函数名称	描述
current_date()	当前日期
current_time()	当前时间
current_timestamp()	当前时间戳
date(datetime)	返回datetime的日期部分
date_add(date,interval d_value_type)	在date中添加日期或时间。interval后的数值可以是：year，day，minute，second
date_sub(date,interval d_value_type)	在date中减去日期或时间。interval后的数值可以是：year，day，minute，second
dateduff(date1,date2)	计算两个日期的差，单位是天，date1-date2
now()	当前日期时间

---

//显示当前日期
mysql> select current_date();
+----------------+
| current_date() |
+----------------+
| 2023-10-09     |
+----------------+
//显示当前时间
mysql> select current_time();
+----------------+
| current_time() |
+----------------+
| 22:37:21       |
+----------------+
//显示当前时间戳
mysql> select current_timestamp();
+---------------------+
| current_timestamp() |
+---------------------+
| 2023-10-09 22:37:30 |
+---------------------+
//显示当前日期+时间
mysql> select now();
+---------------------+
| now()               |
+---------------------+
| 2023-10-09 22:48:56 |
+---------------------+

---

//加上13天
mysql> select date_add('2013-10-10',interval 13 day);
+----------------------------------------+
| date_add('2013-10-10',interval 13 day) |
+----------------------------------------+
| 2013-10-23                             |
+----------------------------------------+
//减去14天
mysql> select date_sub('2013-10-10',interval 14 day);
+----------------------------------------+
| date_sub('2013-10-10',interval 14 day) |
+----------------------------------------+
| 2013-09-26                             |
+----------------------------------------+
//计算两个日期相差的天数
mysql> select datediff('2018-10-3','2012-9-1');
+----------------------------------+
| datediff('2018-10-3','2012-9-1') |
+----------------------------------+
|                             2223 |
+----------------------------------+

---

//date获取datetime的日期部分
mysql> select date(current_timestamp);
+-------------------------+
| date(current_timestamp) |
+-------------------------+
| 2023-10-09              |
+-------------------------+mysql> select date(now());
+-------------+
| date(now()) |
+-------------+
| 2023-10-09  |
+-------------+