On Thursday 22 February 2007 05:10, Rich Shepard wrote:
> 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
Indian, the Arabs learned of zero from the Indians.
> 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
