Unable to update image name in MySQL database

I am trying to update an image in MySQL database but each time I do try to update, other fields (i.e. location) of the is updated but the image name becomes blank.
Below is the code for updating:

if(isset($_POST['edt_Pic']))
{
    
    $id         = mysqli_real_escape_string($con, $_POST["id"]);
    $file       = mysqli_real_escape_string($con, $_POST['file']);
    $fullname   = mysqli_real_escape_string($con, $_POST['fullname']);
    $filename   = $_FILES['file']['name'];
    $file_temp  = $_FILES['file']['tmp_name'];
    $file_size  = $_FILES['file']['size'];
    
    if($file_size > 1048576)
            {
                echo "<script type='text/javascript'>alert('Attached photo exceeds 1Mb. Kindly reduce the size.');
                        </script>";
                echo "<script>window.location.href='users.php'</script>";
            }
            elseif(!empty($_FILES["file"]["tmp_name"]))
               {
                $exp    = explode(".", $file_name);
                $ext    = end($exp);
                $name   = $_FILES['file']['name'];
                
                move_uploaded_file($_FILES["file"]["tmp_name"],"./users/" . $name);
                
                $location   =   "./users/" . $name;
                
            $sql  = "UPDATE     users
                     SET        file = ?, location = ?, fullname = ?
                     WHERE      id = ?";
            
            $stmt = mysqli_prepare($con, $sql);
              
              mysqli_stmt_bind_param($stmt, "sssi", $file, $location, $fullname, $id);
            
                if(mysqli_stmt_execute($stmt))
                    {
                        echo "<script type='text/javascript'>alert('Image for " . $fullname . " has updated successfully.');
                              </script>";
                        echo "<script>window.location.href='users.php'</script>";
                    } 
                        else                    
                    {
                    echo "<script type='text/javascript'>alert('Oops! Something went wrong. Please try again.');
                            </script>";
                    echo "<script>window.location.href='users.php'</script>";
                }
        }
                 
        mysqli_stmt_close($stmt);
}
mysqli_close($con);

I have tried to add the old file name input field but to no luck.