第六次作业

这个作业属于哪个课程	https://edu.cnblogs.com/campus/uzz/cs3
这个作业要求在哪里	https://edu.cnblogs.com/campus/uzz/cs3/homework/13086
这个作业的目标	https://edu.cnblogs.com/campus/uzz/cs3/homework/13086

  alter table curriculum drop primary key;
  alter table grade drop primary key;
 alter table student_info drop primary key;

use studentsdb;create unique index cno_idx on curriculum(课程编号);

create index grade_idx on grade(分数);

create index grade_sid_cid_idx on grade(学号,课程编号);

show index from grade

drop index grade_idx ON grade;

create view v_stu_c as select s.学号,s.姓名, g.课程编号 from student_info as s,grade as g where s.学号=g.学号;

select * from v_stu_c where 学号 ='0003';

create view v_stu_g as select student_info.学号,student_info.姓名,curriculum.课程名称,grade.分数 from student_info ,grade ,curriculum where student_info.学号=grade.学号 and grade.课程编号=curriculum.课程编号;

select avg(分数) from v_stu_g where 学号='0001';

alter view v_stu_g as select 学号,姓名,性别 from student_info ;

insert into v_stu_g (学号,姓名,性别) values (0010,'陈婷婷','女');

delete from v_stu_g where 学号='0010';

update v_stu_g set 分数 = '87' where 课程名称='高等数学' and 姓名='张青平';

drop view v_stu_g;
   drop view v_stu_c;