What is SPARQL prefix?
“PREFIX”, however (without the “@”), is the SPARQL instruction for a declaration of a namespace prefix. It allows you to write prefixed names in queries instead of having to use full URIs everywhere. So it’s a syntax convenience mechanism for shorter, easier to read (and write) queries.
How do you write SPARQL?
Structure of a SPARQL Query
- Prefix declarations, for abbreviating URIs.
- Dataset definition, stating what RDF graph(s) are being queried.
- A result clause, identifying what information to return from the query.
- The query pattern, specifying what to query for in the underlying dataset.
What is a SPARQL service?
SPARQL can be used to express queries across diverse data sources, whether the data is stored natively as RDF or viewed as RDF via middleware. This specification defines the syntax and semantics of SPARQL 1.1 Federated Query extension for executing queries distributed over different SPARQL endpoints.
WHAT IS A in Sparql query?
It’s a SPARQL 1.1 property path which describes a route through a graph between two graph nodes, in your case it denotes the inverse path, i.e. from object to subject, thus, it’s equivalent to. dbpedia:Stephen_King a? subtype . with a being just a shortcut for rdf:type.
Is SPARQL similar to SQL?
SPARQL and SQL have very similar UNION and MINUS operators, which respectively add and remove solutions from a solution set. Because the datatypes of an SQL table are assumed to be uniform across all rows, care must be taken to align the datatypes of the SELECT.
What is DBpedia SPARQL?
DBpedia is a community project that creates and provides public access to critical structured data for what’s commonly referred to as the Linked Open Data Cloud.
What is a SPARQL endpoint?
A SPARQL Endpoint is a Point of Presence on an HTTP network that’s capable of receiving and processing SPARQL Protocol requests. It is identified by a URL commonly referred to as a SPARQL Endpoint URL. What is the SPARQL Protocol?
What is the SPARQL query language?
The SPARQL Query Language is a Declarative Query Language (like SQL) for performing Data Manipulation and Data Definition operations on Data represented as a collection of RDF Language sentences/statements. Every SPARQL Query has a Solution Modifier (or head) and a Query Body.
Is there a SPARQL Client class for PHP?
EasyRdf provides a SPARQL Client class for PHP. OCaml-RDF is an OCaml implementation of RDF graphs and Sparql. Ontorion™ SPARQL Tools for Excel developed by Cognitum can be used to download knowledge from a SPARQL endpoint or from an Ontorion endpoint. It works with MS Excel 2010 and MS Excel 2013.
What is a SPARQL query solution modifier?
Every SPARQL Query has a Solution Modifier (or head) and a Query Body. The Solution Modifier provides the basis for categorizing different types of SPARQL Query solutions. The Query Body comprises a collection of of RDF statement patterns (represented using Turtle Notation) that represent the entity relationships to which a query is scoped.