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@xxxxxxxx (Trent
Shipley) wrote:
On Thursday 2006-06-08 15:14, David Fetter wrote:
On Thu, Jun 08, 2006 at 05:21:07AM -0700, dananrg@xxxxxxxxx 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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