基于教材上的选课表SC，使用嵌套查询查找所有超过所选课程平均分的学生选课记录，正确的SQL语句是________。
A: SELECTSno, Cno, Grade FROMSC SC1WHERE Grade>;(SELECT AVG(Grade) FROMSC SC2);
B: SELECTSno, Cno, Grade FROMSC SC1WHERE Grade>;(SELECT AVG(Grade) FROMSC SC2 WHERE SC2.Cno=SC1.Cno);
C: SELECTSno, Cno, Grade FROMSC SC1WHERE Grade>;(SELECT AVG(Grade) FROMSC SC2 GROUP BY SC2.Cno);
D: SELECTSno, Cno, Grade FROMSC SC1WHERE AVG(Grade)>;(SELECT Grade FROMSC SC2 WHERE SC2.Cno=SC1.Cno);
A: SELECTSno, Cno, Grade FROMSC SC1WHERE Grade>;(SELECT AVG(Grade) FROMSC SC2);
B: SELECTSno, Cno, Grade FROMSC SC1WHERE Grade>;(SELECT AVG(Grade) FROMSC SC2 WHERE SC2.Cno=SC1.Cno);
C: SELECTSno, Cno, Grade FROMSC SC1WHERE Grade>;(SELECT AVG(Grade) FROMSC SC2 GROUP BY SC2.Cno);
D: SELECTSno, Cno, Grade FROMSC SC1WHERE AVG(Grade)>;(SELECT Grade FROMSC SC2 WHERE SC2.Cno=SC1.Cno);
举一反三
- 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' );
- 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’);
- 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 = ' '
- 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