Re: Problem with graphs in SPARQL query in

[Andy Seaborne]

On 27/05/16 14:23, Mikael Pesonen wrote:

Hi,

This query does what i want, that is, lists all graphs having the term
"digitalisaatio"@fi:

PREFIX skos: <http://www.w3.org/2004/02/skos/core#>
PREFIX dcterms: <http://purl.org/dc/terms/>
PREFIX dc: <http://purl.org/dc/elements/1.1/>
SELECT ?s ?graphTitle1  ?graphTitle2
WHERE {
GRAPH ?graph
{
         ?s skos:prefLabel "digitalisaatio"@fi

         OPTIONAL { ?graph dcterms:title ?graphTitle1 }
}}



But when I add new param
OPTIONAL { ?graph dc:title ?graphTitle2}

so that new query is this:
PREFIX skos: <http://www.w3.org/2004/02/skos/core#>
PREFIX dcterms: <http://purl.org/dc/terms/>
PREFIX dc: <http://purl.org/dc/elements/1.1/>
SELECT ?s ?graphTitle1  ?graphTitle2
WHERE {
GRAPH ?graph
{
         ?s skos:prefLabel "digitalisaatio"@fi

         OPTIONAL { ?graph dcterms:title ?graphTitle1 }
         OPTIONAL { ?graph dc:title ?graphTitle2}
}}

This will depend on your data model.

Do you have a complete, minimal example? (some small amount of data and 
a query that you expect to work).

I dont get all the graphs anymore. OPTIONAL should never filter out
data, just add? There must be a logical explanation, but I'm not getting
it. Im using Fuseki.

Which version?

        Andy

By the way:

OPTIONAL { ?graph (dcterms:title|dc:title) ?graphTitle1 }

asks for either dcterms:title or dc:title or both.


Br,
Mikael