<?php
$dbh='localhost';
$dbp='password';
$dbu='db_username';
$dbn='db_name';

if(!($db=mysql_connect($dbh, $dbu, $dbp)))
{
    echo'please wait or refresh the <a href="?">page</a>';
    exit;
}

if (!mysql_select_db($dbn,$db))
{
    echo "Wrong MySQL db name";
    exit;
}

mysql_query('set charset utf8',$db); 
mysql_query('SET names utf8',$db); 
mysql_query('set character_set_client="utf8"',$db); 
mysql_query('set character_set_connection="utf8"',$db); 
mysql_query('set character_set_result="utf8"',$db);

session_name('SESS');
session_start();

$sess=mysql_escape_string(session_id());

if (!preg_match('#[A-z0-9]{32}#i',$sess))$sess=md5(rand(09009,999999));

if (isset($_SESSION['id_user']) && mysql_result(mysql_query("SELECT COUNT(*) FROM `user` WHERE `id` = '$_SESSION[id_user]' LIMIT 1"), 0)==1)
{
    $user=mysql_fetch_array(mysql_query("SELECT * FROM `user` WHERE `id` = '$_SESSION[id_user]'"));
}
?>

Fatal error: Call to undefined function mysql_connect() on line 7