# Task 6 - Find distinct people with optional names, mailboxes and order
BASE <http://www.w3.org/2004/Talks/17Dec-sparql/data/>
PREFIX rdf:  <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX foaf: <http://xmlns.com/foaf/0.1/>

SELECT DISTINCT ?name ?mbox

FROM NAMED <aliceFoaf.ttl>
FROM NAMED <bobFoaf.ttl>
FROM NAMED <celineFoaf.ttl>
FROM NAMED <danFoaf.ttl>
FROM NAMED <eveFoaf.ttl>

WHERE {
  GRAPH ?g { ?person rdf:type foaf:Person .
             OPTIONAL { ?person foaf:name ?name } .
             OPTIONAL { ?person foaf:mbox ?mbox }
           } .
}
ORDER BY ASC[?name]