| <!DOCTYPE html> |
| <html lang="en"> |
| <head> |
| |
| |
| <title>Apache Jena - SPARQL Tutorial - Datasets</title> |
| <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> |
| <meta name="viewport" content="width=device-width, initial-scale=1.0"> |
| |
| <link href="/css/bootstrap.min.css" rel="stylesheet" media="screen"> |
| <link href="/css/bootstrap-extension.css" rel="stylesheet" type="text/css"> |
| <link href="/css/jena.css" rel="stylesheet" type="text/css"> |
| <link rel="shortcut icon" href="/images/favicon.ico" /> |
| |
| <script src="https://code.jquery.com/jquery-2.2.4.min.js" |
| integrity="sha256-BbhdlvQf/xTY9gja0Dq3HiwQF8LaCRTXxZKRutelT44=" |
| crossorigin="anonymous"></script> |
| <script src="/js/jena-navigation.js" type="text/javascript"></script> |
| <script src="/js/bootstrap.min.js" type="text/javascript"></script> |
| |
| <script src="/js/improve.js" type="text/javascript"></script> |
| |
| |
| </head> |
| |
| <body> |
| |
| <nav class="navbar navbar-default" role="navigation"> |
| <div class="container"> |
| <div class="navbar-header"> |
| <button type="button" class="navbar-toggle" data-toggle="collapse" data-target=".navbar-ex1-collapse"> |
| <span class="icon-bar"></span> |
| <span class="icon-bar"></span> |
| <span class="icon-bar"></span> |
| </button> |
| <a class="navbar-brand" href="/index.html"> |
| <img class="logo-menu" src="/images/jena-logo/jena-logo-notext-small.png" alt="jena logo">Apache Jena</a> |
| </div> |
| |
| <div class="collapse navbar-collapse navbar-ex1-collapse"> |
| <ul class="nav navbar-nav"> |
| <li id="homepage"><a href="/index.html"><span class="glyphicon glyphicon-home"></span> Home</a></li> |
| <li id="download"><a href="/download/index.cgi"><span class="glyphicon glyphicon-download-alt"></span> Download</a></li> |
| <li class="dropdown"> |
| <a href="#" class="dropdown-toggle" data-toggle="dropdown"><span class="glyphicon glyphicon-book"></span> Learn <b class="caret"></b></a> |
| <ul class="dropdown-menu"> |
| <li class="dropdown-header">Tutorials</li> |
| <li><a href="/tutorials/index.html">Overview</a></li> |
| <li><a href="/documentation/fuseki2/index.html">Fuseki Triplestore</a></li> |
| <li><a href="/documentation/notes/index.html">How-To's</a></li> |
| <li><a href="/documentation/query/manipulating_sparql_using_arq.html">Manipulating SPARQL using ARQ</a></li> |
| <li><a href="/tutorials/rdf_api.html">RDF core API tutorial</a></li> |
| <li><a href="/tutorials/sparql.html">SPARQL tutorial</a></li> |
| <li><a href="/tutorials/using_jena_with_eclipse.html">Using Jena with Eclipse</a></li> |
| <li class="divider"></li> |
| <li class="dropdown-header">References</li> |
| <li><a href="/documentation/index.html">Overview</a></li> |
| <li><a href="/documentation/query/index.html">ARQ (SPARQL)</a></li> |
| <li><a href="/documentation/assembler/index.html">Assembler</a></li> |
| <li><a href="/documentation/tools/index.html">Command-line tools</a></li> |
| <li><a href="/documentation/rdfs/">Data with RDFS Inferencing</a></li> |
| <li><a href="/documentation/geosparql/index.html">GeoSPARQL</a></li> |
| <li><a href="/documentation/inference/index.html">Inference API</a></li> |
| <li><a href="/documentation/javadoc.html">Javadoc</a></li> |
| <li><a href="/documentation/ontology/">Ontology API</a></li> |
| <li><a href="/documentation/permissions/index.html">Permissions</a></li> |
| <li><a href="/documentation/extras/querybuilder/index.html">Query Builder</a></li> |
| <li><a href="/documentation/rdf/index.html">RDF API</a></li> |
| <li><a href="/documentation/rdfconnection/">RDF Connection - SPARQL API</a></li> |
| <li><a href="/documentation/io/">RDF I/O</a></li> |
| <li><a href="/documentation/rdfstar/index.html">RDF-star</a></li> |
| <li><a href="/documentation/shacl/index.html">SHACL</a></li> |
| <li><a href="/documentation/shex/index.html">ShEx</a></li> |
| <li><a href="/documentation/jdbc/index.html">SPARQL over JDBC</a></li> |
| <li><a href="/documentation/tdb/index.html">TDB</a></li> |
| <li><a href="/documentation/tdb2/index.html">TDB2</a></li> |
| <li><a href="/documentation/query/text-query.html">Text Search</a></li> |
| </ul> |
| </li> |
| |
| <li class="drop down"> |
| <a href="#" class="dropdown-toggle" data-toggle="dropdown"><span class="glyphicon glyphicon-book"></span> Javadoc <b class="caret"></b></a> |
| <ul class="dropdown-menu"> |
| <li><a href="/documentation/javadoc.html">All Javadoc</a></li> |
| <li><a href="/documentation/javadoc/arq/">ARQ</a></li> |
| <li><a href="/documentation/javadoc_elephas.html">Elephas</a></li> |
| <li><a href="/documentation/javadoc/fuseki2/">Fuseki</a></li> |
| <li><a href="/documentation/javadoc/geosparql/">GeoSPARQL</a></li> |
| <li><a href="/documentation/javadoc/jdbc/">JDBC</a></li> |
| <li><a href="/documentation/javadoc/jena/">Jena Core</a></li> |
| <li><a href="/documentation/javadoc/permissions/">Permissions</a></li> |
| <li><a href="/documentation/javadoc/extras/querybuilder/">Query Builder</a></li> |
| <li><a href="/documentation/javadoc/shacl/">SHACL</a></li> |
| <li><a href="/documentation/javadoc/tdb/">TDB</a></li> |
| <li><a href="/documentation/javadoc/text/">Text Search</a></li> |
| </ul> |
| </li> |
| |
| <li id="ask"><a href="/help_and_support/index.html"><span class="glyphicon glyphicon-question-sign"></span> Ask</a></li> |
| |
| <li class="dropdown"> |
| <a href="#" class="dropdown-toggle" data-toggle="dropdown"><span class="glyphicon glyphicon-bullhorn"></span> Get involved <b class="caret"></b></a> |
| <ul class="dropdown-menu"> |
| <li><a href="/getting_involved/index.html">Contribute</a></li> |
| <li><a href="/help_and_support/bugs_and_suggestions.html">Report a bug</a></li> |
| <li class="divider"></li> |
| <li class="dropdown-header">Project</li> |
| <li><a href="/about_jena/about.html">About Jena</a></li> |
| <li><a href="/about_jena/architecture.html">Architecture</a></li> |
| <li><a href="/about_jena/citing.html">Citing</a></li> |
| <li><a href="/about_jena/team.html">Project team</a></li> |
| <li><a href="/about_jena/contributions.html">Related projects</a></li> |
| <li><a href="/about_jena/roadmap.html">Roadmap</a></li> |
| <li class="divider"></li> |
| <li class="dropdown-header">ASF</li> |
| <li><a href="http://www.apache.org/">Apache Software Foundation</a></li> |
| <li><a href="http://www.apache.org/foundation/sponsorship.html">Become a Sponsor</a></li> |
| <li><a href="http://www.apache.org/licenses/LICENSE-2.0">License</a></li> |
| <li><a href="http://www.apache.org/security/">Security</a></li> |
| <li><a href="http://www.apache.org/foundation/thanks.html">Thanks</a></li> |
| </ul> |
| </li> |
| |
| |
| |
| |
| <li id="edit"><a href="https://github.com/apache/jena-site/edit/main/source/tutorials/sparql_datasets.md" title="Edit this page on GitHub"><span class="glyphicon glyphicon-pencil"></span> Edit this page</a></li> |
| </ul> |
| </div> |
| </div> |
| </nav> |
| |
| |
| <div class="container"> |
| <div class="row"> |
| <div class="col-md-12"> |
| <div id="breadcrumbs"> |
| |
|
|
|
|
|
|
|
|
|
|
|
|
| <ol class="breadcrumb">
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| <li><a href='/tutorials'>TUTORIALS</a></li>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
| <li class="active">SPARQL DATASETS</li>
|
|
|
|
|
|
|
|
|
| </ol>
|
|
|
|
|
|
|
| |
| |
| </div> |
| <h1 class="title">SPARQL Tutorial - Datasets</h1> |
| |
| <p>This section covers RDF Datasets - an RDF Dataset is the unit that |
| is queried by a SPARQL query. It consists of a default graph, and a |
| number of named graphs.</p> |
| <h2 id="querying-datasets">Querying datasets</h2> |
| <p>The graph matching operation |
| (<a href="sparql_basic_patterns.html">basic patterns</a>, |
| <a href="sparql_optionals.html"><code>OPTIONAL</code>s</a>, and <a href="sparql_union.html"><code>UNION</code>s</a>) work on |
| one RDF graph. This starts out being the default graph of the |
| dataset but it can be changed by the <code>GRAPH</code> keyword.</p> |
| <pre><code>GRAPH uri { ... pattern ... } |
| |
| GRAPH var { ... pattern ... } |
| </code></pre> |
| <p>If a URI is given, the pattern will be matched against the graph in |
| the dataset with that name - if there isn’t one, the <code>GRAPH</code> clause |
| fails to match at all.</p> |
| <p>If a variable is given, all the named graphs (not the default |
| graph) are tried. The variable may be used elsewhere so that if, |
| during execution, its value is already known for a solution, only |
| the specific named graph is tried.</p> |
| <h3 id="example-data">Example Data</h3> |
| <p>An RDF dataset can take a variety of forms. Two common setups are |
| to have the default graph being the union (the RDF merge) of all |
| the named graphs or to have the default graph be an inventory of |
| the named graphs (where they came from, when they were read etc). |
| There are no limitations - one graph can be included twice under |
| different names, or some graphs may share triples with others.</p> |
| <p>In the examples below we will use the following dataset that might |
| occur for an RDF aggregator of book details:</p> |
| <p>Default graph (<a href="sparql_data/ds-dft.ttl">ds-dft.ttl</a>):</p> |
| <pre><code>@prefix dc: <http://purl.org/dc/elements/1.1/> . |
| @prefix xsd: <http://www.w3.org/2001/XMLSchema#> . |
| |
| <ds-ng-1.ttl> dc:date "2005-07-14T03:18:56+0100"^^xsd:dateTime . |
| <ds-ng-2.ttl> dc:date "2005-09-22T05:53:05+0100"^^xsd:dateTime . |
| </code></pre> |
| <p>Named graph (<a href="sparql_data/ds-ng-1.ttl">ds-ng-1.ttl</a>):</p> |
| <pre><code>@prefix dc: <http://purl.org/dc/elements/1.1/> . |
| |
| [] dc:title "Harry Potter and the Philospher's Stone" . |
| [] dc:title "Harry Potter and the Chamber of Secrets" . |
| </code></pre> |
| <p>Named graph (<a href="sparql_data/ds-ng-2.ttl">ds-ng-2.ttl</a>):</p> |
| <pre><code>@prefix dc: <http://purl.org/dc/elements/1.1/> . |
| |
| [] dc:title "Harry Potter and the Sorcerer's Stone" . |
| [] dc:title "Harry Potter and the Chamber of Secrets" . |
| </code></pre> |
| <p>That is, we have two small graphs describing some books, and we |
| have a default graph which records when these graphs were last |
| read.</p> |
| <p>Queries can be run with the command line application (this would be |
| all one line):</p> |
| <pre><code>java -cp ... arq.sparql |
| --graph ds-dft.ttl --namedgraph ds-ng-1.ttl --namedgraph ds-ng-2.ttl |
| --query query file |
| </code></pre> |
| <p>Datasets don’t have to be created just for the lifetime of the query. |
| They can be created and stored in a database, as would be more |
| usual for an aggregator application.</p> |
| <h3 id="accessing-the-dataset">Accessing the Dataset</h3> |
| <p>The first example just accesses the default graph |
| (<a href="sparql_data/q-ds-1.rq">q-ds-1.rq</a>):</p> |
| <pre><code>PREFIX xsd: <http://www.w3.org/2001/XMLSchema#> |
| PREFIX dc: <http://purl.org/dc/elements/1.1/> |
| PREFIX : <.> |
| |
| SELECT * |
| { ?s ?p ?o } |
| </code></pre> |
| <p>(The “<code>PREFIX : <.></code>” just helps format the output)</p> |
| <pre><code>---------------------------------------------------------------------- |
| | s | p | o | |
| ====================================================================== |
| | :ds-ng-2.ttl | dc:date | "2005-09-22T05:53:05+01:00"^^xsd:dateTime | |
| | :ds-ng-1.ttl | dc:date | "2005-07-14T03:18:56+01:00"^^xsd:dateTime | |
| ---------------------------------------------------------------------- |
| </code></pre> |
| <p>This is the default graph only - nothing from the named graphs |
| because they aren’t queried unless explicitly indicated via |
| <code>GRAPH</code>.</p> |
| <p>We can query for all triples by querying the default graph and the |
| named graphs (<a href="sparql_data/q-ds-2.rq">q-ds-2.rq</a>):</p> |
| <pre><code>PREFIX xsd: <http://www.w3.org/2001/XMLSchema#> |
| PREFIX dc: <http://purl.org/dc/elements/1.1/> |
| PREFIX : <.> |
| |
| SELECT * |
| { |
| { ?s ?p ?o } UNION { GRAPH ?g { ?s ?p ?o } } |
| } |
| </code></pre> |
| <p>giving:</p> |
| <pre><code>--------------------------------------------------------------------------------------- |
| | s | p | o | g | |
| ======================================================================================= |
| | :ds-ng-2.ttl | dc:date | "2005-09-22T05:53:05+01:00"^^xsd:dateTime | | |
| | :ds-ng-1.ttl | dc:date | "2005-07-14T03:18:56+01:00"^^xsd:dateTime | | |
| | _:b0 | dc:title | "Harry Potter and the Sorcerer's Stone" | :ds-ng-2.ttl | |
| | _:b1 | dc:title | "Harry Potter and the Chamber of Secrets" | :ds-ng-2.ttl | |
| | _:b2 | dc:title | "Harry Potter and the Chamber of Secrets" | :ds-ng-1.ttl | |
| | _:b3 | dc:title | "Harry Potter and the Philospher's Stone" | :ds-ng-1.ttl | |
| --------------------------------------------------------------------------------------- |
| </code></pre> |
| <h3 id="querying-a-specific-graph">Querying a specific graph</h3> |
| <p>If the application knows the name graph, it can directly ask a |
| query such as finding all the titles in a given graph |
| (<a href="sparql_data/q-ds-3.rq">q-ds-3.rq</a>):</p> |
| <pre><code>PREFIX dc: <http://purl.org/dc/elements/1.1/> |
| PREFIX : <.> |
| |
| SELECT ?title |
| { |
| GRAPH :ds-ng-2.ttl |
| { ?b dc:title ?title } |
| } |
| </code></pre> |
| <p>Results:</p> |
| <pre><code>--------------------------------------------- |
| | title | |
| ============================================= |
| | "Harry Potter and the Sorcerer's Stone" | |
| | "Harry Potter and the Chamber of Secrets" | |
| --------------------------------------------- |
| </code></pre> |
| <h3 id="querying-to-find-data-from-graphs-that-match-a-pattern">Querying to find data from graphs that match a pattern</h3> |
| <p>The name of the graphs to be queried can be determined with the |
| query itself. The same process for variables applies whether they |
| are part of a graph pattern or the <code>GRAPH</code> form. The query below |
| (<a href="sparql_data/q-ds-4.rq">q-ds-4.rq</a>) sets a condition on the variable used to |
| select named graphs, based on information in the default graph.</p> |
| <pre><code>PREFIX xsd: <http://www.w3.org/2001/XMLSchema#> |
| PREFIX dc: <http://purl.org/dc/elements/1.1/> |
| PREFIX : <.> |
| |
| SELECT ?date ?title |
| { |
| ?g dc:date ?date . FILTER (?date > "2005-08-01T00:00:00Z"^^xsd:dateTime ) |
| GRAPH ?g |
| { ?b dc:title ?title } |
| } |
| </code></pre> |
| <p>The results of executing this query on the example dataset are the |
| titles in one of the graphs, the one with the date later than 1 |
| August 2005.</p> |
| <pre><code>----------------------------------------------------------------------------------------- |
| | date | title | |
| ========================================================================================= |
| | "2005-09-22T05:53:05+01:00"^^xsd:dateTime | "Harry Potter and the Sorcerer's Stone" | |
| | "2005-09-22T05:53:05+01:00"^^xsd:dateTime | "Harry Potter and the Chamber of Secrets" | |
| ----------------------------------------------------------------------------------------- |
| </code></pre> |
| <h2 id="describing-rdf-datasets---from-and-from-named">Describing RDF Datasets - <code>FROM</code> and <code>FROM NAMED</code></h2> |
| <p>A query execution can be given the dataset when the execution |
| object is built or it can be described in the query itself. When |
| the details are on the command line, a temporary dataset is created |
| but an application can create datasets and then use them in many |
| queries.</p> |
| <p>When described in the query, <code>FROM <</code><em><code>url</code></em><code>></code> is used to identify |
| the contents to be in the default graph. There can be more than one |
| <code>FROM</code> clause and the default graph is result of reading each file |
| into the default graph. It is the RDF merge of the individual |
| graphs.</p> |
| <p>Don’t be confused by the fact the default graph is described by one |
| or more URLs in <code>FROM</code> clauses. This is where the data is read |
| from, not the name of the graph. As several FROM clauses can be |
| given, the data can be read in from several places but none of them |
| become the graph name.</p> |
| <p><code>FROM NAMED <</code><em><code>url</code></em><code>></code> is used to identify a named graph. The |
| graph is given the name <em>url</em> and the data is read from that |
| location. Multiple <code>FROM NAMED</code> clauses cause multiple graphs to be |
| added to the dataset.</p> |
| <p>For example, the query to find all the triples in both default |
| graph and named graphs could be written as |
| (<a href="sparql_data/q-ds-5.rq">q-ds-5.rq</a>):</p> |
| <pre><code>PREFIX xsd: <http://www.w3.org/2001/XMLSchema#> |
| PREFIX dc: <http://purl.org/dc/elements/1.1/> |
| PREFIX : <.> |
| |
| SELECT * |
| FROM <ds-dft.ttl> |
| FROM NAMED <ds-ng-1.ttl> |
| FROM NAMED <ds-ng-2.ttl> |
| { |
| { ?s ?p ?o } UNION { GRAPH ?g { ?s ?p ?o } } |
| } |
| </code></pre> |
| <p><a href="sparql_results.html">Next: results</a></p> |
| |
| |
| </div> |
| </div> |
| |
| </div> |
| |
| <footer class="footer"> |
| <div class="container" style="font-size:80%" > |
| <p> |
| Copyright © 2011–2022 The Apache Software Foundation, Licensed under the |
| <a href="http://www.apache.org/licenses/LICENSE-2.0">Apache License, Version 2.0</a>. |
| </p> |
| <p> |
| Apache Jena, Jena, the Apache Jena project logo, Apache and the Apache feather logos are trademarks of |
| The Apache Software Foundation. |
| <br/> |
| <a href="https://privacy.apache.org/policies/privacy-policy-public.html" |
| >Apache Software Foundation Privacy Policy</a>. |
| </p> |
| </div> |
| </footer> |
| |
| |
| <script type="text/javascript"> |
| var link = $('a[href="' + this.location.pathname + '"]'); |
| if (link != undefined) |
| link.parents('li,ul').addClass('active'); |
| </script> |
| |
| </body> |
| </html> |
