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Re: A Question on Integrety

From: Mike Sherrill <MSherrillnonono_at_compuserve.com>
Date: Wed, 17 Dec 2003 06:46:24 -0500
Message-ID: <4nf0uvgse9o84snl6sbtkegjre3up1uhaf@4ax.com>


On 14 Dec 2003 14:04:52 -0800, joe.celko_at_northface.edu (--CELKO--) wrote:

>>> How do I design a database for entities that are subject to
>different business rules throughout their lifecycle!?
[snip]
>I just sent in a three part article to DBAzine.com on this topic. My
>recommendation was a series of "staging tables" which start off with
>the absolute nightmare of making all the columns VARCHAR(<max>) or
>NVARCHAR(<max>) and then move them in steps to other staging tables
>with more and more constraints and proper datatypes as I scrub the
>crap into some kind of usable shape.

Some crap can't be scrubbed.

A lot of legal systems model "what is" differently from "what might be". Think about your current address. Some people might know only the state. (Or only "somewhere out west".) Some people might know only the city and state. Some people might know only the street. Some people might know only one or two digits of the house number. Some people might be recalling the wrong address--the one you lived at five years ago. (But that's still a fact in this context.)

Staging tables don't make sense for data like this. You have to go with a more complex model that segregates assertions of fact from conclusions.

-- 
Mike Sherrill
Information Management Systems
Received on Wed Dec 17 2003 - 05:46:24 CST

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