I am making a form and I wish for the form to be able to be submitted when the checkbox is either ticked or checked. I don't get any other errors when I login without checking the box apart from this one
Notice: Undefined index: stayLoggedIn in /home/sites/2a/d/dbcf5d6440/public_html/MySQL/Challenges/Secretdiary.php on line 91
Here is my code!
<?php
session_start();
 $error="";
if (array_key_exists("logout", $_GET)) {
    unset($_SESSION);
    setcookie("id", "", time() - 60*60);
    $_COOKIE["id"] = "";
} else if(array_key_exists("id", $_SESSION) OR array_key_exists("id", $_COOKIE)) {
    header("Location: loggedinpage.php");
}
    if(array_key_exists("submit", $_POST)) {
        $link = mysqli_connect("XXX", "XXX", "XXX", "XXX");
            if (mysqli_connect_error()) {
                die("Database Connection Error");
            }
        if(!$_POST['email']) {
            $error.= "An Email Address is required<br>";
        }
        if(!$_POST['password']) {
            $error.= "A Password is required<br>";
        }
        if($error != "") {
            $error = "<p>There were error(s) in your form</p>".$error;
        } else {
            if($_POST['signUp'] == '1' ) {
            $query = "SELECT id FROM `users` WHERE email = '".mysqli_real_escape_string($link, $_POST['email'])."' LIMIT 1";
            $result = mysqli_query($link, $query);
            if (mysqli_num_rows($result) > 0) {
                $error = "That email address is taken.";
            } else {
                $query = "INSERT INTO `users` (`email`, `password`) VALUES('".mysqli_real_escape_string($link, $_POST['email'])."', '".mysqli_real_escape_string($link, $_POST['password'])."')";
                if (!mysqli_query($link, $query)) {
                    $error="<p>Could not sign you up, please try again</p>";
                } else {
                    $query = "UPDATE `users` SET password = '".md5(md5(mysqli_insert_id($link)).$_POST['password']). "' WHERE id = ".mysqli_insert_id($link)." LIMIT 1";
                    mysqli_query($link, $query);
                    $_SESSION['id'] = mysqli_insert_id($link);
                    if ($_POST['stayLoggedIn'] == '1') {
                        setcookie("id", mysqli_insert_id($link), time() +  60*60*24*365);
                    }
                } header("Location: loggedinpage.php");
            } 
        } else {
                $query = "SELECT * FROM `users` WHERE email = '".mysqli_real_escape_string($link, $_POST['email'])."'";
                $result = mysqli_query($link, $query);
                $row = mysqli_fetch_array($result);
                if (array_key_exists("id", $row)) {
                    $hashedPassword = md5(md5($row['id']).$_POST['password']);
                    if ($hashedPassword == $row['password']) {
                        $_SESSION['id'] = $row['id'];
                        if ($_POST['stayLoggedIn'] == '1') {
                            setcookie("id", $row ($link), time() +  60*60*24*365);
                    }
                    }
                } 
                }
    }
    }
?>
<div id="error"><?php echo $error; ?></div>
<form method="post">
    <input type="email" name="email" placeholder="Your Email Eg. JoBloggs@me.co.uk">
    <input type="password" name="password" placeholder="Password">
    <input type="checkbox" name="stayLoggedIn" value=1>
    <input type="hidden" name="signUp" value="1">
    <input type="submit" name="submit" value="Sign Up!">
</form>
<form method="post">
    <input type="email" name="email" placeholder="Your Email Eg. JoBloggs@me.co.uk">
    <input type="password" name="password" placeholder="Password">
    <input type="checkbox" name="stayLoggedIn" value=1>
    <input type="hidden" name="signUp" value="0">
    <input type="submit" name="submit" value="Log In!">
</form>
 
     
     
     
    