Sparql

SPARQL allows for a query to consist of [|triple patterns], [|conjunctions] , [|disjunctions] , and optional [|patterns]. Implementations for multiple [|programming languages] exist. [|[4]] "SPARQL will make a huge difference" according to Sir [|Tim Berners-Lee] in a May 2006 interview. There exist tools that allow one to connect and semi-automatically construct a SPARQL query for a SPARQL endpoint, for example ViziQuer.
 * SPARQL** (pronounced " [|sparkle] " [|[1]] ) is an [|RDF query language] ; its name is a [|recursive acronym] that stands for //**S**PARQL **P**rotocol **a**nd **R**DF **Q**uery **L**anguage//. It was standardized by the//RDF Data Access Working Group// (DAWG) of the [|World Wide Web Consortium], and is considered a key [|semantic web] technology. On 15 January 2008, SPARQL became an official W3C Recommendation.

Benefits
SPARQL allows users to write globally unambiguous queries. For example, the following query returns names and emails of every person in the world: .assuming the [|ontologies] in use to describe a [|person] are mapped to [|FOAF] via rules from whatever ontology the original relations were in. This illustrates the [|Semantic Web] 's vision of treating the Web as a single enormous database. Notice that this global unambiguity roots in the fact that every identifier in SPARQL, [|URI], is globally unambiguous, unlike "email" or "e-mail" normally used in [|SQL]. This query can be distributed to multiple SPARQL endpoints, computed distributedly, and results gathered, a procedure known as [|federated query].

Query Forms
The SPARQL language specifies four different query variations for different purposes. SELECT queryUsed to extract raw values from a SPARQL endpoint, the results are returned in a table format.CONSTRUCT queryUsed to extract information from the SPARQL endpoint and transform the results into valid RDF.ASK queryUsed to provide a simple True/False result for a query on a SPARQL endpoint.DESCRIBE queryUsed to extract an RDF graph from the SPARQL endpoint, the contents of which is left to the endpoint to decide based on what the maintainer deems as useful information. Each of these query forms takes a WHERE block to restrict the query although in the case of the DESCRIBE query the WHERE is optional.

Example
Another SPARQL query example that models the question "What are all the country capitals in Africa?": Variables are indicated by a "?" or "$" prefix. Bindings for ?capital and the ?country will be returned. The SPARQL query processor will search for sets of triples that match these four triple patterns, binding the variables in the query to the corresponding parts of each triple. Important to note here is the "property orientation" (class matches can be conducted solely through class-attributes / properties - see [|Duck typing] ) To make queries concise, SPARQL allows the definition of prefixes and base [|URIs] in a fashion similar to [|Turtle]. In this query, the prefix "abc" stands for “http://example.com/exampleOntology#”.

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