Tom Austin wrote:
> Yes, the data needs to be well understood before starting the schema. 
> There should be no anomalies to 'fit in' after the fact.

The absolute best way to make this work out, then, is to record "reality" in 
the database. Ignore how you're going to use the data while you're designing 
what's in the database (to the extent possible). Instead, simply record facts.

Of course you need to know the height of the poles and their locations and 
such, because that's what you do your calculations with.

What I'm trying to say is don't say "our calculations would be easier if our 
data was arranged like *this*."  If you stick with the reality of what's out 
there, you will never run into the situation where you have to *change* data 
you already have in the database.

I know this sounds kind of vague, and it can be hard to get away from it if 
you already have a model of something up and running and you know how that 
works.

-- 
Darren New, San Diego CA, USA (PST)
  "How did he die?"   "He got shot in the hand."
     "That was fatal?"
          "He was holding a live grenade at the time."

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