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
