MySql trigger not doing any action - php

Question

It's probably something stupid but I'm unable to figure it out.The issue is that when i want to perform a check on email_token table,It's not passing.I have a simple query to update the needed data.But every time i get a false on my query.
Here is it:
DELIMITER $$
CREATE TRIGGER email_token_used
BEFORE INSERT
ON email_token FOR EACH ROW
BEGIN
IF(EXISTS(SELECT * FROM email_token WHERE used = 'N' AND usable = 'Y' AND user_id = NEW.user_id)) THEN
UPDATE email_token SET usable='N' WHERE user_id = NEW.user_id;
END IF;
END$$
Here is my table:
Here is the php if needed.It's working without the trigger ,the mail can't be sent since it's not updated in the table:
if(!password_verify($password,$output['password'])){
self::$status = 401;
echo "Pass 1";
}else{
$mail_result = self::$db->query("INSERT INTO email_token(user_id,token,created,expires,used) VALUES('{$output['user_id']}','{$token}',NOW(),DATE_ADD(NOW(), INTERVAL 30 MINUTE),'N')");
if($mail_result){
echo "Pass 2";
$mailer = new Mailer();
$mailer -> send_mail("Token authentication","Token authentication <a href='http://localhost:8888/scripts/functions/collector/login/login_step_2.php?user_id={$token}'>Link</a>",$output['email']);
}else{
self::$status = 409;
echo "Error 1";
}
}
Explanation of the final goal here.
The user logs in,he/she gets a token that is being sent to their email(like a 2 stop verification system).After they get the token,they finish with the login in process.I want to prevent people from having multiple tokens,and if they login several times ,they will get the token on their email.The tokens last for 2min,and i want to update the tokens before to be not valid.
Thanks...

Answer 1

You have run afoul of
A stored function or trigger cannot modify a table that is already
being used (for reading or writing) by the statement that invoked the
function or trigger.
https://dev.mysql.com/doc/refman/5.7/en/stored-program-restrictions.html
I am not sure why you need a trigger here in the first place. It seems to be that you have a situation where INSERT ON DUPLICATE KEY UDPATE can be used. Something like
INSERT INTO email_token(user_id,token,created,expires,used)
VALUES(?,?,NOW(),DATE_ADD(NOW(), INTERVAL 30 MINUTE),'N')
ON DUPLICATE KEY UPDATE usable = 'Y'
Note that you are using string concatenation in your queries. You should be using prepared statements instead.
Based on your comments. It sounds like all you need is a simple INSERT statement (The record needs to be inserted every time). Preceded by an UPDATE statement
UPDATE email_token SET usable='N' WHERE user_id = ?
INSERT INTO email_token(user_id,token,created,expires,used)
VALUES(?,?,NOW(),DATE_ADD(NOW(), INTERVAL 30 MINUTE),'N')
First one invalidates existing records. Second one creates a new record. Still no need for a trigger.

Answer 2

Try it like this:
DELIMITER $$
CREATE TRIGGER email_token_used
BEFORE INSERT
ON email_token FOR EACH ROW
BEGIN
IF(EXISTS(SELECT * FROM email_token WHERE used = 'N' AND usable = 'Y' AND user_id = NEW.user_id)) THEN
BEGIN
UPDATE email_token SET usable='N' WHERE user_id = NEW.user_id;
END;
END IF;
END$$