SELECT TRUNC(TO_NUMBER(SYSDATE - TO_DATE('01-01-1970', 'DD-MM-YYYY')) * (24*60*60*1000)) - (9*60*60*1000) x , TRUNC((sysdate - 9/24 - TO_DATE('197001', 'yyyymm')) * (24*60*60*1000)) y , TRUNC((sysdate - TO_DATE('1970010109', 'yyyymmddhh24')) * (24*60*60*1000)) z FROM dual ; -- 결과 : 1609841237000 SELECT TO_DATE('197001', 'yyyymm') + (1609841237000 + 9*60*60*1000) / (24*60*60*1000) x , TO_DATE('197001', 'yyyymm') + 9/24 + 1609841237000 / (24*60*60*1000) y , TO_DATE('1970010109', 'yyyymmddhh24') + 1609841237000 / (24*60*60*1000) z FROM dual ; -- 결과 : 2021/01/05 19:07:17