(Solved): 1. (4 points) A university database contains information about professors (identified by social sec ...

1. (4 points) A university database contains information about professors (identified by social security number, or SSN) and courses (identified by Course_ID). Professors teach courses; each of the following situations concerns the teach relationship set. For each situation, draw an ER diagram that describes it (assuming no further constraints hold). a) Professors can teach the same course in several semesters, but only the most recent such offering needs to be recorded. (Assume this condition applies in all subsequent questions.) b) Every professor must teach some course. c) Every professor teaches exactly one course (no more, no less). d) Every professor teaches exactly one course (no more, no less), and every course must be taught by some professor.