SQL>
SQL> CREATE OR REPLACE PROCEDURE CallProc1(p1 IN VARCHAR2 := NULL) AS
2 BEGIN
3 DBMS_OUTPUT.PUT_LINE('CallProc1 called with ' || p1);
4 END CallProc1;
5 /
Procedure created.
SQL>
SQL> CALL CallProc1('Hello!');
CallProc1 called with Hello!
Call completed.
SQL> CALL CallProc1();
CallProc1 called with
Call completed.
SQL>
SQL>