Creating a table with two keys?

I know this is probably a simple question, but how do I create a table with two primary keys? Here is what I tried, but it doesn't work:

  create table class
  (

    semester_code   char(3)     not null    primary key,
    course_num      smallint    not null    primary key,
    hours           float       not null

Thanks for any help,

Brian Master Received on Sat Oct 26 1996 - 00:00:00 CEST