Virtuoso Open-Source Edition

  • Topic
  • Discussion

    • How can I include aggregate function values as objects in SPARQL CONSTRUCT queries?

    For a CONSTRUCT query, the aggregate function must be called as part of a subquery in the CONSTRUCT's WHERE clause.

    For example, starting with this SPARQL SELECT query -- 

    SELECT              DISTINCT ?category 
         COUNT(?category) AS ?count
WHERE
  {
    ?s  <http://purl.org/dc/terms/subject>  ?category
    FILTER ( 
             ?s  =<http://dbpedia.org/resource/Higgs_boson>
             || 
             ?s  =<http://dbpedia.org/resource/Gluon>
           )
  }

    The CONSTRUCT query would be -- 

    CONSTRUCT 
  {
    ?category  a                                                     <http://www.w3.org/2004/02/skos/core#Concept> .
    ?category  <http://www.turnguard.com/virtuoso/aggregates#count>  ?count
  }
WHERE 
  {
    { 
      SELECT             DISTINCT ?category 
              COUNT(?category) AS ?count
      WHERE
        {
          ?s   <http://purl.org/dc/terms/subject> ?category
          FILTER (
                   ?s  =<http://dbpedia.org/resource/Higgs_boson> 
                   || 
                   ?s  =<http://dbpedia.org/resource/Gluon>
                 )
        } 
    } 
  }

    View the results of the query execution on the LOD instance.

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