有三个表,即学生表 S、课程表 C 和学生选课表 SC,它们的结构如下: S(S#,SN,SEX,AGE,DEPT) C(C#,CN) SC(S#,C#,GRADE) 其中,S#为学号,SN 为姓名,SEX 为性别,AGE 为年龄,DEPT 为系别,C#为课程 号,CN 为课程名,GRADE 为成绩。 检索选修 4 门以上课程的学生总成绩(不统计不及格的课程),并要求按 总成绩的降序排列出来。正确的 SELECT 语句是()。
A.SELECT S#,SUM(GRADE) FROM SC WHERE GRADE>=60 GROUP BY S# ORDER BY 2 DESC HAVING COUNT(*)>=4
B.SELECT S#,SUM(GRADE) FROM SC WHERE GRADE>=60 GROUP BY S# HAVING COUNT(*)>=4 ORDER BY 2 DESC
C.SELECT S#,SUM(GRADE) FROM SC WHERE GRADE>=60 HAVING COUNT(*)>=4 GROUP BY S# ORDER BY 2 DESC
D.SELECT S#,SUM(GRADE) FROM SC WHERE GRADE>=60 ORDER BY 2 DESC GROUP BY S# HAVING COUNT(*)>=4