Загрузка аватарки для пользователя

Никак не могу добавить возможность загрузки пользователем аватарки. Раньше поле image постоянно обновлялось в базе данных при попытке загрузки новой картинки(сама картинка не появлялась). Теперь я пытаюсь загрузить фотку и появляется вот такое сообщение Can't add new data Incorrect integer value: ' . . ' for column 'id' at row 1. Не совсем понимаю, как это исправить. Сейчас имею вот такой код:

profile.php

<?php
ini_set('display_errors',1);
error_reporting(E_ALL ^E_NOTICE);
error_reporting(E_ALL);
    session_start();
    require_once "./functions/database_functions.php";
    // print out header here
    $title = "Profile";
    require "./template/header.php";
    // connect database
    if(isset($_SESSION['email'])){
        $customer = getCustomerIdbyEmail($_SESSION['email']);
        }
        $conn = db_connect();
    if(isset($_POST['add'])){
    /*EDIT*/    $id = trim($_POST['id']);
    /*EDIT*/    $id = mysqli_real_escape_string($conn, $id);

        $firstname = trim($_POST['firstname']);
        $firstname = mysqli_real_escape_string($conn, $firstname);

        $lastname = trim($_POST['lastname']);
        $lastname = mysqli_real_escape_string($conn, $lastname);

        $email = trim($_POST['email']);
        $email = mysqli_real_escape_string($conn, $email);


        $address = trim($_POST['address']);
        $address = mysqli_real_escape_string($conn, $address);

        $city = trim($_POST['city']);
        $city = mysqli_real_escape_string($conn, $city);

        $zipcode = trim($_POST['zipcode']);
        $zipcode = mysqli_real_escape_string($conn, $zipcode);


        // add image
        if(isset($_FILES['image']) && $_FILES['image']['name'] != ""){
            $image = $_FILES['image']['name'];
            $directory_self = str_replace(basename($_SERVER['PHP_SELF']), '', $_SERVER['PHP_SELF']);
            $uploadDirectory = $_SERVER['DOCUMENT_ROOT'] . $directory_self . "bootstrap/img/";
            $uploadDirectory .= $image;
            move_uploaded_file($_FILES['image']['tmp_name'], $uploadDirectory);
        }

        $query = "INSERT INTO customers VALUES (' . $id . ', '" . $firstname . "', '" . $lastname . "', '" . $email . "', '', '" . $address . "', '" . $city . "', '" . $image . "',  '" . $zipcode . "')";
        $result = mysqli_query($conn, $query);
        if(!$result){
            echo "Can't add new data " . mysqli_error($conn);
            exit;
        } else {
            header("Location: editProfile.php");
        }
    }
?>
            <form method="post" action="profile.php" class="form-row">
    <div class="form-group col-md-6">
        <label for="exampleInputEmail1">Имя</label>
        <input type="text" class="form-control" aria-describedby="emailHelp" value="<?php echo $customer['firstname']?>" name="firstname">
        </div>

        <div class="form-group col-md-6">
            <label for="exampleInputEmail1">Фамилия</label>
            <input type="text" class="form-control" aria-describedby="emailHelp" value="<?php echo $customer['lastname']?>" name="lastname">
        </div>

        <div class="form-group col-md-6">
            <label for="exampleInputEmail1">Email</label>
            <input type="email" class="form-control" aria-describedby="emailHelp" value="<?php echo $customer['email']?>" name="email">
        </div>

        <div class="form-group col-md-6">
            <label for="inputAddress">Адрес</label>
            <input type="text" class="form-control" id="inputAddress" value="<?php echo $customer['address']?>" name="address">
        </div>
    
        <div class="form-group col-md-6">
            <label for="inputCity">Город</label>
            <input type="text" class="form-control" id="inputCity" name="city" value="<?php echo $customer['city']?>">
        </div>
 
        <div class="form-group col-md-6">
            <label for="inputZip">Номер телефона</label>
            <input type="text" class="form-control" id="inputZip" name="zipcode" value="<?php echo $customer['zipcode']?>">
        </div>

    <tr>
        <th>Image</th>
        <td><input type="file" name="image"></td>
    </tr>
        <input type="submit" name="add" value="Add new book" class="btn btn-primary">
        <input type="reset" value="cancel" class="btn btn-default">
    </form>
<?php
    if(isset($conn)) { mysqli_close($conn);}
    require "./template/footer.php";
?>

editProfile.php

<?php
    session_start();

    require_once "./functions/database_functions.php";
    // print out header here
    $title = "Edit Profile";
    require "./template/header.php";
    // connect database
    $conn = db_connect();

        $firstname = trim($_POST['firstname']);
        $firstname = mysqli_real_escape_string($conn, $firstname);
        
        $lastname = trim($_POST['lastname']);
                $lastname = mysqli_real_escape_string($conn, $lastname);
        
        $email = trim($_POST['email']);
        $email = mysqli_real_escape_string($conn, $email);
    
        
        $address = trim(trim($_POST['address']));
        $address = mysqli_real_escape_string($conn, $address);
        
        $city = trim($_POST['city']);
                $city = mysqli_real_escape_string($conn, $city);

        $image = trim($_POST['image']);
        $image = mysqli_real_escape_string($conn, $image);
        
        $zipcode = trim($_POST['zipcode']);
        $zipcode = mysqli_real_escape_string($conn, $zipcode);

    $customer = getCustomerIdbyEmail($_SESSION['email']);
        $id=$customer['id'];
    $query="UPDATE customers set 
    firstname='$firstname', lastname='$lastname' , address='$address', city='$city', zipcode='$zipcode' ,email='$email', image='$image' where id='$id'
    ";
   mysqli_query($conn, $query);

?>
<p class="lead text-success" id="p">Изменения сохранены</p>
   <script>
    
        window.setTimeout(function(){

        //window.location.href = "http://localhost/onlineBookStore/index.php";

        }, 3000);
    
   </script>

<?php

    if(isset($conn)){
        mysqli_close($conn);
    }
    require_once "./template/footer.php";
?>