<?php
include "./includes/Conn.php";
$id  = intval($_POST['id']);
$col = in_array($_POST['field'],['car_make','car_model']) ? $_POST['field'] : exit;
$val = intval($_POST['value']);
$stmt=$conn->prepare("UPDATE cars_sale_inventory SET $col=? WHERE id=?");
$stmt->bind_param('ii',$val,$id);
$stmt->execute();
echo 'ok';