Re: Examples of SQL anomalies?

paul c <toledobysea@xxxxxxxx> wrote:

Bob Badour wrote:
Marshall wrote:

On Jun 30, 10:31 am, "Brian Selzer" <br...@xxxxxxxxxxxxxxxxxxx> wrote:

Well, the OP wanted examples of SQL anomalies, and you've just
confirmed a
big one.

If you have a bag that can contain peaches, but doesn't, then the
answer to
the question "How many peaches are in the bag?" is clearly zero. If
you are
asked by the accountant, "How much were we billed by AT&T this
month?" but
AT&T didn't send a bill, then the answer is clearly zero. That SQL's
COUNT
and SUM are something other than these common sense usages
exemplifies their
anomalous nature.

[I meant to say this in my other post, but]

Brian gets it exactly right here.

Well, except that SQL adds the additional anomaly that
count(*) != sum(1)

ie. SQL can count zero rows with count but not with sum.

I was hoping you two would pipe up about this because as usual, it is
completely unclear whether CELKO is trying to answer the OP's question
or whether he is trying to justify SQL's myriad behaviours. (Not
claiming this is deliberate, though I do have my suspicions!)

Fabian Pascal would say that he is doing a Celko. Now, I have a
sample of my own. Pulling in transfinite numbers to justify SQL's
sum() nonsense is nonsense itself.

Not that I know much about SQL, having given up on it many years ago.

On the matter of 'common sense', I've learned not to trust it, at least
as a first principle, as it often turns out to be a cover phrase meaning
'that's what I thought in the first place' and thus varies dramatically
depending on the person, the moment and the lingo in play. For sure,
bringing up intricate arbitrary logics like Johnston's is phony in this
case. Elementary logic such as described, say, by Bertrand Russell (who
had far fewer axes to grind than Celko and Johnston), in which the empty
set has zero members, happens to agree with Brian S's common sense, so
everybody except of course for the technocratic apologists and
opportunists ought to be content that SQL once again paints itself into
a corner.

It is pretty simple, but gets sold as being difficult.

OTOH, it may be that elementary logic is obscure to many and will
always be so. I remember a first-year logic course where fully three
quarters of 300 exam candidates walked out of the hall in the first five
minutes. I know they weren't finished. (Not sure if it had anything to
do with the professor who was often hospitalized or on crutches because
of his habit of not looking when he crossed the road.) However Celko is

It may have a few surprises, but it is not really that bad.

devious by suggesting that clear explanation lies in the further
complications he touts. He is actually promoting unnecessary and faux
elitism. Also, if it is indeed the case that the average programmer who

Quite.

has grown up at the knees of mostly physical concepts is incapable of
understanding Russell, that can only be an argument for avoiding the
arbitrariness of SQL.

Logic may have a few tricks and traps to it, but it sure beats
the alternatives.

There are a few tricks in FOL that can trip anybody up, but far fewer
than the rather amateur legalese the SQL standard contains.

Quite.

Sincerely,

Gene Wirchenko

Computerese Irregular Verb Conjugation:
I have preferences.
You have biases.
He/She has prejudices.
.

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