Oracle/PLSQL: Retrieve the name of the Oracle instance currently connected to

Question:  How can I get the name of the Oracle database instance that I'm connected to through an SQL statement?

Answer:  You can retrieve the instance name using the sys_context function.

To retrieve the Oracle instance name, you execute the following SQL statement:

select sys_context('USERENV','DB_NAME') as Instance
from dual;

It should return something like this:

INSTANCE
--------------------------------------------------------------------------------------
DBPROD