On Wed, Sep 30, 2009 at 11:13:06AM +0100, Bronagh Grimes wrote:
> I have written some code to calculate basic summary stats and wish to
> then incorporate this code within a macro... I want to run the code
> many multiple times and define the variables (on which the summary
> statistics are calculated) outside of the basic code.
I'd normally do this "outside" Postgres, maybe from something like
Python or Perl.
> For example, see some very basic code below... I would use a macro so
> that I don't have to change 'STUDY_GROUP' in the code each time.
If you want to stay inside PG and use psql, you could rewrite the query
to make this less of a problem.
> select "STUDY_GROUP" , count("STUDY_GROUP")
> from "TABLE1" group by "STUDY_GROUP";
SELECT "STUDY_GROUP", COUNT(*)
GROUP BY 1;
Will do the same thing; except where the column is NULL. You will have
been getting zero before, but now you'll be told how many null entries
you have--this may or may not be what you want. If you don't want it,
you could do:
SELECT v, COUNT(v)
FROM (SELECT "STUDY_GROUP" AS v FROM "TABLE1") x
GROUP BY v;
There would still only be one name to change then and PG would optimize
the query to do the same thing either way so performance shouldn't be
Hope that helps!
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