The difference between current_date and sysdate

Current_date and Sysdate in Oracle display the current system time, the results are basically the same, but there are three different points:

1. Current_date returns the current session time, and Sysdate returns the server time.

2.current_date sometimes a second faster than Sysdate, which may be the result of rounding.

3. If you modify the current session of the time zone, such as the China's time zone is East eight, modified to East nine, then current_date show the time of East Nine, according to the principle of East plus west, current_date should be faster than sysdate an hour.

alter session set nls_date_format= ' Yyyy-mm-dd hh24:mi:ss ';

20:01:26 sql> Select current_date,sysdate from dual;

Current_date sysdate
------------------- -------------------
2009-03-10 20:01:37 2009-03-10 20:01:37

elapsed:00:00:00.00
20:01:37 sql> Select current_date,sysdate from dual;

Current_date sysdate
------------------- -------------------
2009-03-10 20:01:43 2009-03-10 20:01:43

elapsed:00:00:00.01
20:01:43 sql> Select current_date,sysdate from dual;

Current_date sysdate
------------------- -------------------
2009-03-10 20:01:44 2009-03-10 20:01:43

Note that current_date and sysdate are almost a second.

Modify the current session time zone to East area nine

Alter session set Time_zone= ' +09:00 '

20:04:19 sql> Select Current_date,sysdate from dual

Current_date sysdate
------------------- -------------------
2009-03-10 21:04:22 2009-03-10 20:04:22

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