Login to your Oracle SQL. Execute below command.
SQL> select * from REGISTRY$HISTORY; ACTION_TIME ACTION NAMESPACE VERSION ID COMMENTS BUNDLE_SERIES ----------- ------ --------- ------- -- -------- ------------- 16-FEB-12 UPGRADE SERVER 11.2.0.2 4 Upgraded from 10.2.0.4.0 PSU 16-FEB-12 APPLY SERVER 11.2.0.2 4 PSU 11.2.0.2.4 PSU 16-FEB-12 APPLY SERVER 11.2.0.2 4 PSU 11.2.0.2.4 PSU
From here, you can find the action date and action type that performed to the Oracle database
