如何在过期时间后将字符串设置为零？

Question

I am creating a login/registration-script where a user hast to activate his account with a token. Now i have a function that calls a random string.

class.functions.php

public static function generateRandomString($length = 200) {
        $characters = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
        $charactersLength = strlen($characters);
        $randomString = '';
        for ($i = 0; $i < $length; $i++) {
            $randomString .= $characters[rand(0, $charactersLength - 1)];
        }
        return $randomString;
    }

this will output something like this: jTq7tH4dKy66dmnhRev5EjbZDZygN1...

now my question is, how can i set this string empty after 24h, so that the user has to activate his account again.

my thought was about an update query in my database like this:

$statusN = "N" and $statusY = "Y"

the table field from the database:

`user_status` ENUM('Y','N') NOT NULL DEFAULT 'N',

the sql statment:

$sql = "UPDATE formular SET user_status='" . $statusY . "' WHERE user_status='" . $statusN . "'";

but i dont know how to handel it with the time

Here is the inserting of the userdata and the activation_token

register.php

$activationToken = functions::generateRandomString();
    $stmt = $conn->prepare("INSERT INTO formular (firstname, second_firstname, lastname, zipcode, city, street, additionaladdress, country_id_from_apps_countries, username, email, hash, dday, dmonth, dyear, religion, housenumber, activation_token) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)");
    $stmt->bind_param("sssisssssssssssss", $firstname, $secondFirstname, $lastname, $zipcode, $city, $street, $additionaladdress, $country, $username, $email, $hash, $DOB, $MOB, $YOB, $religion, $houseNumber, $activationToken);
    $stmt->execute();
    if ($stmt->affected_rows) {

    }

Answer 1

Checking the timestamp and creating the string are two different things.

On one side, you have to create the string and save it with the actual timestamp.

On a second step, probably with a cronJob you have to check wich tokens in your DB are expired (more than 24 hours old) and set them to null.

You have two different operations in two different pieces of code.

To disable all expired entries, just do a SELECT * from .... where token >= XXX. Foreach result, UPDATE table set token = NULL where ....

and so on.