Oracle Date / Time Function

 -- sysdate 

SELECT sysdate from dual

SYSDATE
2022/02/22

-- systimestamp 

SELECT systimestamp from dual

SYSTIMESTAMP
22-2月 -22 01.28.54.849788 上午 +00:00

-- add_months 

SELECT add_months('2022/02/22', 3)

from dual

ADD_MONTHS('2022/02/22',3)
2022/05/22

SELECT add_months('2022/02/22', -3)

from dual

ADD_MONTHS('2022/02/22',-3)
2021/11/22

-- months_between 

SELECT months_between('2022/02/15', '2023/02/15')

from dual

MONTHS_BETWEEN('2022/02/15','2023/02/15')
-12

--加入trunc

SELECT trunc(systimestamp) from dual

TRUNC(SYSTIMESTAMP)
2022/02/22

SELECT trunc(systimestamp, 'YEAR') from dual

TRUNC(SYSTIMESTAMP,'YEAR')
2022/01/01

SELECT trunc(systimestamp, 'MONTH') from dual

TRUNC(SYSTIMESTAMP,'MONTH')
2022/02/01