Generate rownum (row number) for output records

select
                (select
                            count(*)
                from
                            emp
                where
                            emp.eno <= t1.eno
                ) as rownum,
                t1.*
from
                emp t1
order by
                rownum
 
If field is not ordered already then do

select
            (select
                        count(*)
            from
                        emp
            where
                        emp.eno <= empold.eno
            ) as rownum,
            empold.*
from
            (select * from emp order by eno) as empold