Re: Foreign key problem
Date: Mon, 19 Jun 2006 16:19:01 +0300
"paul c" <toledobythesea_at_oohay.ac> wrote in message news:p9Bkg.46469$IK3.24667_at_pd7tw1no...
> Thanks very much for typing that in. It does look to me as if Codd had
> coherence in mind because he talks of holding a relational database
> together even though his example may be too deep for me.
That's because the context I quoted was *minimal*.
> The test of
> splitting the database eludes me because I don't see how domains and
> relations could be separated. I thought of a relation as being a set of
> sets of mappings between individual values of domains, meaning to me
> that loosely, relations result from "gluing" subsets of domains together
> so I didn't see how one could 'subtract' domains and still be able to
> 'see' a relation.
The example talk about "*alleging* that a relational database viewed as a collection CD of domains and a collection CR of relations *could* be split"
The split is not in CD and CR, but (CD - cd, CR-cr) and (cd, cr). Received on Mon Jun 19 2006 - 15:19:01 CEST