Re: Has E/R had a negative impact on db?
From: J M Davitt <jdavitt_at_aeneas.net>
Date: Sun, 23 Apr 2006 16:43:43 GMT
Message-ID: <39O2g.13337$P2.2577_at_tornado.ohiordc.rr.com>
>
>
> Technically, the latter statement is untrue. Codd distinguishes
> relations and relationships in his early papers, but most folks don't
> any longer.
Date: Sun, 23 Apr 2006 16:43:43 GMT
Message-ID: <39O2g.13337$P2.2577_at_tornado.ohiordc.rr.com>
Bob Badour wrote:
> Jay Dee wrote:
>
>> Neo wrote: >> >>>>>> Just a thought. I don't like entities. In fact I despise entities, >>>>>> as the enemy of good information philosophy. >>>>> >>>>> >>>>> What is your definition of an entity? What steps would one go through >>>>> to verify something is an entity? >>>> >>>> >>>> I refer to them as they are specified by Chen. I've already pointed out >>>> I believe their specification is impossible above simply being >>>> arbitrary so your second question makes no sense to me. >>> >>> >>> Ok, I just wanted to make sure there isn't anything in RM that would be >>> considered an entity. >> >> >> There is nothing in the RM called "entity." >> There is nothing in the RM called "relationship."
>
>
> Technically, the latter statement is untrue. Codd distinguishes
> relations and relationships in his early papers, but most folks don't
> any longer.
Technically, yes; but the relationship Codd described is nothing like the relationships Chen (sort of) described.
Similarly, Date and Darwen have dropped the term 'domain' in
> favour of 'type', which decision certainly eliminates a lot of explaining.
In TTM3, they've stopped using familiar terms because they were familiar terms; no longer does the prose seem to gently guide readers along the path to enlightenment. (This, I think, is due mostly to Darwen's style.) Received on Sun Apr 23 2006 - 18:43:43 CEST