CREATE OR REPLACE PROCEDURE print (n INTEGER) IS 
BEGIN 
  IF n IS NOT NULL THEN 
    DBMS_OUTPUT.PUT_LINE(n); 
  ELSE 
    DBMS_OUTPUT.PUT_LINE('NULL'); 
  END IF; 
END print; 

CREATE TABLE t1 ( 
  c1 INTEGER DEFAULT 0 NOT NULL, 
  c2 INTEGER DEFAULT 1 NOT NULL 
)

DECLARE 
  t1_row t1%ROWTYPE; 
BEGIN 
  DBMS_OUTPUT.PUT('t1.c1 = '); 
  DBMS_OUTPUT.PUT_LINE(NVL(TO_CHAR(t1_row.c1), 'NULL')); 
 
  DBMS_OUTPUT.PUT('t1.c2 = '); 
  DBMS_OUTPUT.PUT_LINE(NVL(TO_CHAR(t1_row.c2), 'NULL')); 
END;