DECLARE
v_index number := 10;
BEGIN
LOOP
    dbms_output.put_line(v_index);
    v_index := v_index - 1;
    EXIT WHEN v_index = 0;
END LOOP;
END;

DECLARE
v_index number := 0;
BEGIN
FOR v_index IN 0..10
LOOP
    dbms_output.put_line(v_index);
END LOOP;
END;

DECLARE
v_index number := 10;
BEGIN
WHILE v_index > 0
LOOP
    dbms_output.put_line(v_index);
    v_index := v_index - 1;
END LOOP;
END;