Re: [Gnumed-devel] NULLS was: Consolidation Proposal: ClearHealth, FreeMED and OpenEMR

[Syan Tan]

> 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
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>have not been properly constructed in the model.  
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>
>
>In clinical applications there are MANY MANY places where this problem
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>exists (especially regarding temporal data).  So, in most cases every
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>attribute (if you insist on using a relational model) in a clinical
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>system should be decomposed into 6NF (a key and a column).  
>
>
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>Otherwise your relations aren't atomic and your application code must be
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>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).