MySQL 存储过程插入大量测试数据

create database testdb6;
use testdb6;
/* 用户表 */
drop table if exists users;
create table users(
id int primary key auto_increment,
name varchar(20)
);
insert into users(name) values ('A');
insert into users(name) values ('B');
insert into users(name) values ('C');
insert into users(name) values ('D');
insert into users(name) values ('E');
insert into users(name) values ('F');
insert into users(name) values ('G');
insert into users(name) values ('H');
insert into users(name) values ('I');
insert into users(name) values ('J');

/* 订单表 */
drop table if exists orders;
create table orders(
id int primary key auto_increment,/*订单id*/
order_no varchar(20) not null,/*订单编号*/
title varchar(20) not null,/*订单标题*/
goods_num int not null,/*订单数量*/
money decimal(7,4) not null,/*订单金额*/
user_id int not null	/*订单所属用户id*/
)engine=myisam default charset=utf8 ;

delimiter $$
drop procedure batch_orders $$

create procedure batch_orders(in max int)
begin
declare start int default 0;
declare i int default 0;
set autocommit = 0;
while i < max do
set i = i + 1;
insert into orders(order_no,title,goods_num,money,user_id)
values (concat('NCS-',floor(1 + rand()*1000000000000 )),concat('订单title-',i),i%50,(100.0000+(i%50)),i%10);
end while;
commit;
end $$
delimiter ;

call batch_orders(10000000);

in和exists





分析：
in执行顺序：先执行in中的子查询，作为我们最外层循环，主查询作为内层循环
exists: 主查询作为最外层循环，子查询作为最内层循环
而根据我们的时间复杂度，最外层循环小于内层循环的时候，使用的时间相对较少
结论：永远小表驱动大表是最优的选择方式