Michal,
It looks like the use of "--namedgraph" isn't expanding the URI
In "--namedgraph ds-ng-1.ttl", "ds-ng-1.ttl" isn't an absolute URI and
it isn't being expanded. If it had, it would be
file:///whatever/ds-ng-1.ttl and because <.> is really
<file:///whatever/> it would be abbreviated.
A work aroung is to use file://$PWD/ds-ng-1.ttl (Linux, MacOS) or the
Windows equivalent.
When a query is parsed, GRAPH :ds-ng-1.ttl is expanded.
You might find it helpful to try the queries without "PREFIX :
<.>" so the full URIs are printed.
If you get FILE in the --namedgraph FILE to be the absolute URI (same
characters) then the abbreviation should work.
Andy
On 08/07/18 22:57, michal.r.256 wrote:
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.
