下列SQL语句中，_____________可以在“学生-课程”数据库正确实现“找出每个学生超过他选修课程平均成绩的课程号”。
A: SELECT Sno，CnoFROM SC xWHERE Grade >=(SELECT AVG(Grade) FROM SC y WHERE y.Sno=x.Sno)
B: SELECT Sno，CnoFROM SC xWHERE (SELECT AVG(Grade) FROM SC y WHERE y.Sno=x.Sno)<=Grade
C: SELECT Sno，CnoFROM SC WHERE Grade >=(SELECT AVG(Grade) FROM SC )
D: SELECT x.Sno，x.CnoFROM SC x, SC yWHERE y.Sno=x.Sno AND x.Grade >=(SELECT AVG(Grade) FROM y)
A: SELECT Sno，CnoFROM SC xWHERE Grade >=(SELECT AVG(Grade) FROM SC y WHERE y.Sno=x.Sno)
B: SELECT Sno，CnoFROM SC xWHERE (SELECT AVG(Grade) FROM SC y WHERE y.Sno=x.Sno)<=Grade
C: SELECT Sno，CnoFROM SC WHERE Grade >=(SELECT AVG(Grade) FROM SC )
D: SELECT x.Sno，x.CnoFROM SC x, SC yWHERE y.Sno=x.Sno AND x.Grade >=(SELECT AVG(Grade) FROM y)
举一反三
- 以下命令是相关子查询的嵌套查询是： A: SELECT * FROM student WHERE sno IN (SELECT sno FROM sc WHERE cno = '1') B: SELECT * FROM student WHERE EXISTS (SELECT * FROM sc WHERE cno = '1' AND sc.sno = student.sno) C: SELECT sno, cno FROM sc x WHERE grade>(SELECT AVG(grade) FROM sc y WHERE y.sno = x.sno) D: 以上都是
- 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;
- 有学生选课表SC(Sno，Cno，Grade)，各属性分别为学号、课程号和成绩；完成下列SQL语句：找出每个学生超过他选修课平均成绩的课程号。 SELECT Sno，Cno FROM SC X WHERE（） (SELECT（） FROM SC Y WHERE Y.Sno=X.Sno)
- 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;
- 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;