select (sysdate - 1 / 24 / 60 * 30) +
DBMS_RANDOM.VALUE(1, 1800) / 3600 / 24 as "过去30分钟随机时间"
FROM DUAL;
select (sysdate - 1 / 24 / 60 * 30) +
DBMS_RANDOM.VALUE(1, 1800) / 3600 / 24 as "过去30分钟随机时间"
FROM DUAL;