select sysdate-e.hiredate from emp e;---算出明天此刻select sysdate+1from dual;---查询出emp表中所有员工入职距离现在入职几月select months_between( sysdate,e.hiredate) from emp e
---查询出emp表中所有员工入职距离现在入职几年select months_between( sysdate,e.hiredate)/12from emp e
--- ---查询出emp表中所有员工入职距离现在入职几周select (sysdate-e.hiredate)/7from emp e