Re: Fabian Pascal and RDBMS deficiencies in fully implementing the relational model

Well, the Date argument against NULLs (and he never endorsed them, or
so he claims) is that they are not data- they represent the absence of
data- so why put non-data in a _data_base.

If you are asking yourself the question how you can have support
multiple meanings in a column, normalize. Then, baldness is just
another value and you don't have to guess if the hair color is unknown,
undefined, or missing.

On Jun 8, 2006, at 10:10 PM, Christopher Browne wrote:

> A long time ago, in a galaxy far, far away, tshipley(at)deru(dot)com (Trent
> Shipley) wrote:
>> On Thursday 2006-06-08 15:14, David Fetter wrote:
>>> On Thu, Jun 08, 2006 at 05:21:07AM -0700, dananrg(at)yahoo(dot)com wrote:
>>
>>> on bag theory[1] and 3-value logic[2]. Until they come up with a
>>> testable system, or Hell freezes over, whichever comes first,
>>> Pascal's book will make a good companion on your shelf to books on
>>> Phlogiston[3] theory, or a decent doorstop, whichever you prefer.
>>
>> I have encountered at least two commercial database products that
>> declared every column "NOT NULL". I have always assumed that this
>> was defensive, preventing stupid programmer mistakes.
>>
>> I recall reading somewhere that Codd proposed multiple flavors of
>> nullity. Are there theoretical proposals for databases with logical
>> systems having more than three values?
>
> Darwen did a paper where he described how you'd cope with not having
> any nulls. It amounted to having a whole bunch of views that would
> have a whole host of special indicator values to replace the multiple
> meanings of NULL...
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