Jan, not clear why you might need bnodes, but one
solution to your problem is to create some unique URI. The INSERT
will then be applied for each match, but the same triple is
generated. hence only one triple is generated for each ?who
binding. For example:
INSERT
{ ?uri example:represents ?who .
}
WHERE
{ ?who example:knows ?whom .
BIND (smf:buildUniqueURI(":something") AS ?uri)
}
-- Scott
On 9/3/11 11:05 AM, Jan Polowinski wrote:
Hello Scott, thank you for the very quick response.
Jan,
the WHERE clause of all SPARQL queries is applied to the
current data graph. CONSTRUCT, INSERT, DELETE, etc. are
applied to the results of the WHERE clause. Therefore
the WHERE clause cannot recursively consider any
INSERTs/DELETEs to the data.
To query the result of inserting some data, you will
need to apply two queries: the insert, then the query.
So it will be something like the following
So I will have to create two queries - one for inserting
the triples and then a second to remove the "duplicates"
that are created without the NOT EXISTS.
In the example, the goal is to create the "represents"
triple exactly once, even when a resource is involved in
multiple knows relations.
So for the (likely) case ...
Peter
knows Tom
Peter knows
Mary
I'd like to create ...
_:go1
represents Peter
but not ...
_:go1
represents Peter
I think a second query deleting the duplicates will do
the job then. Although I don't quite like the idea of
creating triples just to delete them in the next step.
(I
wasn't really able to understand the intent of your
query):
(Go stands for graphic object here. A parallel graph of
graphic objects shall be constructed for the source data.)
Thank you again for clarifying this though it was only a
SPARQL-question, as it seems.
Jan
INSERT
{ #using GRAPH to explicitly state where the data is
inserted in highly recommended
_:0 a :GO .
_:0 :represents ?who .
}
WHERE
{ ?who :knows ?whom .
}
...then you can query the resulting graph:
SELECT ?who ?whom
WHERE
{ ?who :knows ?whom .
NOT EXISTS
{ ?someGO :represents ?who .
} .
}
...which is a strange query because it cannot match
anything after the INSERT.
--
Scott Henninger
Sr, Product & Support Engineer, TopQuadrant, Inc.,
tel: 402-429-3751 / fax: 703 991-8192 / main: 703
299-9330
Training:
Semantic
Technology Training and Intro to TopBraid - Sept.
12-15, 2011, Washington, DC
TopBraid
Advanced Products Training - Sept. 26-29, 2011,
Washington, DC
TQ Blog: Voyages
of the Semantic Enterprise
On 9/3/11 8:28 AM, Jan Polowinski wrote:
I'm trying to construct a graph depending on
a) an existing graph +
b) the already created part of the new graph.
Does the WHERE part of an INSERT statement only consider the graph before starting the INSERT? Or should it consider the newly created triples already? Here is what I tried:
# construct a GO for all subjects in knows-relations
INSERT {
_:0 a :GO .
_:0 :represents ?who .
}
WHERE {
?who :knows ?whom .
NOT EXISTS {
?someGO :represents ?who .
} .
}
Although using NOT EXISTS, in the first run, I create more blank nodes than I want to. In additional runs then everything works as expected.
I'm happy for any hints. Do I expect too much of SPARQL here? Or am I only missing some setting? I could not explicitly find something about this issue in the SPARQL 1.1 Update specification. Does anybody know an alternative to achieve that the newly created triples are immediately considered in the WHERE clause?
Jan
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Dipl. Medien-Inf. Jan
Polowinski
Research Assistant
Technische Universität
Dresden
Department of Computer
Science
Software- and
Multimedia-Technology
01062 Dresden
Phone: +49 351 463 38608
Mobil: +49 176 80158257
E-Mail: [email protected]
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