Question

I’m attemping to execute the following SQL and am receiving errno: 150 ‘cannot create table path_relations’ in response. According to the MySQL documentation this is caused by my FOREIGN KEY restraints having issues. What am I doing wrong?

DROP TABLE IF EXISTS `paths`;
DROP TABLE IF EXISTS `path_relations`;

CREATE TABLE `paths` (
  `id` int(11) unsigned NOT NULL AUTO_INCREMENT,
  `name` varchar(256) CHARACTER SET utf8 DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=24 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;

CREATE TABLE `path_relations` (
    `ancestor` int(11) NOT NULL DEFAULT '0',
    `descendant` int(11) NOT NULL DEFAULT '0',
    PRIMARY KEY(`ancestor`, `descendant`),
    FOREIGN KEY(`ancestor`) REFERENCES paths(`id`),
    FOREIGN KEY(`descendant`) REFERENCES paths(`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;

Answer 1

Does it work if you make paths.id not unsigned?