What are the first names of all professors who are teaching any classes?
select t2.emp_fname from class as t1 join employee as t2 on t1.prof_num = t2.emp_num join professor as t3 on t2.emp_num = t3.emp_num
Which of them are from the Accounting department?
select t2.emp_fname from class as t1 join employee as t2 on t1.prof_num = t2.emp_num join professor as t3 on t2.emp_num = t3.emp_num join department as t4 on t4.dept_code = t3.dept_code where t4.dept_name = 'Accounting'
Also, what classrooms do they teach in?
select t2.emp_fname, t1.class_room from class as t1 join employee as t2 on t1.prof_num = t2.emp_num join professor as t3 on t2.emp_num = t3.emp_num join department as t4 on t4.dept_code = t3.dept_code where t4.dept_name = 'Accounting'