SQL & PL/SQL :: Query To Update Current Value In DBA View To New One

I am looking to build a query to update a current value in a DBA view to a new one.i.e. updating directories based on the current value:

CREATE OR REPLACE DIRECTORY 'DIRECTORY_NAME' AS 'DIRECTORY_PATH'(substr(directory_path, 1,5) + '/&dbname' {i.e. this is different for every database name }+ 'DIRECTORY_PATH'(string after /xyz/)
WHERE DIRECTORY_NAME in
( select DIRECTORY_NAME
from DBA_DIRECTORIES
WHERE DIRECTORY_PATH
like '/xyz/%'
)

i.e. resulting output should be:

CREATE OR REPLACE DIRECTORY 'ABC' AS '/xyz/DBNAME/abc/def/';

(when the directory previously was 'xyz/abc/def/') i.e. basically inserting the db name into the directory.where DBNAME is a variable more directories are added frequently so therefore this needs to be a dynamic procedure to change the directories in the db.