Consider the Schema diagram for a university database shown in Figure 2.8 on page 47 of the textbook.

a. Find the names and IDs of all students who have taken a course taught by Dr. Who. Use at least one natural join in your answer. Be careful with this question! b. Find the department and course id of all classes that were taught or are being taught by an instructor from a different department. Use at least one set operations ( union, intersection, or difference) in your query. c. Find the name and ID of all students who are taking all of the courses that Dr. Who is teaching in the Spring 2020 semester.

student takes ID course id sec id semester 1er 4112 dept_name tot cred grade advisor section course_id sec id semester year building TOOM_10 time_slof_id course course id title dept name credits department dept name building budget time slot time slot id day start time end time instructor classroom prerea course id prereg id ID name building NOOM O Capacity feaches dept_name salary ID course id serid semester Express each of the following queries using relational algebra. (10 points each) Note: Your queries should use as few relations as arguments as possible (i.e. do not include relations that are not needed to produce the results)