当我尝试从表中删除主键时收到此错误：

00:44:25    ALTER TABLE BOOKS DROP PRIMARY KEY  Error Code: 1075. Incorrect table definition; there can be only one auto column and it must be defined as a key 0.000 sec.

下面是我的代码

CREATE DATABASE IF NOT EXISTS BD3;   
USE BD3;

# creare tabele Carti si Library

CREATE TABLE IF NOT EXISTS Books(
id TINYINT NOT NULL PRIMARY KEY AUTO_INCREMENT,
titlu VARCHAR(20) NOT NULL,
autor VARCHAR(25) NOT NULL,
data_aparitie DATE NOT NULL,
editura VARCHAR(15),
gen ENUM('drama', 'SF') NOT NULL

);

ALTER TABLE Books DROP PRIMARY KEY;

回答

ALTER TABLE Books MODIFY id TINYINT NOT NULL, DROP PRIMARY KEY;