FUNCTION get_full_name
(
	p_on_date         IN DATE DEFAULT TRUNC(SYSDATE)
   ,p_person_id       IN NUMBER DEFAULT NULL
   ,p_employee_number IN NUMBER DEFAULT NULL
) RETURN VARCHAR2 IS

	l_full_name peoples.full_name%TYPE;

BEGIN
	SELECT ppl.full_name
	INTO   l_full_name
	FROM   peoples ppl
	WHERE  (ppl.person_id = p_person_id OR ppl.employee_number = p_employee_number)
		   AND p_on_date BETWEEN ppl.start_date AND ppl.end_date
		   AND ROWNUM = 1;

	RETURN NVL(l_full_name, 'Запись не обнаружена!');
END;