Re: Stupid Database Tricks

Brian Selzer wrote:
> Marshall wrote:
> > If the table has only two columns, as I specified, then it
> > [value1,value2] is necessarily unique, by the definition of
> > relation. Even it it wasn't, as may be the case in badly
> > executed SQL tables, there is still no value in adding an
> > additional column which will contain no further information.
>
> The problem is not that the key values aren't unique within a single
> extension of the database, it is that a key value may identify one object in
> the universe in one extension and a different object in another. A
> surrogate key solves this problem because there is a bijective mapping
> between the values in the surrogate domain and all possible objects in the
> universe of discourse.

There is no such "object" as an "object". If you stop thinking in terms of "objects" and "entities" then you will stop having the fake problems which lure you to the surrogate ID crutch.

It's be disccused here many times that "object" is a non-idea, a semantic vacuum, a useless crutch substituting thought that leads only to confusion and problems. You can see here, now, the mis-steps one takes when they confuse their thinking with "entity" or "object" non-sense.

As an exercise, try rewriting your paragraph above without using "object", "entity", "thing" or other such void concepts. In other words, try to actually say some"thing" ;-)

Keith -- Fraud 6 Received on Sun Jun 10 2007 - 20:41:59 CEST