which patchset update is installed on my oracle database ?

a question which pops up regulary is how one can find out which psu is installed on an oracle database. there are at least two possibilities.

if you have access to the server use opatch:

$ORACLE_HOME/OPatch/opatch lsinventory | grep "Database Patch Set Update"
Patch description:  "Database Patch Set Update : 11.2.0.2.8 (14275621)"
Sub-patch  13923804; "Database Patch Set Update : 11.2.0.2.7 (13923804)"
Sub-patch  13696224; "Database Patch Set Update : 11.2.0.2.6 (13696224)"

if you don’t have access to the server but can connect as sys:

col comments for a60
col version for a30
set lines 264
select version,comments from registry$history where comments like '%PSU%';

VERSION 		       COMMENTS
------------------------------ ------------------
11.2.0.2		       PSU 11.2.0.2.3
11.2.0.2		       PSU 11.2.0.2.4
11.2.0.2		       PSU 11.2.0.2.8

you may even check if the database was upgraded from a previous release:

select version,comments from registry$history where comments like '%Upgraded%';

VERSION 		       COMMENTS
------------------------------ ------------------------
11.2.0.3.0		       Upgraded from 11.2.0.2.0