# Sql to create userdetails table:

    CREATE TABLE `userdetails` (
     `user_details_id` int(3) unsigned NOT NULL AUTO_INCREMENT,
     `user_group_id` int(1) unsigned NOT NULL,
     `name` varchar(50) NOT NULL,
     `email_id` varchar(50) NOT NULL,
     `password` varchar(50) NOT NULL,
     `mobile_no` varchar(10) NOT NULL,
     `company_id` int(3) unsigned NOT NULL,
     `date_created` datetime NOT NULL DEFAULT CURRENT_TIMESTAMP,
     `date_updated` datetime NOT NULL,
     `created_by` int(3) unsigned NOT NULL,
     `status` enum('0','1') NOT NULL DEFAULT '0',
     PRIMARY KEY (`user_details_id`),
     UNIQUE KEY `email_id` (`email_id`)
    ) ENGINE=InnoDB DEFAULT CHARSET=latin1;

    # Sql to create qrcode table:
    CREATE TABLE `qrcode` (
     `qrcode_id` int(3) unsigned NOT NULL AUTO_INCREMENT,
     `user_details_id` int(3) unsigned NOT NULL,
     `qrcode_url` varchar(50) NOT NULL,
     `allowed_entries` int(1) unsigned NOT NULL,
     `used_entries` int(1) unsigned NOT NULL,
     `expiry_date` datetime NOT NULL,
     `status` enum('0','1') NOT NULL,
     PRIMARY KEY (`qrcode_id`),
     UNIQUE KEY `user_details_id` (`user_details_id`),
     FOREIGN KEY (`user_details_id`) REFERENCES `userdetails` (`user_details_id `)
    ) ENGINE=InnoDB DEFAULT CHARSET=latin1;

嘿，伙计们，我正试图创建上面的表，但我不断得到错误：

# 1005 - Can't create table `esecurity`.`qrcode` (errno: 150 "Foreign key constraint is incorrectly formed")

我认为这与数据类型有关，但我已经仔细检查了一下，以确保它们是相同的。我不知道我哪里出了问题，但如果有人能解释一下这个问题就太好了。
谢谢。