Edit an improperly created constraint - mysql

Question

I think I may have wrongly created a constraint. I have three tables: Activity, Authentication, Login. I wanted Authentication to be the "primary" table, where I would insert data to create a user, and his details. It would have a one-one relation (id in Login to id in Authentication) with the newly created table, Authentication which stores session ids. The third table would have a one-many relation with multiple rows for AuthenticationID which corresponds to id of Login.
This is what I've created:
| Login | CREATE TABLE `Login` (
`id` int(6) unsigned NOT NULL AUTO_INCREMENT,
`TimeLoggedIn` text NOT NULL,
`sessionid` varchar(255) NOT NULL,
PRIMARY KEY (`id`),
KEY `id` (`id`),
KEY `id_2` (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=13 DEFAULT CHARSET=latin1 |
| Authentication | CREATE TABLE `Authentication` (
`id` int(6) unsigned NOT NULL AUTO_INCREMENT,
`userid` varchar(30) NOT NULL,
`password` varchar(30) NOT NULL,
`role` varchar(20) NOT NULL,
`email` varchar(50) DEFAULT NULL,
`AuthenticationID` int(6) unsigned DEFAULT NULL,
PRIMARY KEY (`id`),
CONSTRAINT `Authentication_ibfk_1` FOREIGN KEY (`id`) REFERENCES `Login` (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=14 DEFAULT CHARSET=latin1 |
| Activity | CREATE TABLE `Activity` (
`num` int(11) NOT NULL AUTO_INCREMENT,
`AuthenticationID` int(6) unsigned NOT NULL,
`TorrentMag` mediumtext NOT NULL,
PRIMARY KEY (`num`),
KEY `FK_myKey2` (`AuthenticationID`),
CONSTRAINT `FK_myKey` FOREIGN KEY (`AuthenticationID`) REFERENCES `Authentication` (`id`) ON DELETE CASCADE ON UPDATE CASCADE,
CONSTRAINT `FK_myKey2` FOREIGN KEY (`AuthenticationID`) REFERENCES `Authentication` (`id`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB AUTO_INCREMENT=104 DEFAULT CHARSET=latin1 |
Unfortunately, when I tried to insert a new row into Authentication (which used to work till I created the constraint),
INSERT INTO Authentication (userid, password, role, email) VALUES ("user", "SeG^SU;B2_&Uhw", "user", "someone#mydomain.com");
it gave the error:
Cannot add or update a child row: a foreign key constraint fails (`episodescopy`.`Authentication`, CONSTRAINT `Authentication_ibfk_1` FOREIGN KEY (`id`) REFERENCES `Login` (`id`))
So I've inadvertently created an inverse relation of what I needed? Also I seem to have created a duplicate constraint on table Activity? How can I fix this?

Answer 1

Here is a suggestion which would hopefully at least point you in the right direction. If you want to create users in the Authentication table, then any other table column which references the primary key of Authentication (namely the id) should be declared as a foreign key reference.
CREATE TABLE Login (
id int(6) unsigned NOT NULL AUTO_INCREMENT,
TimeLoggedIn text NOT NULL,
sessionid varchar(255) NOT NULL,
PRIMARY KEY (id),
KEY id (id),
KEY id_2 (id),
CONSTRAINT fk_1 FOREIGN KEY (id) REFERENCES Authentication (id)
) ENGINE=InnoDB AUTO_INCREMENT=13 DEFAULT CHARSET=latin1
CREATE TABLE Authentication (
id int(6) unsigned NOT NULL AUTO_INCREMENT,
userid varchar(30) NOT NULL,
password varchar(30) NOT NULL,
role varchar(20) NOT NULL,
email varchar(50) DEFAULT NULL,
AuthenticationID int(6) unsigned DEFAULT NULL,
PRIMARY KEY (id)
) ENGINE=InnoDB AUTO_INCREMENT=14 DEFAULT CHARSET=latin1
Your current setup is the opposite, requiring a user to exist in Login before it can be inserted into Authentication.