On 26/01/06, Seaborne, Andy <and...@hp...> wrote:
>
>
> John Vandenberg wrote:
> > Hi,
> >
> > I am trying to select a set of data out of a Mozilla extension
> > install.rdf file. I am using SPARQL because it will be easy for
> > developers to pick up and learn.
> >
> > My problem is that when an optional entry doesnt exist (iconURL), none
> > of the fields are returned. This is the query I was trying to
> > perform.
> >
> > SELECT ?version, ?name, ?description, ?creator, ?icon
> > WHERE (?x, <em:version>, ?version),
> > (?x, <em:name>, ?name),
> > (?x, <em:description>, ?description),
> > (?x, <em:creator>, ?creator),
> > (?x, <em:iconURL>, ?icon)
> > USING em FOR <http://www.mozilla.org/2004/em-rdf#>
> >
> > To work around this, I am individually selecting each optional piece
> > of data. Can this be improved on?
> >
> > --
> > John
>
>
> That syntax is RDQL not SPARQL.
Sorry for the confusion; I am in the process of converting to SPARQL.
> That query exactly translated is:
>
> PREFIX em: <http://www.mozilla.org/2004/em-rdf#>
>
> SELECT ?version ?name ?description ?creator ?icon
> WHERE
> { ?x em:version ?version ;
> em:name ?name ;
> em:description ?description ;
> em:creator ?creator ;
> em:iconURL ?icon .
> }
>
> (Mechanical translation by program - but not a PHP program :-()
>
> and adding optional for iconURL:
>
> PREFIX em: <http://www.mozilla.org/2004/em-rdf#>
>
> SELECT ?version ?name ?description ?creator ?icon
> WHERE
> { ?x em:version ?version .
> ?x em:name ?name .
> ?x em:description ?description .
> ?x em:creator ?creator .
> OPTIONAL { ?x em:iconURL ?icon . }
> }
>
> a little more neatly that is:
>
> PREFIX em: <http://www.mozilla.org/2004/em-rdf#>
> SELECT ?version ?name ?description ?creator ?icon
> WHERE
> { ?x em:version ?version ;
> em:name ?name ;
> em:description ?description ;
> em:creator ?creator .
> OPTIONAL
> { ?x em:iconURL ?icon .}
> }
>
> Hope that helps,
Yes, thanks. Am I right that RDQL does not offer similar functionality?
Also, the docs say that SPARQL support in rdfapi-php requires php 5.1;
are there specific problems that can be fixed or avoided in order to
run it on a locked down Redhat ES3 box with php 4.3.2 ?
--
John
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