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Re: [dotNetRDF-Support] SPARQL
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From: Rob V. <rv...@do...> - 2012-11-27 00:01:49
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Hi Jostinah
As I suggested in a previous email you really need to go learn SPARQL
yourself using a good book/tutorial as previously recommended.
We don't know your data nor the questions you want to ask nor do we have the
time or inclination to do this for you (especially since you already
admitted this is a student project).
I'm not sure if I understand what you mean by the value of the Node? Do you
have textual labels associated with your diseases? Perhaps with the
rdfs:label property? In this case you must have other triples defining
these so you would need to add additional pattern(s) to your query to access
the nodes of the graph with the textual label.
It sounds like you don't have the RDF model completely straight in your
head, if you don't understand that fully you will struggle to write SPARQL
queries against your data.
Rob
From: Jostinah Lam <89...@gm...>
Reply-To: dotNetRDF User Help and Support
<dot...@li...>
Date: Tuesday, November 20, 2012 1:59 PM
To: <dot...@li...>
Subject: [dotNetRDF-Support] SPARQL
> Hello dotnetrdf,
>
> I have already create an owl file and i'm planning to integrate the owl file
> into C#. i use the code below:
> //////////////////////////////////////////////////////////////////////////////
> //////////////////////////////////////////////////////////////////
> IGraph g = new Graph();
> g.LoadFromFile("exData\\PregnancyInducedHypertension.owl");
> try
> {
> Object results = g.ExecuteQuery("SELECT ?NamedDisease WHERE {
> ?s a ?NamedDisease}");
> if (results is SparqlResultSet)
> {
> //SELECT/ASK queries give a SparqlResultSet
> SparqlResultSet rset = (SparqlResultSet)results;
> foreach (SparqlResult r in rset)
> {
> textBox1.Text += r.ToString() + "\r\n";
> }
> }
> else if (results is IGraph)
> {
> //CONSTRUCT/DESCRIBE queries give a IGraph
> IGraph resGraph = (IGraph)results;
> foreach (Triple t in resGraph.Triples)
> {
> textBox1.Text += t.ToString() + "\r\n";
> }
> }
> //////////////////////////////////////////////////////////////////////////////
> ////////////////////////////////////////////
>
> When i query the owl file,i only get this result:
>
> ?NamedDisease = http://www.w3.org/2002/07/owl#Ontology
> ?NamedDisease = http://www.w3.org/2002/07/owl#ObjectProperty
> ?NamedDisease = http://www.w3.org/2002/07/owl#ObjectProperty
> ?NamedDisease = http://www.w3.org/2002/07/owl#ObjectProperty
> ?NamedDisease = http://www.w3.org/2002/07/owl#ObjectProperty
> ?NamedDisease = http://www.w3.org/2002/07/owl#ObjectProperty
> ?NamedDisease = http://www.w3.org/2002/07/owl#ObjectProperty
> ?NamedDisease = http://www.w3.org/2002/07/owl#ObjectProperty...........
> //////////////////////////////////////////////////////////////////////////////
> //////////////////
>
> What i want from the result is the value of the node.not address like that.how
> can i do that?
> When i change the a into rdf:type, it show error "The Namespace URI for the
> given Prefix 'rdf' is not known by the in-scope NamespaceMapper"
> I have already read the answer in Q&A,but i cannot understand what does it
> mean.
> Do i still have to use prefix as such PREFIX
> rdf:<http://www.w3.org/1999/02/22-rdf-syntax-ns#>
>
> Thanks.
> Jostinah
>
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