SELECT'当前时间'AS 描述, TO_CHAR(SYSDATE, 'yyyy-mm-dd hh24:mi:ss') AS 时间 FROM DUAL UNION ALL SELECT'1天前'AS 描述, TO_CHAR(SYSDATE - 1, 'yyyy-mm-dd hh24:mi:ss') AS 时间 FROM DUAL UNION ALL SELECT'1小时前'AS 描述, TO_CHAR(SYSDATE - 1 / 24, 'yyyy-mm-dd hh24:mi:ss') AS 时间 FROM DUAL UNION ALL SELECT'1分钟前'AS 描述, TO_CHAR(SYSDATE - 1 / (24 * 60), 'yyyy-mm-dd hh24:mi:ss') AS 时间 FROM DUAL UNION ALL SELECT'1秒钟前'AS 描述, TO_CHAR(SYSDATE - 1 / (24 * 60 * 60), 'yyyy-mm-dd hh24:mi:ss') AS 时间 FROM DUAL -- 2019-11-29号执行以下 sql -- SELECT TRUNC(SYSDATE - 1) + 1, TRUNC(SYSDATE + 1) FROM dual -- 2019/11/29 2019/11/30