How to update mysql db on session destroy - php

Question

Hello I have question about updating mysql db field with enum 1 and 0 and when the user log in it change it to 1 but when user log out i tried doing this but it won't work...
Also I tried make it as button and if btn is pressed do something and then go to logout.php but it didnt work ...
So my code is this ...
<?php include_once('connect.php');
$logger = $_SESSION["login"];
session_start();
session_unset();
session_destroy();
$mysqli = "UPDATE table SET field='0' WHERE email='$logger'";
if(mysqli_query($con, $mysqli)){
header("Location: index.php");}else echo "Something went wrong!";
?>

Answer 1

Your issue isn't to do with the other two answers, #Gopal states that you should destroy after unsetting the session, however you are setting the variable before unsetting the session. #Marmik also doesn't solve the issue.
Your problem lies here:
$logger = $_SESSION["login"];
session_start();
You're trying to access the session variable before you actually start the session. This is going to give you a blank $logger which you may find if you use echo $logger.
So, how do we solve this. Essentially, we just swap two lines around, so that session_start() is before we try accessing the session variables.
session_start();
$logger = $_SESSION["login"];
If this fails, you may want to check that $_SESSION["login"] has actually been set in the first place with a quick echo $_SESSION['login']; after session_start();
Good luck!

Answer 2

Give session_unset(); session_destroy(); After update query of the table.

Answer 3

what you can do is you can check the session that he is really logedin or not
On Logout.php
<?php
#session_start();
if(!empty($_SESSION['login'])){
include_once('connect.php');
$logger = $_SESSION["login"];
$mysqli = "UPDATE table SET field='0' WHERE email='$logger'";
if(mysqli_query($con, $mysqli)){
session_unset();
session_destroy();
header("Location: index.php");
}
else {
echo "Something went wrong!"
};
}
?>