dbpedia sparql movie query sql - sparql

Question

Hi I'm trying to learn how to query DBpedia using SPARQL. I can't find any website/source that shows me how do this and I'm finding it difficult to learn how to use all the properties (like the ones available at http://mappings.dbpedia.org/index.php?title=Special%3AAllPages&from=&to=&namespace=202 ). Any good source I can learn from?
So for example if I want to check if the wikipedia page http://en.wikipedia.org/wiki/Inception is a movie (property film) or not, how do I do that?

Answer 1

The wikipedia URL http://en.wikipedia.org/wiki/Inception maps to the dbpedia URI http://dbpedia.org/resource/Inception. Dbpedia has a SPARQL endpoint at: http://dbpedia.org/sparql, which you may use to run queries either programmatically or via the html interface.
To check if http://dbpedia.org/page/Inception is a "movie", you have many options. To give you an idea:
If you know the URI of "movie" in dbpedia (it is http://schema.org/Movie), then run an ASK query to check against that type. ASK will return true/false based on whether the pattern in the where clause is valid against the data:
ASK where {
<http://dbpedia.org/resource/Inception> a <http://schema.org/Movie>
}
If you don't know the URI of "movie" then you have a number of options. For example:
Execute an ASK query with a filter on whether the resource has a type that contains the word "movie" somewhere in its uri (or its associated rdfs:label, or both). You would use a regular expression for this:
ASK where {
<http://dbpedia.org/resource/Inception> a ?type .
FILTER regex(str(?type), "^.*movie", "i")
}
Same idea, but return all matches and post-process the results (programmatically I pressume) to see if they match your request:
select distinct ?type where {
<http://dbpedia.org/resource/Inception> a ?type .
FILTER regex(str(?type), "^.*movie", "i")
}
Return all the types of the resource without applying a filter and post-process to see if they match your request:
select distinct ?type where {
<http://dbpedia.org/resource/Inception> a ?type
}
Many options. The SPARQL spec is you number one resource.

Answer 2

First I suggest you start reading up on what exactly SPARQL is. There are tons of really good tutorials such as: this.
If you want to write SPARQL queries on dbpedia, there are various endpoints that you can use. They don't always accept all features that are supported by SPARQL, but if you don't want to go through the trouble of installing one locally, they can be a relatively reliable test environment. The queries that I am going to write below, have been tested on Virtuoso endpoint.
Let's say you want to find all the movies in dbpedia. You first need to know what is the URI for a movie type in dbpedia. If you open Inception in dbpedia, you can see that the type dbpedia-owl:Film is associated to it. So if you want to get the first 100 movies, you just need to call:
select distinct *
where {
?s ?o dbpedia-owl:Film
} LIMIT 100
If you want o know more about each of these movies, you just need to expand your queries by expanding the triples.
select distinct *
where {
?s ?p dbpedia-owl:Film.
?s ?x ?y.
} LIMIT 100