oracle date 형을 unix timestamp 로 변환

SELECT (sysdate - to_date('01-JAN-1970','DD-MON-YYYY') ) * (86400) - (9*3600) AS dt FROM dual; SELECT (create_time - to_date('01-JAN-1970','DD-MON-YYYY') ) * (86400) - (9*3600) AS dt FROM maintext WHERE board_id = 1;