Re: Does entity integrity imply entity identity?
Date: Thu, 6 Aug 2009 07:58:23 -0700 (PDT)
Mr. Scott wrote:
> "Walter Mitty" wrote:
> > Every information system needs a way of marking the absence of data in a
> > place where there might have been data. In some situations, there not
> > only might have been data, but there should have been data. In other
> > situations, a place for data has been created, but it is inapplicable to
> > the situation.
> "Inapplicable data" is an oxymoron, so it doesn't make sense to provide a
> place for it. A table that allows "inapplicable nulls" has a disjunctive
> predicate and should be split up into one base table for each disjunct.
The above comment indicates that you at least know the concept of disjunction and that you understand one alternative to nulls in that case: decomposition. However in other post we have you outlining an example having (in part) such a disjunction:
On Aug 6, 8:42 am, "Mr. Scott" <do_not_re..._at_noone.com> wrote:
> Here's a more concrete example. Software can be delivered to a customer
> over the internet or through the mail or both, but in order to deliver over
> the internet there must be an e-mail address, and in order to deliver
> through the mail there must be a snail-mail address. There may also be a
> delivery contact phone number. So for a given order K, there must be at
> least one of an e-mail address A or a snail-mail address B, and there may be
> a delivery phone number C.
and yet offering no acknowledgement that you already understand some alternatives. In other words you are "holding back" and/or feigning ignorance. This is indicative of troll behavior and/or someone just looking to fight. Please explain yourself.
If you want to have an honest and productive discussion (rather than a merry-go-troll-round) then you need to come straight-out and clearly state 1) the alternatives to null that you already know 2) your view and thought on those alternatives.
KHD Received on Thu Aug 06 2009 - 16:58:23 CEST