– 获得当前日期+时间（date + time） select NOW(); select SYSDATE(); select CURRENT_TIMESTAMP; select CURRENT_TIMESTAMP(); – 获得当前日期 select CURRENT_DATE(); – 获得当前时间 select CURRENT_TIME(); MySQL 日期转换函数、时间转换函数 MySQL Date/Time to Str（日期/时间转换为字符串）函数：date_format(date,format), time_format(time,format)
select date_format(‘2020-07-04 14:12:01’, ‘%Y%m%d%H%i%s’); select date_format(‘2020-07-04 14:12:01’, ‘%Y-%m-%d %H:%i:%s’); MySQL Str to Date （字符串转换为日期）函数：str_to_date(str, format) select str_to_date(‘2020-07-04 14:12:01’, ‘%Y-%m-%d %H:%i:%s’); MySQL （日期、天数）转换函数：to_days(date), from_days(days) select to_days(‘0000-00-00’); – 0 select to_days(‘2020-07-04’); – 737975 select FROM_DAYS(737975); – 2020-07-04
MySQL （时间、秒）转换函数：time_to_sec(time), sec_to_time(seconds)
select time_to_sec(‘01:00:05’); – 3605 select sec_to_time(3605); – ‘01:00:05’
MySQL 拼凑日期、时间函数：makdedate(year,dayofyear), maketime(hour,minute,second)
select makedate(2001,31); – ‘2001-01-31’ select makedate(2001,32); – ‘2001-02-01’ select maketime(12,15,30); – ‘12:15:30’
MySQL 日期时间计算函数
MySQL 为日期增加一个时间间隔：date_add() set @dt = now();
select date_add(@dt, interval 1 day); – add 1 day select date_add(@dt, interval 1 hour); – add 1 hour select date_add(@dt, interval 1 minute); – … select date_add(@dt, interval 1 second); select date_add(@dt, interval 1 microsecond); select date_add(@dt, interval 1 week); select date_add(@dt, interval 1 month); select date_add(@dt, interval 1 quarter); – add 1 季度 3个月 select date_add(@dt, interval 1 year);
MySQL adddate(), addtime()函数，可以用 date_add() 来替代。下面是 date_add() 实现 addtime() 功能示例：
set @dt = ‘2010-07-04 00:00:00’; select date_add(@dt, interval ‘01:15:30’ hour_second); – 2010-07-04 01:15:30 select date_add(@dt, interval ‘1:1’ YEAR_MONTH); – 2011-08-04 00:00:00 select date_add(@dt, interval ‘1 1:15:30’ day_second); – 2010-07-05 01:15:30
MySQL 为日期减去一个时间间隔：date_sub()
select date_sub(‘1998-01-01 00:00:00’, interval ‘1 1:1:1’ day_second); – 1997-12-30 22:58:59
MySQL 日期、时间相减函数：datediff(date1,date2), timediff(time1,time2) MySQL datediff(date1,date2)：两个日期相减 date1 - date2，返回天数。 select datediff(‘2008-08-08’, ‘2008-08-01’); – 7 select datediff(‘2008-08-01’, ‘2008-08-08’); – -7
MySQL timediff(time1,time2)：两个日期相减 time1 - time2，返回 time 差值。 select timediff(‘2008-08-08 08:08:08’, ‘2008-08-08 00:00:00’); – 08:08:08 select timediff(‘08:08:08’, ‘00:00:00’); – 08:08:08 注意：timediff(time1,time2) 函数的两个参数类型必须相同。
MySQL 时间戳（timestamp）转换、增、减函数： timestamp(date) – date to timestamp timestamp(dt,time) – dt + time timestampadd(unit,interval,datetime_expr) – timestampdiff(unit,datetime_expr1,datetime_expr2) –
select timestamp(‘2008-08-08’); – 2008-08-08 00:00:00 select timestamp(‘2008-08-08 08:00:00’, ‘01:01:01’); – 2008-08-08 09:01:01 select timestamp(‘2008-08-08 08:00:00’, ‘10 01:01:01’); – 2008-08-18 09:01:01
select timestampadd(day, 1, ‘2008-08-08 08:00:00’); – 2008-08-09 08:00:00 select date_add(‘2008-08-08 08:00:00’, interval 1 day); – 2008-08-09 08:00:00
MySQL timestampadd() 函数类似于 date_add()。 select timestampdiff(year,‘2002-05-01’,‘2001-01-01’); – -1 select timestampdiff(day ,‘2002-05-01’,‘2001-01-01’); – -485 select timestampdiff(hour,‘2008-08-08 12:00:00’,‘2008-08-08 00:00:00’); – -12
select datediff(‘2008-08-08 12:00:00’, ‘2008-08-01 00:00:00’); – 7
MySQL timestampdiff() 函数就比 datediff() 功能强多了，datediff() 只能计算两个日期（date）之间相差的天数。
