> -----Original Message----- > From: public-rdf-dawg-comments-request@w3.org [mailto:public-rdf-dawg- > comments-request@w3.org] On Behalf Of Lee Feigenbaum > Sent: 21 August 2008 18:26 > To: al@jku.at > Cc: Semantic Web; public-rdf-dawg-comments@w3.org > Subject: Re: SPARQL question: get distinct list of datatypes used for > literals > > > Andreas Langegger wrote: > > > Hi there, > > > > maybe sb can tell me if this is still possible: I'd like to fetch all > > datatype URIs used for object literals in a dataset. There is the > > dataset predicate which can be used in filter expressions to filter > > literals to a known datatype like xsd:string: FILTER(datatype(?val) = > > xsd:string). > > > > But can I bind the value to a variable somehow? With a filter it can't > > work (consider FILTER(datatype(?val) = ?dt) where ?val is bound to > > literal values and ?dt should give me the type). I could use property > > functions, but I'd like to stay with SPARQL specs. Maybe there is a way > > to do it I just can't see... > > > > thanks, > > AndyL > > AndyL, > > There's no way to do this (select functions of values from a > graph/dataset) in the SPARQL specification. > > As you said, various implementations provide extensions that will do > this. Please see: > > http://esw.w3.org/topic/SPARQL/Extensions/Selecting_Expressions > > Lee > Yes - in strict SPARQL (simple entailment), a query can only return RDF terms found in the graph itself. I'm sure someone can correct me, but D-entailment comes close: sec 5.1 of RDF sSemantics has the text: """ Say that an RDF graph recognizes a datatype URI reference aaa when the graph rdfs-entails a datatyping triple of the form aaa rdf:type rdfs:Datatype . """ Andy(S)Received on Thursday, 21 August 2008 21:15:30 UTC
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