Basic Oracle Concepts and Programming Question:

A stored function can be called as part of expression in any PL/SQL statement. One simplest way to call a stored function is to a dummy SELECT statement as shown in the following tutorial script using SQL*Plus:

SQL> CREATE OR REPLACE FUNCTION GET_SITE
2 RETURN VARCHAR2 AS
3 BEGIN
4 RETURN 'globalguidelinee.com';
5 END;
6 /
Function created.

SQL> SELECT get_site() FROM dual;

GET_SITE()
---------------------------------
globalguidelinee.com

DUAL is not a real table or view. It is commonly used to with SELECT statement to evaluate expressions.