‏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 S# FORM SC WHERE C#="C2"AND GRADE＞=(SELECT GRADE FORM SC WHERE C#="C2") B: SELECT S# FORM SC WHERE C#="C2"AND GRADE IN(SELECT GRADE FORM SC) WHERE C#="C2" C: SELECT S# FORM SC WHERE C#="C2"AND GRADE NOT IN(SELECT GRADE FORM SC WHERE C#="C2") D: SELECT S# FORM SC WHERE C#="C2"AND GRADE＞=ALL(SELECT GRADE FORM SC WHERE C#="C2")

要从SC表中查找缺成绩（SCORE）的学生学号（NO），相应的SQL语句是（ ）。 A: SELECT NO FROM SC WHERE SCORE = 0 B: SELECT NO FROM SC WHERE SCORE IS 'NULL' C: SELECT NO FROM SC WHERE SCORE = NULL D: SELECT NO FROM SC WHERE SCORE IS 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’);

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语句为（ ）。 A: select S B: from sc where C C: =‘C2’and grade>= (select grade from sc where C D: =‘C2’) E: select S F: from sc where C G: =‘C2’and grade in (select grade from sc where C H: =‘C2’) I: select S J: from sc where C K: =‘C2’and grade not in (select grade from sc where C L: =‘C2’) M: select S N: from sc where C O: =‘C2’and grade>=all (select grade from sc where C P: =‘C2’)

检索选修“C2”课程的学生中成绩最高的学生的学号。正确的SELECT语句是（ ）。 A: SELECT s B: FROM sc WHERE c C: =’C2’ AND grade＞＝(SELECT grade FROM sc WHERE c D: =’C2’); E: SELECT s F: FROM sc WHERE c G: =’C2’ AND grade IN(SELECT grade FROM sc WHERE c H: =’C2’); I: SELECT s J: FROM sc WHERE c K: =’C2’ AND grade NOT IN(SELECT grade FORM sc WHERE c L: =’C2’); M: SELECT s N: FROM sc WHERE c O: =’C2’ AND grade＞＝(SELECT max(grade) FROM sc WHERE c P: =’C2’);

有学生选课表sc，其结构如下： sc(学号, 课程号, 成绩)，用SQL检索同时选修课程号为“C1”和“C5”的学生的学号的正确命令是( )。 A: SELECT 学号 FROM sc WHERE 课程号='C1' AND 课程号='C5'; B: SELECT 学号 FROM sc WHERE 课程号='C1' AND 课程号= (SELECT 课程号 FROM sc WHERE 课程号='C5'); C: SELECT 学号 FROM sc WHERE 课程号='C1' AND 学号= (SELECT 学号 FROM sc WHERE 课程号='C5'); D: SELECT 学号 FROM sc WHERE 课程号='C1' AND 学号 IN (SELECT 学号 FROM sc WHERE 课程号='C5');

检索选修课程号为“D3”的学生中成绩最高的学生的学号，正确的、SELECT语句是______ A: SELECT S# B: FROM SC C: WHERE C#='D3'AND GRADE＞= D: (SELECT GRADE FROM SC E: WHERE C#='D3')； F: SELECT S# G: FROM SC H: WHERE C#='D3'AND GRADE IN I: (SELECT GRADE FROM SC J: WHERE C#='D3')； K: SELECT S# L: FROM SC M: WHERE C#='D3'AND GRADE NOT IN N: (SELECT GRADE FROM SC O: WHERE C#='D3')； P: SELECT S# Q: FROM SC R: WHERE C#='D3'AND GRADE＞=ALL S: (SELECT GRADE FROM SC T: WHERE C#='D3')；

下列查询中,属于相关子查询的有（）。 A: SELECT * FROM student WHERE sno IN (SELECT sno FROM sc WHERE cno='1'); B: SELECT sno, cno FROM SC x WEHRE grade>=(SELECT AVG(grade) FROM SC y WHERE y.sno = x.sno); C: SELECT sname FROM student WHERE EXISTS(SELECT * FROM sc WHERE sno=student.sno AND cno='1'); D: SELECT sname FROM student WHERE NOT EXISTS(SELECT * FROM course WHERE NOT EXISTS(SELECT * FROM sc WHERE sc.sno=student.sno AND sc.cno=course.cno));

列出SC表中所有考试不及格的学生的学号Sno（无须重复），其SQL语句为（ ） A: SELECT DISTINCT Sno FROM SC WHERE Grade<60; B: SELECT DISTINCT Sno FROM SC WHERE Grade IS NULL; C: SELECT Sno FROM SC WHERE Grade<60; D: SELECT ALL Sno FROM SC WHERE Grade<60;