oracle行号排序问题

1、创建一个student，并且插入数据

create table student(name varchar(12),age int)

insert into student values('z1','1');
insert into student values('z2','6');
insert into student values('z3','2');
insert into student values('z4','3');
insert into student values('z5','7');
commit;

2、直接按照age进行排序显示行号：

select * from(select rownum rw,t.* from student t order by t.age asc)

3另一种查询，能够很好地查找：

select row_number() over( order by t.age asc) rw,t.* from student t