SQL & PL/SQL

Hi,

I know how to bring up comma separated list of values tied to a particular key, however I wish to show up non-existing rows as well.  Here is my data

We have max value_codes and hence 3 value names in our table.  Key_col is transaction data.

keycol                value_code            value_name
-------               -----------          -----------
100                      'A'                 'ABC'
100                      'P'                 'PQR'
100                      'X'                 'XYZ'
200                      'P'                 'PQR'
300                      'A'                 'ABC'
300                      'P'                 'PQR'
400                      'X'                 'XYZ'
500                      'A'                 'ABC'

I want so generate output in text file in the following format
100        ABC        PQR        XYZ
200                   PQR
300        ABC        PQR
400                              XYZ
500        ABC

Could you please advice if this is possible by writing query?