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Re: Constraints and Functional Dependencies

From: Bob Badour <bbadour_at_pei.sympatico.ca>
Date: Wed, 28 Feb 2007 03:06:15 GMT
Message-ID: <Hk6Fh.2275$PV3.31034@ursa-nb00s0.nbnet.nb.ca>


Gene Wirchenko wrote:

> mAsterdam <mAsterdam_at_vrijdag.org> wrote:
>

>>paul c wrote:
>>
>>>mAsterdam wrote:
>>>
>>>>...
>>>>A rephrase to (i) could be:
>>>>
>>>><reference>
>>>>(i a)
>>>>    A relation R with attribute a (written as R(a)) having
>>>>    a as a reference into S(b)
>>>>    is expressed as follows:
>>>>
>>>>        forall R(a): exists S(b): a = b
>>>>
>>>>        Note that b need not be a ck to S, hence 'into', not 'to'.
>>>></reference>
>>>>
>>>>But what exactly is the reference referencing?
>>>
>>>I'm sure there is a term for that kind of English phrasing.  For myself, 
>>>the phrase "reference referencing" seems unnecessarily ornamental.  

Passive voice. Rephrasing in the active voice, one gets "But what exactly does the reference reference?" or "But what exactly does the reference refer to?"

I think of the passive and reflexive voices as 'weak' but I suppose 'ornamental' works too.

>>Ornamental? I am a non-native speaker of English - maybe a
>>native speaker (you are, aren't you?) can put into less words
>>than this what I mean with it.

Plenty of native english speakers would use the passive voice just as mAsterdam did. I find continental europeans no more likely to use the passive or reflexive voices than anglophones. South asians on the other hand...

A continental european is much more likely to use a stronger active voice like: "But to what exactly refers the reference?"

>>How would you say: "The stuff referenced is not a tuple in S, >>but a subset of S".

A tuple is a subset of S. I would simply say the value exists in S.

> "What is referred to is not a tuple in S, but a subset of S."
>
> I am confused by it though. Do you mean "What is referred to is
> a subset of S." (emphasis on set) or "What is referred to is a tuple
> in a subset of S." (subset definition not specified)?

He wants to emphasize the relative cardinality could be greater than 1.

>>>In ordinary English, one relation references another. 

>
> ^^^^^^^^^^
> "refers to".
Or references. In data management, one more often sees the verb "to reference" than the verb "to refer to". I don't know whether the SQL
keyword drives that preference or whether someone chose a less-popular verb to emphasize a precise technical definition.
>>One relation may reference several others.
>>What do you call the individual referencing attribute sets?

>
> I do not know.
>
>
>>What do you call the stuff being referenced?

>
> "referee" is possible, but probably "target" or "object".
>
> [snip]
>
> Sincerely,
>
> Gene Wirchenko
>
> Computerese Irregular Verb Conjugation:
> I have preferences.
> You have biases.
> He/She has prejudices.
Received on Tue Feb 27 2007 - 21:06:15 CST

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