如何使用sparql从RDF Triple中提取主题(Name)与谓词的比较

Question

http://www.example.com/teach.rdfs/John   http://www.example.com/teach.rdfs#position "Full Professor"        
http://www.example.com/teach.rdfs/John   http://www.example.com/teach.rdfs#course"Math"
http://www.example.com/teach.rdfs/John   http://www.example.com/teach.rdfs#student"Undergraduate"
http://www.example.com/teach.rdfs/Arthur http://www.example.com/teach.rdfs#position "Assistant Professor"
http://www.example.com/teach.rdfs/Arthur http://www.example.com/teach.rdfs#course"Web Engineering"
http://www.example.com/teach.rdfs/Arthur http://www.example.com/teach.rdfs#student"Graduate"

如果这些是三元组，我想找到教研究生的助理教授

 Lecturer       Position
 Arthur         Assistant Professor 

如何使用SPARQL提取上述日期

Answer 1

据我所知，您的数据没有任何合法的RDF序列化，但是将其转换为N3序列化相当容易。在同一文档中同时使用http://.../teach.rdfs#和http://.../teach.rdfs/作为前缀是相当不寻常的。看到其中一个很常见，但不是两个都有。但这并不违法，所以我们可以利用它。在N3格式，这是你的数据作为一个文件，data.n3:

@prefix teach1: <http://www.example.com/teach.rdfs/> .
@prefix teach2: <http://www.example.com/teach.rdfs#> .
teach1:John teach2:position "Full Professor" .
teach1:John teach2:course "Math" .
teach1:John teach2:student "Undergraduate" .
teach1:Arthur teach2:position "Assistant Professor" .
teach1:Arthur teach2:course "Web Engineering" .
teach1:Arthur teach2:student "Graduate" .

查询也很简单。下面是一个名为query.sparql的文件:

PREFIX teach1: <http://www.example.com/teach.rdfs/>
PREFIX teach2: <http://www.example.com/teach.rdfs#>
SELECT ?lecturer ?position WHERE {
  VALUES ?position { "Assistant Professor" }
  ?lecturer teach2:position ?position ;
            teach2:student "Graduate" .
}

这个查询唯一有点不寻常的是使用了VALUES ?position { "Assistant Professor" }。我使用VALUES表单的原因是您想要的结果在输出中包含了"Assistant Professor"。如果我们排除VALUES ...部分，我们可以将模式重写为

  ?lecturer teach2:position "Assistant Professor" ;
            teach2:student "Graduate" .

仍然找到相同的?lecturer s，但是没有绑定到"Assistant Professor"的变量。有了数据和查询，我们可以使用Jena的ARQ命令行工具对数据运行查询:

$ arq --query query.sparql --data data.n3 
-----------------------------------------
| lecturer      | position              |
=========================================
| teach1:Arthur | "Assistant Professor" |
-----------------------------------------