Question: Which countries adopted the Euro?
SPARQL query:
PREFIX prop: <http://dbpedia.org/property/>
PREFIX onto: <http://dbpedia.org/ontology/>
PREFIX res: <http://dbpedia.org/resource/>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
SELECT DISTINCT ?uri
WHERE {
          ?uri rdf:type onto:Country .
        { ?uri onto:currency res:Euro . } 
        UNION 
        { ?uri prop:currencyCode 'EUR'@en . }
}