设表SC中存放了学生的学号(Sno)、课程号(Cno)和成绩(Grade),现需要查询选修1号课程的学生平均成绩,下面SQL语句正确的是()。
A: SELECTGrade(AVG) FROM SC WHERE Cno=’1’
B: SELECTGrade(AVG) FROM SC WHERE Sno=’1’
C: SELECTAVG(Grade) FROM SC WHERE Sno=’1’
D: SELECTAVG(Grade) FROM SC WHERE Cno=’1’
A: SELECTGrade(AVG) FROM SC WHERE Cno=’1’
B: SELECTGrade(AVG) FROM SC WHERE Sno=’1’
C: SELECTAVG(Grade) FROM SC WHERE Sno=’1’
D: SELECTAVG(Grade) FROM SC WHERE Cno=’1’
举一反三
- 查询所有有成绩的学生学号和课程号。正确的SELECT语句是（）。 A: Select sno , cno from sc where grade < > null B: Select sno as 学号, cno as 课程号 from sc where grade is not null C: Select sno , cno from sc where grade !=‘ ’ D: Select sno , cno from sc where grade is not null
- 已知学生选课信息表：sc（sno，cno，grade）。查询“至少选修了一门课程，但没有学习成绩的学生学号和课程号”的SQL语句是（ ）。 A: SELECT sno,cno FROM sc WHERE grade=NULL B: SELECT sno,cno FROM sc WHERE grade IS C: SELECT sno,cno FROM sc WHERE grade IS NULL D: SELECT sno,cno FROM sc WHERE grade=
- “查询没有学习成绩的学生的学号和课程号”的SQL语 句是( ) (2.0) A: SELECT sno,cno FROM SC WHERE grade = NULL B: SELECT sno,cno FROM SC WHERE grade IS ' ' C: SELECT sno,cno FROM SC WHERE grade IS NULL D: SELECT sno,cno FROM SC WHERE grade = ' '
- 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，Cno FROM SC WHERE Grade <> NULL B: SELECT Sno，Cno FROM SC WHERE Grade NOT NULL C: SELECT Sno，Cno FROM SC WHERE Grade >0 D: SELECT Sno，Cno FROM SC WHERE Grade IS NOT NULL
- 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’);