text: create table teacher
  (
      teacher_id         bigint(20) unsigned primary key auto_increment comment '教师表主键',
      teacher_name       varchar(32)   not null comment '教师姓名',
      teacher_age        char(3)       not null comment '教师年龄',
      last_month_average decimal(5, 2) not null comment '上个月平局分',
      joined_time        datetime      not null comment '入职时间',
      create_time        datetime      not null default current_timestamp comment '信息创建时间',
      update_time        datetime      not null default current_timestamp on update CURRENT_TIMESTAMP comment '信息更新时间',
      is_delete          tinyint(1)             default 0 comment '是否删除【1为是，0为否】'
  ) engine = innodb
    auto_increment = 1
    default charset = utf8;
  
  
  create table student
  (
      id           bigint(20) unsigned primary key auto_increment,
      student_name varchar(10) not null,
      student_age  varchar(5)  not null,
      class_id     bigint(20)  not null,
      is_delete    tinyint default 0,
      index idx_clsid (class_id),
      index idx_name (student_name),
      index idx_age (student_age)
  ) engine = innodb
    auto_increment = 1
    default charset = utf8;
  
  INSERT INTO student (student_name, student_age, class_id)
  VALUES ("张三", "12", 1),
         ("李四", "13", 1),
         ("王五", "11", 2);