Re: NULLs

Edward A. Sarog wrote: > > In article <5jqnqr$dh3@cssun.mathcs.emory.edu>, thabib@bob.zentropy.soft > aware.com writes > >You could also point to Codd's Relational Model, which explains that the > >purpose of a null field is represent the absence of data, because it is > >either unknown or unecessary. Replacing null with default values, would > >presume the presence of data that is valid, thus ruining the model of the > >databases as it was created orginally. Hope this helps. > > > > Correct but there should be no unknown data in the database. > i.e. if you don't know then find out before trying to enter it into > MY database. :-> That's not quite true. You mean no unknown key values. Every database should allow for the storage of unlnown data. Are you saying that I can't add a contact until I know their EXACT street address? > I've heard the argument that if you allow nulls then you're design > is flawed.... Again, you're referring to null key values. Allowing null attributes does not constitute a bad database design. Cheers, -- Mark. +------------------------------------------------------------------+ |Mark D. Stock - The West Solutions Group http://www.west.co.za | | The Informix FAQ is at http://www.iiug.org | |mailto:marks@west.co.za +-----------------------------------------+ |Tel: +27 11 803 2151 |If it doesn't work, force it! | |Fax: +27 11 803 2189 |If it breaks, it needed replacing anyway!| |Cell: +27 83 250 2325 |Well, that's how I code anyway! | +------------------------+-----------------------------------------+