It's great that you wrote an introduction to RDF with database folks in mind.
However, as the comparisons between RDF and SQL databases become more detailed, so the suspicion grows that anything you do in RDF can also be usefully done in SQL augmented with recursion or iteration. It may be just a question of being a bit sophisticated about how you design the representation of metadata, subclasses, inheritance, URIs, and so forth into relational tables. Then you could get the benefit of industrial strength reasoning over gigabytes of data.
To illustrate the SQL+recursion approach, there's an executable little example of second order inheritance via ISA, called SemanticWebOntology1, at
Here's a way to explore this further that may lead to some rather robust debate. Try posting your introduction to RDF to the database lists below. This is likely to generate quite a bit heat, but also hopefully some enlightenment for both the RDF and database communities.
Hope this helps. Cheers, -- Adrian
Business Rule Applications in English, Using Your Oracle Database
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The following is an article I wrote for some friends, to help them
understand RDF after coming from a relational database point of view.
It might be a little inaccurate in places, but the concepts are fairly
Feel free to print, post and/or modify: I'm putting this into the public
domain. Attribute it to me (email@example.com) if you like, but
that's not a requirement either.