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Re: [Gnumed-devel] NULLS was: Consolidation Proposal: ClearHealth, FreeM
From: |
Syan Tan |
Subject: |
Re: [Gnumed-devel] NULLS was: Consolidation Proposal: ClearHealth, FreeMED and OpenEMR |
Date: |
Fri, 08 Jul 2005 20:25:36 +0800 |
> If an
>
>attribute is missing then you will have an invalid data type.
>
>
>
>Therefore, if an attribute is allowed to be missing then the relations
>
>have not been properly constructed in the model.
>
>
>
>In clinical applications there are MANY MANY places where this problem
>
>exists (especially regarding temporal data). So, in most cases every
>
>attribute (if you insist on using a relational model) in a clinical
>
>system should be decomposed into 6NF (a key and a column).
>
>
>
>Otherwise your relations aren't atomic and your application code must be
>
>created to handle these exceptions.
testing for null isn't that hard, happens all the time
when doing application programming, especially in java, for some reason.
Java (and others) have a null object pattern , so the infamous
NullPointerException
doesn't choke a program so frequenty,
may be a Null row for the relational model ? ;)
> Therefore, why constrain yourself
>
>with a data model (relational) that doesn't fit anyway?
because it's cheap , there's no lock-in, and widely understood ( SQL,
at least when people avoid using dialect features).