Try select date_part('year', signedup), date_part('month', signedup), count(*) from member group by date_part('year', signedup), date_part('month', signedup) order by date_part('year', signedup), date_part('month', signedup) -- greg
pgsql-general by date:
Соглашаюсь с условиями обработки персональных данных