Data format and display

Hello list,

I have a table that contains this raw data:

  epr_procode | epr_tipo | epr_mes | epr_valor |      zert_title
-------------+----------+---------+-----------+----------------------
  00C188      | VTA      | 200309  | 2116.0000 | Venta
  00C188      | CTO      | 200309  | 1600.0700 | Costo
  00C188      | VTA      | 200311  | 3450.0000 | Venta
  00C188      | CTO      | 200311  | 2687.4200 | Costo

I need to display it this way:

TITULO         |200309    |200310   |200311     |200312
-------------+----------+---------+-----------+----------------------
Venta         |2116.0000 |0.0000   |3450.0000  |0.0000
Costo         |1600.0700 |0.0000   |2687.4200  |0.0000


Notice I must display the missing 200310 and 200312 empty data since
users retrieves the info in four months based data set, of course that
data does not exist since there were no trans in those months. Any idea
or suggestion to get it done in Postgresql.

Thanks in advance



--
Sinceramente,
Josué Maldonado.

"Las palabras de aliento después de la censura son como el sol tras el
aguacero."