query: PREFIX wikibase: <http://wikiba.se/ontology#>
  PREFIX wd: <http://www.wikidata.org/entity/> 
  PREFIX wdt: <http://www.wikidata.org/prop/direct/>
  PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
  
  SELECT (GROUP_CONCAT(?number; separator=", ") as ?numbers) ?player ?playerLabel ?birthday (GROUP_CONCAT(?nationalityLabel; separator=", ") as ?nationalities)
  WHERE 
  {
    wd:Q21011427 wdt:P527 ?player .
    OPTIONAL { ?player wdt:P569 ?birthday }.
    OPTIONAL { ?player wdt:P1618 ?number }
    OPTIONAL { 	?player wdt:P27 ?nationality .
    				?nationality rdfs:label ?nationalityLabel FILTER(lang(?nationalityLabel)="en")
      		}
    SERVICE wikibase:label {
      bd:serviceParam wikibase:language "en" .
    }
  }
  GROUP BY ?player ?playerLabel ?birthday