Question

my question is: How should I edit the following tables:

CREATE TABLE users(
id int UNSIGNED AUTO_INCREMENT PRIMARY KEY,
name varchar(20) NOT NULL,
surname varchar(20) NOT NULL,
faculty varchar(35) NOT NULL,
username varchar(20) NOT NULL UNIQUE,
password varchar(20) NOT NULL,
is_admin boolean NOT NULL DEFAULT 0,
account_limit int UNSIGNED,
created_at datetime
) CHARACTER SET utf8 COLLATE utf8_general_ci;



CREATE TABLE test_results(
id int UNSIGNED AUTO_INCREMENT PRIMARY KEY, 
test_id int UNSIGNED NOT NULL,
test_person_id int UNSIGNED NOT NULL,
score float UNSIGNED NOT NULL,
standard_deviation float UNSIGNED NOT NULL,
average_answer_time float UNSIGNED NOT NULL, 
removed boolean NOT NULL DEFAULT 0,
created_at datetime,
FOREIGN KEY (test_id) REFERENCES test_tasks(id) ON UPDATE CASCADE, FOREIGN KEY (test_person_id) REFERENCES test_persons(id) ON UPDATE CASCADE) CHARACTER SET utf8 COLLATE utf8_general_ci;

So that if I delete a row from the users-table, I don’t get any constraint errors etc. in the test_results-table if a row in test_results has a row which has a foreing key that references to the user-table row?

UPDATE: sorry I hesitated when making the question:

here are all my tables:

CREATE TABLE users(
id int UNSIGNED AUTO_INCREMENT PRIMARY KEY,
name varchar(20) NOT NULL,
surname varchar(20) NOT NULL,
faculty varchar(35) NOT NULL,
username varchar(20) NOT NULL UNIQUE,
password varchar(20) NOT NULL,
is_admin boolean NOT NULL DEFAULT 0,
account_limit int UNSIGNED,
created_at datetime
) CHARACTER SET utf8 COLLATE utf8_general_ci;


CREATE TABLE test_groups(
id int UNSIGNED AUTO_INCREMENT PRIMARY KEY,
user_id int UNSIGNED NOT NULL,
name varchar(60) NOT NULL, 
password varchar(20) NOT NULL,
tests varchar(60),
created_at datetime,
FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE ON UPDATE CASCADE
) CHARACTER SET utf8 COLLATE utf8_general_ci;



CREATE TABLE test_persons(
id int UNSIGNED AUTO_INCREMENT PRIMARY KEY,
group_id int UNSIGNED NOT NULL,
username varchar(45) NOT NULL UNIQUE,
tries int UNSIGNED NOT NULL,
created_at datetime,
FOREIGN KEY (group_id) REFERENCES test_groups(id) ON DELETE CASCADE ON UPDATE CASCADE
) CHARACTER SET utf8 COLLATE utf8_general_ci;



CREATE TABLE test_tasks(
id int UNSIGNED AUTO_INCREMENT PRIMARY KEY,
user_id int UNSIGNED NOT NULL,
name varchar(45) NOT NULL,
type varchar(20) NOT NULL,
description text NOT NULL,
question_time int UNSIGNED DEFAULT 500,
answer_time int UNSIGNED DEFAULT 3000,
random_questions boolean NOT NULL DEFAULT 1,
questions varchar(150),
created_at datetime,
FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE ON UPDATE CASCADE) CHARACTER SET utf8 COLLATE utf8_general_ci;



CREATE TABLE test_results(
id int UNSIGNED AUTO_INCREMENT PRIMARY KEY, 
test_id int UNSIGNED NOT NULL,
test_person_id int UNSIGNED NOT NULL,
score float UNSIGNED NOT NULL,
standard_deviation float UNSIGNED NOT NULL,
average_answer_time float UNSIGNED NOT NULL, 
removed boolean NOT NULL DEFAULT 0,
created_at datetime,
FOREIGN KEY (test_id) REFERENCES test_tasks(id) ON UPDATE CASCADE, FOREIGN KEY (test_person_id) REFERENCES test_persons(id) ON UPDATE CASCADE) CHARACTER SET utf8 COLLATE utf8_general_ci;

NOW IF I TRY TO REMOVE A ROW FROM user-table I get constraint error, why? I’m new with mysql

Answer 1

write

ALTER TABLE `test_results`
ADD CONSTRAINT `tbl_userplan_ibfk_1` 
FOREIGN KEY (`test_person_id`) REFERENCES `test_persons(id)`  
ON DELETE CASCADE ON UPDATE CASCADE

and foreign key worked in the way @David W described in comment