Question: Which countries in the European Union adopted the Euro?
SPARQL query:
PREFIX prop: <http://dbpedia.org/property/>
PREFIX res: <http://dbpedia.org/resource/>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX yago: <http://dbpedia.org/class/yago/>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
SELECT DISTINCT ?uri ?string
WHERE 
{
	?uri rdf:type yago:EuropeanUnionMemberStates .
        { ?uri prop:currency res:Euro . } 
        UNION 
        { ?uri prop:currencyCode ?code . FILTER regex(?code,'EUR') }
        OPTIONAL { ?uri rdfs:label ?string. FILTER (lang(?string) = 'en') }
}