SQL> select rownum,dname from dept;

    ROWNUM DNAME
---------- --------------
         1 ACCOUNTING
         2 RESEARCH
         3 SALES
         4 OPERATIONS

sql>select dname, row_number() over (order by dname)
  2    from dept;
 
DNAME          ROW_NUMBER()OVER(ORDERBYDNAME)
-------------- ------------------------------
ACCOUNTING                                  1
OPERATIONS                                  2
RESEARCH                                    3
SALES                                       4