check is within period/time_frame if is_time_based = 1

is_time_based.sql

SELECT * 
FROM gb_m_promo p 
LEFT JOIN  gb_n_promo_period t ON p.promo_code = t.promo_code
WHERE TRUE
AND CASE WHEN is_time_based = 1 THEN CURTIME() BETWEEN from_time AND to_time ELSE TRUE END;




# time diff
SELECT TIMESTAMPDIFF(SECOND, '2012-06-06 13:13:55', '2012-06-06 15:20:18')

# date.add/date.sub
SELECT DATE_ADD(starts_at, INTERVAL ((execution_count+ 1) * duration_day) DAY);

# time.add/time.sub
select ADDTIME('00:00:00',  '07:00:00');