Here are the rules about IN parameters:

► A formal IN parameter acts like constant. It can not be assigned with new values.

► An actual IN parameter can take a value or a variable.

► An actual IN parameter is passed by reference to the specified value or the value of the specified variable.

► An actual IN parameter will not receive any value from the formal parameter.

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

SQL> CREATE OR REPLACE PROCEDURE WELCOME AS

2 SITE CHAR(80) := 'rendc.org';

3 PROCEDURE WELCOME_PRINT(S IN CHAR) AS

4 BEGIN

5 DBMS_OUTPUT.PUT_LINE('Welcome to ' || S);

6 -- S := 'Google.com'; -- Not allowed

7 END;

8 BEGIN

9 WELCOME_PRINT('MySpace.com');

10 WELCOME_PRINT(SITE);

11 END;

12 /

SQL> EXECUTE WELCOME;

Welcome to MySpace.com

Welcome to rendc.org