数据库课后作业

数据库大作业11.针对习题10的四个表，用SQL语言完成以下各项操作：（1）给学生表增加一属性Nation（民族），数据类型为Varchar（20）；ALTER TABLE dbo.Student ADD Nation VarChar(20);SElECT *FROM dbo.Student;（2）删除学生表中新增的属性Nation；ALTER TABLE dbo.Student DROP COLUMN Nation;SElECT *FROM dbo.Student; （3）向成绩表中插入记录（“”，“3”，80）；INSERT INTO dbo.Grade VALUES (,3,80);SElECT *FROM dbo.Grade; （4）将学号为“”的学生的成绩修改为70分；UPDATE dbo.Grade SET Gmark = 70 WHERE Sno = ;SElECT *FROM dbo.Grade;（5）删除学号为“”的学生的成绩记录；DELETE FROM dbo.Grade WHERE Sno = ;SElECT *FROM dbo.Grade;（6）在学生表的Clno属性上创建一个名为IX_Class的索引，以班级号的升序排序；CREATE INDEX IX_CLASS ON dbo.Student(Clno);SELECT *FROM dbo.Student;（7）删除IX_Class索引。 DROP INDEX Student.IX_CLASS; SELECT *FROM dbo.Student;12. 针对习题10的四个表，用SQL语言完成以下各项查询：（1）找出所有被学生选修了的课程号； SELECT DISTINCT Cno FROM Grade,Student WHERE Grade.Sno = Student.Sno;（2）找出01311班女学生的个人信息；SELECT * FROM StudentWHERE Ssex = 女 AND Clno = 01311;（3）找出0311班和01312班的学生姓名、性别、出生年份；SELECT Sname,Ssex,(2014-Sage) AS 出生年份 FROM StudentWHERE Clno IN(01311,01312);（4）找出所有姓李的学生的个人信息；SELECT * FROM StudentWHERE Sname LIKE 李%;（5）找出学生李勇所在班级的学生人数；SELECT COUNT(*) AS 李勇班级人数FROM StudentWHERE Clno IN( SELECT Clno FROM Student WHERE Sname = 李勇); （6）找出课程名为操作系统的平均成绩、最高分、最低分；SELECT MAX(Gmark) AS 最高分 ,MIN(Gmark) AS 最低分 ,AVG(Gmark) AS 平均成绩FROM Grade g,Course cWHERE g.Cno IN(SELECT c.Cno FROM Course WHERE c.Cname = 操作系统); （7）找出选修了课程的学生人数；SELECT COUNT(DISTINCT Sno) AS 选修了课程的学生人数FROM Grade;（8）找出选修了课程操作系统的学生学号和姓名；SELECT S.Sno,S.SnameFROM Student S,Grade GWHERE S.Sno IN( SELECT G.Sno FROM Grade WHERE G.Cno = ( SELECT Cno FROM Course WHERE Cname = 操作系统); （9）找出2000级计算机软件班的成绩为空的学生姓名。SELECT S.SnameFROM Student SWHERE S.Sno NOT IN( SELECT Sno FROM Grade) AND S.Clno = (SELECT Clno FROM Class WHERE Inyear = 2000 AND Speciality = 计算机软件); 13. 针对习题10的四个表，用SELECT的嵌套查询完成以下各项查询：（1）找出与李勇在同一个班级的学生信息；SELECT *FROM StudentWHERE Clno = (SELECT Clno FROM Student WHERE Sname = 李勇) AND Sname NOT IN(李勇); （2）找出所有与李勇有相同选修课程的学生信息；SELECT *FROM StudentWHERE Sno IN( SELECT Sno FROM Grade WHERE Grade.Cno IN( SELECT Cno FROM Grade WHERE Sno = ( SELECT Sno FROM Student WHERE Sname = 李勇) AND Sname NOT IN(李勇); （3）找出年龄介于学生李勇与25岁之间的学生信息（已知李勇的年龄小于25岁）；SELECT *FROM StudentWHERE Sage (SELECT Sage FROM Student WHERE Sname = 李勇); （4）找出选修了课程操作系统的学生学号与姓名；SELECT Sno,SnameFROM StudentWHERE Sno IN(SELECT Sno FROM Grade WHERE Cno = (SELECT Cno FROM Course WHERE Cname = 操作系统); （5）找出没有选修1号课程的所有学生姓名；SELECT Sname FROM Student WHERE Sno NOT IN(SELECT Sno FROM Grade WHERE Cno = 1); （6）找出选修了全部课程的学生姓名。SELECT Sname FROM Student WHERE NOT EXISTS(SELECT * FROM Course WHERE NOT EXISTS(SELECT * FROM Grade WHERE Sno= Student.Sno AND Cno= Course.Cno);14. 针对习题10的四个表，用SQL语言完成以下各项查询：（1）查询选修了3门以上的课程的学生学号及其成绩，并按成绩的降序排列；SELECT Sno,GmarkFROM GradeWHERE Cno = 3ORDER BY Gmark DESC;（2）查询全体学生信息，要求查询结果按班级号升序排列同一班级按年龄降序排列；SELECT *FROM StudentORDER BY Clno,Sage DESC;（3）求每个课程号及相应的选课人数；SELECT Cno,COUNT(Cno) AS 选修人数FROM GradeGROUP BY Cno;（4）查询选修了3门以上课程的学生学号。SELECT Sno,COUNT(Sno) AS 选修课程数FROM GradeGROUP BY Sno HAVING(COUNT(Sno)3); 15. 针对习题10的四个表，用SQL语言完成以下各项操作：（1）将01311班的全体学生的成绩置零； UPDATE GradeSET Gmark = 0WHERE Sno IN(SELECT Sno FROM Student WHERE Clno = 01311); （2）删除2001级计算机软件的全体学生的选课记录； DELETE FROM GradeWHERE Sno IN (SELECT Sno FROM Student WHERE Clno = (SELECT Clno FROM Class WHERE Inyear = 2001 AND Speciality = 计算机软件); （3）学生李勇已退学，从数据库中删除有关他的记录；UPDATE ClassSET Monitor = NULLWHERE Clno = (SELECT Clno FROM Student WHERE Sname = 李勇)DELETE FROM GradeWHERE Sno = (SELECT Sno FROM Student WHERE Sname = 李勇) DELETE FROM StudentWHERE Sname = 李勇;（4）对每个班，求学生的平均年龄，并把结果存入数据库。CREATE VIEW V_SagAS SELECT Clno,AVG(Sage) AS Sag FROM Student GROUP BY Clno; 16.视图操作：（1）建立01311班选修了1号课程的学生视图Stu_01311_1； CREATE VIEW Stu_01311_1 AS SELECT * FROM Student WHERE Sno IN(SELECT Sno FROM Grade WHERE Cno = 1) AND Clno = 01311;（2）建立01311班选修了1号课程并且不及格的学生视图Stu_01311_2；CREATE VIEW Stu_01311_2AS SELECT * FROM Student WHERE Sno IN(SELECT Sno FROM Grade WHERE Cno = 1 AND Gmark 1990; （5）查询01311班选修了1号课程并且成绩不及格的学生的学号、姓名、出生年份。SELECT *FROM Stu_yearWHERE Sno IN (SELECT Sno FROM Stu_01311_2); 第四章 触发器11.对于成绩管理数据库,为成绩管理数据库中的Student表创建一触发器:当向表中插入或删除记录时,修改Class表中相应的班级人数 CREATE TRIGGER fri_stu ON Student AFTER INSERT,DELETE AS IF UPDATE(Sno) UPDATE Class SET Number = Number + 1 WHERE Clno = (SELECT Clno FROM INSERTED)