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| == SPARQL Examples from Lecture 03==
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| The data are available in this Blazegraph triple store:
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| [http://sandbox.i2s.uib.no http://sandbox.i2s.uib.no] , but you may need to be inside the UiB network (or on VPN.)
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|
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| ===List properties===
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|
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| SELECT DISTINCT ?p WHERE {
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| ?s ?p ?o .
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| } LIMIT 100
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|
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| ===List types===
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|
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| PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
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| SELECT DISTINCT ?t WHERE {
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| ?s rdf:type ?t .
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| } LIMIT 100
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|
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| ===List authors===
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| PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
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| PREFIX foaf: <http://xmlns.com/foaf/0.1/>
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| SELECT DISTINCT ?p WHERE {
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| ?s rdf:type foaf:Person .
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| ?s ?p ?o .
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| } LIMIT 100
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|
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| ===Prefixes used===
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| The examples below will assume that these are in place.
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| PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
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| PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
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| PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
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| PREFIX owl: <http://www.w3.org/2002/07/owl#>
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| PREFIX dc: <http://purl.org/dc/terms/>
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| PREFIX bibo: <http://purl.org/ontology/bibo/>
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| PREFIX foaf: <http://xmlns.com/foaf/0.1/>
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| PREFIX skos: <http://www.w3.org/2004/02/skos/core#>
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| PREFIX ss: <http://semanticscholar.org/>
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| PREFIX kg: <http://i2s.uib.no/kg4news/>
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| PREFIX sp: <http://i2s.uib.no/kg4news/science-parse/>
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| PREFIX th: <http://i2s.uib.no/kg4news/theme/>
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| SELECT DISTINCT ?p WHERE {
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| ?s rdf:type ss:Paper .
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| ?s ?p ?o .
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| } LIMIT 100
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|
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| ===Explain all types and properties===
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| SELECT ?pt ?e WHERE {
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| ?pt rdfs:comment ?e .
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| } LIMIT 100
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| ===List main papers===
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| SELECT * WHERE {
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| ?paper rdf:type kg:MainPaper .
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| ?paper dc:date ?year .
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| }
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| Add this to show datatypes!
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| BIND ( DATATYPE(?year) AS ?type )
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| Add this to only show years with the right type.
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| FILTER ( DATATYPE(?year) = xsd:gYear )
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| ===Group and count main papers by year===
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| SELECT ?year (COUNT(?paper) AS ?count) WHERE {
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| ?paper rdf:type kg:MainPaper .
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| ?paper dc:date ?year .
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| FILTER ( DATATYPE(?year) = xsd:gYear )
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| }
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| GROUP BY ?year
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| Add this to order the results
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| ORDER BY ?year
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| Add this to order and only show years with more than 5 papers.
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| HAVING (?count > 5)
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| ORDER BY DESC(?count)
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|
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| ===Show papers===
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| SELECT ?paper ?year WHERE {
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| ?paper rdf:type kg:MainPaper .
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| ?paper dc:date ?year .
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| FILTER ( DATATYPE(?year) = xsd:gYear )
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|
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| }
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| Change last lines to show papers without an xsd:gYear too.
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| OPTIONAL {
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| ?paper dc:date ?year .
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| FILTER ( DATATYPE(?year) = xsd:gYear )
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| }
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|
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| ===Alternative values for variables===
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| SELECT ?p ?n ?year WHERE {
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| ?p rdf:type kg:MainPaper .
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| ?p dc:contributor ?a .
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| ?a foaf:name ?n .
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| ?p dc:date ?year .
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| FILTER ( CONTAINS( ?n, ?str ) )
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| FILTER ( CONTAINS( STR(?year), ?yr) )
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| VALUES ?str { "Andreas" "David" }
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| VALUES ?yr { "2020" "2019" }
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| }
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| ===Property paths (composite properties)===
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| This query:
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| SELECT ?p ?n WHERE {
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| ?p rdf:type kg:MainPaper .
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| ?p dc:contributor ?c .
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| ?c foaf:name ?n .
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| }
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| Can be simplified by eliminating ?c:
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| SELECT ?p ?n WHERE {
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| ?p rdf:type kg:MainPaper .
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| ?p dc:contributor / foaf:name ?n .
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| }
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| Can be further simplified by first reversing rdf:type:
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| SELECT ?p ?n WHERE {
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| kg:MainPaper ^rdf:type ?p .
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| ?p dc:contributor / foaf:name ?n .
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| }
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| ...and the eliminating ?p:
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| SELECT ?n WHERE {
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| kg:MainPaper ^rdf:type / dc:contributor / foaf:name ?n .
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| }
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| ===Retrieve titles of papers that mention SPARQL===
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| Get papers with topics labelled "SPARQL":
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| SELECT ?t WHERE {
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| ?t ^dc:title / dc:subject / skos:prefLabel "SPARQL" .
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| }
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| Some labels also go via a theme:
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| SELECT ?t WHERE {
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| ?t ^dc:title / dc:subject / th:theme / skos:prefLabel "SPARQL" .
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| }
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| We can get both using a path with an optional element (the '?'):
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| SELECT ?t WHERE {
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| ?t ^dc:title / dc:subject / th:theme? / skos:prefLabel "SPARQL" .
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| }
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| ===Using an external SPARQL endpoint===
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| We limit to a single label to avoid time-outs and rate limitations:
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| SELECT ?a ?n ?r WHERE {
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| ?a rdf:type ss:Topic .
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| ?a skos:prefLabel ?n .
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| FILTER ( ?n = "SPARQL" )
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| BIND ( STRLANG( ?n, "en" ) AS ?n2 )
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| SERVICE <https://dbpedia.org/sparql> {
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| ?r rdfs:label ?n2 .
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| }
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| } LIMIT 1
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| ===Insert 4-digit years for all main papers===
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| Main papers that do not have an xsd:gYear:
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| SELECT * WHERE {
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| ?p rdf:type kg:MainPaper .
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| ?p dc:date ?d .
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| FILTER ( DATATYPE(?d) = xsd:gYear )
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|
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| }
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| Show the datatypes:
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| SELECT * WHERE {
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| ?p rdf:type kg:MainPaper .
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| ?p dc:date ?d .
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| FILTER ( DATATYPE(?d) = xsd:dateTime )
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| BIND ( year( ?d ) AS ?dt )
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| }
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| Insert 4-digit years:
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| INSERT { ?paper dc:date ?year }
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| WHERE {
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| ?paper rdf:type kg:MainPaper .
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| ?paper dc:date ?date .
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| FILTER( DATATYPE(?date) != xsd:gYear )
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| BIND ( YEAR(?date) AS ?year )
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| }
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| (Actually, these years are xsd:integer- s, not quite xsd:gYear-s.)
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