Re: In an RDBMS, what does "Data" mean?

From: Anthony W. Youngman <>
Date: Fri, 4 Jun 2004 00:34:15 +0100
Message-ID: <>

In message <c9l1rc$1c7$>, Dawn M. Wolthuis <> writes
>> > Certainly with current
>> > relational databases accessed with SQL, you're relying on either an
>> > application programmed OVER the database, or a view which gives you
>> > multiple copies of data of which the original only had one.
>> Huh?
>It think it is worth noting that is far more difficult to retrieve an
>invoice the way it looked originally after chopping it up (that 1NF thing
>again) and then using SQL to show the invoice again. It is possible,
>however, so perhaps Wol has looked at some more difficult specimens.
>Loosely stated - SQL can only place on a single line entities that are
>related to each other on that one line. Stick with me here, I know I said
>that poorly.

What I'm trying to say is that if we use SQL, we get a corrupted version of the data back (ie data that went in ONCE comes back MULTIPLY DUPLICATED), *or* we use an application (such as CrystalReports) which is not part of the database to retrieve the relevant bits from the relevant table.

The database itself doesn't know which tables represent "the set of invoices" and doesn't know how to retrieve a single instance of "invoice" from it - it needs to be told by an external influence, namely a query.


Anthony W. Youngman - wol at thewolery dot demon dot co dot uk
HEX wondered how much he should tell the Wizards. He felt it would not be a
good idea to burden them with too much input. Hex always thought of his reports
as Lies-to-People.
The Science of Discworld : (c) Terry Pratchett 1999
Received on Fri Jun 04 2004 - 01:34:15 CEST

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