How do I filter a Sparql query?

How do I filter a Sparql query?

FILTER(condition) is a clause you can insert into your SPARQL query to, well, filter the results. Inside the parentheses, you can put any expression of boolean type, and only those results where the expression returns true are used.

What types of queries does SPARQL support?

SPARQL also supports aggregation, subqueries, negation, creating values by expressions, extensible value testing, and constraining queries by source RDF graph. The results of SPARQL queries can be result sets or RDF graphs.

What is the result type of a SPARQL describe query?

The DESCRIBE form returns a single result RDF graph containing RDF data about resources. […] The description is determined by the query service. So, the resources you unexpectedly receive maybe describing the resources you actually want.

How do you write queries in SPARQL?

A SPARQL query comprises, in order:

1. Prefix declarations, for abbreviating URIs.
2. Dataset definition, stating what RDF graph(s) are being queried.
3. A result clause, identifying what information to return from the query.
4. The query pattern, specifying what to query for in the underlying dataset.

What is the difference between SPARQL and SQL?

Comparing RDF and SQL data. SQL does this by accessing tables in relational databases, and SPARQL does this by accessing a web of Linked Data. (Of course, SPARQL can be used to access relational data as well, but it was designed to merge disparate sources of data.)

What does SPARQL stand for?

SPARQL Protocol and RDF Query Language
SPARQL is a recursive acronym, which stands for SPARQL Protocol and RDF Query Language. SPARQL consists of two parts: query language and protocol. The query part of that is pretty straightforward. SQL is used to query relational data. XQuery is used to query XML data.

Why is SPARQL query?

SPARQL, short for “SPARQL Protocol and RDF Query Language”, enables users to query information from databases or any data source that can be mapped to RDF. The SPARQL standard is designed and endorsed by the W3C and helps users and developers focus on what they would like to know instead of how a database is organized.

What is construct query in SPARQL?

SPARQL has several query forms. The SELECT query form returns variable bindings. The CONSTRUCT query form returns an RDF graph. The graph is built based on a template which is used to generate RDF triples based on the results of matching the graph pattern of the query.

How do I run a Sparql query?

Executing the query

1. Windows setup. Execute: bat\sparql.bat –data=doc\Tutorial\vc-db-1.rdf –query=doc\Tutorial\q1.rq.
2. bash scripts for Linux/Cygwin/Unix. Execute: bin/sparql –data=doc/Tutorial/vc-db-1.rdf –query=doc/Tutorial/q1.rq.
3. Using the Java command line applications directly. (This is not necessary.)

Is SPARQL like SQL?

SPARQL vs SQL Just like SQL allows users to retrieve and modify data in a relational database, SPARQL provides the same functionality for NoSQL graph databases like Ontotext’s GraphDB. In addition, a SPARQL query can also be executed on any database that can be viewed as RDF via a middleware.

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.

Can you use any function in a SPARQL filter?

We can use any SPARQL function in the FILTER expressions. For example, the year function applied to a date value will return the year component as an integer value. So the following query will return the exact same results as the previous query but the filter is written in a slightly different way:

How to skip the first n results in SPARQL?

We can skip the first N results by adding an OFFSET N clause at the end of the query where N is a positive integer. A paging capability can be supported by using LIMIT and OFFSET. We can filter the results returned by a query using a FILTER expression.

Is there a way to test a string in SPARQL?

SPARQL provides an operation to test strings, based on regular expressions. This includes the ability to ask SQL “LIKE” style tests, although the syntax of the regular expression is different from SQL. The syntax is: The flags argument is optional. The flag “i” means a case-insensitive pattern match is done.

Which is the main query form in SPARQL?

The main query form in SPARQL is a SELECT query which, by design, looks a bit like a SQL query. A SELECT query has two main components: a list of selected variables and a WHERE clause for specifying the graph patterns to match: SELECT WHERE { }

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