Limit Rows in sql query output

We are intrested in fetching output on rows wise for ex.

in first iteration 1 .. 50
second iteration 51 .. 100
Third iteration 101 .. 150 so on .

SELECT * FROM (SELECt m.*,rownum r FROm EM_INFO m ORDER BY DBNAME ASC) WHERE r >=1 AND r <=50

or

SELECT * FROM (SELECt m.*,rownum r FROm EM_INFO m ) WHERE r >=1 AND r <=50 and ORDER BY DBNAME ASC

I've tried with both the above queries but its not displaying in the sorted order Can somebody help me pls .

Regards
Bala

--
http://www.freelists.org/webpage/oracle-l