方法一：利用rownum和差集函数minus
select * from (
select * from emp order by sal)
where rownum<13
minus
select * from(
select * from emp order by sal)
where rownum<10
方法二：利用rownum取别名来选取特定行
select * from (
select rownum rn,e.* from (
select * from emp order by sal) e)
where rn between 11 and 13
