Re: [Gnumed-devel] Statistics

[Karsten Hilbert]

On Fri, Feb 08, 2013 at 11:51:25PM +0000, Jim Busser wrote:

> >> How do I know how many patients I have seen in a day, month,
> > 
> > Which one ?   Or maybe you need to be a bit more specific
> > which time ranges you want to aggregate and which you want
> > to compare.
> > 
> >> or last year
> > 
> > select count(1)
> > from dem.identity d_i
> > where
> >     d_i.pk in (
> >             select fk_patient from clin.encounter
> >             where
> >                     fk_type in (select pk from clin.encounter_type where 
> > description in ('list', 'of', 'interesting', 'types')
> >                             and
> >                     started between 'year-01-01' and 'year-12-31'
> >     )
> > ;
> 
> Will the above count an individual patient more than once,
> in the case where they had more than one encounter in the
> interval of interest (and thereby generating the 'volume' of
> patients seen, not distinct patients)?

Ah, indeed. That's why I often ask for clarification as to
what's actually meant. Yes, this counts *encounters*, not
patients. One would need to DISTINCT ON fk_patient:

select count(1)
from dem.identity d_i
where
        d_i.pk in (
                select distinct fk_patient from clin.encounter
                where
                        fk_type in (select pk from clin.encounter_type where 
description in ('list', 'of', 'interesting', 'types'))
                                and
                        started between 'year-01-01' and 'year-12-31'
        )
;

Untested.

Karsten
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