SELECT
    [Quarter], [Name], SUM(StudentsCount)
    FROM (SELECT
    CASE
        WHEN MONTH(e.[DATE]) BETWEEN 1 AND 3 THEN 'Q1'
        WHEN MONTH(e.[DATE]) BETWEEN 4 AND 6 THEN 'Q2'
        WHEN MONTH(e.[DATE]) BETWEEN 7 AND 9 THEN 'Q3'
        WHEN MONTH(e.[DATE]) BETWEEN 10 AND 12 THEN 'Q4'
        ELSE 'TBA'
    END AS [Quarter],
    s.[Name],
    COUNT(se.StudentId) AS StudentsCount
    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 >= 4.00
    GROUP BY s.[Name], e.[DATE]
    ) AS t
    GROUP BY [Name], [Quarter]
    ORDER BY [Quarter], [Name]