Função Oracle ADD MONTHS

-- ADICIONAR O MÊS

SELECT TRUNC(SYSDATE) AS Data_atual,
       ADD_MONTHS(TRUNC(SYSDATE), 5) AS ADD_MONTHS
  FROM dual;

SELECT ADD_MONTHS(TO_DATE('29/02/16', 'DD/MM/YY'),1) AS ADD_MONTHS
  FROM dual;

SELECT ADD_MONTHS(TO_DATE('28/02/17', 'DD/MM/YY'),1) AS ADD_MONTHS
  FROM dual;

SELECT ADD_MONTHS(TO_DATE('27/02/16', 'DD/MM/YY'),1) AS ADD_MONTHS
  FROM dual;

SELECT TRUNC(SYSDATE) AS Data_atual,
       ADD_MONTHS(TRUNC(SYSDATE), -1) AS ADD_MONTHS
  FROM dual;