MySQL錯誤1452-無法添加或更新子行：外鍵約束失敗

Question

我已經看過其他人關於此主題的問題，但似乎無法找到我的錯誤來自哪裏。任何幫助將不勝感激。

CREATE TABLE stocks (
id INT AUTO_INCREMENT NOT NULL, 
user_id INT(11) UNSIGNED NOT NULL, 
ticker VARCHAR(20) NOT NULL, 
name VARCHAR(20), 
rating INT(11), 
position ENUM("strong buy", "buy", "sell", "strong sell", "neutral"), 
next_look DATE, 
privacy ENUM("public", "private"), 
PRIMARY KEY(id), 
FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE 
) 
ENGINE=InnoDB DEFAULT CHARSET=utf8; 



CREATE TABLE IF NOT EXISTS `stocks_tags` (
    `stock_id` INT NOT NULL, 
    `tag_id` INT NOT NULL, 
    PRIMARY KEY (`stock_id`,`tag_id`), 
    KEY `fk_stock_tag` (`tag_id`), 
    KEY `fk_tag_stock` (`stock_id`) 
) ENGINE=InnoDB DEFAULT CHARSET=utf8; 

ALTER TABLE `stocks_tags` 
    ADD CONSTRAINT `fk_stock_tag` FOREIGN KEY (`tag_id`) REFERENCES `tags` (`id`) ON DELETE CASCADE ON UPDATE CASCADE, 
    ADD CONSTRAINT `fk_tag_stock` FOREIGN KEY (`stock_id`) REFERENCES `stocks` (`id`) ON DELETE CASCADE ON UPDATE CASCADE; 



CREATE TABLE tags(
id INT AUTO_INCREMENT NOT NULL PRIMARY KEY, 
tags VARCHAR(30), 
UNIQUE(tags) 
) 
ENGINE=INNODB DEFAULT CHARSET=utf8; 

而我得到的錯誤：

Database_Exception [ 1452 ]: Cannot add or update a child row: a foreign key constraint 
fails (`ddmachine`.`stocks_tags`, CONSTRAINT `fk_stock_tag` FOREIGN KEY (`tag_id`) REFERENCES 
`tags` (`id`) ON DELETE CASCADE ON UPDATE CASCADE) [ INSERT INTO `stocks_tags` (`stock_id`, 
`tag_id`) VALUES (19, 'cash') ] 

我沒看到別人也有類似的問題，我能想到的，可能有助於發現問題，我包括儘可能多基於他們的枚舉列，但不認爲就是這樣。

Answer 1

這意味着標籤表中缺少tag_id cash ...不應將tag_id設置爲整數嗎？

（在此查詢我的意思）

INSERT INTO `stocks_tags` (`stock_id`, `tag_id`) VALUES (19, 'cash')