What is the course id of the most recent course registration?
select course_id from student_course_registrations order by registration_date desc limit 1
Give the student id instead.
select student_id from student_course_registrations order by registration_date desc limit 1
Give the student details.
select t2.student_details from student_course_registrations as t1 join students as t2 on t1.student_id = t2.student_id order by t1.registration_date desc limit 1