select trunc(sysdate) from dual;--2017/9/11
select trunc(sysdate) + 1 from dual;--2017/9/12
select sysdate from dual; --从系统获取时间2017/9/11 9:20:56
select trunc(sysdate) + 1 from dual;--2017/9/12
select sysdate from dual; --从系统获取时间2017/9/11 9:20:56