1. MySQL 获得当前时间戳函数：current_timestamp, current_timestamp()
mysql> select current_timestamp, current_timestamp();
+———————+———————+
| current_timestamp | current_timestamp() |
+———————+———————+
| 2008-08-09 23:22:24 | 2008-08-09 23:22:24 |
+———————+———————+
2. MySQL （Unix 时间戳、日期）转换函数：
unix_timestamp(),
unix_timestamp(date),
from_unixtime(unix_timestamp),
from_unixtime(unix_timestamp,format)
下面是示例：
select unix_timestamp(); — 1218290027
select unix_timestamp(‘2008-08-08’); — 1218124800
select unix_timestamp(‘2008-08-08 12:30:00’); — 1218169800
select from_unixtime(1218290027); — ‘2008-08-09 21:53:47’
select from_unixtime(1218124800); — ‘2008-08-08 00:00:00’
select from_unixtime(1218169800); — ‘2008-08-08 12:30:00’
select from_unixtime(1218169800, ‘%Y %D %M %h:%i:%s %x’); — ‘2008 8th August 12:30:00 2008’
3. 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) —
请看示例部分：
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。