JOINS - Grouping

SELECT   courses.name AS course, 
         COUNT(students.name) AS numberOfStudents
FROM     students JOIN courses
ON       students.courseId = courses.id
GROUP BY courses.name

SELECT   courses.name AS course, 
         COUNT(students.name) AS numberOfStudents
FROM     courses LEFT JOIN students
ON       students.courseId = courses.id
GROUP BY courses.name

Exercise - JOINs with GROUP BY - 1