚款,则建议与4个仓库进行可能的浏览,在这种情况下,你应当在其邮寄名单上与他们联系——。

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