How can I upload a specific row without updating all the rows?

So, I have made a table called supplies_table and inside the table is id, name, and files. And I also made an upload button where it can upload a pdf BLOB file into the files column. Yes, it can upload a pdf file in the files column but the problem is that when I upload a file to a specific row, the other rows also updates with the same pdf file I uploaded.

Here's my code:

<?php

session_start();

$servername = "localhost";
$username = "root";
$password = "";
$dbname = "myDatabase";

$connect = mysqli_connect($servername, $username, $password, $dbname);

if(count($_FILES) > 0)
{
    if(is_uploaded_file($_FILES['file']['tmp_name']))
    {
        $_SESSION['id'];
        $file = file_get_contents($_FILES['file']['tmp_name']);
        $sql = "UPDATE supplies_table SET files = ? WHERE id=id";
        $statement = $connect->prepare($sql);
        $statement->bind_param('s',$file);
        $current_id = $statement->execute();
    }
}
mysqli_close($connect);
?>

What can I do to update just one row in the table?