connect by level

SELECT LEVEL

FROM DUAL

CONNECT BY LEVEL <= 31

;

SELECT TO_CHAR((BASE_MONTH + LEVEL - 1), 'YYYYMMDD') YYYYMMDD

FROM

(

    SELECT TO_DATE('201306', 'YYYYMM') BASE_MONTH

    FROM DUAL

)

CONNECT BY (BASE_MONTH + LEVEL - 1) BETWEEN BASE_MONTH AND LAST_DAY(BASE_MONTH)

ORDER BY YYYYMMDD

;