The Oracle ROWNUM pseudocolumn returns a number indicating the order in which Oracle database selects the row from a table or from a join query.

Oracle ROWNUM pseudocolumn example

Select rownum, type, name
From jobs  
Where rownum > 1200;
Order By name;

Select * From
(Select * From jobs Order By job_id)
Where rownum < 100;

Select name, sal From
(Select name, sal 
From jobs 
Order By name asc, sal desc ) 
Where rownum < 325;