oracle中的rownum

create table person(ID char(6), name VARCHAR2(100));
insert into person values('200001',‘徐一’);
insert into person values('200002',‘李二’);
insert into person values('200003',‘张三’);
insert into person values('200004',‘小四’);

commit;

等于1：select rownum,id,name from student where rownum=1;

大于2：select * from(select rownum no ,id,name from student) where no>2;

闭区间：select * from (select rownum no,id,name from student where rownum<=3 ) where no >=2;

rownum伪列，每次查询都是从1开始，因此要想查询，大于或者区间须要用子查询。