[Rdfapi-php-interest] beginner SPARQL question

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

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