SPARQL-cheatsheet

All those SPARQL commands & tricks that you keep on forgetting ヽ༼ຈل͜ຈ༽ﾉ

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Query Forms

SELECT

...

CONSTRUCT

Returns a graph specified by a graph template.

within the CONSTRUCT triples are created based on the variables established within the WHERE query

PREFIX wd: <http://www.wikidata.org/entity/>
PREFIX wdt: <http://www.wikidata.org/prop/direct/>
PREFIX mo: <http://semantics.id/ns/example/movie#>
prefix ex: <http://semantics.id/ns/example#> 
CONSTRUCT
    { 
     ?iri a mo:Movie ;
        mo:hasWikidataLink ?s ;
        mo:hasIMDBResource ?imdbRes ;
        mo:title ?title ;
    }
WHERE {
    SERVICE <https://query.wikidata.org/sparql>
    {
        ?s wdt:P31 wd:Q24869 ; #instance_of feature film  
        wdt:P345 ?imdbId ; 
        wdt:P1476 ?title .
        BIND(IRI(CONCAT("https://www.imdb.com/title/", ?imdbId )) AS ?imdbRes) .
        BIND( IRI(CONCAT("http://semantics.id/ns/example#", ?imdbId )) AS ?iri) .
   }
}
LIMIT 2

Resulting in new triples

@prefix ex:  <http://semantics.id/ns/example#> .
@prefix mo:  <http://semantics.id/ns/example/movie#> .
@prefix wd:  <http://www.wikidata.org/entity/> .
@prefix wdt: <http://www.wikidata.org/prop/direct/> .

ex:tt0461770  a             mo:Movie ;
        mo:hasIMDBResource  <https://www.imdb.com/title/tt0461770> ;
        mo:hasWikidataLink  wd:Q490464 ;
        mo:title            "Enchanted"@en .

ex:tt0070215  a             mo:Movie ;
        mo:hasIMDBResource  <https://www.imdb.com/title/tt0070215> ;
        mo:hasWikidataLink  wd:Q964009 ;
        mo:title            "Il mio nome è Nessuno"@it .

ASK

DESCRIBE

String Operations

• UCASE() convert to upper-case
• LCASE() convert to lower-case
• STRLEN() lenght of a string
• SUBSTR() substring of first arg, second arg: start position; third arg: character lenght;
• STRSTARTS()string in first arg starts with string in second arg
• STRENDS() string in first arg ends with string in second arg
• CONTAINS() string in second arg is within first arg. Example: CONTAINS("SPARQL", "QL") is True. FILTER(CONTAINS(str(?term), "iao") || CONTAINS(str(?term), "bfo") || CONTAINS(str(?term), "obo"))

Logic operators

• sameTerm & !sameTerm (more efficient and =)
• =, !=, >, >=, <, <=
• AND: && OR: ||
• IN and NOT IN: ?foo IN ("bar", "anotherbar")
• isIRI isIRI
• isBlank: only bank nodes FILTER (isBlank(?term)) filter out FILTER (!isBlank(?term))
• isLiteral

Functions

• lang Returns the language tag.
  • FILTER(lang(?label) = 'es')
  • any @en variant (will match all of these: @en, @en-US, @en-GB) FILTER(langMatches(lang(?label), 'en'))
• datatype returns the datatype of a literal
  • BIND( datatype(?shoeSize) AS ?datatype)

Aggregation Functions

• COUNT
• SUM
• AVG
• MIN, MAX
• SAMPLE
• GROUP_CONCAT

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Tips to speedup SPARQL Queries:

• reduce search space
• avoid OPTIONAL clauses (when possible), or have them follown non-optional clauses
• avoid FILTER or try having them earlier - so search space is reduced:
  • FILTER(sameTerm(?term1, ?term2)) is faster that FILTER(?terms = ?term)
  • idem for !sameTerm being faster that !=
  • regexs are expensive
• avoid DISTINCT
• avoid SORT BY in large amount of results
• reduce printout named variables - allows for more optimization flexibility from the SPARQL processor

SPARQL Resources

• “SPARQL Functions Reference — GraphDB Free 9.10.0 Documentation.” https://graphdb.ontotext.com/documentation/free/sparql-functions-reference.html.
• DuCharme, Bob. Learning SPARQL: Querying and Updating with SPARQL 1.1. Second edition. Sebastopol, CA: O’Reilly Media, 2013.
• “SPARQL 1.1 Query Language.” https://www.w3.org/TR/sparql11-query/.
• “Bob DuCharme Blog.” http://www.bobdc.com/blog/.
• “Module: SPARQL — Web Portal for RDF.Rb.” http://rdf.greggkellogg.net/yard/SPARQL.html.
• “Wikidata:Request a Query - Wikidata.” https://www.wikidata.org/wiki/Wikidata:Request_a_query.