Primary Key with serial

["x asasaxax" <xanaruto@xxxxxxxxx>]

Hi,


   I have the following table    create table product(cod serial, user_cod bigint, constraint product_fk Foreign Key(user_cod) references user(cod), constraint product_pk Primary Key(cod, user_cod));

What i want to happend is that:
user_cod            cod
1                         1 
1                         2 
1                         3 
2                         1 
3                         1 
3                         2

Can serial do that? If not, what can  i do to make this happen?

Thanks a lot