Oracle兼容-函数-SYSTIMESTAMP()函数

1. 语法

1. SYSTIMESTAMP
2. SYSTIMESTAMP()

2. 定义和用法

SYSTIMESTAMP() 函数的作用是返回当前的日期和时间，类似于原生的函数NOW()。当未显式指定微秒位数时，时间的微秒位数默认值为6。

3. 示例

1. -- 默认微秒位数为6
2. greatsql> SELECT SYSTIMESTAMP FROM DUAL;
3. greatsql> SELECT SYSTIMESTAMP, SYSTIMESTAMP() FROM DUAL;
4. +----------------------------+----------------------------+
5. | SYSTIMESTAMP               | SYSTIMESTAMP()             |
6. +----------------------------+----------------------------+
7. | 2023-11-02 17:43:25.990131 | 2023-11-02 17:43:25.990131 |
8. +----------------------------+----------------------------+

10. -- 自行指定微秒位数
11. greatsql> SELECT SYSTIMESTAMP(0), SYSTIMESTAMP(3) FROM DUAL;
12. +---------------------+-------------------------+
13. | SYSTIMESTAMP(0)     | SYSTIMESTAMP(3)         |
14. +---------------------+-------------------------+
15. | 2023-11-02 17:43:45 | 2023-11-02 17:43:45.189 |
16. +---------------------+-------------------------+

18. -- 指定微秒位数超出范围会报错
19. greatsql> SELECT SYSTIMESTAMP(10) FROM DUAL;
20. ERROR 1426 (42000): Too-big precision 10 specified for 'now'. Maximum is 6.

22. greatsql> SELECT SYSTIMESTAMP(-1) FROM DUAL;
23. ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '-1) FROM DUAL' at line 1

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