检索选课人数少于4人的课程号。正确的SQL语句是( )
A: SELECT CNO FROM SC WHERE COUNT(*)<;4
B: SELECT CNO FROM SC GROUP BY CNO HAVING COUNT(*)<;4
C: SELECT DISTINCT CNO FROM SC ORDER BY CNO
D: SELECT CNO FROM SC WHERE COUNT(CNO)<;4
A: SELECT CNO FROM SC WHERE COUNT(*)<;4
B: SELECT CNO FROM SC GROUP BY CNO HAVING COUNT(*)<;4
C: SELECT DISTINCT CNO FROM SC ORDER BY CNO
D: SELECT CNO FROM SC WHERE COUNT(CNO)<;4
举一反三
- 查询选修了数学课(课程号为2)的学生人数,可以使用的查询语句是: 。 A: SELECT MAX(*) FROM SC WHERE Cno = 2; B: SELECT AVG(Sno) FROM SC WHERE Cno = 2; C: SELECT COUNT(*) FROM SC WHERE Cno = 2; D: SELECT COUNT(Sname) FROM SC WHERE Cno = 2;
- 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，检索被全部学生所选修的课程的SQL可以描述为（ ） A: SELECT Cno FROM SC WHERE (Select Count(Sno) FROM SC GROUP BY Cno) = (SELECT Count(*) FROM Student) ; B: SELECT Cno FROM SC x WHERE NOT EXISTS (SELECT * FROM Student s WHERE NOT EXISTS (SELECT * FROM SC y WHERE x.Cno = y.Cno AND s.Sno= y.Sno); C: SELECT Cno FROM SC x WHERE NOT EXISTS (( SELECT Sno FROM Student) EXCEPT （ SELECT y.Sno FROM SC y, Student z WHERE x.Cno=y.Cno AND z.Sno=y.Sno)); D: 以上答案都不对
- 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 SNO FROM SC WHERE CNO='C2' AND GRADE >= ( SELECT GRADE FORM SC WHERE CNO='C2' ); B: SELECT SNO FROM SC WHERE CNO='C2' AND GRADE IN ( SELECT GRADE FORM SC WHERE CNO='C2' ); C: SELECT SNO FROM SC WHERE CNO='C2' AND GRADE NOT IN ( SELECT GRADE FORM SC WHERE CNO='C2' ); D: SELECT SNO FROM SC WHERE CNO='C2' AND GRADE >= ALL ( SELECT GRADE FORM SC WHERE CNO='C2' );
- 在MySQL中,假设有学生选课表SC(sno,cno,score)。那么列出所有选修课程超过5门的学生学号以及选修课程数目,其正确的SQL语句为()。 A: select sno,count(cno)from scwhere count(cno)>=5; B: select sno,count(cno)from scgroup by sno where count(cno)>=5; C: select sno,count(cno)from scgroup by sno having count(cno)>=5; D: select sno,count(cno)from scgroup by cno having count(cno)>=5;