how to save to utf8 in php - php

Question

I wanna save chinese
if I don't have use utf8 to save it will be "?" ,so how to use utf8 to save.
or have other way can save chinese , make it not be "?".
thank help for everyone.
this it my php code (source code on internet)
<?php
/*
* Following code will create a new product row
* All product details are read from HTTP Post Request
*/
// array for JSON response
$response = array();
// check for required fields
if (isset($_POST['name']) && isset($_POST['price']) && isset($_POST['description'])) {
$name = $_POST['name'];
$price = $_POST['price'];
$description = $_POST['description'];
// include db connect class
require_once __DIR__ . '/db_connect.php';
// connecting to db
$db = new DB_CONNECT();
// mysql inserting a new row
$result = mysql_query("INSERT INTO products(name, price, description) VALUES('$name', '$price', '$description')");
// check if row inserted or not
if ($result) {
// successfully inserted into database
$response["success"] = 1;
$response["message"] = "Product successfully created.";
// echoing JSON response
echo json_encode($response);
} else {
// failed to insert row
$response["success"] = 0;
$response["message"] = "Oops! An error occurred.";
// echoing JSON response
echo json_encode($response);
}
} else {
// required field is missing
$response["success"] = 0;
$response["message"] = "Required field(s) is missing";
// echoing JSON response
echo json_encode($response);
}
?>

Answer 1

if you get your data from a form in browser you have to set the browser to utf8 like this :
<meta charset="UTF-8">
and you have to set your database's table
collation to utf8
and your php connection to database to utf8
mysql_query("SET NAMES 'utf8'");

Answer 2

before
$result = mysql_query("INSERT INTO products(name, price, description) VALUES('$name', '$price', '$description')");
try
mysql_query("SET CHARSET utf8");