Exercise The university wants to create a database for teaching. The database needs to contain information about the different courses, the different versions of the courses given during different occasions, the teachers, and the students taking the courses. A course contains a unique course code and a name. It also has one or more examination moments such written exam, lab work, project. Each version of a course has a date (when the course is given) and information about course literature. A course version has exactly one examiner which should be a teacher, and one or more teachers teaching the classes. Teachers can be examiner for several course versions as well as teach in several course versions. Students can sign up for many course versions. The database should also store the final grades for students for the different courses.