SELECT nt.[Quarter],
       nt.Name AS SubjectName,
       COUNT(nt.Name) AS StudentCount
FROM
(SELECT CASE
           WHEN MONTH(e.Date) >= 1 AND MONTH(e.Date) < 4 THEN 'Q1'
           WHEN MONTH(e.Date) >= 4 AND MONTH(e.Date) < 7 THEN 'Q2'
           WHEN MONTH(e.Date) >= 7 AND MONTH(e.Date) < 10 THEN 'Q3'
           WHEN MONTH(e.Date) >= 9 AND MONTH(e.Date) < 13 THEN 'Q4'
           WHEN e.date IS NULL THEN 'TBA'
       END AS [Quarter],
       s.Name
FROM Exams AS e
JOIN Subjects AS s
ON s.Id = e.SubjectId
JOIN StudentsExams AS se
ON se.ExamId = e.Id
WHERE se.Grade >= 4
) AS nt
GROUP BY nt.[Quarter], nt.Name
ORDER BY nt.Quarter