开门见山
SQL> select systimestamp from dual;
SYSTIMESTAMP --------------------------------------------------------------------------- 24-JUL-20 01.05.53.444682 PM +00:00 SQL> alter session set time_zone ='-4:00';
Session altered.
SQL> select systimestamp from dual;
SYSTIMESTAMP --------------------------------------------------------------------------- 24-JUL-20 01.06.04.351449 PM +00:00 |
SQL> select current_timestamp from dual;
CURRENT_TIMESTAMP --------------------------------------------------------------------------- 24-JUL-20 09.18.28.961463 AM -04:00
SQL> alter session set time_zone ='UTC';
Session altered.
SQL> select current_timestamp from dual;
CURRENT_TIMESTAMP --------------------------------------------------------------------------- 24-JUL-20 01.18.49.432865 PM UTC |
SQL> select sysdate from dual;
SYSDATE ------------------- 2020-07-24 13:21:38
SQL> select current_date from dual;
CURRENT_DATE ------------------- 2020-07-24 13:21:49
SQL> alter session set time_zone ='-1:0';
Session altered.
SQL> select current_date from dual;
CURRENT_DATE ------------------- 2020-07-24 12:22:08
SQL> select sysdate from dual;
SYSDATE ------------------- 2020-07-24 13:22:13
|
SQL> select dbtimezone from dual;
DBTIME ------ +00:00 SQL> select sessiontimezone from dual;
SESSIONTIMEZONE --------------------------------------------------------------------------- -01:00 |
说明
- 以sys开头返回的系统时间,与数据库所在的服务器相关;
- 以current开头返回的客户端时区设置相关的时间,是服务器时间根据时区设置转换而来;
- 单元格1表示systimestamp不随time_zone设置而变化,其获取的系统的时戳(带时区TIMESTAMP WITH TIME ZONE);
- 单元格2表示current_timestamp随time_zone设置而变化,返回的系统时间根据会话时区转换而来;
- 单元格3 与单元格1/2类似,用于区别系统时间和客户端时区的时间;
- 单元格4是查询系统时区和会话时区的两个函数