LEFT JOIN plus IS NULL finds rows with no match

To list the students who joined no club, keep everyone with a LEFT JOIN, then keep only the rows where the club columns came back NULL. A NULL there means that student matched no club at all. It reads oddly at first: you join two tables in order to find where nothing matched.

SELECT s.name
FROM students s
LEFT JOIN clubs c ON c.id = s.club_id
WHERE c.id IS NULL;