MySQL优化概述

CREATE DATABASE temp0919;
USE temp0919;

#创建表DEPT
CREATE TABLE dept( /*部门表*/
    deptno MEDIUMINT   UNSIGNED  NOT NULL  DEFAULT 0, 
    dname VARCHAR(20)  NOT NULL  DEFAULT "",
    loc VARCHAR(13) NOT NULL DEFAULT ""
) ENGINE=MyISAM DEFAULT CHARSET=utf8 ;

#创建表EMP雇员
CREATE TABLE emp(
    empno  MEDIUMINT UNSIGNED  NOT NULL  DEFAULT 0, /*编号*/
    ename VARCHAR(20) NOT NULL DEFAULT "", /*名字*/
    job VARCHAR(9) NOT NULL DEFAULT "",/*工作*/
    mgr MEDIUMINT UNSIGNED NOT NULL DEFAULT 0,/*上级编号*/
    hiredate DATE NOT NULL,/*入职时间*/
    sal DECIMAL(7,2)  NOT NULL,/*薪水*/
    comm DECIMAL(7,2) NOT NULL,/*红利*/
    deptno MEDIUMINT UNSIGNED NOT NULL DEFAULT 0 /*部门编号*/
)ENGINE=MyISAM DEFAULT CHARSET=utf8 ;

#工资级别表
CREATE TABLE salgrade
(
    grade MEDIUMINT UNSIGNED NOT NULL DEFAULT 0,
    losal DECIMAL(17,2)  NOT NULL,
    hisal DECIMAL(17,2)  NOT NULL
)ENGINE=MyISAM DEFAULT CHARSET=utf8;

INSERT INTO salgrade VALUES (1,700,1200);
INSERT INTO salgrade VALUES (2,1201,1400);
INSERT INTO salgrade VALUES (3,1401,2000);
INSERT INTO salgrade VALUES (4,2001,3000);
INSERT INTO salgrade VALUES (5,3001,9999);


#定义一个新的命令结束符合
delimiter $$
#删除自定的函数
drop function rand_string $$

#创建一个函数(随机产生字符串) 
#rand_string(n INT) rand_string 是函数名 (n INT) //该函数接收一个整数
create function rand_string(n INT) 
returns varchar(255) #该函数会返回一个字符串
begin 
    #chars_str定义一个变量 chars_str,类型是 varchar(100),默认值‘abcdefghijklmnopqrstuvwxyzABCDEFJHIJKLMNOPQRSTUVWXYZ‘;
    declare chars_str varchar(100) default
        ‘abcdefghijklmnopqrstuvwxyzABCDEFJHIJKLMNOPQRSTUVWXYZ‘;
    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 $$


#函数: 随机产生部门编号
drop function rand_num $$

create function rand_num( )
returns int(5)
begin 
    declare i int default 0;
    set i = floor(10+rand()*500);
    return i;
end $$


#******************************************
#向emp表中插入记录(海量的数据)
drop procedure insert_emp $$

#随即添加雇员[光标]  400w
create procedure insert_emp(in start int(10),in max_num int(10))
begin
    declare i int default 0; 
    #把autocommit设置成0，不自动提交
    set autocommit = 0;  
    repeat
        set i = i + 1;
        insert into emp values ((start+i) ,rand_string(6),‘SALESMAN‘,0001,curdate(),2000,400,rand_num());
    until i = max_num
    end repeat;
    commit;
end $$


delimiter ;
#调用刚刚写好的函数, 4000000条记录,从100001号开始
call insert_emp(100001,4000000);


#**************************************************************
#  向dept表中插入记录

delimiter $$
drop procedure insert_dept $$

create procedure insert_dept(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 dept values ((start+i) ,rand_string(10),rand_string(8));
        until i = max_num
    end repeat;
    commit;
end $$

delimiter ;
call insert_dept(100,10);