mysql的日期/时间函数
2011-03-04 10:44
585 查看
没事整理下，方便以后查阅
一、
Mysql
获得当前日期时间
Now()
:
获得当前的
日期+
时间（date + time
）函数：
mysql> select now();
+---------------------+
|
now()
|
+---------------------+
| 2011-03-01 10:26:23 |
+---------------------+
1 row in set (0.00 sec)
同等的函数还包括current_timestamp(),localtime()
，但是now()
最容易记忆，所以推荐使用。
Sysdate()
:
日期时间函数跟 now()
类似，不同之处在于：now()
在执行开始时值就得到了， sysdate()
在函数执行时动态得到值。
看下面的例子就明白了：
mysql> select
now(),sleep(3),now();
+---------------------+----------+---------------------+
|
now()
| sleep(3) |
now()
|
+---------------------+----------+---------------------+
| 2011-03-01
10:51:43 | 0 | 2011-03-01 10:51:43 |
+---------------------+----------+---------------------+
1 row in set (3.02
sec)
mysql> select
sysdate(),sleep(3),sysdate();
+---------------------+----------+---------------------+
|
sysdate() |
sleep(3) |
sysdate() |
+---------------------+----------+---------------------+
| 2011-03-01
10:52:09 | 0 | 2011-03-01 10:52:12 |
+---------------------+----------+---------------------+
1 row in set (3.00
sec)
可以看到，虽然中途 sleep 3
秒，但 now()
函数两次的时间值是相同的； sysdate()
函数两次得到的时间值相差 3
秒
也可以只取当前日期或者当前时间
Curdate():
获得当前日期
mysql> select
curdate();
+------------+
| curdate() |
+------------+
| 2011-03-01 |
+------------+
1 row in set (0.01
sec)
Curtime()
:
获得当前时间（time
）函数
mysql> select
curtime();
+-----------+
| curtime() |
+-----------+
| 10:55:12 |
+-----------+
1 row in set (0.00
sec)
二、
Mysql
日期时间的抽取extract
通过这一功能，我们可以从一个时间中抽取自己想要的部分，例如
mysql> set
@ct='2011-03-01 11:16:14.123456';
Query OK, 0 rows
affected (0.01 sec)
设置变量ct
为某一时间值，精确到微妙
获取其日期值
mysql> select
date(@ct);
+------------+
| date(@ct) |
+------------+
| 2011-03-01 |
+------------+
1 row in set (0.00
sec)
查看此日期所属季度
mysql> select
quarter(@ct);
+--------------+
| quarter(@ct) |
+--------------+
|
1 |
+--------------+
1 row in set (0.00
sec)
查看此日期属于当年哪一周
mysql> select
week(@ct);
+-----------+
| week(@ct) |
+-----------+
|
9 |
+-----------+
1 row in set (0.00
sec)
另外还有year(),day(),hour(),minute(),second()
等，在此不一一赘述。
采用extract()
，也可以实现类似的功能，语法格式为extract(year from @ct)
，
不足之处在于需要多敲几次键盘
Dayof
函数
:
Dayofweek(),dayofmonth(),dayofyear()
分别返回日期再一周、一月以及一年中的位置
mysql> select
dayofweek(@ct);
+----------------+
| dayofweek(@ct) |
+----------------+
|
3 |
+----------------+
1 row in set (0.00
sec)
注意：其实3
月1
号是星期二，但是返回数字3
，因为是从Sunday
开始算起的(1=Sunday,2=Monday,
…)
mysql> select
dayofmonth(@ct);
+-----------------+
| dayofmonth(@ct) |
+-----------------+
|
1 |
+-----------------+
1 row in set (0.00
sec)
mysql> select
dayofyear(@ct);
+----------------+
| dayofyear(@ct) |
+----------------+
|
60 |
+----------------+
1 row in set (0.00
sec)
Week()
函数
查看日期属于当年的第几周
mysql> select
weekofyear(@ct);
+-----------------+
| weekofyear(@ct) |
+-----------------+
|
9 |
+-----------------+
1 row in set (0.00
sec)
返回星期名和月份名的函数
Dayname()
—计算日期是星期几
mysql> select
dayname(@ct);
+--------------+
| dayname(@ct) |
+--------------+
|
Tuesday |
+--------------+
1 row in set (0.02
sec)
Monthname()
—计算日期是哪一月
mysql> select
monthname(@ct);
+----------------+
| monthname(@ct) |
+----------------+
|
March |
+----------------+
1 row in set (0.00
sec)
Last_day()
:
返回月份中最后一天
mysql> select
now();
+---------------------+
|
now()
|
+---------------------+
| 2011-03-01
13:15:00 |
+---------------------+
1 row in set (0.00
sec)
mysql> select
last_day(now());
+-----------------+
| last_day(now()) |
+-----------------+
|
2011-03-31 |
+-----------------+
1 row in set (0.00
sec)
通过该函数，可以计算出当前月份有多少天
mysql> select
now(),day(last_day(now())) ;
+---------------------+----------------------+
|
now()
| day(last_day(now())) |
+---------------------+----------------------+
| 2011-03-01
13:17:12
|
31 |
+---------------------+----------------------+
1 row in set (0.00
sec)
三、Mysql
的日期时间计算函数
Date_add()
:
为日期增加一个时间间隔
具体语法为date_add(@ct,
interval num year/quarter/month/week/day/hour/minute/secont/microsecond);
注意:
此函数并不改变变量@ct
的实际值
mysql> set
@ct=now();
Query OK, 0 rows
affected (0.00 sec)
mysql> select
@ct;
+---------------------+
|
@ct
|
+---------------------+
| 2011-03-01
15:09:16 |
+---------------------+
1 row in set (0.00
sec)
mysql> select
date_add(@ct,interval 1 day);
+------------------------------+
|
date_add(@ct,interval 1 day) |
+------------------------------+
| 2011-03-02 15:09:16
|
+------------------------------+
1 row in set (0.00
sec)
mysql> select
@ct;
+---------------------+
|
@ct
|
+---------------------+
| 2011-03-01
15:09:16 |
+---------------------+
1 row in set (0.00
sec)
mysql> select date_add(@ct,interval
1 week);
+-------------------------------+
|
date_add(@ct,interval 1 week) |
+-------------------------------+
| 2011-03-08
15:09:16 |
+-------------------------------+
1 row in set (0.00
sec)
类似功能还有adddate(),addtime()
等函数
，与之相对应的是date_sub()
，顾名思义就是日期减法
另类日期函数
Period_add(P,N):
日期加/
减去N
月，其中P
的格式应为yyyymm
或yymm
Period_diff(P1,P2):
日期p1-p2
，返回N
个月
mysql> select
period_add(201103,2),period_add(201103,-2) ;
+----------------------+-----------------------+
|
period_add(201103,2) | period_add(201103,-2) |
+----------------------+-----------------------+
|
201105
|
201101 |
+----------------------+-----------------------+
1 row in set (0.00
sec)
mysql> select
period_diff('201103','201101');
+--------------------------------+
|
period_diff('201103','201101') |
+--------------------------------+
|
2 |
+--------------------------------+
1 row in set (0.00
sec)
日期时间相减函数
Datediff(date1,date2)
:
两个日期date1-date2
mysql> select
datediff('2011-03-09','2011-03-01');
+-------------------------------------+
|
datediff('2011-03-09','2011-03-01') |
+-------------------------------------+
|
8 |
+-------------------------------------+
1 row in set (0.00
sec)
mysql> select
datediff('2011-03-01','2011-03-09');
+-------------------------------------+
|
datediff('2011-03-01','2011-03-09') |
+-------------------------------------+
|
-8 |
+-------------------------------------+
1 row in set (0.00
sec)
Timediff(time1,time2)
:
两个时间相减
mysql> select
timediff('2011-03-03 15:33:00','2011-03-02 15:33:59');
+-------------------------------------------------------+
|
timediff('2011-03-03 15:33:00','2011-03-02 15:33:59') |
+-------------------------------------------------------+
|
23:59:01
|
+-------------------------------------------------------+
1 row in set (0.00
sec)
mysql> select
timediff('15:33:00','15:33:59');
+---------------------------------+
|
timediff('15:33:00','15:33:59') |
+---------------------------------+
|
-00:00:59
|
+---------------------------------+
1 row in set (0.00
sec)
四
mysql
日期、时间转换函数
Time_to_sec(time)
:
时间—>
秒 转换函数
Sec_to_time(num)
:
秒-->
时间 转换函数
mysql> select
time_to_sec('01:00:00');
+-------------------------+
|
time_to_sec('01:00:00') |
+-------------------------+
|
3600 |
+-------------------------+
1 row in set (0.00
sec)
mysql> select
sec_to_time(3600);
+-------------------+
| sec_to_time(3600)
|
+-------------------+
|
01:00:00 |
+-------------------+
1 row in set (0.00
sec)
To_days(date)
:
日期-->
天 转换函数 起始日期为0000-00-00
From_days(num)
:
天-->
日期 将数字转换为具体的日期
mysql> select
to_days('2011-03-01');
+-----------------------+
|
to_days('2011-03-01') |
+-----------------------+
|
734562 |
+-----------------------+
1 row in set (0.00
sec)
mysql> select
from_days(734562);
+-------------------+
| from_days(734562)
|
+-------------------+
|
2011-03-01 |
+-------------------+
1 row in set (0.00
sec)
Str_to_date(str,date)
:
字符串-->
日期 转换函数
可以将一些杂乱无章的字符转换为日期格式
mysql> select
str_to_date('01.03.2011', '%m.%d.%Y');
+---------------------------------------+
|
str_to_date('01.03.2011', '%m.%d.%Y') |
+---------------------------------------+
|
2011-01-03
|
+---------------------------------------+
1 row in set (0.00
sec)
mysql> select
str_to_date('01/03/2011', '%m/%d/%Y');
+---------------------------------------+
| str_to_date('01/03/2011',
'%m/%d/%Y') |
+---------------------------------------+
|
2011-01-03
|
+---------------------------------------+
1 row in set (0.00
sec)
小练习：
以表centralmobile_logs
为例，目前该表总共有270
多万条数据
mysql> select
count(*) from centralmobile_logs;
+----------+
| count(*) |
+----------+
| 2725403 |
+----------+
1 row in set (0.00
sec)
现在对其做一些统计
查询过去30
天总共有多少数据
mysql> select
count(*) from centralmobile_logs where to_days(curdate())-
to_days(create_time)<=30;
+----------+
| count(*) |
+----------+
| 2367518 |
+----------+
1 row in set (3.38
sec)
mysql> select
count(*) from centralmobile_logs where datediff(curdate(),create_time) <=30;
+----------+
| count(*) |
+----------+
| 2367518 |
+----------+
1 row in set (3.29
sec)
查看每月第一天的数据
mysql> select
count(*) from centralmobile_logs where dayofmonth(create_time)=1;
+----------+
| count(*) |
+----------+
| 161293
|
+----------+
1 row in set (3.14
sec)
查看11
年1
月31
日之前的数据
mysql> select
count(*) from centralmobile_logs where create_time <='2011-01-31 00:00:00';
+----------+
| count(*) |
+----------+
| 413797
|
+----------+
1 row in set (0.17
sec)
查看11
年整个二月份的数据
mysql> select
count(*) from centralmobile_logs where monthname(create_time)='February' and
year(create_time)=2011;
+----------+
| count(*) |
+----------+
| 2149284 |
+----------+
1 row in set (3.94
sec)
查看11
年每个周日的累积数据
mysql> select
count(*) from centralmobile_logs where dayname(create_time)='Sunday' and
year(create_time)=2011;
+----------+
| count(*) |
+----------+
| 479033
|
+----------+
1 row in set (3.88
sec)
查看每天零点时分插入的数据总和
mysql> select
count(*) from centralmobile_logs where time(create_time)='00:00:00';
+----------+
| count(*) |
+----------+
|
37 |
+----------+
1 row in set (3.99
sec)
一、
Mysql
获得当前日期时间
Now()
:
获得当前的
日期+
时间（date + time
）函数：
mysql> select now();
+---------------------+
|
now()
|
+---------------------+
| 2011-03-01 10:26:23 |
+---------------------+
1 row in set (0.00 sec)
同等的函数还包括current_timestamp(),localtime()
，但是now()
最容易记忆，所以推荐使用。
Sysdate()
:
日期时间函数跟 now()
类似，不同之处在于：now()
在执行开始时值就得到了， sysdate()
在函数执行时动态得到值。
看下面的例子就明白了：
mysql> select
now(),sleep(3),now();
+---------------------+----------+---------------------+
|
now()
| sleep(3) |
now()
|
+---------------------+----------+---------------------+
| 2011-03-01
10:51:43 | 0 | 2011-03-01 10:51:43 |
+---------------------+----------+---------------------+
1 row in set (3.02
sec)
mysql> select
sysdate(),sleep(3),sysdate();
+---------------------+----------+---------------------+
|
sysdate() |
sleep(3) |
sysdate() |
+---------------------+----------+---------------------+
| 2011-03-01
10:52:09 | 0 | 2011-03-01 10:52:12 |
+---------------------+----------+---------------------+
1 row in set (3.00
sec)
可以看到，虽然中途 sleep 3
秒，但 now()
函数两次的时间值是相同的； sysdate()
函数两次得到的时间值相差 3
秒
也可以只取当前日期或者当前时间
Curdate():
获得当前日期
mysql> select
curdate();
+------------+
| curdate() |
+------------+
| 2011-03-01 |
+------------+
1 row in set (0.01
sec)
Curtime()
:
获得当前时间（time
）函数
mysql> select
curtime();
+-----------+
| curtime() |
+-----------+
| 10:55:12 |
+-----------+
1 row in set (0.00
sec)
二、
Mysql
日期时间的抽取extract
通过这一功能，我们可以从一个时间中抽取自己想要的部分，例如
mysql> set
@ct='2011-03-01 11:16:14.123456';
Query OK, 0 rows
affected (0.01 sec)
设置变量ct
为某一时间值，精确到微妙
获取其日期值
mysql> select
date(@ct);
+------------+
| date(@ct) |
+------------+
| 2011-03-01 |
+------------+
1 row in set (0.00
sec)
查看此日期所属季度
mysql> select
quarter(@ct);
+--------------+
| quarter(@ct) |
+--------------+
|
1 |
+--------------+
1 row in set (0.00
sec)
查看此日期属于当年哪一周
mysql> select
week(@ct);
+-----------+
| week(@ct) |
+-----------+
|
9 |
+-----------+
1 row in set (0.00
sec)
另外还有year(),day(),hour(),minute(),second()
等，在此不一一赘述。
采用extract()
，也可以实现类似的功能，语法格式为extract(year from @ct)
，
不足之处在于需要多敲几次键盘
Dayof
函数
:
Dayofweek(),dayofmonth(),dayofyear()
分别返回日期再一周、一月以及一年中的位置
mysql> select
dayofweek(@ct);
+----------------+
| dayofweek(@ct) |
+----------------+
|
3 |
+----------------+
1 row in set (0.00
sec)
注意：其实3
月1
号是星期二，但是返回数字3
，因为是从Sunday
开始算起的(1=Sunday,2=Monday,
…)
mysql> select
dayofmonth(@ct);
+-----------------+
| dayofmonth(@ct) |
+-----------------+
|
1 |
+-----------------+
1 row in set (0.00
sec)
mysql> select
dayofyear(@ct);
+----------------+
| dayofyear(@ct) |
+----------------+
|
60 |
+----------------+
1 row in set (0.00
sec)
Week()
函数
查看日期属于当年的第几周
mysql> select
weekofyear(@ct);
+-----------------+
| weekofyear(@ct) |
+-----------------+
|
9 |
+-----------------+
1 row in set (0.00
sec)
返回星期名和月份名的函数
Dayname()
—计算日期是星期几
mysql> select
dayname(@ct);
+--------------+
| dayname(@ct) |
+--------------+
|
Tuesday |
+--------------+
1 row in set (0.02
sec)
Monthname()
—计算日期是哪一月
mysql> select
monthname(@ct);
+----------------+
| monthname(@ct) |
+----------------+
|
March |
+----------------+
1 row in set (0.00
sec)
Last_day()
:
返回月份中最后一天
mysql> select
now();
+---------------------+
|
now()
|
+---------------------+
| 2011-03-01
13:15:00 |
+---------------------+
1 row in set (0.00
sec)
mysql> select
last_day(now());
+-----------------+
| last_day(now()) |
+-----------------+
|
2011-03-31 |
+-----------------+
1 row in set (0.00
sec)
通过该函数，可以计算出当前月份有多少天
mysql> select
now(),day(last_day(now())) ;
+---------------------+----------------------+
|
now()
| day(last_day(now())) |
+---------------------+----------------------+
| 2011-03-01
13:17:12
|
31 |
+---------------------+----------------------+
1 row in set (0.00
sec)
三、Mysql
的日期时间计算函数
Date_add()
:
为日期增加一个时间间隔
具体语法为date_add(@ct,
interval num year/quarter/month/week/day/hour/minute/secont/microsecond);
注意:
此函数并不改变变量@ct
的实际值
mysql> set
@ct=now();
Query OK, 0 rows
affected (0.00 sec)
mysql> select
@ct;
+---------------------+
|
@ct
|
+---------------------+
| 2011-03-01
15:09:16 |
+---------------------+
1 row in set (0.00
sec)
mysql> select
date_add(@ct,interval 1 day);
+------------------------------+
|
date_add(@ct,interval 1 day) |
+------------------------------+
| 2011-03-02 15:09:16
|
+------------------------------+
1 row in set (0.00
sec)
mysql> select
@ct;
+---------------------+
|
@ct
|
+---------------------+
| 2011-03-01
15:09:16 |
+---------------------+
1 row in set (0.00
sec)
mysql> select date_add(@ct,interval
1 week);
+-------------------------------+
|
date_add(@ct,interval 1 week) |
+-------------------------------+
| 2011-03-08
15:09:16 |
+-------------------------------+
1 row in set (0.00
sec)
类似功能还有adddate(),addtime()
等函数
，与之相对应的是date_sub()
，顾名思义就是日期减法
另类日期函数
Period_add(P,N):
日期加/
减去N
月，其中P
的格式应为yyyymm
或yymm
Period_diff(P1,P2):
日期p1-p2
，返回N
个月
mysql> select
period_add(201103,2),period_add(201103,-2) ;
+----------------------+-----------------------+
|
period_add(201103,2) | period_add(201103,-2) |
+----------------------+-----------------------+
|
201105
|
201101 |
+----------------------+-----------------------+
1 row in set (0.00
sec)
mysql> select
period_diff('201103','201101');
+--------------------------------+
|
period_diff('201103','201101') |
+--------------------------------+
|
2 |
+--------------------------------+
1 row in set (0.00
sec)
日期时间相减函数
Datediff(date1,date2)
:
两个日期date1-date2
mysql> select
datediff('2011-03-09','2011-03-01');
+-------------------------------------+
|
datediff('2011-03-09','2011-03-01') |
+-------------------------------------+
|
8 |
+-------------------------------------+
1 row in set (0.00
sec)
mysql> select
datediff('2011-03-01','2011-03-09');
+-------------------------------------+
|
datediff('2011-03-01','2011-03-09') |
+-------------------------------------+
|
-8 |
+-------------------------------------+
1 row in set (0.00
sec)
Timediff(time1,time2)
:
两个时间相减
mysql> select
timediff('2011-03-03 15:33:00','2011-03-02 15:33:59');
+-------------------------------------------------------+
|
timediff('2011-03-03 15:33:00','2011-03-02 15:33:59') |
+-------------------------------------------------------+
|
23:59:01
|
+-------------------------------------------------------+
1 row in set (0.00
sec)
mysql> select
timediff('15:33:00','15:33:59');
+---------------------------------+
|
timediff('15:33:00','15:33:59') |
+---------------------------------+
|
-00:00:59
|
+---------------------------------+
1 row in set (0.00
sec)
四
mysql
日期、时间转换函数
Time_to_sec(time)
:
时间—>
秒 转换函数
Sec_to_time(num)
:
秒-->
时间 转换函数
mysql> select
time_to_sec('01:00:00');
+-------------------------+
|
time_to_sec('01:00:00') |
+-------------------------+
|
3600 |
+-------------------------+
1 row in set (0.00
sec)
mysql> select
sec_to_time(3600);
+-------------------+
| sec_to_time(3600)
|
+-------------------+
|
01:00:00 |
+-------------------+
1 row in set (0.00
sec)
To_days(date)
:
日期-->
天 转换函数 起始日期为0000-00-00
From_days(num)
:
天-->
日期 将数字转换为具体的日期
mysql> select
to_days('2011-03-01');
+-----------------------+
|
to_days('2011-03-01') |
+-----------------------+
|
734562 |
+-----------------------+
1 row in set (0.00
sec)
mysql> select
from_days(734562);
+-------------------+
| from_days(734562)
|
+-------------------+
|
2011-03-01 |
+-------------------+
1 row in set (0.00
sec)
Str_to_date(str,date)
:
字符串-->
日期 转换函数
可以将一些杂乱无章的字符转换为日期格式
mysql> select
str_to_date('01.03.2011', '%m.%d.%Y');
+---------------------------------------+
|
str_to_date('01.03.2011', '%m.%d.%Y') |
+---------------------------------------+
|
2011-01-03
|
+---------------------------------------+
1 row in set (0.00
sec)
mysql> select
str_to_date('01/03/2011', '%m/%d/%Y');
+---------------------------------------+
| str_to_date('01/03/2011',
'%m/%d/%Y') |
+---------------------------------------+
|
2011-01-03
|
+---------------------------------------+
1 row in set (0.00
sec)
小练习：
以表centralmobile_logs
为例，目前该表总共有270
多万条数据
mysql> select
count(*) from centralmobile_logs;
+----------+
| count(*) |
+----------+
| 2725403 |
+----------+
1 row in set (0.00
sec)
现在对其做一些统计
查询过去30
天总共有多少数据
mysql> select
count(*) from centralmobile_logs where to_days(curdate())-
to_days(create_time)<=30;
+----------+
| count(*) |
+----------+
| 2367518 |
+----------+
1 row in set (3.38
sec)
mysql> select
count(*) from centralmobile_logs where datediff(curdate(),create_time) <=30;
+----------+
| count(*) |
+----------+
| 2367518 |
+----------+
1 row in set (3.29
sec)
查看每月第一天的数据
mysql> select
count(*) from centralmobile_logs where dayofmonth(create_time)=1;
+----------+
| count(*) |
+----------+
| 161293
|
+----------+
1 row in set (3.14
sec)
查看11
年1
月31
日之前的数据
mysql> select
count(*) from centralmobile_logs where create_time <='2011-01-31 00:00:00';
+----------+
| count(*) |
+----------+
| 413797
|
+----------+
1 row in set (0.17
sec)
查看11
年整个二月份的数据
mysql> select
count(*) from centralmobile_logs where monthname(create_time)='February' and
year(create_time)=2011;
+----------+
| count(*) |
+----------+
| 2149284 |
+----------+
1 row in set (3.94
sec)
查看11
年每个周日的累积数据
mysql> select
count(*) from centralmobile_logs where dayname(create_time)='Sunday' and
year(create_time)=2011;
+----------+
| count(*) |
+----------+
| 479033
|
+----------+
1 row in set (3.88
sec)
查看每天零点时分插入的数据总和
mysql> select
count(*) from centralmobile_logs where time(create_time)='00:00:00';
+----------+
| count(*) |
+----------+
|
37 |
+----------+
1 row in set (3.99
sec)
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