Enter all course codes that your course has. When the students registers, they choose their course code. This makes it easy to generate separate statistics for Chalmers and GU. Prefixing the course codes with CTH and GU makes it easier for the students to choose right.
You can remove course codes as long as no students have registered.
After the first student has registered you can, however, add new course codes and change the already existing ones.
In the database each student is connected to a course code. This connection is based on the number of the course code. For example, if a student selects the course code CTH: TDA200 he/she will be connected to the first course code. Changing the name of the first course code will, therefore, also change the name of the course code for that student.