查询选修了2门课程以上的学生学号（）
A: select sid,count(*) from sc group by sid having count(*)>=2
B: select sid,count(*) from sc group by sid where count(*)>=2
C: select sid,count(*) from sc where count(*)>=2 group by sid
D: select sid,count(*) from sc group by cid having count(*)>=2
A: select sid,count(*) from sc group by sid having count(*)>=2
B: select sid,count(*) from sc group by sid where count(*)>=2
C: select sid,count(*) from sc where count(*)>=2 group by sid
D: select sid,count(*) from sc group by cid having count(*)>=2
举一反三
- 按课程号分类，统计相应的选课人数（） A: select cid, count(distinct sid) from sc group by cid B: select cid, count(*) from student group by cid C: select cid, count(distinct cid) from sc group by cid D: select cid, count(distinct sid) from student group by cid
- 按照学号进行分组，统计学生的平均成绩（） A: select sid, avg(grade) from student group by cid B: select sid, avg(grade) from student group by sid C: select sid, avg(grade) from sc group by sid D: select sid, avg(grade) from sc group by cid
- 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;
- 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