选择阿拉伯字符会导致MYSQL中出现问号.如何修复

阿拉伯字符的select语句返回?????。。为什么？

php代码：

<?php
    require_once("db.php");
    $code=$_GET["code"];
    $query = "SELECT id,name,price,code from metro_goods where code=$code";
    $result = mysql_query($query) or die(mysql_error());
    $arr=array();
    $i=0;
    while ($row = @mysql_fetch_assoc($result)){
        $arr[$i]=array("id"=>$row['id'],"name"=>$row['name'],"price"=>$row["price"],"code"=>$row["code"]);
        $i++;
    }
        echo json_encode(array("data"=>$arr));
 ?>

结果：

{"data":[{"id":"55121","name":"???? ??? ????? - ???","price":"16","code":"42217572"}]}

编辑：

设置字符集时

$rating_conn = mysql_connect($rating_dbhost, $rating_dbuser, $rating_dbpass) or die  ('Error connecting to mysql');
    mysql_set_charset('utf8',$rating_conn); 

输出变为：

{"data":[{"id":"55121","name":"'u0645'u0632'u064a'u0644 'u0639'u0631'u0642 'u0646'u064a'u0641'u064a'u0627 - 'u0633'u062a'u0643","price":"16","code":"42217572"}]}