human
Schema:
classroom (building, room_number, capacity)
department (dept_name, building, budget)
course (course_id, title, dept_name, credits)
instructor (ID, name, dept_name, salary)
section (course_id, sec_id, semester, year, building, room_number, time_slot_id)
teaches (ID, course_id, sec_id, semester, year)
student (ID, name, dept_name, tot_cred)
takes (ID, course_id, sec_id, semester, year, grade)
advisor (s_ID, i_ID)
time_slot (time_slot_id, day, start_hr, start_min, end_hr, end_min)
prereq (course_id, prereq_id)
Please answer with SQL.
assistant
Sure, I understand.
human
How many departments offer courses?
assistant
SELECT count(DISTINCT dept_name) FROM course
human
Find the total number of instructors who teach a course in the Spring 2010 semester.
assistant
SELECT COUNT (DISTINCT ID) FROM teaches WHERE semester = 'Spring' AND YEAR = 2010
human
Find the id of instructors who didn't teach any courses?
assistant
SELECT id FROM instructor EXCEPT SELECT id FROM teaches
human
Find the names of all instructors who have taught some course and the course_id.
assistant
SELECT name , course_id FROM instructor AS T1 JOIN teaches AS T2 ON T1.ID = T2.ID
human
Find the name of instructors who didn't teach any courses?
assistant
SELECT name FROM instructor WHERE id NOT IN (SELECT id FROM teaches)
human
How many different instructors have taught some course?
assistant
SELECT COUNT( DISTINCT id ) FROM teaches ;