Re: 3 value logic. Why is SQL so special?
From: J M Davitt <jdavitt_at_aeneas.net>
Date: Thu, 21 Sep 2006 00:53:46 GMT
Message-ID: <uolQg.7335$L15.3409_at_tornado.ohiordc.rr.com>
>
>
> You are incorrectly assuming that each nullable column gives rise to a
> separate table. Based on the three or four dozen databases that I work
> with regularly that wouldn't usually happen. In most cases a table will
> have 5, 10, maybe more nullable columns because it conflates two or three
> different entity types. Thus just one or two additional tables are often
> sufficient.
Date: Thu, 21 Sep 2006 00:53:46 GMT
Message-ID: <uolQg.7335$L15.3409_at_tornado.ohiordc.rr.com>
Roy Hann wrote:
> "Chris Lim" <blackcap80_at_hotmail.com> wrote in message
> news:1158642255.069101.30980_at_h48g2000cwc.googlegroups.com...
>
>>Marshall wrote: >> >>>In comp.lang.java.programmer, it was not uncommon to have >>>someone describe a problem that would trivially be solved >>>by adding a new class, but they would reject that solution because >>>"too many classes." >> >>The key difference here is 'trivially'. Adding lots (and we are talking >>about lots when you consider the number of nullable columns) of tables >>makes it much hard to query that data (especially if you also disallow >>outer joins!). And if you are going to prove me wrong with an example, >>at least use a table with lots of nullable columns instead of just one >>or two.
>
>
> You are incorrectly assuming that each nullable column gives rise to a
> separate table. Based on the three or four dozen databases that I work
> with regularly that wouldn't usually happen. In most cases a table will
> have 5, 10, maybe more nullable columns because it conflates two or three
> different entity types. Thus just one or two additional tables are often
> sufficient.
Shh!! Next thing you know you'll have folks thinking that life is simpler with two or three more "tables" than it is with a dozen or so more "columns" of ambiguous... content. (What? You thought I was going to say, "data?" Or, "values?" Ha!)
> But if more were required, so what? You've got to write the code to sort it
> out somewhere, so why not in the query?
>
> Roy
>
>
Received on Thu Sep 21 2006 - 02:53:46 CEST