若要求“查询选修了3门以上课程的学生的学号”,正确的SQL语句是( )
A: SELECT sNo FROM SC GROUP BY sNo WHERE COUNT(*)> 3
B: SELECT sNo FROM SC GROUP BY sNo HAVING COUNT(*)> 3
C: SELECT sNo FROM SC ORDER BY sNo WHERE COUNT(*)> 3
D: SELECT sNo FROM SC ORDER BY sNo HAVING COUNT(*)> 3
A: SELECT sNo FROM SC GROUP BY sNo WHERE COUNT(*)> 3
B: SELECT sNo FROM SC GROUP BY sNo HAVING COUNT(*)> 3
C: SELECT sNo FROM SC ORDER BY sNo WHERE COUNT(*)> 3
D: SELECT sNo FROM SC ORDER BY sNo HAVING COUNT(*)> 3
举一反三
- 下列查询语句中，错误的是（）。 A: SELECT Sno， COUNT（*） FROM SC GROUP BY Sno B: SELECT Sno FROM SC GROUP BY Sno WHERE COUNT（*）> 3 C: SELECT Sno FROM SC GROUP BY Sno HAVING COUNT（*）> 3 D: SELECT Sno FROM SC GROUP BY Sno
- 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;
- 下列查询语句中，错误的是（）。 A: ASELECT Sno， COUNT（*） FROM SC GROUP BY Sno B: BSELECT Sno FROM SC GROUP BY Sno WHERE COUNT（*）> 3 C: CSELECT Sno FROM SC GROUP BY Sno HAVING COUNT（*）> 3 D: DSELECT Sno FROM SC GROUP BY Sno
- 基于“学生-选课-课程”数据库中的三个关系: 学生表S(SNO,SNAME,SEX,BIRTHYEAR,DEPT),主码为SNO 课程表C(CNO,CNAME,TEACHER),主码为CNO 选课表SC(SNO,CNO,GRADE),主码为(SNO,CNO) [br][/br]查找“选修了至少5门课程的学生的学号”,正确的SQL语句是( )。 A: SELECT SNO FROM SC GROUP BY SNO HAVING COUNT(*) >=5; B: SELECT SNO FROM SC GROUP BY SNO WHERE COUNT(*) >=5; C: SELECT SNO FROM SC HAVING COUNT(*) >=5; D: SELECT SNO FROM SC WHERE COUNT(*) >=5;
- 如果想限制sc(sno,cno,grade)表中每人最多选三门课，如何用断言表示？sc(sno,cno,grade)表示选修（学号，课程号，成绩） A: Create assertion asse1 check(3>=all( select count(*) from sc group by sno)) B: Create assertion asse1 check(3>=any( select count(*) from sc group by sno)) C: Create assertion asse1 check(3>=some( select count(*) from sc group by sno)) D: Create assertion asse1 check(3>= select count(*) from sc group by sno)