（1）select empno,ename,sal from emp where rownum < 4;

    select empno,ename,sal
 from(select *,rownum rn from emp) where rn between
 6 and 10
  
   -------- 这种*语法才支持
   select empno,ename,sal
 from(select e.*,rownum rn from emp e) where rn between
 6 and 10;

（2）排序后分页:

select empno,ename,sal from
 (select e.*,row_number() over (order by sal) rn from emp e)
   where rn between 4 and 6