MySQL auto_increment

Question

use wcdb;

create table user (
    id int primary key auto_increment comment '编号',
    name varchar(10) unique not null comment '姓名',
    age int check ( age <= 120 && age > 0 ) comment '年龄',
    status char(1) default '1' comment '状态',
    gender char(1)
) comment '用户表';

insert into user(name, age, status, gender)
    values ('Tom1',19,'0','男');

insert into user(name, age, status, gender)
    values ('Tom2',22,'0','男');

/*
insert into user(name, age, status, gender)
    values (null,22,'0','男');
*/   -- 报错：name不能为null

insert into user(name, age, status, gender)
    values ('Tom3',21,'0','男');

/*
insert into user(name, age, status, gender)
    values ('Tom3',21,'0','男');
*/   -- 报错：name不能重复

insert into user(name, age, status, gender)
    values ('Tom4',80,'1','男');

为什么Tom4对应的id为5而不是4？如果SQL报错的语句也会执行id自增的话，那id值为什么不是6？

Answer 1

这个没有什么固定的解释，插入失败多了，顺序会自己变乱https://www.cnblogs.com/waterserver/p/12236049.html