What is the highest number of enrollments any student has?
select count ( * ) from student_course_enrolment as t1 join students as t2 on t1.student_id = t2.student_id group by t1.student_id order by count ( * ) desc limit 1
How many students have 5 enrollments?
select count ( * ) from ( select * from student_course_enrolment as t1 join students as t2 on t1.student_id = t2.student_id group by t1.student_id having count ( * ) = 5 )
What is that student's registration ID?
select t1.registration_id from student_course_enrolment as t1 join students as t2 on t1.student_id = t2.student_id group by t1.student_id having count ( * ) = 5
Can you give me the student ID of registration ID 19?
select student_id from student_course_enrolment where registration_id = 19
What is the personal name of student ID 15?
select personal_name from students where student_id = 15