Foreign key referring to primary key in the same table Mysql - mysql

Question

# 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),
`password` varchar(50) NOT NULL,
`mobile_no` varchar(10) NOT NULL,
`company_id` int(3) unsigned,
`vehicle_id` varchar(10),
`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`),
FOREIGN KEY (`user_group_id`) REFERENCES `usergroups` (`user_group_id`),
FOREIGN KEY (`company_id`) REFERENCES `companies` (`company_id`),
FOREIGN KEY (`created_by`) REFERENCES `userdetails` (`user_details_id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
Focusing on the 'user_details_id' and 'created_by' columns, the conflict arises when created_by is not referring to an existing user_details_id.
Meaning, if I am creating my own profile with the required details, my user_details_id has not been generated yet and hence I do not know what value to input into the created_by field (which is ideally supposed to contain my user_details_id).
I would appreciate if anyone can guide me in the right direction on how to approach such a conflict, and if there is a way to determine what the value of the user_details_id field could be before it's even generated.
Thanks.

Answer 1

You can't handle it by temporarily disabling foreign key checks by setting server variable foreign_key_checks
SET FOREIGN_KEY_CHECKS=0;
INSERT INTO cities userdetails(....);
SET FOREIGN_KEY_CHECKS = 1;

Answer 2

# 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),
`password` varchar(50) NOT NULL,
`mobile_no` varchar(10) NOT NULL,
`company_id` int(3) unsigned,
`vehicle_id` varchar(10),
`date_created` datetime NOT NULL DEFAULT CURRENT_TIMESTAMP,
`date_updated` datetime NOT NULL,
`created_by` int(3) unsigned,
`status` enum('0','1') NOT NULL DEFAULT '0',
PRIMARY KEY (`user_details_id`),
UNIQUE KEY `email_id` (`email_id`),
FOREIGN KEY (`user_group_id`) REFERENCES `usergroups` (`user_group_id`),
FOREIGN KEY (`company_id`) REFERENCES `companies` (`company_id`),
FOREIGN KEY (`created_by`) REFERENCES `userdetails` (`user_details_id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
Allowing created_by to accept NULL values seems to be a quick fix to this problem as that can imply user is self-created.