CURRENT_TIMESTAMP vs. SYSDATE in Oracle: What's the Difference?

Understanding the Differences in CURRENT_TIMESTAMP and SYSDATE in Oracle Databases

When querying for the current date and time in an Oracle database, you may encounter different results when using the CURRENT_TIMESTAMP and SYSDATE functions. This discrepancy can be attributed to differences in time zones and database settings.

CURRENT_TIMESTAMP

The CURRENT_TIMESTAMP function returns the current date and time in the time zone of the client session. If the client session is not explicitly set to a specific time zone, Oracle will use the default time zone of the operating system.

SYSDATE

In contrast, the SYSDATE function returns the system date and time, which is maintained by the database server itself. This value is always stored in the database's default time zone, which is typically set during the database configuration.

Time Zone Discrepancies

The difference in time between CURRENT_TIMESTAMP and SYSDATE can occur when the client session and the database server are located in different time zones. For example, if the client session is in the Pacific Time zone (UTC-8) and the database server is in the Eastern Time zone (UTC-5), the CURRENT_TIMESTAMP value will be three hours ahead of the SYSDATE value.

Database Configuration

In addition to time zone differences, database settings can also affect the behavior of these functions. For instance, the NLS_DATE_FORMAT parameter specifies the format of the date and time values returned by Oracle. If this parameter is set differently on the client session and the database server, the output of CURRENT_TIMESTAMP and SYSDATE may appear different.

Conclusion

Understanding the differences between CURRENT_TIMESTAMP and SYSDATE is crucial to ensure accurate date and time handling in Oracle databases. By considering the time zone and database configuration, developers can avoid confusion and ensure that their applications retrieve the correct date and time for their intended use.

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