用下面的表违反约束上插入
CREATE TABLE `Play` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`user_id` int(11) DEFAULT NULL,
`room_id` int(11) DEFAULT NULL,
PRIMARY KEY (`id`),
KEY `IDX_FEBB7184A76ED395` (`user_id`),
KEY `IDX_FEBB718454177093` (`room_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=1 ;
CREATE TABLE `User` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`username` varchar(255) NOT NULL,
`nickname` varchar(255) NOT NULL,
`email` varchar(255) NOT NULL,
PRIMARY KEY (`id`),
UNIQUE KEY `UNIQ_2DA17977F85E0677` (`username`),
UNIQUE KEY `UNIQ_2DA17977A188FE64` (`nickname`),
UNIQUE KEY `UNIQ_2DA17977E7927C74` (`email`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=1 ;
INSERT INTO `User` VALUES(1, 'user', 'nickname', '[email protected]');
CREATE TABLE `Room` (
`id` int(11) NOT NULL AUTO_INCREMENT,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=1 ;
INSERT INTO `Room` VALUES(1);
ALTER TABLE `Play`
ADD CONSTRAINT `play_ibfk_1` FOREIGN KEY (`user_id`) REFERENCES `User` (`id`),
ADD CONSTRAINT `play_ibfk_2` FOREIGN KEY (`room_id`) REFERENCES `Room` (`id`);
,并试图运行下面的语句
INSERT INTO `Play` (`id` ,`user_id` ,`room_id`) VALUES (NULL , '1', '1')
我得到一个错误
#1452 - Cannot add or update a child row: a foreign key constraint fails
(`play`, CONSTRAINT `play_ibfk_1` FOREIGN KEY (`user_id`) REFERENCES `User` (`id`))
两组数据,#1数据库中存在用户和#1房间。这怎么会失败?我对SQL很熟悉,但我不知道这种情况下的错误是什么......
听起来很愚蠢,但只是为了确保当你从'User'选择id时,你会得到什么id ='1'? – yokoloko
那么,如果我检查'1',我会得到用户。如果我检查“1”,我自然会得到一个错误......但是为什么查询会插入“1”呢?我使用phpMyAdmin创建它,并自动添加'''? –