- From: Enrico Franconi <franconi@inf.unibz.it>
- Date: Wed, 18 May 2011 09:30:15 +0200
- To: Juan Sequeda <juanfederico@gmail.com>
- Cc: Ivan Herman <ivan@w3.org>, Richard Cyganiak <richard@cyganiak.de>, public-rdb2rdf-wg@w3.org
On 18 May 2011, at 06:59, Juan Sequeda wrote: > So does that mean that you would translate all NULL values to a triple with rdb2rdf:NULL? That makes sense and would make the current direct mapping information preserving. Definitely not. Take the case of a RDB with a Person table, having ID, name, and age. If you query (in SQL with a simple conjunctive query) all the people with the same age of a specific person in the table having a NULL value as age, you do *not* get the people whose age is a NULL value. However, with your naive translation in RDF of this database, you would get the wrong answer with the same query translated in SPARQL. cheers --e.
Received on Wednesday, 18 May 2011 07:30:44 UTC