Every once in a while you’ll need to find the patch level of your database. With what I do on a daily basis, there are times when I need to gather this for many databases while on site somewhere.
The easiest way to get this information is from the OPatch utility. The OPatch utility can be found under $ORACLE_HOME/OPatch.
The above command will list out all the currently applied patches to your Oracle environment using the files in the oraInventory.
To find this same information from inside the database, there are a two views that can be used.
SQL>select * from sys.v$version ;
SQL>select * from sys.registry$history;
I really like the sys.registry$history because if gives you a running history of your applied patches and upgrades. Check it out next time you do an upgrade on your database.