日期函数
1 now 当前时间
mysql> select now(); +---------------------+ | now() | +---------------------+ | 2015-07-15 23:15:12 | +---------------------+ 1 row in set
2 curDate() 当前日期
mysql> select curDate(); +------------+ | curDate() | +------------+ | 2015-07-15 | +------------+ 1 row in set
3 curTime() 当前时间
mysql> select curTime(); +-----------+ | curTime() | +-----------+ | 23:15:21 | +-----------+ 1 row in set
4 时间添加函数 date_add()
mysql> select date_add('2015-6-1',interval 365 day); +---------------------------------------+ | date_add('2015-6-1',interval 365 day) | +---------------------------------------+ | 2016-05-31 | +---------------------------------------+ 1 row in set mysql> select date_add('2015-6-1',interval -365 day); +----------------------------------------+ | date_add('2015-6-1',interval -365 day) | +----------------------------------------+ | 2014-06-01 | +----------------------------------------+ 1 row in set mysql> select date_add('2015-6-1',interval 3 week); +--------------------------------------+ | date_add('2015-6-1',interval 3 week) | +--------------------------------------+ | 2015-06-22 | +--------------------------------------+ 1 row in set
5 datediff() 时间差值
mysql> select datediff('2015-7-15','2015-7-1'); +----------------------------------+ | datediff('2015-7-15','2015-7-1') | +----------------------------------+ | 14 | +----------------------------------+ 1 row in set
6 date_format 日期格式化
mysql> select date_format('2015-07-15','%m月%d日%Y年'); +------------------------------------------+ | date_format('2015-07-15','%m月%d日%Y年') | +------------------------------------------+ | 07月15日2015年 | +------------------------------------------+ 1 row in set
信息函数
1 connection_id() 当前连接的线程ID
mysql> select connection_id(); +-----------------+ | connection_id() | +-----------------+ | 47 | +-----------------+ 1 row in set2 user() 当前用户
mysql> select user(); +----------------+ | user() | +----------------+ | root@localhost | +----------------+ 1 row in set3 version() 当前数据库版本
mysql> select version(); +---------------------+ | version() | +---------------------+ | 5.0.22-community-nt | +---------------------+ 1 row in set4 last_insert_id() 最后一次插入的ID
mysql> select * from dept; +----+----------+ | id | deptName | +----+----------+ | 2 | 安全部 | +----+----------+ 1 row in set mysql> insert into dept(deptName) values('研发部'); Query OK, 1 row affected mysql> select last_insert_id(); +------------------+ | last_insert_id() | +------------------+ | 3 | +------------------+ 1 row in set5 database() 当前数据库
mysql> select database(); +------------+ | database() | +------------+ | t1 | +------------+ 1 row数学函数 1 ceil() 向上取整,也叫进一取整
mysql> select ceil(12.33); +-------------+ | ceil(12.33) | +-------------+ | 13 | +-------------+ 1 row in set mysql> select ceil(12.01); +-------------+ | ceil(12.01) | +-------------+ | 13 | +-------------+ 1 row in set mysql> select ceil(12.89); +-------------+ | ceil(12.89) | +-------------+ | 13 | +-------------+ 1 row in set2 floor() 向下取整,也叫舍一取整
mysql> select floor(12.98); +--------------+ | floor(12.98) | +--------------+ | 12 | +--------------+ 1 row in set3 mod 取莫 类似 %
mysql> select 3 mod 4; +---------+ | 3 mod 4 | +---------+ | 3 | +---------+ 1 row in set4 div 除 类似/
mysql> select 3 div 5; +---------+ | 3 div 5 | +---------+ | 0 | +---------+ 1 row in set mysql> select 3 div 1; +---------+ | 3 div 1 | +---------+ | 3 |
5 power(m,n) 幂运
mysql> select power(2,4); +------------+ | power(2,4) | +------------+ | 16 | +------------+ 1 row in set
算 m的n次方
6 round() 四舍五入
mysql> select round(2.44); +-------------+ | round(2.44) | +-------------+ | 2 | +-------------+ 1 row in set mysql> select round(2.456,2); +----------------+ | round(2.456,2) | +----------------+ | 2.46 | +----------------+ 1 row in set
7 truncate() 截取 字段 后面的参数是小数点的位数
mysql> select truncate(12.33,1); +-------------------+ | truncate(12.33,1) | +-------------------+ | 12.3 | +-------------------+ 1 row in set mysql> select truncate(23.3333,3); +---------------------+ | truncate(23.3333,3) | +---------------------+ | 23.333 | +---------------------+ 1 row in set