title: Use a numeric value as string value in SPARQL
body: <p>Is possible to use somehow a numeric value as a string value in a SPARQL query?  For instance, consider the following RDF data, query, and desired result:</p>
  
  <h3>Knowledge base</h3>
  
  <pre><code>@prefix gr:  &lt;http://purl.org/goodrelations/v1#&gt;.
  @prefix xsd: &lt;http://www.w3.org/2001/XMLSchema#&gt;.
  
  :o a gr:QuantitativeValueFloat;
       gr:hasMinValueFloat "1,0"^^xsd:float
       gr:hasMaxValueFloat "10,0"^^xsd:float
  </code></pre>
  
  <h3>Query</h3>
  
  <pre class="lang-sql prettyprint-override"><code>PREFIX gr: &lt;http://purl.org/goodrelations/v1#&gt;    
  SELECT ?o ?v
  WHERE {
    ?o a gr:QuantitativeValueFloat;
         gr:hasMinValueFloat ?vMin;
         gr:hasMaxValueFloat ?vMax.
    CONCAT((?vMin, ?vMax) as ?v)
  }
  </code></pre>
  
  <h3>Ideal Result</h3>
  
  <pre><code>-----------------
  | o  | v        | 
  =================
  | :o | 1,0-10,0 | 
  -----------------
  </code></pre>