Re: WWW/Internet 2009: 2nd CFP until 21 September
From: paul c <toledobythesea_at_oohay.ac>
Date: Thu, 13 Aug 2009 02:00:16 GMT
Message-ID: <QsKgm.38900$Db2.18218_at_edtnps83>
>
> I'm even more confused.
>
>
Date: Thu, 13 Aug 2009 02:00:16 GMT
Message-ID: <QsKgm.38900$Db2.18218_at_edtnps83>
Mr. Scott wrote:
> "paul c" <toledobythesea_at_oohay.ac> wrote in message
> news:IYAgm.40873$PH1.30537_at_edtnps82...
>> Mr. Scott wrote: >> ... >>> I'm confused. What requirement are you referring to? Are you referring >>> to the requirement that nulls be eliminated or the fact that an order >>> isn't an order without a delivery destination? The referential cycle was >>> a consequence of trying to eliminate nulls. ... >> I meant the requirement that a delivery address can't be recorded without >> an order date.
>
> I'm even more confused.
>
>
- in SQL, just what does decompositon of tables mean? Does it mean what relational decomposition means, ie., lossless projection, or something else?
- (allow me to drop the parenthesis and use braces, just because it makes me happier to avoid any nuance of implementation language) Does the relation {X,A,B,C} have one predicate or several?
- If the answer to 2) is 'several predicates', is this because a
disjunction is involved or because nulls are involved and what are those
predicates?
- if the answer to 2) is 'one predicate', what does projection on any of the four columns mean?