MySQL Foreign keys - Error 150 while creating tables - mysql

Question

I have written some SQL code to create five tables with several relations(foreign keys).
The first foreign key relation works fine, the tables are created without any errors, but when I try to create gasten_url_toegangscodes I get the following error:
#1005 - Can't create table 'dbname.gasten_url_toegangscodes' (errno: 150).
I've read the docs about foreign keys and I still can't find the problem.. The most strange thing about this is that it works in the first three tables..
Can anyone help me please?
My full SQL code is:
CREATE TABLE IF NOT EXISTS `groepen` (
`id` tinyint(3) NOT NULL AUTO_INCREMENT,
`naam` varchar(50) NOT NULL DEFAULT '',
`status` tinyint(1) NOT NULL DEFAULT '1',
PRIMARY KEY (`id`)
) ENGINE=InnoDB;
CREATE TABLE IF NOT EXISTS `gasten` (
`id` int(5) NOT NULL AUTO_INCREMENT,
`bedrijf` varchar(100) NOT NULL DEFAULT '',
`uniek` varchar(64) NOT NULL,
`groepid` tinyint(3) NOT NULL,
PRIMARY KEY (`id`),
FOREIGN KEY (groepid) REFERENCES `groepen` (`id`) ON DELETE CASCADE ON UPDATE NO ACTION
) ENGINE=InnoDB;
CREATE TABLE IF NOT EXISTS `passen` (
`id` tinyint(3) NOT NULL AUTO_INCREMENT,
`naam` varchar(30) NOT NULL DEFAULT '',
`color` varchar(7) NOT NULL DEFAULT '#FFFFFF',
`bekend` tinyint(1) NOT NULL DEFAULT '0',
`welkom` tinyint(1) NOT NULL DEFAULT '0',
`aantal` tinyint(1) NOT NULL DEFAULT '0',
`nummer` int(11) NOT NULL DEFAULT '0',
`begrens` tinyint(1) NOT NULL DEFAULT '0',
`status` tinyint(1) NOT NULL DEFAULT '1',
`priority` int(11) NOT NULL DEFAULT '0',
PRIMARY KEY (`id`),
KEY `naam` (`naam`)
) ENGINE=InnoDB;
CREATE TABLE IF NOT EXISTS `gasten_url_toegangscodes` (
`uniek` varchar(64) NOT NULL,
`unieke_url_code` char(64) NOT NULL,
`salt` char(16) NOT NULL,
FOREIGN KEY (uniek) REFERENCES `gasten` (`uniek`) ON DELETE CASCADE ON UPDATE NO ACTION
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
CREATE TABLE IF NOT EXISTS `gasten_tickets` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`pas_id` tinyint(3) NOT NULL,
`uniek` varchar(64) NOT NULL,
`barcode` char(16) NOT NULL,
`secret_key` char(32) NOT NULL,
`download_count` int(11) NOT NULL DEFAULT '0',
`last_download_time` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
`scanned` enum('N','Y') NOT NULL,
`scanned_datetime` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00',
PRIMARY KEY (`id`),
FOREIGN KEY (uniek) REFERENCES `gasten` (`uniek`) ON DELETE CASCADE ON UPDATE NO ACTION,
FOREIGN KEY (pas_id) REFERENCES `passen` (`id`) ON DELETE CASCADE ON UPDATE NO ACTION
) ENGINE=InnoDB;
Thanks in advance!

Answer 1

Create an index on gasten.uniek
CREATE TABLE IF NOT EXISTS `gasten` (
`id` int(5) NOT NULL AUTO_INCREMENT,
`bedrijf` varchar(100) NOT NULL DEFAULT '',
`uniek` varchar(64) NOT NULL,
`groepid` tinyint(3) NOT NULL,
PRIMARY KEY (`id`),
INDEX `idx_uniek` (`uniek`),
FOREIGN KEY (groepid) REFERENCES `groepen` (`id`) ON DELETE CASCADE ON UPDATE NO ACTION
) ENGINE=InnoDB;
And set the charset of the FK in gasten_url_toegangscodes the same as that of the related column in gasten.
Assuming gasten is UTF-8:
CREATE TABLE IF NOT EXISTS `gasten_url_toegangscodes` (
/* use same charset for this column */
`uniek` varchar(64) NOT NULL CHARSET UTF-8,
`unieke_url_code` char(64) NOT NULL,
`salt` char(16) NOT NULL,
FOREIGN KEY (uniek) REFERENCES `gasten` (`uniek`) ON DELETE CASCADE ON UPDATE NO ACTION
) ENGINE=InnoDB DEFAULT CHARSET=latin1;