基础篇03：SQL约束内容

 create table user (

    
     id int primary key auto_increment comment '主键',
    
     name varchar(10) not null unique comment '姓名',
    
     age tinyint unsigned check ( age > 0 and age <= 120 ) comment '年龄',
    
     status char(1) default '1' comment '状态',
    
     gender char(1) comment '性别'
    
 ) comment '用户表';