- From: Eric Prud'hommeaux <eric@w3.org>
- Date: Mon, 7 Dec 2009 18:32:47 -0500
- To: public-rdb2rdf-wg@w3.org, Alexandre Bertails <bertails@w3.org>
* Eric Prud'hommeaux <eric@w3.org> [2009-12-05 17:16-0500] > I'll be working on this more, but here's a start on the slides > introducing algebra for RDB->RDF and (corresponding) SPARQL->SQL > mappings. I broke the link on the wiki (pointed to my laptop). http://www.w3.org/2009/Talks/1215-SWObjects-egp/ covers everything I want to tomorrow. I've covered most of the algebra differences between SPARQL over an SQL triples view and SPARQL over generic (e.g. 3FN) relational data. I know that a lot of this requires the narrative in my head, but if anyone notices something conspicuously absent by tomorrow's call, let me know. > If folks want to play with this stuff, try downloading > the appropriate SPARQL from > http://sourceforge.net/projects/swobjects/files/ > and executing "SPARQL -s http://hr.example/DB/ -e > "PREFIX emplP: <http://hr.example/DB/Employee#> > SELECT ?empName ?managName > WHERE { ?emp emplP:lastName ?empName . > ?emp emplP:manager ?manager . > ?manager emplP:lastName ?managName }" > > You should see: > > SELECT emp.lastName AS empName, manager.lastName AS managName > FROM Employee AS emp > INNER JOIN Employee AS manager ON manager.id=emp.manager > > which corresponds closely (modulo NULLs) to the results expected in > http://www.w3.org/2008/07/MappingRules/StemMapping#bgp1 > > The pitch is that this is a doable and useful task and that the world > will buy us many beers for accomplishing this. > -- > -ericP -- -ericP
Received on Monday, 7 December 2009 23:33:23 UTC