Re: relational mapping?

On Thu, 3 May 2001, Danny Ayers wrote:

> Has anyone come across a mapping of the relational model to RDF? I'm sure
> there's a pretty direct one possible at a low level (tuple to tuple I
> suppose), but it'll save me some thought and a lot of time if someone's
> already looked into this. Alternatively, if there's an RDFS around that
> contains RDBMS terms (schema, table, column etc) I'd very much like to hear
> about it. I'm wanting to operate at this latter level, but it would be nice
> to be on firm foundations.

I've done quite a bit of thinking about it; got some paper notes which
I'm in the (slow) process of typing up. You're right, there's a simple
mechanical mapping of rows in a table to RDF; what you lose by this is
the natural linking of properties.

For a sufficiently normalised relational schema*, you can generally
produce a mapping
	(primary key) -> resource
	(other values) -> properties
	(foreign key) -> link to resource representing primary key for
			foreign table

jan

* that is, very (what, fifth NF?): for instance, moving one-to-one data
into a separate table if the data describes a separate concept; it's
generally possible to produce a normalised schema from a less normalised
(ie, more real-world) one with the judicious use of views.

-- 
jan grant, ILRT, University of Bristol. http://www.ilrt.bris.ac.uk/
Tel +44(0)117 9287163 Fax +44 (0)117 9287112 RFC822 jan.grant@bris.ac.uk
( echo "ouroboros"; cat ) > /dev/fd/0 # it's like talking to yourself sometimes