ช่วยแก้เป็น mysqli ผมแก้ไม่ผ่านมาหลายวันแล้วครับ พยายามแล้ว

$finfo = mysqli_fetch_field_direct($result, 1);
printf("Name:     %s\n", $finfo->name);

<?php
$db=new mysqli('localhost','test','test','test');
if($db->connect_error) die($db->connect_error);
if($stmt=$db->prepare('select * from test_date where id=?')){
	$id=1;
	$stmt->bind_param('i',$id);
	$stmt->execute();
	$rs = $stmt->get_result();
	$ro=$rs->fetch_object();
	var_dump($ro);
}else echo $db->error;

if($stmt=$db->prepare('update tablename set amount=amount - ? where field >= ? and id=?')){
	$id=1; $amt=400;
	$stmt->bind_param('iii',$amt,$amt,$id);
	if(!$stmt->execute()) die("เกิดข้อผิดพลาด 1 <br>" . print_r($stmt->error_list,true));
	if($stmt->affected_rows>0){
		echo "update complete";
	}else{
		echo "update error";
	}
}else echo $db->error;