- From: Steve Harris <S.W.Harris@ecs.soton.ac.uk>
- Date: Tue, 4 Nov 2003 12:27:48 +0000
- To: www-rdf-interest@w3.org
On Mon, Nov 03, 2003 at 09:28:20 +0000, Bill de hÓra wrote:
> Suppose I had a data set pertaining to a single person, or a
> business, but that person or business has no URI identifier (and
> probably can't be allowed to have one). I imagine I'd use a bnode or
> something in RDF to hang the properties off.
>
> How would I best model the data set so I could hang a property of it
> in turn?
Some RDF engines (including mine, 3store) record the source of each
triple against an RDF context. RDF itself doesnt specify a way of doing
this, except arguably reification, but I dont think many people would
recomment you use that.
3store exposes context as a 4th segment of the RDQL expression, so you can
make queries like:
SELECT ?s, ?p, ?o
WHERE (?s, ?p, ?o, ?c),
(?c, <dc:creator>, "Bill de hÓra")
i.e. "return all the triples in graphs created by Bill de hÓra"
?c and co. can be used just like any other RDQL variable.
Caveats:
This is a nono-standard extension to RDF (theres no requiremnt to record
the source of a triple, many engines dont)
It only works at the file level (RDF has no finer contextm mechanism)
Its a non-standard extension to RDQL, to allow you to specify the
model/source/context of a triple.
- Steve
Received on Tuesday, 4 November 2003 07:27:49 UTC