Good evening, I am trying to get through the tutorial (I am beginner) and I am experiencing unexpected behavior of these queries (even if Im copypasting the tutorials): Here is the link to referenced tutorial page: https://jena.apache.org/tutorials/sparql_datasets.html
First attempt, this query works fine: PREFIX xsd: <http://www.w3.org/2001/XMLSchema#> PREFIX dc: <http://purl.org/dc/elements/1.1/> PREFIX : <.> SELECT * { ?s ?p ?o } Results: ---------------------------------------------------------------------- | s | p | o | ====================================================================== | :ds-ng-2.ttl | dc:date | "2005-09-22T05:53:05+01:00"^^xsd:dateTime | | :ds-ng-1.ttl | dc:date | "2005-07-14T03:18:56+01:00"^^xsd:dateTime | ---------------------------------------------------------------------- Second, this works pretty good too: PREFIX xsd: <http://www.w3.org/2001/XMLSchema#> PREFIX dc: <http://purl.org/dc/elements/1.1/> PREFIX : <.> SELECT * { { ?s ?p ?o } UNION { GRAPH ?g { ?s ?p ?o } } } Results not absolutely the same (the referenced named graph names are not exactly the same in the first and the third column (the colon missing and the <> instead), and I was not able to change this, although I was trying pretty hard as I thought that there could be the cause of my issue) --------------------------------------------------------------------------------------------- | s | p | o | g | ============================================================================================= | :ds-ng-2.ttl | dc:date | "2005-09-22T05:53:05+01:00"^^xsd:dateTime | | | :ds-ng-1.ttl | dc:date | "2005-07-14T03:18:56+01:00"^^xsd:dateTime | | | _:b0 | dc:title | "Harry Potter and the Chamber of Secrets" | <ds-ng-1.ttl> | | _:b1 | dc:title | "Harry Potter and the Philospher's Stone" | <ds-ng-1.ttl> | | _:b2 | dc:title | "Harry Potter and the Sorcerer's Stone" | <ds-ng-2.ttl> | | _:b3 | dc:title | "Harry Potter and the Chamber of Secrets" | <ds-ng-2.ttl> | --------------------------------------------------------------------------------------------- Now, this query is the first that doesnt work at all: PREFIX dc: <http://purl.org/dc/elements/1.1/> PREFIX : <.> SELECT ?title { GRAPH :ds-ng-2.ttl { ?b dc:title ?title } } Results are blank all the time: --------- | title | ========= --------- Same result with this query: PREFIX xsd: <http://www.w3.org/2001/XMLSchema#> PREFIX dc: <http://purl.org/dc/elements/1.1/> PREFIX : <.> SELECT ?date ?title { ?g dc:date ?date . FILTER (?date > "2005-08-01T00:00:00Z"^^xsd:dateTime ) GRAPH ?g { ?b dc:title ?title } } I have tried many things I googled out (but no exact solution for this problem) and nothing worked, I have no idea what could be wrong. Thanks for every support.
