向 MySQL 发出命令时,出现错误“#1075 - table 定义不正确;”

When issuing a command to MySQL, I'm getting that error "#1075 - Incorrect table definition;"

CREATE TABLE onscreen( 
   id int(2) not null AUTO_INCREMENT,
   subject varchar(100) not null,
   content varchar(100) not null,
   date datetime not null
);

整个错误信息是:

Incorrect table definition; there can be only one auto column and it must be defined as a key

这很清楚:MySQL 要求您将 auto-increment 列定义为主键:

CREATE TABLE onscreen( 
    id int(2) not null AUTO_INCREMENT primary key,  --> here
    subject varchar(100) not null, 
    content varchar(100) not null, 
    date datetime not null 
)

Demo on DB Fiddle