I am not sure I understand you notation and the term 'double key'.
An index that uses more columns?
You want to use the 'name' and 'code' columns for that 'key' ??
If you want it to be a PRIMARY key you do from 'ALTER TABLE' – just check both columns
If it is not a PRIMARY key but just a plain index you to from 'manage indexes'.
Both are available from the table context menu.