[Mulgara-dev] Problem w/ "insert select ..."
Andrae Muys
andrae at netymon.com
Thu Mar 29 03:36:22 UTC 2007
On 29/03/2007, at 11:08 AM, Eric Brown wrote:
>
> I also tried inserting into a different model -- same error. It
> also seemed like I should have been able to make the query simpler
> -- insert select $s <http://rdf.topazproject.org/RDF/
> organizationType> 'bar' from <...> where $s <http://
> rdf.topazproject.org/RDF/organizationType> 'foo' into <...> -- but
> that's how I saw the error the first time and expanded it just in
> case mulgara was demanding variables instead of just tuples.
>
> I can open a JIRA issue, but I thought I'd double check that it
> isn't something stupid I'm doing first.
This is a known bug, http://mulgara.org/jira/browse/MGR-43. The
simpler query you mention is indeed the intended phrasing.
> BTW, What I'm really need to do is insert followed by delete. It
> would be nice if ITQL had a "update select ..." or "replace
> select ..." ability.
Neither update nor replace have any meaning when working with rdf.
Updating a _property_ of an _instance_ is an operation that only
makes sense when you have a concept of an _instance_ ---
correspondingly update is an rdfs level operation. What mulgara does
provide is the concept of a transaction. OTOH I would like to see
improved support for compound operations. Something along the lines
of haskell's do syntax combined with a query/operation monad. I've
been referring to this as let-expressions, but really it about
providing the ability to integrate side-effects (insert/delete)
cleanly into sequences/sets of queries.
Andrae
--
Andrae Muys
andrae at netymon.com
Principal Mulgara Consultant
Netymon Pty Ltd
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