-- 修改时间：ADDDATE(date,INTERVAL expr unit)

-- 含义：date时间，expr 表达式值，unit表达式对应的时间单位

-- unit :  SECOND,MINUTE,HOUR,DAY,MONTH,YEAR

SELECT ADDDATE(NOW(),INTERVAL -60 SECOND)

SELECT ADDDATE(NOW(),INTERVAL -1 MINUTE)

SELECT ADDDATE(NOW(),INTERVAL -1 HOUR)

SELECT ADDDATE(NOW(),INTERVAL -1 DAY)

SELECT ADDDATE(NOW(),INTERVAL -1 MONTH)

SELECT ADDDATE(NOW(),INTERVAL -1 YEAR)