- From: Alexandre Bertails <bertails@w3.org>
- Date: Thu, 19 May 2011 14:32:40 +0200
- To: David McNeil <dmcneil@revelytix.com>
- Cc: Enrico Franconi <franconi@inf.unibz.it>, Richard Cyganiak <richard@cyganiak.de>, Ivan Herman <ivan@w3.org>, Pat Hayes <phayes@ihmc.us>, Michael Hausenblas <michael.hausenblas@deri.org>, W3C RDB2RDF <public-rdb2rdf-wg@w3.org>
On Thu, 2011-05-19 at 07:28 -0500, David McNeil wrote: > > > Again, we have already agreed we would provide the information > about the > schema, meaning that is actually possible to retrieve the NULL > values. > > Is it right? > > > Alexandre - Not from my perspective. I don't see how relational schema > information allows for the inferencing of Bob's age from the example > below. I think an explicit triple like: <200> <age> <NULL> or <Bob> > <age> <NULL> is required to preserve the presence of the NULL in the > [200 NULL] tuple. If I have the schema, I know where I expect to find the value. If I don't find it, I can deduce it's coming from a NULL. Alexandre. > > > ID NAME > > 100 Joe > > 200 Bob > > 300 Sue > > > > ID AGE > > 100 30 > > 200 NULL > > -David >
Received on Thursday, 19 May 2011 12:32:53 UTC