SELECT CURDATE(), DATE_SUB(CURDATE(),INTERVAL DAY(CURDATE())-1 DAY);
SELECT CURDATE(), LAST_DAY(CURDATE());
SELECT DATE_SUB(DATE_SUB(CURDATE(),INTERVAL DAY(CURDATE())-1 DAY), INTERVAL 1 MONTH);
SELECT CURDATE(), DATE_ADD(CURDATE(),INTERVAL -WEEKDAY(CURDATE()) DAY);
待續……