Why Do CURRENT_TIMESTAMP and SYSDATE Return Different Times in Oracle?

Exploring the Discrepancy Between CURRENT_TIMESTAMP and SYSDATE in Oracle

When querying for the current date and time using Oracle's SELECT statement, you may encounter a perplexing distinction between the values returned by CURRENT_TIMESTAMP and SYSDATE. This discrepancy stems from the inherent differences in their respective functions:

Understanding the Roles of CURRENT_TIMESTAMP and SYSDATE

• CURRENT_TIMESTAMP: This function returns the current date and time based on the session's time zone setting.
• SYSDATE: In contrast, SYSDATE provides the system date and time, which reflects the timezone where the Oracle database is physically located.

Impact of Time Zone Settings

The key to understanding the disparity lies in the time zone configurations. If the time zone of your client session differs from the server housing the Oracle database, the values obtained from CURRENT_TIMESTAMP and SYSDATE will likely vary.

For instance, if your server is in a 4:00 timezone while your client session is in a 4:30 timezone, you'll witness a 30-minute difference between the results of these functions. This is because CURRENT_TIMESTAMP considers your session's timezone, rendering it 30 minutes behind the server's time.

Other Contributing Factors

Aside from time zone discrepancies, there's a remote possibility for minor deviations between CURRENT_TIMESTAMP and SYSDATE if the clocks on the server and client are not synchronized. However, this scenario appears unlikely in the given context.

Conclusion

To ensure consistency in your temporal queries, it's crucial to align the time zones of your client session and the Oracle database server. By doing so, CURRENT_TIMESTAMP and SYSDATE will yield identical values, accurately reflecting the current date and time in the system's timezone.

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