Odd No Even No

1.How to fetch alternate records from a table.Like Even /Odd Records.

Even Record :-
select * from (select  rownum rn,employee_id,last_name from employees order by rn) where mod(rn,2)=0

        RN EMPLOYEE_ID LAST_NAME
---------- ----------- -------------------------
         2         199 Grant
         4         201 Hartstein
         6         203 Mavris
         8         205 Higgins
        10         100 King
        12         102 De Haan
        14         104 Ernst
        16         106 Pataballa
        18         108 Greenberg
        20         110 Chen
        22         112 Urman



Odd Record
select * from (select  rownum rn,employee_id,last_name from employees order by rn) where mod(rn,2)!=0

        RN EMPLOYEE_ID LAST_NAME
---------- ----------- -------------------------
         1         198 OConnell
         3         200 Whalen
         5         202 Fay
         7         204 Baer
         9         206 Gietz
        11         101 Kochhar
        13         103 Hunold
        15         105 Austin
        17         107 Lorentz
        19         109 Faviet
        21         111 Sciarra