A: SELECT Sno, Sname FROM Student, SC WHERE Student.Sno = SC.Sno ANDSC.Cno= ‘2’ AND SC.Grade > 90
B: SELECT Student.Sno, Sname FROM Student, SC WHERE Student.Sno = SC.Sno ANDSC.Cno=‘2’AND SC.Grade > 90
C: SELECT Sno, Sname FROM Student, SC WHERE SC.Cno=‘2’AND SC.Grade > 90
D: SELECT Student.Sno, Sname FROM Student, SC WHERE Student.Sno = SC.Sno AND SC.Grade > 90
举一反三
- 查询每个学生的学号、姓名、选修的课程名及成绩，下列（)的操作是正确的。 A: select student,sno,sname,grade from student,sc where student.sno=sc.sno and sc.cno=course.cno B: select student,sno,sname,grade from student,sc,cource where student.sno=sc.sno C: select student,sno,sname,grade from student,sc,cource where sc.cno=course.cno D: select student,sno,sname,grade from student,sc,cource where student.sno=sc.sno and sc.cno=course.cno
- 在学生选课数据库中，查询选修了课程的学生的学号、姓名，SQL语句可为（ ） A: SELECT DISTINCT Sno, Sname FROM Student, SC WHERE Student.Sno = SC.Sno; B: SELECT Sno, Sname FROM Student, SC WHERE Student.Sno = SC.Sno; C: SELECT DISTINCT Sno, DISTINCT Sname FROM Student WHERE Student.Sno IN (SELECT Sno FROM SC); D: SELECT Sno, Sname FROM Student WHERE Student.Sno IN (SELECT DISTINCT Sno FROM SC);
- 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));
- 下列SQL语句中，_________可以在“学生-课程”数据库正确实现“查询所有选修了1号课程的学生姓名”。 A: SELECT SnameFROM Student, SCWHERE SC.Cno= '1' B: SELECT SnameFROM Student, SCWHERE Student.Sno=SC.Sno AND SC.Cno= 1 C: SELECT Sname FROM Student WHERE Sno= (SELECT Sno FROM SC WHERE Cno= '1') D: SELECT Sname FROM Student WHERE EXISTS (SELECT * FROM SC WHERE Sno=Student.Sno AND Cno= '1')
- 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
内容
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【多选题】针对学生选课数据库S_T，以下()操作实现了student表与sc之间的自然连接。 A. select student.* , cno, grade from student join sc on student.sno=sc.sno B. select student.* , sc.* from student , sc where student.sno=sc.sno C. select student.sno, sname, ssex, sage, sdept , cno, grade from student , sc where student.sno=sc.sno D. select student.* , cno, grade from student , sc where student.sno=sc.sno
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有关系S(SNO, SNAME, SAGE)，C(CNO, CNAME)，SC(SNO, CNO, GRADE)。其中SNO是学生号，SNAME是学生姓名，SAGE是学生年龄， CNO是课程号，CNAME是课程名称，GRADE是成绩。以下（ ）SQL语句可以实现查询选修了'C002'号课程的学生姓名。 A: SELECT SNAME FROM S, SC WHERE S.SNO=SC.SNO AND CNO='C002' B: SELECT SNAME FROM S WHERE SNO IN (SELECT SNO FROM SC WHERE CNO='C002') C: SELECT SNAME FROM S WHERE SNO = (SELECT SNO FROM SC WHERE CNO='C002') D: SELECT SNAME FROM S WHERE SNO NOT IN (SELECT SNO FROM SC WHERE CNO='C002')
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基于学生—选课—课程数据库中的三个基本表：学生的信息表：STUDENT(sno, sname, sex, age, dept)主码为sno课程信息表：COURSE(cno,cname, teacher)主码为cno学生选课信息表：SC(sno, cno, grade)主码为(sno, cno) “查询没有学习成绩的学生的学号和课程号”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="
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查询没有选数据库基础课程的同学学号和姓名。select sno,sname from student where ____________(select ______ from sc ,course where _______________ and cname='数据库基础') A: not exists；* ; course.cno=sc.cno and student.sno=sno B: not exists；sno ; course.cno=sc.cno and student.sno=sc.sno C: sno not in ; sno ; course.cno=sc.cno D: sno not in ; * ; course.cno=sc.cno and student.sno=sc.sno
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下列SQL语句中，_____________可以在“学生-课程”数据库正确实现“查询选修2号课程且成绩在90分以上的所有学生的学号和姓名”。 A: SELECT Sno, SnameFROM Student, SCWHERE Student.Sno = SC.Sno AND SC.Cno= ‘2’ AND SC.Grade > 90 B: SELECT Student.Sno, SnameFROM Student, SCWHERE Student.Sno = SC.Sno AND SC.Grade > 90 C: SELECT Sno, SnameFROM Student, SCWHERE SC.Cno= ‘2’ AND SC.Grade > 90 D: SELECT Student.Sno, SnameFROM Student, SCWHERE Student.Sno = SC.Sno AND SC.Cno= ‘2’ AND SC.Grade > 90