How to add composite primary key to table

Question

create table d(id numeric(1), code varchar(2)) 

After I create the above table how can I add a composite primary key on both fields and also a foreign key?

Answer 1

In Oracle, you could do this:

create table D (   ID numeric(1),   CODE varchar(2),   constraint PK_D primary key (ID, CODE) ); 

Answer 2

alter table d add constraint pkc_Name primary key (id, code)

should do it. There's lots of options to a basic primary key/index depending on what DB your working with.