[Gnumed-devel] postgres boolean checks, and (e.g) diagnoses

[J Busser]

Just making sure I am interpreting the constraints correctly for 
example in clin_diag

the schema specifies:

> clin_diag_is_active CHECK (((is_chronic = false) OR ((is_chronic = 
> true) AND (is_active = true))))

Does a "check" function as a validity test that is applied only when 
the boolean is attempted to be set as "true" or does it test the 
validity of both true and false values?

In this example
- if the diagnosis is *not* chronic, then both is_active is permitted 
to be either true or false?
- in order to be is_active, the diagnosis must also be chronic? This 
is confusing because the diagnosis defaults to is_active but NOT 
is_chronic, also IMHO during the first episode of any problem (say 
pneumonia) it remains active until it is resolved, there may be a 
requirement to check that a post-pneumonia chest x-ray has returned 
to normal but it is not a chronic condition.

BTW I am still thinking about the recent questions about health issues etc