Which professors do have a Ph.D.?
select * from professor where prof_high_degree = 'Ph.d.'
Also, which of these are in the history department?
select * from professor as t1 join department as t2 on t1.dept_code = t2.dept_code where t2.dept_name = 'History' and t1.prof_high_degree = 'Ph.d.'
What are their first names and location of their offices?
select t1.emp_fname, t2.prof_office from employee as t1 join professor as t2 on t1.emp_num = t2.emp_num join department as t3 on t3.dept_code = t2.dept_code where t3.dept_name = 'History' and t2.prof_high_degree = 'Ph.d.'