Sparql: getting all politicians who ruled a city -

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i'm new sparql , i'm trying understand how resources need building query. started trying politicians ruled city or country, , @ moment following:

i started following links in snorql (in prefixes) , looking entity adding "politician" @ end. found 1 : 

prefix : <http://dbpedia.org/resource/>

so wrote http://dbpedia.org/resource/politician , resource exist. tryed use in way:

prefix dbo: <http://dbpedia.org/ontology/> prefix dbpedia: <http://dbpedia.org/resource/> select ?thing {     ?thing :politician .    ?thing dbo:birthplace dbpedia:italy. } limit 50

run in virtuoso.

even if remove second line of select, have no results. if change first line with: ?thing dbo:person. or if remove it, people born in italy. not politicians. second problem don't need politicians born ruled place. how or can find kind of "relations/descriptors"? googling , copy-pasting existing examples, understand how more specific things.

thanks in advance

your first query isn't working because politician not part of default (:) namespace, instead present in dbpedia ontology namespace (dbo).

so, query should be:

prefix dbo: <http://dbpedia.org/ontology/> prefix dbpedia: <http://dbpedia.org/resource/> select ?thing {     ?thing dbo:politician .    ?thing dbo:birthplace dbpedia:italy. } limit 50

to list politician ruled italy need know predicate "ruled". once have can construct query.

to list predicates present in database can write this

select distinct(?b) {  ?a ?b ?c. }

and list predicates.

i recommend browse through 1 or 2 politician , see predicates have check if 1 works you.


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