How to combine DELETE and LEFT JOIN?

Question

SQL

There is a table of users (user) and a table of students (students). If a student takes acad. vacation, then information about him in students is deleted, but as user he remains. The task is to find and remove just such students, they have student_id - NULL.
Tell me, where is the error?

DELETE FROM user LEFT JOIN students ON user.id = students.student_id WHERE student_id IS NULL

Answer 1

Those. the task to delete all users who are not students?
If yes, then you can try this:

DELETE user
  FROM user u
 WHERE NOT EXISTS(SELECT 1
                    FROM students s
                   where s.student_id = u.id)

Answer 2

multi-table delete has a slightly different syntax , you must explicitly specify the tables from which records should be deleted

DELETE `user` FROM `user` LEFT JOIN `students` ON `user`.id = `students`.student_id WHERE student_id IS NULL