Cesbron, Brice wrote: > Hello, > > For now I'm using Virtuoso Open Source on an Ubuntu and I'm trying to do > some Sparql queries over my database. > Some are ok but I've an error with this one : > > PREFIX rdfs: <http://www.w3.org/200/01/rdf-schema#> > SPARQL SELECT ?s from <http://iaf-dl> WHERE { ?s rdfs:subClassOf ?o }; > > I took a look on tutorials but I didn't see examples...Maybe I have read > too fast. > Can you explain me what happens please? > Because if there is an error I don't know what is that error....
Hi, The above confuses two ways of performing the sparql query. First way: in isql or the Conductor's isql window, if you want to do sparql-within-sql then you prefix the whole sparql bit with the keyword "sparql". You've got a prefix statement which the sql engine will not understand, before you tell it you're talking sparql. Hence solution #1: move `sparql' to immediately before `prefix' and the above will work in isql: > sparql PREFIX rdfs: <http://www.w3.org/200/01/rdf-schema#> > SELECT ?s from <http://iaf-dl> WHERE { ?s rdfs:subClassOf ?o }; Second way: if you're using the /isparql interface (`advanced' tab) then you're already talking sparql and `sparql' is not a valid sparql keyword. Hence solution #2: remove `sparql' altogether and the trailing semicolon and it'll work in isparql: > PREFIX rdfs: <http://www.w3.org/200/01/rdf-schema#> > SELECT ?s from <http://iaf-dl> WHERE { ?s rdfs:subClassOf ?o } For development purposes, I would use the #2 approach, isparql, to build my sparql queries; if you're subsequently embedding them in sql code for an application (eg in a VSP page or somesuch) then take the working sparql query, stick the word `sparql' in front of it and off you go. Have you seen http://virtuoso.openlinksw.com/wiki/main/Main/VOSSPARQL , particularly the list of example queries linked at http://virtuoso.openlinksw.com/wiki/main/Main/VOSODSSparqlSamples ? They might help somewhat. HTH, ~Tim -- Tim Haynes Product Development Consultant OpenLink Software <http://www.openlinksw.com/>
