Re: A simple notation, again
Date: Tue, 17 Jul 2007 23:44:47 GMT
Message-ID: <Pvcni.126327$xq1.124179_at_pd7urf1no>
Bob Badour wrote:
> paul c wrote: >
>> Brian Selzer wrote:
...
>>> I don't think this is quite right.
>>>
>>> Suppose t is a tuple whose presence in A or in B would not violate
>>> any constraints. Then t must necessarily be an element of either A
>>> or its complement, and t must necessarily be an element of either B
>>> or its compliment. Now, if t does not appear in A union B, then t
>>> must necessarily be an element of both the complement of A and the
>>> complement of B. As a result, an insert of t into the view, A union
>>> B, does not map to any one of these operations: (1) an insert of t
>>> into A, (2) an insert of t into B, or (3) an insert of t into both A
>>> and B.
>>> ...
>>
>>
>> I mentioned "insert ... to a view" but I think I shouldn't have,
>> because dbms's don't insert into views!
> > > But they damned well should!
Heh, you betcha mister president, General Buck Turgidson might have said that. I'll call you Buck and you can call me Dr. Strangelove. He went a little ape when he found out that Premier Kissoff was keeping the Doomsday Machine a secret. Views are a clever make-believe and by definition, at least person must be aware of the secret (that the view isn't a base table/relvar). I don't know why I keep getting drawn into these arguments based on views having tuples, which they don't, and views having complements, which they don't, only the base relvars/relations/tables have tuples and complements. Most users don't need to know this but the ones that do know the secret shouldn't pretend otherwise.
p Received on Wed Jul 18 2007 - 01:44:47 CEST