ขึ้น ERROR การติดต่อกับฐานข้อมูลค่ะ รบกวนช่วยทีค่ะ

<?php
date_default_timezone_set('Asia/Bangkok');
$host = "localhost";//Main Host
$username = "admin_user"; //Database Username
$password = "admin_pass"; //Database Password
$db = "admin_db"; //Database Name
$connect = mysql_connect("$host","$username","$password");
mysql_select_db("$db", $connect);
mysql_query("SET NAMES utf8");

$sqlconfig="select * from configwebsite where id=1";
$db_query=mysql_select_db($db);
$resultc=mysql_fetch_array($db_query);
$idconfig=$resultc[id];
?>