Re: [Rdfapi-php-interest] beginner SPARQL question

[John V. <ja...@gm...>]

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