MySQL Foreign Key Reference Syntax - mysql

Question

I am using XAMPP server on Windows PC. Recently i was learning about and working with MySQL relational tables. I was creating a MySQL query to create a table with foreign key reference. My code is as follows:
CREATE TABLE loginattempts (
id int(16) NOT NULL,
loginattempts tinyint(9) NOT NULL,
attemptdate DATETIME NOT NULL
)
FOREIGN KEY (id) REFERENCES users(id)
ON DELETE CASCADE
ON UPDATE CASCADE
ENGINE = INNODB;
I have another table named users in my DB. When i execute the above query i get an error which is something like this:
Error [1064]: MySQL Syntax not correct Correspond to your MariaDB Documentation.
Is there anything wrong in my syntax if so please correct me!
Help will be highly appreciated. The above query is supposed to be written in PHP My Admin.
P.S.(If you find any mistakes feel free to edit)

Answer 1

The definition goes inside the create table statement:
CREATE TABLE loginattempts (
id int(16) NOT NULL,
loginattempts tinyint(9) NOT NULL,
attemptdate DATETIME NOT NULL,
FOREIGN KEY (id) REFERENCES users(id)
ON DELETE CASCADE
ON UPDATE CASCADE
) ENGINE = INNODB;
int(16) and tinyint(9) don't really make sense. An integer has up to 10 possible digits in its representation and a tinyint up to 3.
Often, foreign keys are given names. In addition, I recommend:
Each table have its own id, named after the table (i.e. userId rather than id).
Foreign keys have the same name as the primary key, where possible.
Constraints have names.
So, I would suggest:
CREATE TABLE loginattempts (
loginAttemptId int auto_increment primary key,
userId int NOT NULL,
loginattempts tinyint NOT NULL,
attemptdate DATETIME NOT NULL,
CONSTRAINT fk_loginattempts_userid FOREIGN KEY (userId) REFERENCES users(userId)
ON DELETE CASCADE
ON UPDATE CASCADE
) ENGINE = INNODB;
Of course, this requires changing the users table so the primary key is userId rather than id.
Here is a db<>fiddle.