CREATE OR REPLACE TYPE nt_type IS TABLE OF NUMBER; 

CREATE OR REPLACE PROCEDURE print_nt (nt nt_type) AUTHID DEFINER IS 
  i  NUMBER; 
BEGIN 
  i := nt.FIRST; 
 
  IF i IS NULL THEN 
    DBMS_OUTPUT.PUT_LINE('nt is empty'); 
  ELSE 
    WHILE i IS NOT NULL LOOP 
      DBMS_OUTPUT.PUT('nt.(' || i || ') = '); 
      DBMS_OUTPUT.PUT_LINE(NVL(TO_CHAR(nt(i)), 'NULL')); 
      i := nt.NEXT(i); 
    END LOOP; 
  END IF; 
 
  DBMS_OUTPUT.PUT_LINE('---'); 
END print_nt; 

DECLARE 
  nt nt_type := nt_type();  -- nested table variable initialized to empty 
BEGIN 
  print_nt(nt); 
  nt := nt_type(90, 9, 29, 58); 
  print_nt(nt); 
END;