Updated on Kisan Patel
Yes, it is possible to create primary key on combination of columns on the table.
To do that select columns to create primary key on by selecting the first column in the design mode by clicking on the left most box and the hold the ctrl key (on keyboard) and clicking on the 2nd column left most box.
By using this trick you can creates primary key on both columns and notifying it by keeping the key symbol for both columns.