bibi黑马MySQL学习笔记之约束

-- 约束演示

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

) comment '用户表';

-- 插入数据
insert into user(name,age,status,gender) values ('tom1',19,'2','男'),('tom2',13,'0','男');
insert into user(name,age,status,gender) values ('tom3',19,'2','男');

insert into user(name,age,status,gender) values (null,19,'2','男');

insert into user(name,age,status,gender) values ('tom5',19,'2','男');

insert into user(name,age,gender) values ('tom7',19,'男');

结果展示