Dynamic Count

Hi,

I want to do something like this:

 
SELECT COUNT( DISTINCT (select) ) INTO count_aux
FROM (pa_tab)
WHERE (where-where_tab).

Where the tabçe select has the name of the fields i want to distinguish in count operation.

This gives me a dump during runtime of my program, that he don't know the fields in SELECT clause.

Is it possible? How?

Regards,

Pedro Bessa