Two Primary Keys

[Victor Subervi]

Hi;
I have the following:

create table pics (
   picture_id int auto_increment primary key,
   product_sku int not null primary key,
   picture_num int not null,
   picture_desc varchar(100),
   picture_data longblob
);

which doesn't work I need to auto_increment and declare primary key on two
fields. How do?
TIA,
Victor