Results filtered out even though the data is there

问题

Here's my query:

PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> 
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> 
PREFIX foaf: <http://xmlns.com/foaf/0.1/> 
PREFIX : <http://dbpedia.org/resource/> 
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>

SELECT DISTINCT ?resource ?parentOrSpouse
WHERE { 
?resource a dbo:Royalty ; 
rdfs:label ?label ; 
dbo:parent ?parent ; 
dbo:birthDate ?bd ; 
dbo:birthPlace ?bp . 
?bp dbo:isPartOf :England . 
FILTER(?bd < '1900-01-01'^^xsd:dateTime) . 
FILTER(?bd > '1800-01-01'^^xsd:dateTime) . 
FILTER(LANGMATCHES(LANG(?label), 'en')) . 
{ ?resource dbo:parent ?parentOrSpouse } UNION { ?resource dbo:spouse ?parentOrSpouse }
?parentOrSpouse dbo:birthPlace ?psbp .
?psbp dbo:isPartOf :England . 
}
ORDER BY(?bd)

This searches for all royals born in England between 1800 and 1900 that have a spouse or parent that is born in England.

Result

In the result list I get
http://dbpedia.org/page/George_V with http://dbpedia.org/page/Mary_of_Teck listed as a spouse, but not Mary_of_Teck listed while George is clearly born in England.

Why is Mary disappearing? There are a lot of other people disappearing that should clearly be on the list when I look at the data.

回答1:

So the solution to Mary not showing up is to use dbo:parent|dbo:spouse/dbo:wikiPageRedirects?, since George is refered by Mary via a redirect.

The other problem was dbo:birthPlace/dbo:location?/dbo:isPartOf dbr:England throwing an error that is probably(?) related to a bug in the compiler. Using ?parentOrSpouse dbo:birthPlace|dbo:birthPlace/dbo:location/dbo:isPartOf :England . instead seems to work fine.

Credit goes to @AKSW.

来源：https://stackoverflow.com/questions/53327523/results-filtered-out-even-though-the-data-is-there

标签

sparql

dbpedia