title: Filtering SPARQL results by day and month
body: <p>I'm currently using the <a href="http://dbpedia.org/snorql" rel="nofollow">http://dbpedia.org/snorql</a> website to launch some basic request like the one below:</p>
  
  <pre><code>PREFIX dbpedia0: &lt;http://dbpedia.org/ontology/&gt;
  SELECT ?body ?value WHERE {
  ?body a dbpedia0:Person.
  ?body dbpedia0:birthDate ?value.
  }
  ORDER BY ?value
  </code></pre>
  
  <p>I would like to find a way of filtering the results so that only people born on day <code>X</code> month <code>Y</code> are being selected (no matter the birth year). I have been trying to do so with many approaches like:</p>
  
  <p>1) Basic filtering: <code>FILTER(xsd:date(?value) = "2000-01-01"^^xsd:date)</code>
  But I don't now how to precise the fact that I don't care about the year...</p>
  
  <p>2) Use the <code>MONTH()</code> and <code>DAY()</code> functions that should lead to integer values representing month and day... But these don't seem to work as my date type is said to be an invalid input argument.</p>
  
  <p>3) Convert the date into a string variable. And then test if the ending characters of this string variable (corresponding to month and day) match the required month and day. That would be something like : <code>FILTER(STRENDS(CONVERT(CHAR, ?value),"01-01") = true)</code></p>
  
  <p>Apparently, none of the methods listed above is properly working... haha.
  Please don't blame me for the poor syntax of my request as I'm just beginning with SPARQL commands.</p>
  
  <p>I would be very grateful for any help from on or another over there !!!</p>