Re: In an RDBMS, what does "Data" mean?
Date: Sat, 15 May 2004 00:30:41 GMT
Message-ID: <Rwdpc.824$SZ4.41_at_newsread2.news.pas.earthlink.net>
Anthony W. Youngman wrote:
> In message <2gkdtnF3saspU1_at_uni-berlin.de>, Alan <alan_at_erols.com> writes
>
>> From "Fundamentals of Database Systems", Elmasri & Navathe [some direct >> quote, some rephrased for brevity] : >> >> Data: Known facts that can be recorded and have implicit meaning. [direct >> quote]
>
> Nice quote. But I'm being philosophical here. Mass, Energy, and Time are
> all (from Newton's standpoint) simple, immutable things. Space is as
> well, although it's slightly different, because it's three orthogonal
> instances of length.
>
> By these standards, "data" is woefully vague and undefined.
The recording of a mass, or of the energy of an object, or the time at which an event was perceived to occur, or any of a myriad other things, could be data. So, data encompasses all of the things you mention and many other things too.
> And it's not
> even atomic! Within the theory it's chopped up into tuples, which are
> themselves chopped up into (I'm not into terminology here) keys,
> attributes, relations, and probably other stuff besides.
Hmmm - that's an odd set of comments. Data generally are atomic facts. The way I'd view it is that a tuple is composed of individual pieces of data. And tuples are certainly not chopped up into relations. Attributes within a tuple contain 'atomic facts' (though when you get into sub-structures such as relation-valued attributes, the definition of atomic is more complex). Keys are properties of relations, etc. My goodness me, that paragraph is so confused as to be close to meaningless - and what meaning there is is almost all completely antithetical to the theory behind a RDBMS, which is what the subject of the thread is discussing.
-- Jonathan Leffler #include <disclaimer.h> Email: jleffler_at_earthlink.net, jleffler_at_us.ibm.com Guardian of DBD::Informix v2003.04 -- http://dbi.perl.org/Received on Sat May 15 2004 - 02:30:41 CEST