- From: Richard Cyganiak <richard@cyganiak.de>
- Date: Wed, 18 May 2011 15:54:05 +0100
- To: Enrico Franconi <franconi@inf.unibz.it>
- Cc: Ivan Herman <ivan@w3.org>, Pat Hayes <phayes@ihmc.us>, Michael Hausenblas <michael.hausenblas@deri.org>, W3C RDB2RDF <public-rdb2rdf-wg@w3.org>
On 18 May 2011, at 14:20, Enrico Franconi wrote: > Please let me note first that my arguments are not about "what a NULL value possibly does mean among various possibilities", but they are about "what a NULL value normatively means in the SQL standard". RDF cannot express the complete semantics of SQL NULLs. A complete “direct mapping” is not possible without changing the semantics of RDF to closed-world and adding three-value logic to SPARQL. I believe that this WG has not been chartered to do that. > To mimic this in RDF2RDF, my suggestion would be to translate a NULL value as a special constant from a special datatype, and then we should provide precise directives on how a query language should deal with this. This is not a good solution. As far as I know, no one implements anything like it, and no implementer or user is requesting it. I conclude that it is not needed and a waste of WG resources. Best, Richard
Received on Wednesday, 18 May 2011 14:54:34 UTC