PostgreSQL - crear función en psql

create or replace function ex12()

	returns void as $$

	DECLARE

		nombre CURSOR FOR SELECT sigles FROM partit_politic;

		tupla varchar(7);

	BEGIN

		FOR tupla IN nombre LOOP

			update partit_politic

			set vots_totals =

				(select sum(vots)

				from vots_adjudicats

				where partit = tupla)

			where sigles = tupla;

		END LOOP;

	END;

	$$ LANGUAGE plpgsql;

BEGIN

    update partit_politic set vots_totals=A.total_votos

        from (select partit, sum(vots) as total_votos

            from vots_adjudicats

                group by partit) A where A.partit=sigles

END;