针对学生选课表sc（sno, cno, grade），其中sno为学号，cno为课程号，grade为成绩。以下（ ）语句可查询选修了两门以上成绩在90分以上课程的学生学号。 A: select sno from sc where grade>90 group by sno having count(cno)>2; B: select sno from sc where grade>90 group by sno having count(*)>2; C: select sno from sc where grade>90 and count(*)>2 group by sno; D: select sno from sc where grade>90 group by sno having count(sno)>2;

在学生选课数据库中，查询平均成绩大于等于60分的同学，SQL语句为（ ） A: SELECT Sno, AVG(Grade) FROM SC GROUP BY Sno HAVING AVG(Grade)>=60; B: SELECT Sno FROM SC WHERE Grade>=60 GROUP BY Sno; C: SELECT Sno, Grade FROM SC GROUP BY Sno HAVING AVG(Grade)>=60; D: SELECT Sno FROM SC GROUP BY Sno HAVING Grade >=60;

以下（ ）语句可查询选修了三门以上成绩在80分以上课程的学生学号。 A: select sno from scwhere grade>80group by snohaving count(cno)>3 B: select sno from scwhere grade>80group by snohaving count(*)>3 C: select sno from scwhere grade>80 and count(*)>3group by sno D: select sno from scwhere grade>80group by snohaving count(sno)>3

下列函数依赖中属于平凡函数依赖的有() A: (Sno,Cname)->(Cname,Grade) B: (Sno,Cname)->(Sname,Grade) C: (Sno,Sname)->Sname D: (Sno,Cname,Grade)->(Cname,Grade)

if score >= 60.0: grade = 'D'elifscore >= 70.0: grade = 'C'elifscore >= 80.0: grade = 'B'else : grade = 'A'分析以上程序,输出等级为‘A’的输入是: A: 95 B: 100 C: 30 D: 90

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;

检索选修课程‘C2’的学生中成绩最高的学生的学号。正确的SELECT语句是( )。 A: SELECT S B: FORM SCWHERE C C: =‘C2’ AND GRADE>=(SELECT GRADE FORM SCWHERE C D: =‘C2’) E: SELECT S F: FORM SCWHERE C G: =‘C2’ AND GRADE IN(SELECT GRADE FORM SCWHERE C H: =‘C2’) I: SELECT S J: FORM SCWHERE C K: =‘C2’ AND GRADE NOT IN(SELECT GRADE FORM SCWHERE C L: =‘C2’) M: SELECT S N: FORM SCWHERE C O: =‘C2’ AND GRADE>=ALL(SELECT GRADE FORM SCWHERE C P: =‘C2’)

查询编号为'c01'的课程考试成绩在80-89之间的学生的学号,下列（）语句不能实现。 A: select sno ,grade from sc where cno='c01' and grade between 80 and 89 B: select sno ,grade from sc where cno='c01' and grade>=80 and grade<90 C: select sno ,grade from sc where cno='c01' and not (grade90) D: select sno ,grade from sc where cno='c01' and grade in (80-89)

检索选修了课程”C1”的学生中成绩最高的学生的学号，正确的SELECT语句为（ ） A: SELECT Sno FROM SC WHERE Cno=’C1’ AND GRADE >=ALL (SELECT Grade FROM SC WHERE Cno=’C1’); B: SELECT Sno FROM SC WHERE Cno=’C1’ AND GRADE IN (SELECT Grade FROM SC WHERE Cno=’C1’); C: SELECT Sno FROM SC WHERE Cno=’C1’ AND GRADE > ANY (SELECT Grade FROM SC WHERE Cno=’C1’); D: SELECT Sno FROM SC WHERE Cno=’C1’ AND GRADE >= (SELECT Grade FROM SC WHERE Cno=’C1’);

在学生选课数据库中，将所有选了课程‘DB’且分数在60~70分之间的学生的成绩增加百分之十，SQL语句为（ ） A: UPDATE SC SET Grade=Grade*1.1 WHERE Cno=’DB’ AND Grade BETWEEN 60 AND 70; B: UPDATE SC SET Grade+=Grade*0.1 WHERE Cno=(Select Cno From Course WHERE Cname=’DB’) AND Grade >= 60 AND Grade <=70; C: UPDATE SC SET Grade=Grade*1.1 WHERE Cno=(Select Cno From Course WHERE Cname=’DB’) AND Grade <= 60 AND Grade >=70; D: UPDATE SC SET Grade=Grade*1.1 WHERE Cno IN (Select Cno From Course WHERE Cname=’DB’) AND Grade BETWEEN 60 AND 70;