Using row number in IBM DB2

Most of us are very familiar with using rownum function to get the number of rows in a select query. But rownum in IBM DB2 is used in a bit different way.

ROWNUMBER() OVER() AS ROWNUM

For Example:

select   Column1 , ROWNUMBER() OVER() AS ROWNUM  from  TABLE where 

Column2 = 'A'   AND Column3 <> ' ' ;