Multiple Primary Keys

Hi all,

How to create a table with multiple primary key?
I'm trying this manner but don't work.

CREATE TABLE A ( FIELD1 INT PRIMARY KEY, FIELD2 INT PRIMARY KEY);

and

CREATE TABLE A ( FIELD1 INT , FIELD2 INT , PRIMARY KEY(FIELD1, FIELD2);

But i've the following message:

ERROR: CREATE TABLE / PRIMARY KEY multiple primary keys for table 'A' are not allowed.

How to do?

Best Regards.

Isaías