用SQL语言检索选修课程在5门以上(含5门)的、姓名和平均成绩,并按平均成绩降序排序,正确的命令是
A.
SELECT S.,姓名,平均成绩FROM S,SC; WHERE S.=SC.; GROUP BY S. HAVING COUNT(*)>=5 ORDER BY 平均成绩 DESC
B.
SELECT ,姓名,AVG(成绩)FROM S,SC; WHERE S.=SC.AND COUNT(*)>=5; GROUP BY ORDER BY 3 DESC
C.
SELECT S.,姓名,AVG(成绩)平均成绩 FROM S,SC; WHERE S.=SC.AND COUNT(*)>=5; GROUP BY S. ORDER BY平均成绩 DESC
D.
SELECT S.,姓名,AVG(成绩)平均成绩 FROM S,SC; WHERE S.;SC,; GROUP BY S. HAVING COUNT(*)>=5 ORDER BY 3 DESC