Use Oracle add_months () function

add_month (date, num) function is processed mainly date, date date to be processed, num digital subtraction of date, and on a monthly basis.

E.g:

SQL> SELECT ADD_MONTHS(SYSDATE, 1) FROM SYS_USER; // 下一个月的日期
SQL> SELECT ADD_MONTHS(SYSDATE, -1) FROM SYS_USER; // 上一个月的日期