insert into Studenten (MatrNr, Name) values (28121, 'Archimedes');
insert into hoeren select MatrNr, VorlNr from Studenten, Vorlesungen where Titel = 'Selber Atmen';
update studenten set GebDatum = GebDatum + 10;
delete from Studenten where Semester > 13;
delete from hoeren where vorlnr = (select VorlNr from Vorlesungen where Titel = 'Selber Atmen');