1. 定义计算机系学生基本情况视图V_Computer；
CREATE VIEW V_COMPUTER
AS
SELECT *
FROM student
WHEREsdept='is'
2. 将Student Course 和sc表中学生的学号，姓名，课程号，课程名，成绩定义为视图V_S_C_G
CREATE VIEW V_S_C_G
AS
SELECT
student.sno,student.sname,course.cno,course.cname,grade
FROMstudent,course,sc
WHEREstudent.sno=sc.sno
3. 将各系学生人数，平均年龄定义为视图V_NUM_AVG
create view V_NUM_AVG(number,avg,sdept)
as
select count(sno)deptnum,avg(sage)age,sdept
from student
group by sdept
4. 将各位学生选修课程的门数及平均成绩定义为视图V_AVG_S_G
create view V_AVG_S_G(学号,姓名,选修门数,平均成绩)
as
selectstudent.sno ,sname,count(*),avg(grade)
fromstudent,course,sc
wherestudent.sno=sc.sno and sc.cno=course.cno
group by student.sno,sname
5. 各门课程的选修人数及平均成绩定义为视图V_AVG_C_G
CREATE VIEW V_AVG_C_G(课程号,平均成绩,选修人数)
AS
SELECTSC.CNO,AVG(GRADE),COUNT(CNO)
FROMSC
GROUP BY CNO