sql - Different CURRENT_TIMESTAMP and SYSDATE in oracle

Question

After executing this SQL in oracle 10g:

SELECT SYSDATE, CURRENT_TIMESTAMP  FROM DUAL

I receive this strange output:

What is cause of the difference in time? The server time is equal of SYSDATE value

Answer 1

CURRENT_DATE and CURRENT_TIMESTAMP return the current date and time in the session time zone.

SYSDATE and SYSTIMESTAMP return the system date and time - that is, of the system on which the database resides.

If your client session isn't in the same timezone as the server the database is on (or says it isn't anyway, via your NLS settings), mixing the SYS* and CURRENT_* functions will return different values. They are all correct, they just represent different things. It looks like your server is (or thinks it is) in a +4:00 timezone, while your client session is in a +4:30 timezone.

You might also see small differences in the time if the clocks aren't synchronised, which doesn't seem to be an issue here.