On Thu, 22 Feb 2007, Tim Tassonis wrote:
> I do still think it is a bit of an oddity, the concept of the null column.
> From my experience, it creates more problems than it actually solves and
> generally forces you to code more rather than less in order to achieve
> your goals.
Tim,
Long ago, a lot of database applications used 99, or 999, or -1 to
indicate an unknown value. However, those don't fit well with a textual
field and they will certainly skew results if used in arithmetic
calculations in numeric fields.
The concept of NULL representing an unknown value, and therefore one that
cannot be compared with any other value including other NULLs, is no
different from the concept of zero which was not in mathematics for the
longest time until some insightful Arab mathematician saw the need for a
representation of 'nothing' in arithmetic and higher mathematics.
There was probably resistance to that idea, too, as folks tried to wrap
their minds around the idea that 'nothing' could be validly represented by a
symbol and it was actually necessary to advance beyond what the Greeks and
Romans -- and everyone else -- could do. Now, one would be thought a bit
strange to question the validity of zero.
NULL solves as many intransigent problems with digital data storage and
manipulation in databases as zero did in the realm of counting.
HTH,
Rich
--
Richard B. Shepard, Ph.D. | The Environmental Permitting
Applied Ecosystem Services, Inc. | Accelerator(TM)
<http://www.appl-ecosys.com> Voice: 503-667-4517 Fax: 503-667-8863
