举一反三
- 对于学生信息表:student(sno,sname,sex,age,grade),查询学习成绩为空的学生的学号和姓名,下面语句正确的是 A: SELECT sno,sname FROM student WHERE grade=NULL B: SELECT sno,sname FROM student WHERE grade IS NULL C: SELECT sno,age FROM student WHERE grade IS NULL D: SELECT sno,age FROM student WHERE grade=NULL
- 在学生表student中查询学生的学号和姓名,可以用命令:select 学号,姓名 student;
- 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
- 查询STUDENT表中成绩大于90分的学号,正确的命令是 A: SELECT 学号 WHERE 成绩>90 B: SELECT 学号 FROM STUDENT SET 成绩>90 C: SELECT 学号 FROM STUDENT WHERE 成绩>90 D: SELECT 学号 FROM STUDENT FOR 成绩>90
- 以下定义的4个视图中,能够进行更新操作的是_________。 A: CREATE VIEW S_AVG(学号,平均分) AS SELECT 学号,AVG(分数) FROM score WHERE 分数IS NOT NULL GROUP BY 学号 B: CREATE VIEW S_MALE(学号,姓名) AS SELECT 学号,姓名 FROM student WHERE 班号='09031' C: CREATE VIEW S_FEMALE(姓名,出生日期) AS SELECT 姓名,出生日期 FROM student WHERE 性别='女' D: CREATE VIEW S_G(学号,姓名,课程名,分数) AS SELECT S.学号,姓名,课程名,分数 FROM student S,score SC,course C WHERE S.学号=S 学号AND S 课程号 = 课程号
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以下定义的4个视图中,能够进行更新操作的是( )。 A: CREATE VIEW S_MALE(学号,姓名) AS SELECT 学号,姓名 FROM student WHERE 班号='09031' B: CREATE VIEW S_G(学号,姓名,课程名,分数) AS SELECT S.学号,姓名,课程名,分数 FROM student S,score SC,course C WHERE S.学号=SC. 学号AND SC. 课程号 = C. 课程号 C: CREATE VIEW S_AVG(学号,平均分) AS SELECT 学号,AVG(分数) FROM score WHERE 分数IS NOT NULL GROUP BY 学号 D: CREATE VIEW S_FEMALE(姓名,出⽣⽇期) AS SELECT 姓名,出⽣⽇期 FROM student WHERE 性别='⼥'
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以下定义的4个视图中,能够进行更新操作的是_________。 A: CREATE VIEW S_MALE(学号,姓名) AS SELECT 学号,姓名 FROM student WHERE 班号='09031' B: CREATE VIEW S_G(学号,姓名,课程名,分数) AS SELECT S.学号,姓名,课程名,分数 FROM student S,score SC,course C WHERE S.学号=SC. 学号AND SC. 课程号 = C. 课程号 C: CREATE VIEW S_AVG(学号,平均分) AS SELECT 学号,AVG(分数) FROM scoreWHERE 分数IS NOT NULL GROUP BY 学号 D: CREATE VIEW S_FEMALE(姓名,出生日期) AS SELECT 姓名,出生日期 FROM student WHERE 性别='女'
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关系模式Student(学号,姓名,年龄,所在系),查询IS系全体学生( ) A: Π所在系=‘IS’(Student) B: σ所在系=‘IS’(Student) C: Π学号,所在系(Student) D: σ所在系,学号(Student)
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第4单元,设有学生表student(学号,姓名,系名,课程号,成绩),查询至少选修了4门课程的学生学号及平均成绩的正确语句是() A: SELECT 学号, AVG(成绩) AS 平均成绩 FROM student GROUP BY 学号 HAVING COUNT(课程号)>3; B: SELECT 学号, AVG(成绩) AS 平均成绩 FROM student GROUP BY 课程号 HAVING COUNT(课程号)>3; C: SELECT 学号, AVG(成绩) AS 平均成绩 FROM student GROUP BY 学号 HAVING COUNT(课程号)>4; D: SELECT 学号, AVG(成绩) AS 平均成绩 FROM student GROUP BY 课程号 HAVING COUNT(DISTINCT 学号)>3;
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以下定义的4个视图中,能够进行更新操作的是( )。 A: CREATE VIEW S_G(学号,姓名,课程名,分数) AS<br>SELECT S.学号,姓名,课程名,分数 FROM student S,score SC,course C<br>WHERE S.学号=SC.学号 AND SC.课程号=C.课程号 B: CREATE VIEW S_AVG(学号,平均分数) AS<br>SELECT 学号,AVG(分数) FROM score WHERE 分数 IS NOT NULL<br>GROUP BY 学号 C: CREATE VIEW S_MALE(学号,姓名) AS<br>SELECT 学号,姓名 FROM student WHERE 班号=’1501’ D: CREATE VIEW S_FEMALE(姓名,出生日期) AS<br>SELECT 姓名,出生日期 FROM student WHERE 性别=’女’