一：毫秒转换为日期:

SELECT TO_CHAR(1530867673000 / (1000 * 60 * 60 * 24) +      
        TO_DATE('1970-01-01 08:00:00', 'YYYY-MM-DD HH:MI:SS'), 'YYYY-MM-DD HH24:MI:SS') AS CDATE      
 FROM DUAL;

二：日期转换毫秒:

SELECT TO_NUMBER(TO_DATE('2005-03-29 12:30:45', 'YYYY-MM-DD HH24:MI:SS') -
                 TO_DATE('1970-01-01 8:0:0', 'YYYY-MM-DD HH24:MI:SS')) * 24 * 60 * 60 * 1000
  FROM DUAL;