• 2022-06-07
    第4单元,设有学生表student(学号,姓名,系名,课程号,成绩),查询至少选修了4门课程的学生学号及平均成绩的正确语句是()
    A: SELECT 学号, AVG(成绩) AS 平均成绩 FROM student GROUP BY 学号 HAVING COUNT(课程号)>3;
    B: SELECT 学号, AVG(成绩) AS 平均成绩 FROM student GROUP BY 课程号 HAVING COUNT(课程号)>3;
    C: SELECT 学号, AVG(成绩) AS 平均成绩 FROM student GROUP BY 学号 HAVING COUNT(课程号)>4;
    D: SELECT 学号, AVG(成绩) AS 平均成绩 FROM student GROUP BY 课程号 HAVING COUNT(DISTINCT 学号)>3;
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