In a patch’s README file, the prerequisite patches and patch levels that must be in place before that patch is applied are listed. Patches are indicated by a patch number (usually seven digits long), for example, 4712852. Patch levels  are usually of the form 11i.<PRODUCT CODE>.<LETTER>, for example, 11i.GL.H.

To determine if a particular prerequisite patch has already been applied to the system, query the AD_BUGS table.

Step 1:        Source the environment to load SQL*Plus. Either the applications tier environment or database tier environment can be sourced.

[applmgr@appslinux /]$ cd /u2/oracle/vis2appl/
[applmgr@appslinux vis2appl]$ . APPSORA.env

Step 2:        Load SQL*Plus:

[applmgr@appslinux vis2appl]$ sqlplus apps/apps

Step 3:        To determine whether a particular patch has been applied, query the BUG_NUMBER column of the AD_BUGS table for the patch number. For example, to determine if the patch 4712852 has been applied to the system, issue this SQL query:

SQL> select bug_number, creation_date from ad_bugs where bug_number = '4712852';
BUG_NUMBER                     CREATION_DATE
------------------------------ -------------
4712852                        16-MAR-07

If the query returns a row, the patch has been applied, whereas if the query does not return any rows, then the patch has not been applied.

Step 4:        To determine the patch level of a product, query the PATCH_LEVEL columns of the FND_PRODUCT_INSTALLATIONS table. For example, to determine the patch level for the GL product, issue this SQL query:

SQL> select patch_level, status from fnd_product_installations where patch_level like '%GL%';
PATCH_LEVEL                    S
------------------------------ -
11i.GL.H                       I