http://arjudba.blogspot.com/2008/05/globalnames-and-globalname-in-oracle.html

To view and change global_name
22:53:34 system@TESTPRD> select * FROM global_name;

GLOBAL_NAME
——————————————————————————-
TESTPRD.WORLD

22:53:43 system@TESTPRD> ALTER DATABASE RENAME GLOBAL_NAME TO TESTDV.WORLD;

22:54:22 system@ALOCPRD> select * FROM global_name;

GLOBAL_NAME
——————————————————————————-
TESTDV.WORLD

• General DBA