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’)

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 SC WHERE C C: =“C2” AND GRAD>=(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”)

查询没有选修1号课程的学生姓名（）。 A: select snamefrom student,scwhere student.sno=sc.sno and cno!='1' B: select snamefrom sno not in(select snofrom scwhere cno='1' ) C: select snamefrom sno in(select snofrom scwhere cno!='1' ) D: select snamefrom sno not exists(select*from scwhere student.sno and sc.sno and cno='1' )

‌下列SQL语句中，________可以在“学生-课程”数据库中实现“查询所有有成绩的学生学号和课程号”。​ A: SELECT Sno，CnoFROM SCWHERE Grade NOT NULL B: SELECT Sno，CnoFROM SCWHERE Grade <> NULL C: SELECT Sno，CnoFROM SCWHERE Grade IS NOT NULL D: SELECT Sno，CnoFROM SCWHERE Grade >0

‏下列SQL语句中，_____________可以在“学生-课程”数据库正确实现“计算1号课程的学生平均成绩”。‍ A: SELECT AVG(Grade)FROM SCWHERE Cno= ' 1 ' B: SELECT MAX(Grade)FROM SCWHERE Cno= 1 C: SELECT MIN(Grade)FROM SCWHERE Cno= 1 D: SELECT AVG(Grade)FROM SCWHERE Cno= 1

针对S_T数据库，查询既选修了1号课程又选修3号课程的学生学号，以下不正确的SQL命令是（ ）。 A: select snofrom scwhere cno='1' and cno='3' B: select snofrom scwhere cno='1'intersectselect snofrom scwhere cno='3' C: select snofrom scwhere cno='1' and sno in(select snofrom scwhere cno='3') D: select a.snofrom sc a,sc bwhere a.sno=b.sno and a.cno='1' and b.cno='3'

题中假定学生关系是S(S#,SN.,SEX,AGE)，课程关系是C(C#,CNAME,TEACH-ER)，学生选课关系是SC(S#,C#,GRADE)。 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# FORM SCWHERE C#="C2"AND GRADE＞=(SELECT GRADE FORM SCWHERE C#="C2") B: SELECT S# FORM SCWHERE C#="C2"AND GRADE IN(SELECT GRADE FORM SC.WHERE C#="C2" C: SELECT S# FORM SCWHERE C#="C2"AND GRADE NOT IN(SELECT GRADE FORM SCWHERE C#="C2") D: SELECT S# FORM SCWHERE C#="C2"AND GRADE＞=ALL(SELECT GRADE FORM SCWHERE C#="C2")

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&gt;80group by snohaving count(cno)&gt;3 B: select sno from scwhere grade&gt;80group by snohaving count(*)&gt;3 C: select sno from scwhere grade&gt;80 and count(*)&gt;3group by sno D: select sno from scwhere grade&gt;80group by snohaving count(sno)&gt;3

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。查询选修课程“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: FROM SCWHERE C C: =“C2” AND GRADE >= (SELECT GRADE FROM SCWHERE C D: =“C2”) E: SELECT S F: FROM SCWHERE C G: =“C2” AND GRADE IN (SELECT MAX(GRADE) FROM SCWHERE C H: =“C2”) I: SELECT S J: FROM SCWHERE C K: =“C2” AND GRADE IN (SELECT GRADE FROM SCWHERE C L: =“C2”) M: SELECT S N: FROM SCWHERE C O: =“C2” AND GRADE > ALL (SELECT GRADE FROM SCWHERE C P: =“C2”)

‎下列SQL语句中，_____________可以在“学生-课程”数据库正确实现“查询选修2号课程且成绩在90分以上的所有学生的学号和姓名”。‏ A: SELECT Sno, SnameFROM Student, SCWHERE Student.Sno = SC.Sno AND SC.Cno= ‘2’ AND SC.Grade > 90 B: SELECT Student.Sno, SnameFROM Student, SCWHERE Student.Sno = SC.Sno AND SC.Grade > 90 C: SELECT Sno, SnameFROM Student, SCWHERE SC.Cno= ‘2’ AND SC.Grade > 90 D: SELECT Student.Sno, SnameFROM Student, SCWHERE Student.Sno = SC.Sno AND SC.Cno= ‘2’ AND SC.Grade > 90