Table schema:
CREATE TABLE students (student_id VARCHAR); CREATE TABLE courses (course_name VARCHAR, course_id VARCHAR); CREATE TABLE student_course_registrations (course_id VARCHAR, student_id VARCHAR)

Question: How many registed students do each course have? List course name and the number of their registered students?
SQL: SELECT T3.course_name, COUNT(*) FROM students AS T1 JOIN student_course_registrations AS T2 ON T1.student_id = T2.student_id JOIN courses AS T3 ON T2.course_id = T3.course_id GROUP BY T2.course_id