PHP msqli ->query() 乱码解决

$mysqli = new mysqli(‘localhost’,’root’,’password’,’dbname’);//mysqli链接数据库的写法

//$mysqli->query(“SET NAMES utf8”);//写法一

mysqliquery( db,”SET NAMES utf8”);//写法二

        $efly_id= $_REQUEST["efly_id"];
        echo $efly_id;
        $mysql_server="localhost";
        $mysql_user="root";
        $mysql_password="123456";
        $mysql_database="efly_service_database";
        echo $mysql_database;
        $conn=new mysqli($msql_server,$mysql_user,$mysql_password,$mysql_database);

        if(!$conn->connect_error){
        echo "数据库连接成功";
        $conn->query("set names utf8");
        $select="select username from efly_service_user where efly_id= 'a'";
        $result=  $conn->query($select);
         while($row=mysqli_fetch_assoc($result)){
        echo "
".$row["username"]."
";
}
//        echo "
 $username
";
        $conn->close();
        }else{
        echo "数据库连接失败";
        }
?>