MQL实验（三）视图与游标

1.建立计算机系学生的视图student_cs,视图中包含sno，sname,dept,sex，totalcredit。使用select命令显示视图中的数据。

sql 复制代码

create view student_cs as 
select student.sno,sname,dept,sex,totalcredit from student 
where dept='计算机';
select * from student_cs;

create view student_cs as

2.向student_cs视图中录入学生sno：001242，sname：王五，dept:通信工程，sex:女,totalcredit:40，并用select命令查询显示上述录入的sno,sname,dept,sex,totalcredit信息。

sql 复制代码

insert into student(sno,sname,dept,sex,totalcredit)
values('001242','王五','通信工程','女','40');
select sno,sname,dept,sex,totalcredit from student where sno=001242;

3.建立通信工程系选修了"计算机基础"课程且成绩在80分以上的学生的视图，视图中包括sno,sname,cname,grade。用select命令显示视图中所有数据。

sql 复制代码

create view shitu(sno,sname,cname,grade) as
select student.sno,sname,cname,grade from student
join score on student.sno=score.sno
join course on score.cno=course.cno
where cname='计算机基础' and grade>80 and dept='通信工程';
select *from shitu;

4.将学生的学号及其平均成绩定义为一个视图S_G,视图包括sno,avggrade两个字段。用select命令显示视图S_G所有数据。

sql 复制代码

create view S_G as
select score.sno,avg(grade) from score
group by sno;
select *from S_G;

5.将Score中课程成绩超过该课平均分的学生学号定义成一个视图GOOD_SC，视图包括cno,sno,grade。用select命令显示视图GOOD_SC所有内容。

sql 复制代码

create view GOOD_SC as
select score.sno ,score.cno,grade from score where 
grade>(select avg(grade)from score where cno=score.cno );
select *from GOOD_SC;

6.基于视图S_G查询"通信工程"系学生的平均成绩，要求输出sno，sname,avggrade。

sql 复制代码

select student.sno,sname,avggrade from S_G join student on S_G.sno=student.sno
where dept='通信工程';

7.雇员表employees结构定义如下：（表中的数据由系统提供）

CREATE TABLE employees (

id INT,

name VARCHAR(50) NOT NULL,

salary DECIMAL(20, 2) NOT NULL,

PRIMARY KEY (id)

);

编写带有游标的存储过程，实现为职工长10%的工资。从最低工资开始长，最后工资总额限制在60万元以内。将涨过工资的职工id、name、涨后的工资，存入下面的临时表temp。

CREATE TABLE temp (

id INT,

name VARCHAR(50) NOT NULL,

salary DECIMAL(20, 2) NOT NULL

);

特别提示：要求编写存储过程后，用call命令调用过程，并用select命令显示temp表中的内容。

sql 复制代码

delimiter $$
create procedure updatesalaries() 
begin
    DECLARE curid INT;   
    DECLARE curname VARCHAR(50);   
    DECLARE cursal DECIMAL(20,2);   
    DECLARE flat TINYINT DEFAULT 0;   
    DECLARE sum DECIMAL(20,2);   
    DECLARE cur CURSOR FOR 
    SELECT id,name,salary FROM employees ORDER BY salary;   
declare continue handler for not found set flat=1;
select sum(salary) into sum from employees;
open cur;
 label:loop
       fetch cur into curid,curname,cursal;
       if flat=1 then  
          leave label;
       end if;
       if sum>600000 then
          leave label;
       end if;
       update employees set salary=salary*1.1 where id=curid;
       set sum=sum+cursal*0.1;
       insert into temp values(curid,curname,cursal*1.1);
  end loop label;
end $$
delimiter ;
call updatesalaries();
select * from temp;