Question

I’m new to SPARQL and I’m trying to select two or more data properties from entity.
I have Artist entity which has two data properties (id and name). I’m trying to obtain a result like this:

 id         Name
 0         Artist 1
 1         Artist 2

But what I’m getting is this:

 id         Name
 0         Artist 1
 0         Artist 2
 1         Artist 1
 1         Artist 2

Here is my SPARQL query:

PREFIX wits:   <http://wits.org/song/> 
SELECT ?name, ?id 
FROM <http://wits.org/song> 
WHERE
{ 
    <http://wits.org/song/Artist>  wits:Name ?name .
    <http://wits.org/song/Artist>  wits:ID ?id 
}

Here is RDF implementation of Artist Class:

<!ENTITY www "http://www.wits.org/" >
<owl:Class rdf:about="&www;Artist">
        <rdfs:subClassOf rdf:resource="&owl;Thing"/>
        <rdfs:subClassOf>
            <owl:Restriction>
                <owl:onProperty rdf:resource="&www;song#ID"/>
                <owl:allValuesFrom rdf:resource="&xsd;unsignedInt"/>
            </owl:Restriction>
        </rdfs:subClassOf>
        <rdfs:subClassOf>
            <owl:Restriction>
                <owl:onProperty rdf:resource="&www;song#Name"/>
                <owl:qualifiedCardinality rdf:datatype="&xsd;nonNegativeInteger">1</owl:qualifiedCardinality>
                <owl:onDataRange rdf:resource="&xsd;string"/>
            </owl:Restriction>
        </rdfs:subClassOf>
    </owl:Class>

This is INSERT command which was executed previously:

PREFIX wits: <http://wits.org/song/>
        INSERT DATA INTO <http://wits.org/song> {
        wits:Artist wits:Name "Artist 2"
        wits:ID 1 .
        }

What am I doing wrong?

Any help is appreciated.
125125

Answer 1

I guess you are inserting the following data.

    INSERT DATA INTO <http://wits.org/song> {
        wits:Artist wits:Name "Artist 0"; wits:ID 0 .
        wits:Artist wits:Name "Artist 1"; wits:ID 1 .
    }

which is wrong because wits:Artist would have both names and both ids, you need to give different URIs to each Artist and provide the class as rdf:type.

The right way according to your ontology would be …

    INSERT DATA INTO <http://wits.org/song> {
        wits:Artist0 a wits:Artist; wits:Name "Artist 0"; wits:ID 0 .
        wits:Artist1 a wits:Artist; wits:Name "Artist 1"; wits:ID 1 .
    }

a is equivalent to rdf:type. In here we’re saying that wits:Artist0 is type of class wits:Artist with name Artist 0 and id 0.