Hello everybody i'm using a SPARQL query to retrieve properties and values of a specified resource. For example if i ask for Barry White, i obtain: birth place, associatedBand, recordLabels and so on.
Instead for any instance such as "Hammerfall", i obtain only this results:
Query results
But i want properties and values as shown in this page: Correct results.
My query is:
PREFIX db: <http://dbpedia.org/resource/>
PREFIX prop: <http://dbpedia.org/property/>
PREFIX onto: <http://dbpedia.org/ontology/>
SELECT ?property ?value
WHERE { db:Hammerfall?property ?value }
Anyone can tell me how to access to the correct resource and obtain corrects properties and values in every case?
select ?p ?o { dbpedia:HammerFall ?p ?o }
SPARQL results
The particular prefix doesn't matter; I just used dbpedia: because it's predefined on the endpoint as http://dbpedia.org/resource/, just like your db:. The issue is that HammerFall has a majuscule F in the middle, but your query uses a miniscule f.
As an alternative, since the results for Hammerfall (with a miniscule f) do include
http://dbpedia.org/ontology/wikiPageRedirects http://dbpedia.org/resource/HammerFall
you could use a property path to follow any wikiPageRedirects paths:
select ?p ?v {
dbpedia:Hammerfall dbpedia-owl:wikiPageRedirects* ?hammerfall .
?hammerfall ?p ?v
}
SPARQL results
See Retrieving dbpedia-owl:type value of resource with dbpedia-owl:wikiPageRedirect value? for more about that approach.
Related
I am trying to extract the manufacturer section of this dbpedia page http://dbpedia.org/page/Diageo. However my SPARQL query returns nothing. Yet I can return most other values on the page, such as keyPersons which has the exact same layout.
PREFIX dbpedia-owl: <http://dbpedia.org/ontology/>
SELECT ?label
WHERE { <http://dbpedia.org/resource/Diageo>
dbpedia-owl:keyPerson ?label }
PREFIX dbpedia-owl: <http://dbpedia.org/ontology/>
SELECT ?label
WHERE { <http://dbpedia.org/resource/Diageo>
dbpedia-owl:manufacturer ?label }
Any ideas?
In DBpedia, an entity page displays statements in which an entity may be not only a subject, but also an object. In the latter case, respective property appears as "is ... of".
Conversely, the page you have linked to says that dbr:Diageo is dbo:manufacturer of dbr:Johnnie_Walker etc. This means that dbr:Johnnie_Walker dbo:manufacturer dbr:Diageo holds, not that dbr:Diageo dbo:manufacturer dbr:Johnnie_Walker does.
By the way, rdfs:range of dbo:manufacturer is dbo:Organization.
Thus, you should looking for triples that match reversed pattern:
SELECT * WHERE { ?variable dbo:manufacturer ?dbr:Diageo . }
Or, using property paths:
SELECT * WHERE { dbr:Diageo ^dbo:manufacturer ?variable . }
Try it on DBpedia
I am trying to retrieve the publication date and the no.of pages for books in DBpedia. I tried the following query and it gives empty results. I see that these are properties under book(http://mappings.dbpedia.org/server/ontology/classes/Book) but could not retrieve it.
I would like to know if there is an error in the code or if dbpedia does not store these dates related to books.
SELECT ?book ?genre ?date ?numberOfPages
WHERE {
?book rdf:type dbpedia-owl:Book .
?book dbp:genre ?genre .
?book dbp:firstPublicationDate ?date .
OPTIONAL {?book dbp:numberOfPages ?numberOfPages .}
}
The dbp:firstPublicationDate does not work for two reasons:
First, as pointed in the first answer, you used the wrong prefix.
But even if you correct it, you'll see that you would still have no results. Then the best thing to do is to test with the minimum number of patters, in you case you should as for books with first publication date, two triple pattern only. If you still don't get results, you should test how <http://dbpedia.org/ontology/firstPublicationDate> is actually used with a query like this:
SELECT ?class (COUNT (DISTINCT ?s) AS ?instances)
WHERE {
?s <http://dbpedia.org/ontology/firstPublicationDate> ?date ;
a ?class
}
GROUP BY ?class
ORDER BY DESC(?instances)
LIMIT 1000
Mapping based properties are using the namespace http://dbpedia.org/ontology/, thus, the prefix must be dbo instead of dbp, which stands for http://dbpedia.org/property/.
PREFIX dbo: <http://dbpedia.org/ontology/>
PREFIX dbp: <http://dbpedia.org/property/>
SELECT ?book ?genre ?date ?numberOfPages
WHERE {
?book a dbo:Book ;
dbp:genre ?genre ;
dbo:firstPublicationDate ?date .
OPTIONAL {?book dbp:numberOfPages ?numberOfPages .}
}
Some additional comments:
put the prefixes to the SPARQL query such that others here can run it without any exceptions (also in the future) - the current SPARQL query uses dbpedia-owl but this one is not pre-defined on the official DBpedia anymore - it's called dbo instead
which brings me to the second point -> if you're using a public SPARQL endpoint, show its URL
you can start debugging your own SPARQL query by simply starting with only parts of it and adding more triple patterns then, e.g. in your case you could check if there is any triple with the property with
PREFIX dbp: <http://dbpedia.org/property/>
SELECT * WHERE {?book dbp:firstPublicationDate ?date } LIMIT 10
Update
As Ivo Velitchkov noticed in his answer below, the property dbo:firstPublicationDate is only used for mangas, etc., i.e. written work that was published periodically. Thus, the result will be empty.
I am trying this query:
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
SELECT ?label
WHERE
{
?AGE rdfs:label ?label.
}
I need all the values of AGE from my model but instead this query is giving me other resources values which have the same property label .
For example I have connected the resource gender to have a property rdfs:label. So in my result I get both age values and gender values.
Can anybody tell me where am I wrong ?
It seems you may be assigning some semantics to the variable '?AGE'. SPARQL is a graph pattern matching language and anything with a '?' as the first character is a variable - or better yet, an unknown in the graph pattern match. I.e., the following is an equivalent query to yours:
SPARQL ?label
WHERE
{ ?s rdfs:label ?label .
}
This will find all triples that have a rdfs:label property and select the value of ?label.
If you have a specific resource you want to query, then specify that resource in the subject, for example:
PREFIX ex: <http://example.org/ex>
SPARQL ?label
WHERE
{ ex:AGE rdfs:label ?label .
}
So understanding the difference between an unknown (denoted by '?' (or '$')) and a known (a qname or a full URI) is important to understand how SPARQL performs graph pattern matching.
Lots of SPARQL learning material on the Web, so a suggestion is to look into some of these to learn some basics.
Why does this SPARQL query return no data?
PREFIX dbpedia-owl: <http://dbpedia.org/ontology/>
PREFIX dbpedia: <http://dbpedia.org/resource/>
SELECT *
WHERE {
<http://dbpedia.org/resource/Louis,_Prince_of_Condé_(1530–1569)> dbpedia-owl:abstract ?abstract
}
LIMIT 1
If you look at the DBpedia page, it shows the person has an abstract. Is it to do with the brackets in the URL? If so, how can I get round this?
This URI does not lead to the same result as the DBpedia page - for what ever reason. You can see this with
PREFIX dbpedia-owl: <http://dbpedia.org/ontology/>
PREFIX dbpedia: <http://dbpedia.org/resource/>
SELECT *
WHERE {
<http://dbpedia.org/resource/Louis,_Prince_of_Condé_(1530–1569)> ?p ?o
}
LIMIT 100
But it has an owl:sameAs relation to
http://dbpedia.org/resource/Louis,_Prince_of_Cond%C3%A9_(1530%E2%80%931569)
That means if you use this URI in your query, it should work as expected. But you should indeed apply a FILTER on the language, e.g. 'en' for English abstracts.
As AKSW mentions, the resource actually doesn't have many properties, but is connected to the "canonical" version by an owl:sameAs link. You can keep using the IRI that you're using now, follow owl:sameAs in either direction to any of its equal resources (let's call them ?s), and then ask for the abstract of ?s. (And then it's not a bad idea to filter by language, if that's applicable.) You can do this with a query like this (note that the current DBpedia endpoint uses dbo:, now, not the older dbpedia-owl:):
select ?abstract where {
<http://dbpedia.org/resource/Louis,_Prince_of_Condé_(1530–1569)> (owl:sameAs|^owl:sameAs)* ?s .
?s dbo:abstract ?abstract .
filter langMatches(lang(?abstract),'en')
}
It does not have dbpedia-owl:abstract predicate. If you list its predicates you find the following properties:
http://www.w3.org/2002/07/owl#sameAs
http://xmlns.com/foaf/0.1/name
http://purl.org/dc/elements/1.1/description
http://dbpedia.org/ontology/alias
http://dbpedia.org/ontology/birthYear
http://dbpedia.org/ontology/deathYear
http://dbpedia.org/ontology/viafId
http://dbpedia.org/ontology/deathPlace
http://dbpedia.org/ontology/deathDate
http://dbpedia.org/ontology/birthPlace
http://dbpedia.org/ontology/birthDate
I am trying to retrieve the value of the dbpedia-owl:influenced in this page e.g: Andy_Warhol
The query I write is:
PREFIX rsc : http://dbpedia.org/resource
PREFIX dbpedia-owl :http://dbpedia.org/ontology
SELECT ?o WHERE {
rsc:Andy_Warhol dbpedia-owl:infuenced ?o .
}
but it is EMPTY.
Strange is that when I have the same query for another property from the ontology type like "birthPlace", the sparql engine gives the result back:
SELECT ?o WHERE {
rsc:Andy_Warhol dbpedia-owl:birthplace ?o .
}
which is a link to another resource:
dbpedia.org/resource/Pittsburgh
I am just confused how to write this query?
besides several formal errors addressed in the answer of #Joshua, there is also the semantic problem that the properties you are looking for - in this case - seem to be found on the entities that were influenced.
this query might give you the desired results
PREFIX rsc: <http://dbpedia.org/resource/>
PREFIX dbpedia-owl: <http://dbpedia.org/ontology/>
SELECT ?s WHERE {
?s dbpedia-owl:influencedBy rsc:Andy_Warhol .
}
run query
There are a few issues here. One is that the SPARQL, as presented, isn't correct. I edited to make the prefix syntax legal, but the prefixes were still wrong (they didn't end with a final slash). You don't want to be querying for http://dbpedia.org/resourceAndy_Warhol after all; you want to query for http://dbpedia.org/resource/Andy_Warhol. Some standard namespaces for DBpedia are listed on their SPARQL endpoint. Using those namespaces and the SPARQL endpoint, we can ask for all the triples that have http://dbpedia.org/resource/Andy_Warhol as the subject with this query:
SELECT * WHERE {
dbpedia:Andy_Warhol ?p ?o .
}
In the results produced there, you'll see the one using http://dbpedia.org/ontology/birthPlace (note the captial P in birthPlace), but you won't see any triples with the predicate http://dbpedia.org/ontology/infuenced, so it makes sense that your first query has no results. Do you have some reason to suppose that there should be some results?