What are the codes of the accounting department?
select dept_code from department where dept_name = "Accounting"
Which professors are in that department?
select * from professor as t1 join department as t2 on t1.dept_code = t2.dept_code where dept_name = "Accounting"
How many are there?
select count(*) from professor as t1 join department as t2 on t1.dept_code = t2.dept_code where dept_name = "Accounting"