I don't why can't you use pl/sql even from front end apps, they can call stored procs and they can results ..

Here is another solution ..

Create a view on table test having columns test1,test2 ..

syntax:create view test1 as select rownum id,test1,test2 from test ;

select * from test1 where mod(id,2) <> 0;


Good luck


Raghu