![]() The result of this query is essentially a copy of the data in the ex125.ttl graph, becauseĪll it had were triples with predicates of ab: You also can use the GRAPH keyword to ask for all the triples from a particular named The result (with the paragraph of description about Hocking trimmed at “.”) has theġ4 triples about him pulled from the two "Joseph Hocking (November 7, 1860–March 4, 1937) was The CONSTRUCT graph pattern in this query has two triple patterns. Gp:Hocking_Joseph ?gutenProperty ?gutenValue. The following shows a variation on the ex172.rq query from the last chapter, this time pulling triples about Josephġ06 | Chapter 4: Copying, Creating, and Converting Data (and Finding Bad Data) This may not seem especially exciting, but when you use this technique to gather dataįrom one or more remote sources, it gets more interesting. Should look familiar here is what ARQ returns after running query ex176.rq on the ARQ returns them as a Turtle text file, which Triples depends on the processor you use. Not as a formatted report with a column for each named variable. The set of triple patterns (just one in ex176.rq) that describe what toĬreate is itself a graph pattern, so don’t forget to enclose it in curly braces.Ī SPARQL query processor returns the data for a CONSTRUCT query as actual triples, WHERE keyword, but specifies a triple to create with each set of values that got bound | person | pĪ CONSTRUCT version of the same query has the same graph pattern following the The subjects, predicates, and objects get stored in the ?person, ?p, and ?o variables, andĪRQ returns these values with a column for each variable: ![]() Triples where that same subject has an ab:firstName value of “Craig” and an We want the subject, predicate, and object of all As a review, imagine that we want to query the followingĭataset from Chapter 1 for all the information about Craig Ellis. The CONSTRUCT keyword lets you create triples, and those triples can be exact copies We’ll also see some examples of how to put ASK to use, and we’llġ04 | Chapter 4: Copying, Creating, and Converting Data (and Finding Bad Data) Most of this chapter covers the broad range of uses that people find for the CONSTRUCT query form. Of DESCRIBE queries, so this query form isn’t very popular, but it’s worth playing This has led to inconsistent implementations The SPARQL specification leaves it up to the query processor to decide which triples to send back asĪ description of the named resource. DESCRIBE asks for triples that describe a particular resource.You can use sets of these rules to automate qualityĬontrol in your data processing pipeline. This is great for expressing business rules about conditions that should or should In a particular dataset or not, and the processor returns a boolean true or false. ASK asks a query processor whether a given graph pattern describes a set of triples.To identify data that doesn’t conform to specific business rules. This lets you copy, create, and convert RDF data, and it makes it easier Without changing them, or you can pull values out and use those values to create You can pull triples directly out of a data source In SPARQL, SELECT is known as a query form, and there are three more: SELECT keyword, and SPARQL APIs will load the values into a suitable data structureįor the programming language that forms the basis of that API. ![]() Processors such as ARQ typically show the result of a SELECT query as a table of rowsĪnd columns, with a column for each variable name that the query listed after the It lets you request data from aĬollection whether you want a single phone number or a list of first names, last names,Īnd phone numbers of employees hired after January 1st sorted by last name. Query Forms: SELECT, DESCRIBE, ASK, and CONSTRUCTĪs with SQL, SPARQL’s most popular verb is SELECT. Several examples take advantage of the BIND keyword and functions that are only The general ideas described in this chapter work with SPARQL 1.0 as well as 1.1, but Operation lets you ask for information about the resource represented by a particular URI.
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