Find the total number of students and total number of instructors for each department.
SELECT count(DISTINCT T2.id) ,  count(DISTINCT T3.id) ,  T3.dept_name FROM department AS T1 JOIN student AS T2 ON T1.dept_name  =  T2.dept_name JOIN instructor AS T3 ON T1.dept_name  =  T3.dept_name GROUP BY T3.dept_name
total number of students for each department = count(DISTINCT student.id) WHERE student.dept_name = department.dept_name; total number of instructors for each department = count(DISTINCT instructor.id) WHERE instructor.dept_name = department.dept_name;