Hello Eddy, > 1. A simple SPARQL select query: > I've been running similar to the next query, in hundreds of variants > (with parameters) but I don't get a reply in Virtuoso: > > PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> > SELECT ?s ?p ?pl ?o > where { > <#SdnEntry_2786786> ?p ?o . > ?p rdfs:label ?pl . > }
?s is unbound (because it is not used at all) and not optional at the same time, resulting in empty result set. Either remove ?s from SELECT result set list or write something like PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> SELECT ?s ?p ?pl ?o where { ?s ?p ?o . ?p rdfs:label ?pl . . filter (?s = <#SdnEntry_2786786>) } > When I make the union: > PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> > SELECT ?s ?p ?pl ?o > where { > {<#SdnEntry_2786786> ?p ?o} > UNION > {?p rdfs:label ?pl} > } > I get the pairs property/value and property/label separately. > So, I can't filter the result neither. Yes, you have a "concatenation" of all properties of <#SdnEntry_2786786> and all labels of all properties. These two branches of UNION are totally independent from each other. That's probably not what you want. Best Regards, Ivan Mikhailov OpenLink Software http://virtuoso.openlinksw.com
