学生课程数据库有三个表,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