Re: separation of church and state?

From: paul c <>
Date: Sun, 07 Oct 2007 15:40:41 GMT
Message-ID: <Z57Oi.506$th2.148_at_pd7urf3no>

Roy Hann wrote:
> "Marshall" <> wrote in message

>> On Oct 6, 9:48 am, "Roy Hann" <specia..._at_processed.almost.meat> wrote:
>>> "paul c" <> wrote in message
>>> news:hoONi.6504$_K.2827_at_pd7urf3no...
>>>> It seems a little doctrinaire to me.  I can agree that the "result 
>>>> isn't a
>>>> relation" but on the other hand a user could see such a result without
>>>> knowing that "ORDER BY" was involved and not be faulted for taking it 
>>>> to
>>>> be a relation.
>>> What user ever would?  Users never see relations. They see various kinds 
>>> of
>>> reports (using the word "report" to mean anything users get to see).

> [goofy stuff snipped]
>> All that goofy stuff I wrote above can be argued for, but why?

> That was pretty much my point: Paul was thinking about possibly true facts
> but in an irrelevant framework.
> Roy

Could be. Maybe one of Date's meanings is that no system that supports both ordering and some relational algebra is purely relational, even if the "pure" relational part of it could be isolated in some way from the rest! If so, calling the paragraph "doctrinaire" might be a bit of a slur.

Also, I should say that my main interest in this stuff is nearly always implementation, this includes making sure that an implementation doesn't veer off in directions that aren't sound.

When Codd himself talked of projection and "desired permutation" (admittedly he was talking of columns, not rows) I think an ordinary person could be forgiven for not separating the above two "parts" of a system. When it comes to implementations, I'd fault one that performed a presentation sort that wasn't "any desired permutation" (as Codd put it) but I wouldn't blame one that happened to echo some ordering that was already present in its "stored representation". Received on Sun Oct 07 2007 - 17:40:41 CEST

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