如题，关联外键的时候，报错类型匹配。但是两个 类型都是int

sql 如下：

CREATE TABLE IF NOT EXISTS `alert_receiver_map` (   `id` INT UNSIGNED AUTO_INCREMENT,   `alert_id` INT NOT NULL,   `receiver_id` INT NOT NULL,   PRIMARY KEY ( `id` ),   FOREIGN KEY (`alert_id`) REFERENCES alert_conditions ( id ),   FOREIGN KEY (`receiver_id`) REFERENCES receivers ( id ))ENGINE=InnoDB DEFAULT CHARSET=utf8;

show engine innodb status 查看 还是报类型不匹配，仔细瞅了瞅；最后发现是unsigned 导致的。

一个无符号，一个正常int 导致的类型不匹配。