Cannot add foreign key constraint - mysql

Question

I have created a database "webportal". and this is my "user" table script
DROP TABLE IF EXISTS `user`;
CREATE TABLE `user` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`username` varchar(255) DEFAULT NULL,
`password` varchar(255) DEFAULT NULL,
`firstName` varchar(255) DEFAULT NULL,
`lastName` varchar(255) DEFAULT NULL,
`dateRegistered` DATE DEFAULT NULL,
`skypeID` int(11) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8;
and this one is "catalog" table script.
DROP TABLE IF EXISTS `catalog`;
create table catalog(
`id` int(11) NOT NULL AUTO_INCREMENT,
`user_id` int(11) NOT NULL,
`link` VARCHAR(100) NOT NULL,
`comment` VARCHAR(100) NOT NULL,
`inserDate` DATE DEFAULT NULL,
`content` longblob NOT NULL,
PRIMARY KEY (`id`),
CONSTRAINT `fk_catalog` FOREIGN KEY (`user_id`) REFERENCES `user` (`id`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
and when I try to execute the second script in the command line, I get this error...
ERROR 1215 (HY000): Cannot add foreign key constraint.
What is wrong with this code?

Answer 1

It seems you are using a old version of MySQL, you can add a INDEX clause to foreign key field to fix the problem:
DROP TABLE IF EXISTS `catalog`;
create table `catalog`(
`id` int(11) NOT NULL AUTO_INCREMENT,
`user_id` int(11) NOT NULL,
`link` VARCHAR(100) NOT NULL,
`comment` VARCHAR(100) NOT NULL,
`inserDate` DATE DEFAULT NULL,
`content` longblob NOT NULL,
PRIMARY KEY (`id`),
INDEX (`user_id`),
CONSTRAINT `fk_catalog` FOREIGN KEY (`user_id`) REFERENCES `user` (`id`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8;