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2. A university database contains information about professors (identified by social security number, or SSN, with name, email and office number as attributes) and courses (identified by courseid, with course name, session number, url for syllabi, and offered department name). Professors teach courses and can teach the same course in several semesters, and each offering must be recorded. Every course must be taught by exactly one professor (no more, no less), and every professor must teach some course(s) Draw an ER diagram that captures this information. (10pts) 3. Suppose relations R(A,C) and s(B,C,D) have the following tuples shown in Tables 1 an respectively. (10pts) (1) Compute the natural join of R and S. Assume each tuple T has schemaAC T(A, B, C, D). (2) Compute the theta-join of R and S with the condition R.A - S.B AND R.A