For the most part, blank nodes in SPARQL queries function exactly as variables which cannot be returned to the user/client. So, the following two queries behave identically: SELECT ?title WHERE { _:book :hasTitle ?title } SELECT ?title WHERE { ?book :hasTitle ?title } However, a SPARQL query may not reuse the same blank node label twice in different basic graph patterns. That is, the following is not a legal SPARQL query: SELECT ?title WHERE { _:book rdfs:seeAlso ?g .

While SPARQL does support nested graph patterns, it does not directly support subqueries (for example, the FROM clause of a SPARQL query cannot itself contain a CONSTRUCT query which generates the dataset to be queried against). The Data Access Working Group postponed this issue in early 2005.

Several software packages exist which allow SPARQL queries to generate answers from data sources other than RDF, such as relational databases, LDAP servers, or XML data. The community maintains a list of these tools at the W3C ESW Wiki.

It is sometimes desirable to use SPARQL to query triples entailed from subclass, subproperty, range, domain, and other relations which can be represented using RDF Schema. The SPARQL specification defines the results of queries based on RDF simple entailment. However, the specification does present a general, parametrized definition of graph pattern matching that can be expanded to other entailments beyond RDF simple entailment.

For the most part, the answer to this question is the same as the above answer regarding RDFS entailment. However, OWL-DL axioms do not always result in a unique deductive closure, and as such querying OWL-DL entailments requires instantiating the parametrized SPARQL basic graph pattern definition with values appropriate for OWL-DL entailment. The open-source OWL-DL reasoner, Pellet, will answer SPARQL queries while considering OWL-DL entailments.

There is no built-in support within SPARQL to query hierarchical structures of an unknown depth (e.g. trees or lists), to query transitive relations, or to query via XPath like paths. The Data Access Working Group postponed this issue in early 2005. Repeated queries. A repeating structure can be queried via a series of queries.

SPARQL is a recursive acronym standing for SPARQL Protocol and RDF Query Language. As the name implies, SPARQL is a general term for both a protocol and a query language. Most uses of the SPARQL acronym refer to the RDF query language. In this usage, SPARQL is a syntactically-SQL-like language for querying RDF graphs via pattern matching. The language's features include basic conjunctive patterns, value filters, optional patterns, and pattern disjunction.

A combination of the SPARQL OPTIONAL keyword and the bound(...) filter function can be used to mimic some universally quantified queries. As an example, consider this query which finds the minimum price of every book in the underlying default graph: PREFIX ex: <http://example.org/> SELECT ?book ?minprice WHERE { ?book a ex:book ; ex:price ?minprice . OPTIONAL { ?book ex:price ?otherprice . FILTER( ?otherprice < ?minprice ) . } . FILTER ( !bound(?otherprice) ) .

There are a variety of SPARQL tutorials and introductions scattered around the Web. Some notable ones include:

The creators of several SPARQL implementations provide online services where SPARQL queries can be input and executed against either canned datasets or arbitrary datasets (identified by URLs). The community maintains a list of SPARQL endpoints on the W3C ESW Wiki.

On January 15, 2008, the W3C published the three SPARQL specifications as Recommendations. This means that the specifications have been endorsed by the W3C membership and should be considered stable documents.

In all languages, ABOUT queries increase the number of relevant documents returned by a query. In English, the ABOUT query returns documents based on the concepts of your query, not only the exact word or phrase you specify (e.g. you can issue a query that finds all documents about the subject politics, not just the documents that contain the word politics).

Security Bank Online requires 128-bit encryption (a high level of coding for security purposes). If your computer browser does not have this level of encryption, a blank screen may be displayed. At the top of the screen you may see a message displaying the need of 128-bit encryption and JavaScript. If just the Online ID and Password fields go blank after you have tried to login, you may need to enable your "cookies".

This is a quirk of Internet Explorer. When you select a service that requires Find It McGill to search another database, "about:blank" is shown while the search is taking place. Once results are displayed, the "about:blank" disappears and the correct URL for the site displays.

Date fields in queries are special in how they handle blank values; you must use the Is operator (instead of =) and the special value NULL. For example, to show a list of active employees, you want to show records where the termination date Is NULL. In the Query Wizard, click the advanced view and replace the comparison operator and date value from No.

When flash loads XML data by default any carriage returns and linefeeds are displayed as empty XML nodes. The exact reason that Macromedia did this is unclear however, when writing code to manipulate XML information it is important to make sure you always check the node XML object to make sure it is not a blank node. Do this by checking the node name to make sure you have correct node, this will also ensure that if extra data is added to the XML your movie will still work.

The SPARQL protocol requires that the results of SPARQL CONSTRUCT and DESCRIBE queries be RDF graphs. SELECT and ASK queries, on the other hand, usually have their results returned as XML (or sometimes as JSON). However, as part of the group's test suite, the DAWG includes an RDF vocabulary which can be used to represent the results of SELECT or ASK queries in RDF.

The DAWG defines an XML serialization format, the SPARQL Query Results XML Format, which is used to return the results of SPARQL SELECT and ASK queries. The SPARQL protocol requires that the results of SPARQL CONSTRUCT and DESCRIBE queries be RDF graphs, which can be represented using the XML-based RDF/XML syntax.

JSON is a lightweight serialization format which is a subset of JavaScript's literal-object notation. It is a useful format to use for SPARQL results when a Web client is issuing the queries and processing the results. The DAWG has published a Note defining a JSON format that closely follows the SPARQL Query Results XML Format, and which can be used to return the results of SPARQL SELECT and ASK queries. public-sparql-dev@w3.

The Millennium Project is organized into regional "Nodes." Each Node consists of a group of individuals and institutions that identify creative and advanced experts to participate in Millennium Project research and initiate and conduct their own research. They interconnect global and local perspectives.

The ~ operator does regular expression matching, and ~* does case-insensitive regular expression matching. The case-insensitive variant of LIKE is called ILIKE. Case-insensitive equality comparisons are normally expressed as: SELECT * FROM tab WHERE lower(col) = 'abc'; This will not use an standard index.

For example: if a mountain's name is Mount Zester and another mountain is named Mount Abraham, ideally Mount Zester would show up alphabetically with the "Z" words and Mount Abraham would show up with the "A" words. However, if the query names are listed as "Mount Zester" and "Mount Abraham" then they will both show up with the "M" words.

Create a form named "Search Form" with simple text fields that will be used to refer to the Notes fields of the documents in the "Search View" below. Name these fields form_Field1 and form_Field2 which correspond to Notes fields named Field1 and Field2. Add a field named "SaveOptions" with a default value of "0" (with the quotes) so the form is not saved when submitted.

My Toonopedia™ is a work in progress, and always will be. In most cases, the reason I haven't covered a particular topic is simply that I haven't gotten to it yet. I will — but I can't say when, because I don't do them on any sort of a schedule. When I get to one — that's when it gets done. No, I don't do them in order of worthiness, by whatever criterion worthiness is measured. And there are still a lot of very worthy toons I haven't done yet. But I'm getting there.

The meanings of many TCS songs have been discussed on the list at some point. However, trying to find these discussions in the archives would be very difficult. If you want to discuss a particular song, by all means post a message to the list and try to get some discussion going.

If your caller waits until after the beep to hang up but does not speak, an empty message will be generated. Make the greeting longer so callers will have plenty of time to hang up before they get to the beep.

The jury is still out on best practices surrounding using SPARQL compared to other query languages. Some benefits of SPARQL include: Implicit join syntax. SPARQL queries RDF graphs, which consist of various triples expressing binary relations between resources, by specifying a subgraph with certain resources replaced by variables.

There is currently no established, interoperable method for representing or accessing functional descriptions of SPARQL endpoints. (This is not to be confused with the WSDL which describes the SPARQL Protocol itself.) The Data Access Working Group postponed this topic in 2005, leaving behind a draft "of historical interest only.

The performance of a SPARQL query against any particular dataset depends not only upon the size of the dataset but also on the nature of the dataset's storage (a relational store, a native triple store, LDAP, etc.), the complexity of the query itself, optimizations in use by the SPARQL engine, the distribution of the data, and other environmental factors.

SPARQL provides the function, regex(), which can be used to test whether a literal value contains a certain substring: SELECT ?title WHERE { _:book :title ?title . FILTER (regex(?title, "SPARQL")) . } The regex() function expects its first argument to be either a plain literal without a language tag or else a typed literal with a datatype of xsd:string. Plain literals with a language tag or typed literals of other datatypes will evaluate to a type error which causes the filter to fail.