Context: CREATE TABLE Student_Course_Enrolment (student_id VARCHAR); CREATE TABLE Students (middle_name VARCHAR, student_id VARCHAR)
Question: Find the student ID and middle name for all the students with at most two enrollments.
Answer: SELECT T1.student_id, T2.middle_name FROM Student_Course_Enrolment AS T1 JOIN Students AS T2 ON T1.student_id = T2.student_id GROUP BY T1.student_id HAVING COUNT(*) <= 2