mysql 深入学习三 索引优化三 （分页、关联、count(）、字段选择 的优化)

-- 示例表：
CREATE TABLE `t1` (
    `id` int(11) NOT NULL AUTO_INCREMENT,
    `a` int(11) DEFAULT NULL,
    `b` int(11) DEFAULT NULL,
    PRIMARY KEY (`id`),
    KEY `idx_a` (`a`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

create table t2 like t1;

--  插入一些示例数据
--  往t1表插入1万行记录
drop procedure if exists insert_t1;
delimiter ;;
create procedure insert_t1()
begin
    declare i int;
    set i=1;
    while(i<=10000)do
        insert into t1(a,b) values(i,i);
        set i=i+1;
    end while;
end;;
delimiter ;
call insert_t1();

-- 往t2表插入100行记录
drop procedure if exists insert_t2;
delimiter ;;
create procedure insert_t2()
begin
    declare i int;
    set i=1;
    while(i<=100)do
        insert into t2(a,b) values(i,i);
        set i=i+1;
    end while;
end;;
delimiter ;
call insert_t2();