SELECT * FROM people;

SELECT DATEDIFF(NOW(), birthdate) FROM people;

SELECT name, birthdate, DATEDIFF(NOW(), birthdate) FROM people;

SELECT birthdt FROM people;

SELECT birthdt, DATE_ADD(birthdt, INTERVAL 1 MONTH) FROM people;

SELECT birthdt, DATE_ADD(birthdt, INTERVAL 10 SECOND) FROM people;

SELECT birthdt, DATE_ADD(birthdt, INTERVAL 3 QUARTER) FROM people;

SELECT birthdt, birthdt + INTERVAL 1 MONTH FROM people;

SELECT birthdt, birthdt - INTERVAL 5 MONTH FROM people;

SELECT birthdt, birthdt + INTERVAL 15 MONTH + INTERVAL 10 HOUR FROM people;