How to create rownum or auto number

Question

Hi All,
I got some problem in create rownum or auto number in following table condition.
eg.
MeasID PosID Desc
==== ====== ===
P01 1 Abc
P01 1 Cde
P01 2 Abc
P01 2 Efg
P01 2 Xyz
in select statement, I would like to make it look like:
Num MeasID PosID Desc
=== ==== ====== ===
1 P01 1 Abc
2 P01 1 Cde
1 P01 2 Abc
2 P01 2 Efg
3 P01 2 Xyz
How can I create a running number and make like some short like group by PosID?

Answer 1

Use analytic row_number:
with t as (
           select 'P01' MeasID,'1' PosID,'Abc' Descr from dual union all
           select 'P01','1','Cde' from dual union all
           select 'P01','2','Abc' from dual union all
           select 'P01','2','Efg' from dual union all
           select 'P01','2','Xyz' from dual
select  row_number() over(partition by MeasID,PosID order by Descr) num,
        MeasID,
        PosID,
        Descr
  from  t
  order by MeasID,
           PosID,
           Descr
       NUM MEA P DES
         1 P01 1 Abc
         2 P01 1 Cde
         1 P01 2 Abc
         2 P01 2 Efg
         3 P01 2 Xyz
SQL> SY.