Different ways to fetch Incremental data from oracle tables

Incremental Query 
Method 1: Fetch the record between two records
SELECT  * FROM (SELECT  emp.*, rownum rn FROM emp ) WHERE  rn between 2 and 5;

Method 2: Fetch the record between two records
SELECT  * FROM (SELECT  q.*, rownum rn FROM( SELECT  * FROM  emp ) q ) WHERE  rn BETWEEN 2 AND 5;

Method 3: Fetch the last record form table
SELECT  * FROM (SELECT  q.*, rownum rn FROM (SELECT * FROM  emp) q ) WHERE  rn=(select max(rownum) from emp);