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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@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 - 11:43:43 CDT

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