給定它的wikiPageID查詢Dbpedia資源不適用於某些ID

Question

我試圖從給出他的wikiPageID的dbpedia查詢某個特定人的數據。我試過這個SPARQL查詢來查詢邁克爾傑克遜：

PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> 
PREFIX dbo: <http://dbpedia.org/ontology/> 
PREFIX dbp: <http://dbpedia.org/property/> 
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> 

SELECT ?name (SAMPLE (?photoLink) as ?photo) (SAMPLE (?occupation) as occup) 
(SAMPLE (?spouse) as ?spouses) (SAMPLE (?spName) as ?sname) 
(SAMPLE (?spOccupation) as ?spOccu) (SAMPLE (?deathPlace) as ?death) 
(SAMPLE(?birthPlace) as ?birth) (SAMPLE(?deathDate) as ?dDate) 
(SAMPLE(?birthDate) as ?bDate) { 

VALUES ?wikiPageID { 14995351 } 
?res a dbo:Person. 
?res dbp:name ?name. 
?res dbo:wikiPageID ?wikiPageID. 
?res dbp:birthPlace ?birthPlace. 
?res dbp:birthDate ?birthDate. OPTIONAL{?res dbo:occupation ?occupation}. 
OPTIONAL{?res dbo:thumbnail ?photoLink}. 
OPTIONAL{?res dbo:spouse ?spouse. ?spouse dbp:name ?spName. 
?spouse dbo:occupation ?spOccupation}. 
OPTIONAL{?res dbp:deathDate ?deathDate. ?res dbp:deathPlace ?deathPlace}. 
} 

GROUP BY (?name) 

查詢返回空結果。但是，當我改變其他人的wikiPageID（如託比馬奎爾 - 163228）它的作品。造成差異的原因是什麼？

Answer 1

如果您查看DBpedia http://dbpedia.org/page/Michael_Jackson上的邁克爾傑克遜頁面，您可以很容易地發現它沒有dbp:name屬性或dbp:birthPlace，甚至沒有dbp:birthDate。若要解決該問題，請將OPTIONAL也添加到這些屬性中：

OPTIONAL{?res dbp:name ?name}. 
OPTIONAL{?res dbp:birthPlace ?birthPlace}. 
OPTIONAL{dbp:birthDate ?birthDate}.