From: <Alec.Cawley@stripped>
> "Martijn Tonies" <m.tonies@stripped> wrote on 16/03/2006 11:02:32:
>
> > Well, the question still is if you should store "unknown" at all ;)
> >
> > Not according to Date: you should store what is known. See the remarks
> > about the "true propositions", from which relational databases are
> derived
> > (but you probably know that).
>
> As someone totally unread in the theory of databases, that seems unduly
> puritanical. I assume that what Date would propose is that you have
> another table (related by master key) in which, if you do not know
> something, you do not enter it. But this means that if you have 10
> different pieces of potentially but not necessarily available information
> about a single master record (e.g. a person), you have to do a 10-way join
> in order to retrieve all the information about them. Replacing a
> theoretically ugly null flag with a 10 way join strikes me, as an engineer
> rather than a theoretician, the wrong side of the elegance/practicality
> trade-off.
Using NULLs as well as de-normalization brings the risk of
integrity problems to your storage, storing what is right is only
a good thing.
And when it comes to having to writing JOINs for all your queries,
lo and behold, I bring you the wonder of the VIEW.
;-)
Martijn Tonies
Upscene Productions
http://www.upscene.com
