我有两个表,结构如下。当我尝试添加到 books 表时出现错误,我无法添加或更新我期望的子行。我希望在添加到 books 表之前,可以创建一个触发器来将出版商名称添加到 publisher 表。
这是我第一次使用触发器,我不确定自己做错了什么,也找不到示例。
create table publishers
(name varchar(25) not null,
address varchar(55),
phone varchar(12),
PRIMARY KEY(name)
) ENGINE = INNODB;
create table books
(book_id int(4) not null auto_increment,
title varchar(40),
publisher_name varchar(25),
primary key (book_id),
foreign key (publisher_name) references publishers(name) ON UPDATE CASCADE ON DELETE CASCADE
) ENGINE=INNODB;
以及我要创建的触发器:
DELIMITER ///
CREATE TRIGGER add_publisher BEFORE insert ON books
FOR EACH ROW
BEGIN
INSERT INTO publishers(name) values (books.pubisher_name);
END;
///
DELIMITER ;
最佳答案
将 books.publisher_name 替换为 NEW.publisher_name。
DELIMITER ///
CREATE TRIGGER add_publisher BEFORE insert ON books
FOR EACH ROW
BEGIN
INSERT INTO publishers(name) values (NEW.publisher_name);
END;
///
DELIMITER ;
关于mysql - 插入子表时触发将值插入父表,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/47462656/