1、你按秒看明白了。 SQL> alter session set nls_date_format='YYYY-MM-DD HH24:MI:SS'; 2、select sysdate from dual; 2014-09-24 17:18:30 select to_date('15-JUL-02') from dual; 0015-07-02 00:00:00 select trunc(sysdate) from dual; 2014-09-24 00:00:00 3、所以你用trunc(sysdate)就对了 select trunc(sysdate)-to_date('15-JUL-02') from dual;