Question

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有人可以帮助我吗？我到处搜寻！我要回答的问题是：对于他/她参加的所有课程，学生的累积成绩点是多少。

Answer 1

您应该单独按学生进行汇总，然后取CASE表达式的加权平均值：

SELECT
    S.FirstName,
    S.LastName,
    SUM(CreditHours *
        CASE Grade WHEN 'A' Then 4
                   WHEN 'B' Then 3
                   WHEN 'C' Then 2
                   WHEN 'D' Then 1
                   WHEN 'F' Then 0 END) / SUM(CreditHours) AS GradePoint
FROM Student s
INNER JOIN Enrollment e
    ON s.StudentID = e.StudentID
INNER JOIN Course c
    ON e.CourseID = c.CourseID 
GROUP BY
    s.FirstName,
    s.LastName;

使用字母等级计算GPA-SQL

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