Why Do `CURRENT_TIMESTAMP` and `SYSDATE` Show Different Times in Oracle?

Disparity in CURRENT_TIMESTAMP and SYSDATE in Oracle

In Oracle, executing the query SELECT SYSDATE, CURRENT_TIMESTAMP FROM DUAL may yield unexpected discrepancies in their values. This behavior stems from the fundamental difference between these two functions.

CURRENT_TIMESTAMP vs. SYSDATE

• CURRENT_TIMESTAMP: Represents the current date and time in the session's time zone, as determined by the NLS settings.
• SYSDATE: Represents the system date and time of the database server.

Discrepancies in Results

If the client session is not in the same time zone as the server (or if NLS settings differ), mixing SYS and CURRENT_ functions can produce varying results. For instance, if the server is in a 4:00 time zone and the client is in a 4:30 time zone, CURRENT_TIMESTAMP will show a time 30 minutes ahead of SYSDATE.

Additional Factors

Beyond time zone differences, slight disparities in time can also occur due to unsynchronized clocks. However, this is typically not the primary source of the observed differences.

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