SPARQL

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SPARQL is a standard query language for data on the web (which, in turn, is expressed in RDF). It was standardized by the W3C in 2007. You can ask an endpoint for any answers that match a specific pattern that you provide. For example, asking

SELECT ?event WHERE {
  ?e <http://www.semanticweb.org/id/Property-3AHas_location_city> <http://www.semanticweb.org/id/Beijing> .
  ?e rdfs:label ?event
 }

will return the label of all events that are located in Beijing (or, more exactly, all labels of entities that are subject in a triple with the property http://www.semanticweb.org/id/Property-3AHas_location_city and the object http://www.semanticweb.org/id/Beijing .)

As of 2011, a new version of the SPARQL standard, called SPARQL 1.1, is underway. This version specifically adds update capabilities and is already supported by many implementations.

SPARQL in Semantic MediaWiki

Since version 1.6.0, Semantic MediaWiki can directly its data to RDF databases that then offer SPARQL web services for querying the wiki. This is described in Help:Using SPARQL and RDF stores.

Further resources