On 25/09/13 15:10, Sven R. Kunze wrote:
On 09/25/2013 04:02 PM, Dave Reynolds wrote:
On 25/09/13 14:57, Sven R. Kunze wrote:
On 09/25/2013 03:53 PM, Dave Reynolds wrote:
Hi Damian,
On 25/09/13 14:16, Damian Steer wrote:
On 25/09/13 12:03, Stuart Williams wrote:
On 25/09/2013 11:26, Hugh Glaser wrote:
You'll get me using CONSTRUCT soon :-)
(By the way, Tim's actual CONSTRUCT WHERE query isn't allowed
because
of the FILTER).
Good catch... yes - I've been bitten by that kind of thing too...
that
not all that's admissible in a WHERE 'body', is admissible in a
CONSTRUCT 'body'.
As far as I'm aware it is -- Tim's original simply misplaced a curly
brace. The filter ought to be in the WHERE body.
CONSTRUCT is essentially SELECT with a tabular data -> rdf system
bolted
at the end of the pipeline.
I think the point people were making is that the syntactic shortform
"CONSTRUCT WHERE" with implicit template only applies when you have a
simple basic graph pattern [1].
If the WHERE clause is more complex, e.g. with a FILTER, then you need
an explicit construct template.
Dave
[1] http://www.w3.org/TR/sparql11-query/#constructWhere
How did you come to that conclusion?
Based on the part of the specification given by link [1] above, which
says (my emphasis):
"A short form for the CONSTRUCT query form is provided for the case
where the template and the pattern are the same and the pattern is
just a basic graph pattern **(no FILTERs and no complex graph patterns
are allowed in the short form)**."
Dave
I see, Dave. However, my intention was to understand the reason behind
that decision. This quote is not a justification, just a description of
what's expected to work.
I can't see why restricting the set of where clauses is necessary.
You can consult the email archives and telecon meeting minutes for the
discussions. The spec is not going to have a justification for every
decision; that's not a spec anymore!
It gets increasingly difficult to define what the implicit template
should be. What about OPTIONALS? UNION? Subquery? There was a
consideration of BGP+FILTER.
In the end, given the constraints of time and other features, the simple
case (simple to explain, to implement and to specify) where the
template and the WHERE pattern are the same was put in the spec.
Otherwise you need to give the relation of WHERE to template.
Andy
