将 MySQL 数据类型的值限制在特定范围内(最好不是 ENUM)
我想将字段中可以存储的数据类型值限制为特定范围的整数值:[0,10].
I want to limit the datatype value that can be stored within a field to a specific range of integer values: [0,10].
在 PHP 脚本中的用户输入时，我验证并清理数据以确保它在 0 到 10 的范围内.但是，有没有办法通过某种数据类型或约束?
On user input within a PHP script I validate and sanitise the data to make sure it is within the range 0 to 10. However, is there a way to ensure this remains true within the votes table itself via some sort of datatype or constraint?
目前我将 int 值存储在一个 UNSIGNED TINYINT 中，当然它的范围是 0-255.我知道 ENUM 作为一种选择.但是，我读过使用数字时不建议使用:http://komlenic.com/244/8-reasons-why-mysqls-enum-data-type-is-evil/
At the moment I store the int value within an UNSIGNED TINYINT which of course has the range of 0-255. I am aware of ENUM as an option. However, I have read that it is not advisable when using numbers: http://komlenic.com/244/8-reasons-why-mysqls-enum-data-type-is-evil/
SQL:
CREATE TABLE votes (
vote_id MEDIUMINT UNSIGNED NOT NULL AUTO_INCREMENT,
article_id MEDIUMINT UNSIGNED NOT NULL,
user_id MEDIUMINT UNSIGNED NOT NULL,
user_vote TINYINT UNSIGNED NOT NULL,
PRIMARY KEY (vote_id),
FOREIGN KEY (article_id) REFERENCES articles (article_id) ON DELETE CASCADE ON UPDATE NO ACTION,
FOREIGN KEY (user_id) REFERENCES users (user_id) ON DELETE CASCADE ON UPDATE NO ACTION,
CONSTRAINT article_uservoted UNIQUE KEY (user_id, article_id),
INDEX vote_value (article_id, user_id, user_vote)
) ENGINE=INNODB;
希望有人能帮忙.
推荐答案
您可以创建一个允许投票值的表并在您的投票表中添加一个外键，因此当您尝试使用 user_vote 值而不是现有值插入投票时在您的 allowed_votes 表中，您会收到一个约束失败错误:
You can create a table of allowed vote values and add a foreign key in your votes table, so when you try to insert a vote with user_vote value other than existing in your allowed_votes table you get a constraint fail error:
CREATE TABLE allowed_votes (
vote_rank TINYINT UNSIGNED NOT NULL,
PRIMARY KEY (vote_rank)
) ENGINE = InnoDB;
INSERT INTO allowed_votes( vote_rank ) VALUES(1),(2),(3),(4),(5),(6),(7),(8),(9),(10);
ALTER TABLE votes
ADD FOREIGN KEY (user_vote) REFERENCES allowed_votes (vote_rank);
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