What are the first names of all professors?
select emp_fname from professor as t1 join employee as t2 on t1.emp_num = t2.emp_num
Which of those are in the History department?
select t2.emp_fname, t1.prof_office from professor as t1 join employee as t2 on t1.emp_num = t2.emp_num join department as t3 on t1.dept_code = t3.dept_code where t3.dept_name = 'History'
Of those, who does not have a Ph.D.?
select t2.emp_fname, t1.prof_office from professor as t1 join employee as t2 on t1.emp_num = t2.emp_num join department as t3 on t1.dept_code = t3.dept_code where t3.dept_name = 'History' and t1.prof_high_degree ! = 'Ph.d.'