Basic Oracle Concepts and Programming Question:

Here are the rules about OUT parameters:

► A formal OUT parameter acts like an un-initialized variable. It must be assigned with new values before the end of the procedure or function.
► An actual OUT parameter must be a variable.
► An actual OUT parameter will not pass any value to the formal parameter.
► An actual OUT parameter will receive a copy of the value from the formal parameter at the end of the procedure or function.

Here is good example of a procedure with an OUT parameter:

SQL> CREATE OR REPLACE PROCEDURE WELCOME AS
2 SITE CHAR(40) := 'globalguideline.com';
3 MESSAGE CHAR(80);
4 PROCEDURE WELCOME_PRINT(S IN CHAR, M OUT CHAR) AS
5 BEGIN
6 M := 'Welcome to ' || S;
7 END;
8 BEGIN
9 WELCOME_PRINT('MySpace.com', MESSAGE);
10 DBMS_OUTPUT.PUT_LINE(MESSAGE);
11 WELCOME_PRINT(SITE, MESSAGE);
12 DBMS_OUTPUT.PUT_LINE(MESSAGE);
13 END;
14 /

SQL> EXECUTE WELCOME;
Welcome to MySpace.com
Welcome to globalguideline.com