选项
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
正确答案：A
名词解析
至少选4门课，因此GROUP BY（课程号）>3，C错。同一人至少4门，因此group by 学号，B错、D错。答案A。