Aufbau der Datenbank:

class: id, klassensprecher, klassenleiter
grades: subject, student_id, grade, date
student: id, gender, forename, name, adress, city, zip, email, telephone, birthday, color, kilograms, centimeters, class_id
teacher: id, gender, forename, name, adress, city, zip, email, telephone, birthday, color, subject_1, subject_2
teacher_class_subject: subject, class_id, teacher_id