year(date)
mysql> select year('99-09-01');
-> 1999
month(date)
mysql> select month('1999-09-01');
-> 9
hour(time)
mysql> select hour('10:05:03');
-> 10
- date_format 함수에서 '%H' 를 사용하면 두 자리수의 숫자로 리턴된다. (01, 02.. )
- hour 함수는 1, 2, .. 9, 10, 11과 같이 리턴한다.
minute(time)
mysql> select minute('99-09-01 10:05:03');
-> 5
second(time)
mysql> select second('10:05:03');
-> 3
DATEDIFF : 날짜 간 차이 (일 반환)
mysql> DATEDIFF(날짜1, 날짜2);
-> 날짜1- 날짜2
TIMESTAMPDIFF : 연/분기/월/주/일/시/분/초 지정하여 차이 반환
- YEAR/QUARTER
- MONTH/WEEK/DAY
- HOUR/MINUTE/SECOND
mysql> TIMESTAMPDIFF(단위, 날짜1, 날짜2);
SELECT TIMESTAMPDIFF(YEAR, '2017-03-01', '2018-03-28'); -> 1
SELECT TIMESTAMPDIFF(QUARTER, '2017-03-01', '2018-03-28'); -> 4
SELECT TIMESTAMPDIFF(MONTH, '2017-03-01', '2018-03-28'); -> 12
SELECT TIMESTAMPDIFF(WEEK, '2017-03-01', '2018-03-28'); -> 56
SELECT TIMESTAMPDIFF(DAY, '2017-03-01', '2018-03-28'); -> 392
SELECT TIMESTAMPDIFF(HOUR, '2017-03-01', '2018-03-28'); -> 9408
SELECT TIMESTAMPDIFF(MINUTE, '2017-03-01', '2018-03-28'); -> 564480
