special insert for postgres

gistfile1.sql

--does not work...
CREATE OR REPLACE FUNCTION myinsert(tablename text, g geometry, s hstore) RETURNS integer AS $$
	DECLARE i integer;
	DECLARE sequencename text;
	DECLARE sql text;
	BEGIN
		sequencename = tablename || '_sequence_id';
		i = nextval(sequencename);
		sql = 'INSERT INTO ' || tablename || '(id, geom, store) VALUES ('|| i ||', '|| g ||','|| s ||');';
		EXECUTE sql;
		RETURN i;
	END;

$$ LANGUAGE plpgsql;