mysql函数编写和存储过程

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#建表
#创建表CLASS
CREATE TABLE classes( /*班级表*/
classno MEDIUMINT   UNSIGNED  NOT NULL  DEFAULT 0,
classname VARCHAR(20)  NOT NULL  DEFAULT "",
loc VARCHAR(13) NOT NULL DEFAULT ""
) ENGINE=innodb DEFAULT CHARSET=utf8;

#创建表STUDENTS学生表
CREATE TABLE students
(studentno  MEDIUMINT UNSIGNED  NOT NULL  DEFAULT 0,
studentname VARCHAR(20) NOT NULL DEFAULT "",
job VARCHAR(9) NOT NULL DEFAULT "",
mgr MEDIUMINT UNSIGNED NOT NULL DEFAULT 0,
hiredate DATE NOT NULL,
sal DECIMAL(7,2)  NOT NULL,
comm DECIMAL(7,2) NOT NULL,
classno MEDIUMINT UNSIGNED NOT NULL DEFAULT 0
)ENGINE=innodb DEFAULT CHARSET=utf8 ;

#学生薪水级别表(1-5000,2-5000-8000 3-8000+)
CREATE TABLE salgrade
(
grade MEDIUMINT UNSIGNED NOT NULL DEFAULT 0,
losal DECIMAL(17,2)  NOT NULL,
hisal DECIMAL(17,2)  NOT NULL
)ENGINE=innodb DEFAULT CHARSET=utf8;

INSERT INTO salgrade VALUES (1,1500,5000);
INSERT INTO salgrade VALUES (2,5001,8000);
INSERT INTO salgrade VALUES (3,8001,12000);
INSERT INTO salgrade VALUES (4,12001,15000);
INSERT INTO salgrade VALUES (5,15001,59999);


#创建一个随机产生字符串的函数：
create function rand_string(n INT)
returns varchar(255)
deterministic
begin
declare chars_str varchar(100) default
        'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
declare return_str varchar(255) default '';
declare i int default 0;
while i<n do
        set return_str = concat(return_str,substring(chars_str,floor(1+rand()*52),1));
set i = i + 1;
end while;
return return_str;
end ||

#创建一个随机产生的数字
create function rand_num(n INT)
returns int(5)
deterministic
begin
declare i int default 0;
set i = floor(1+rand()*n);
return i;
end ||


#存储过程：
#插入学生
create procedure insert_students(in start int(10),in max_num int(10))
begin
declare i int default 0;
set autocommit = 0;
repeat
set i = i + 1;
insert into students values((start+i),rand_string(6),'salesman',0001,curdate(),2000,400,rand_num(500));
until i = max_num
end repeat;
commit;
end ||

#插入班级
create procedure insert_class(in start int(10),in max_num int(10))
begin
declare i int default 0;
set autocommit = 0;
repeat
set i = i + 1;
insert into class values((start+i),rand_string(10),rand_string(8));
until i = max_num
end repeat;
commit;
end ||