SPARQL

This SPARQL query includes a bit of logic to identify which data from the various files goes together, but that's fairly simple.

Its syntax is similar to that of SQL, and SPARQL queries consist of a series of triple patterns and modifiers.

SPARQL, depending on the engine that you run it against, can be completely distributed through something known as the linked data effect.

With SPARQL, your coupling with data can be very abstract because of the distributed but interlinked nature of the RDF.

Defined as "a repository of RDF graphs managed by a single service" it serves as the endpoint to which any SPARQL statement will be posted.

SPARQL was designed to be capable of querying multiple data sources distributed across the Web.

So far, you've seen two ways to run a simple SPARQL query: using the command-line sparql utility, and using Java code with the Jena API.

Your first thought when comparing the two listings is likely to be that the SPARQL version clearly has many more lines than the SQL version.

Alternatively, named graphs can be provided to the sparql command with --named URL, with the URL giving the location of the graph.

There's a lot more to SPARQL than it is possible to cover here, so do use the Resources below to find out more about SPARQL's features.

However, for our purposes, simple closely coupled functions are used to exemplify the similarities and differences between SPARQL and SQL.

The FILTER keyword in SPARQL restricts the results of a query by imposing constraints on values of bound variables.

It's worth taking a look at the similarities and differences between CRUD operations when developed in SQL and SPARQL.

In fact, these SPARQL endpoints are often additional interfaces added on to existing relational databases.

Several utilities are available to expose existing data as a Web endpoint queryable through SPARQL, the query language of the Semantic Web.

The next line of the SPARQL code describes the query request.

Another approach to extracting data from the XML of a SPARQL result set is to apply an XSLT.

This endpoint is identified by a URL passed as an argument when you create the SPARQLWrapper object stored in the script's sparql object.

By using SPARQL's FILTER keyword to indicate that you only want an artist name and album name matching the indicated patterns.

The core standards are RDF for representation, SPARQL for querying, RDFS for structuring, and OWL for structuring and reasoning.

SPARQL is an additional method of querying, not necessarily an immediate replacement of SQL.

Moving beyond linkedmdb. org, you can find other public SPARQL endpoints that give you access to a wider range of data.

Please note, as mentioned in the previous section, that different variables pass into the SQL and the SPARQL versions.

The same SPARQL queries can include content contributed by relational databases, REST services, native RDF triplestores and now documents.

A graph is specified at runtime on the command line with the sparql --data URL option, where URL is the graph's location.

Examples using named graphs have shown you how combining multiple graphs in SPARQL opens up your querying options.

To fully embrace the Semantic Web idea, you can apply traditional Web-development techniques to RDF data using SPARQL.

Most SPARQL discussions focus on the query language and the protocol that provide the Q and P in its name.

The SPARQL Protocol And RDF Query Language (SPARQL) is currently under discussion as a W3C Working Draft.

SPARQL query tool: Experiment with this demo provided by the author.

The first two lines of the SPARQL are the PREFIX declarations.

The RDF data is sorted, cross-referenced, and converted to XML by a SPARQL engine.

Jenabean also has support for binding to a SPARQL (SPARQL Query Language for RDF) result.

To execute the above SQL and SPARQL statements, you must connect to the system somehow.

Now let's look at a very simple SPARQL query over the bloggers model.

SPARQL queries are created and executed with Jena via classes in the com. hp. hpl. jena. query package.

Named graphs are used within a SPARQL query with the GRAPH keyword, in conjunction with either a graph URI or a variable name.

And the fact that the SPARQL query language has come out now means that all kinds of data can be surfaced as RDF.

SPARQL endpoints provide access to databases through queries that use the W3C standard SPARQL query language.

In addition to implementing SPARQL, ARQ's query engine can also parse queries expressed in RDQL or its own internal query language.

The function declarations in the SQL and SPARQL versions are identical.

In addition to the background graph, SPARQL can query any number of named graphs.

To make sure that you are all set, call sparql from the command line, and make sure you see its usage message.

In this section, I'll introduce more of SPARQL's features, and the more complex queries they enable.

Both RDF and SPARQL are technologies within what has been dubbed the Semantic Web stack.

Now, compare the SQL-based PHP code in Listing 9 with the SPARQL-based PHP code in Listing 10 for the humble read operation.

Now, compare the SQL-based PHP code in Listing 13 with the SPARQL-based PHP code in Listing 14 for the delete operation.

Now compare the SQL-based PHP code in Listing 15 with the SPARQL-based PHP code in Listing 16 for the update operation.

SPARQL is the query language for the Semantic Web.

Now, compare the SQL-based code in Listing 3 with the SPARQL-based code in Listing 4 for the same create operation.

Now compare the SQL-based code in Listing 7 with the SPARQL-based code in Listing 8 for the update operation.

Because the range of connection methods for SQL and SPARQL vary, it isn't feasible to cover these in any detail here.

The WHERE statements are quite different from each other because with SPARQL, you must specify which schemas to use to fetch data.

Now, compare the SQL-based code in Listing 5 with the SPARQL-based code in Listing 6.

This tutorial introduces SPARQL and the data formats it is based on.

Of course, there are also reasons why you may not want to move away from SQL, and they are probably perfectly valid reasons.

What makes it new this time is that the query language in use is SPARQL, instead of the more well-known SQL.

The draft from HP does not raise nor answer this question, but the SPARQL Update Wiki gives some hints in its Q&A section

Translating an entirely free-text question into a SPARQL query

Anatomy of a simple SPARQL query

After gathering RDF versions of all the data, I use another SPARQL query, in Listing 1, to extract the data for the final report

Listing 2. arq command specifying data sources, location of SPARQL query, and results format

Writing the SPARQL queries for the journal system

This is the URL of the SPARQL-based endpoint in which I will be doing my searches. This example uses the DBpedia endpoint at