题目内容

查询选修了数学课（课程号为2）的学生人数，可以使用的查询语句是：

A. SELECT MAX() FROM SC WHERE Cno = 2;
B. SELECT AVG(Sno) FROM SC WHERE Cno = 2;
C. SELECT COUNT() FROM SC WHERE Cno = 2;
D. SELECT COUNT(Sname) FROM SC WHERE Cno = 2;

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更多问题

查询被选修过的课程数量，可以使用的查询语句是：（）

A. SELECT COUNT(DISTINCT Cno) FROM SC;
B. SELECT AVG(DISTINCT *) FROM SC;
C. SELECT COUNT(ALL Cno) FROM SC;
D. SELECT COUNT(*) FROM SC;

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查询最低成绩大于85分的学生学号和平均成绩，可以使用的查询语句是：（）

A. SELECT Sno, AVG(Grade) FROM SC HAVING MIN(Grade) > 85 GROUP BY Sno;
B. SELECT Sno, AVG(Grade) FROM SC GROUP BY Sno HAVING MIN(Grade) > 85;
C. SELECT Sno, AVG(Grade) FROM SC WHERE MIN(Grade) > 85 GROUP BY Sno;
D. SELECT Sno, AVG(Grade) FROM SC GROUP BY Sno WHERE MIN(Grade) > 85;

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