CREATE TABLE section (course_id VARCHAR, sec_id VARCHAR, semester VARCHAR, year DECIMAL, building VARCHAR, room_number VARCHAR, time_slot_id VARCHAR)
CREATE TABLE classroom (building VARCHAR, room_number VARCHAR, capacity DECIMAL)
CREATE TABLE student (ID VARCHAR, name VARCHAR, dept_name VARCHAR, tot_cred DECIMAL)
CREATE TABLE prereq (course_id VARCHAR, prereq_id VARCHAR)
CREATE TABLE advisor (s_ID VARCHAR, i_ID VARCHAR)
CREATE TABLE course (course_id VARCHAR, title VARCHAR, dept_name VARCHAR, credits DECIMAL)
CREATE TABLE teaches (ID VARCHAR, course_id VARCHAR, sec_id VARCHAR, semester VARCHAR, year DECIMAL)
CREATE TABLE takes (ID VARCHAR, course_id VARCHAR, sec_id VARCHAR, semester VARCHAR, year DECIMAL, grade VARCHAR)
CREATE TABLE time_slot (time_slot_id VARCHAR, day VARCHAR, start_hr DECIMAL, start_min DECIMAL, end_hr DECIMAL, end_min DECIMAL)
CREATE TABLE instructor (ID VARCHAR, name VARCHAR, dept_name VARCHAR, salary DECIMAL)
CREATE TABLE department (dept_name VARCHAR, building VARCHAR, budget DECIMAL)

How many courses have two prerequisites? Show me a bar chart grouping by title, and sort y-axis in desc order.
SELECT title, COUNT(title) FROM course AS T1 JOIN prereq AS T2 ON T1.course_id = T2.course_id GROUP BY title ORDER BY COUNT(title) DESC
SELECT "title", COUNT("title") FROM "course" AS "T1" JOIN "prereq" AS "T2" ON "T1"."course_id" = "T2"."course_id" GROUP BY "title" ORDER BY COUNT("title") DESC NULLS LAST