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
