SELECT t1.ClassID, t1.StudentCount, t2.TeacherNames
FROM (
SELECT s.ClassID, COUNT(s.StudentID) StudentCount
FROM Student s
GROUP BY s.ClassID) AS t1 JOIN (
SELECT t.ClassID, STRING_AGG(t.TeacherName, ',') TeacherNames
FROM Teacher t
GROUP BY t.ClassID
) AS t2 ON t1.ClassID = t2.ClassID
承上題，撰寫SQL statement來刪除名為abc的學生的成績
DELETE FROM Exam
WHERE StudentID IN (SELECT s.StudentID FROM Student s WHERE s.StudentName = 'abc')
