mysql 自增id feature 測試

一、建表插入數據

查看錶結構

插入數據

insert into tb_staff values(null,'hr','li2',24);
insert into tb_staff values(null,'tech','li3',35);
insert into tb_staff values(null,'tech','li4',35);
insert into tb_staff values(null,'tech','li5',40);
insert into tb_staff values(null,'hr','li6',26);

查看數據自增id，根據順序自動增長

二、刪除單條記錄再插入

刪除數據後再插入新數據 ，自增id會繼續增長，不會複用原id，除非重置

刪除id爲7的一條數據

delete from tb_staff where id = 7 ;
select * from tb_staff where id = 7;

插入新的數據，查看自增id

insert into tb_staff values(null,'hr','li6',26);

三、重置自增id，再插入數據

重置自增id,數據量大重置會很是慢

alter table tb_staff auto_increment =1;

再插入數據，查看自增id爲順序自增

insert into tb_staff values(null,'hr','li6',26);

清空表語句

truncate table tb_name;