Database Creation Date
A simple way that can check the creation date of a database. When the data is running, no matter the instance is open or mounted, we can query the database like this:
[oracle@primary01 ~]$ sqlplus / as sysdba
...
SQL> alter session set nls_date_format='YYYY-MM-DD HH24:MI:SS';
Session altered.
SQL> select name, created from v$database;
NAME CREATED
--------- -------------------
ORCLCDB 2020-11-28 21:10:53
The result shows the creation data of the database.