sql函数_NOW(),SYSDATE(),CURDATE(),CURTIME()

mysql>SELECT NOW(),SYSDATE(),CURDATE(),CURTIME();

+---------------------+---------------------+------------+-----------+
| now()               | sysdate()           | curdate()  | curtime() |
+---------------------+---------------------+------------+-----------+
| 2019-06-12 15:54:43 | 2019-06-12 15:54:43 | 2019-06-12 | 15:54:43  |
+---------------------+---------------------+------------+-----------+

now()：语句开始执行时间；

sysdate()：实时的系统时间