Can't get this SPARQL query to work

dbpedia, rdf, semantic-web, sparql

Solution

Okay, I was missing that "Depeche Mode" couldn't be selected using an rdf:type of http://dbpedia.org/ontology/MusicalArtist. This seems to work:

SELECT ?subject 
       ?artistName 
WHERE {
  { 
    ?subject rdf:type <http://dbpedia.org/ontology/MusicalArtist> .
    ?subject rdfs:label ?artistName .
    FILTER ( str(?artistName) = "Depeche Mode" )
  } 
  UNION 
  {
    ?subject rdf:type <http://dbpedia.org/ontology/Band> .
    ?subject rdfs:label ?artistName .
    FILTER ( str(?artistName) = "Depeche Mode" )
  }
}

Problem

Okay, I'm just learning to use SPARQL to query data from dbpedia.org and I'm using dbpedia's http://dbpedia.org/snorql/ to run my queries in. I am trying to get a list of MusicalArtists based on searching for the same string over three fields like so: ``` SELECT ?subject ?artistRdfsLabel ?artistFoafName ?artistDbpedia2Name WHERE { ?subject rdf:type <http://dbpedia.org/ontology/MusicalArtist> . OPTIONAL { ?subject rdfs:label ?artistRdfsLabel . } OPTIONAL { ?subject foaf:name ?artistFoafName . } OPTIONAL { ?subject dbpedia2:name ?artistDbpedia2Name . } FILTER ( str(?artistRdfsLabel) = "Stevie Nicks" || str(?artistFoafName) = "Stevie Nicks" || str(?artistDbpedia2Name) = "Stevie Nicks" ) } LIMIT 10 ``` This works because "Stevie Nicks" has all three fields (rdfs:label, foaf:name, dbpedia2:name). But when I try to query by another MusicalArtist that doesn't have all three ("Depeche Mode" for example) I get no results. I have tried various things like BIND(COALESCE(?field,...,...) AS ?artistName) to filter by ?artistName and I also tried UNION but nothing seems to work. Can someone point out the error of my SPARQL ways? :) Thanks! Jason

Original source