MySQL cascade update failed when foreign key column referenced in composite primary key

问题

Unlike the similar other questions, I get error #1452 when updating the parent row. Why does it happen? Thank you in advance.

Here are the relevant tables:

CREATE TABLE IF NOT EXISTS `user`
(
    `username` VARCHAR(100) NOT NULL,
    `password` VARCHAR(200) NOT NULL,
    `name` VARCHAR(100),
    `surname` VARCHAR(100),
    `icon` BLOB,
    PRIMARY KEY (username)
);

CREATE TABLE IF NOT EXISTS `document`
(
    `owner` VARCHAR(100) NOT NULL,
    `name` VARCHAR(100) NOT NULL,
    `sharing_link` VARCHAR(200) UNIQUE NOT NULL,
    PRIMARY KEY (`owner`, `name`),
    FOREIGN KEY (`owner`) REFERENCES user(`username`) ON UPDATE CASCADE
);

CREATE TABLE IF NOT EXISTS sharing
(
    `sharing_user` VARCHAR(100) NOT NULL,
    `document_owner` VARCHAR(100) NOT NULL,
    `document_name` VARCHAR(100) NOT NULL,
    PRIMARY KEY (`sharing_user`, `document_owner`, `document_name`),
    FOREIGN KEY (`sharing_user`) REFERENCES user(`username`) ON UPDATE CASCADE,
    FOREIGN KEY (`document_owner`, `document_name`) REFERENCES `document`(`owner`, `name`) ON UPDATE CASCADE
);

And here how to reproduce the error:

INSERT INTO `user` (`username`, `password`, `name`, `surname`, `icon`) VALUES ('fruggeri', 'fruggeri', 'Franco', 'Ruggeri', NULL);
INSERT INTO `document` (`owner`, `name`, `sharing_link`) VALUES ('fruggeri', 'document', 'sharing_link');
INSERT INTO `sharing` (`sharing_user`, `document_owner`, `document_name`) VALUES ('fruggeri', 'fruggeri', 'document');
UPDATE `user` SET `username` = 'new_fruggeri' WHERE `user`.`username` = 'fruggeri'

Resulting error:

#1452 - Cannot add or update a child row: a foreign key constraint fails (`collaborative_text_editor`.`sharing`, CONSTRAINT `sharing_ibfk_1` FOREIGN KEY (`sharing_user`) REFERENCES `user` (`username`) ON UPDATE CASCADE)

来源：https://stackoverflow.com/questions/63600963/mysql-cascade-update-failed-when-foreign-key-column-referenced-in-composite-prim

标签

mysql

sql

foreign-keys

Cascade

composite-primary-key