Tell me all information on lecturers who have taught a course.
select * from class as t1 join employee as t2 on t1.prof_num = t2.emp_num
What are the corresponding course descriptions?
select t3.crs_description from class as t1 join employee as t2 on t1.prof_num = t2.emp_num join course as t3 on t1.crs_code = t3.crs_code
Also, what are those professors' first names, office locations, and department name?
select t2.emp_fname, t4.prof_office, t3.crs_description, t5.dept_name from class as t1 join employee as t2 on t1.prof_num = t2.emp_num join course as t3 on t1.crs_code = t3.crs_code join professor as t4 on t2.emp_num = t4.emp_num join department as t5 on t4.dept_code = t5.dept_code