Db.php

<?php
class Db{
    private $server   = 'localhost';
    private $userName = 'root';
    private $passwrod = '';
    private $select = 'catalog';
    private $charset = "utf8";
    private $sql = "";
    function __construct(){
        $this->sql();
        $this->query($this->sql);
    }
    function connect(){
        return mysql_connect($this->server, $this->userName,$this->passwrod);
    }
    function select_db(){
        return mysql_select_db($this->select);
    }
    function charset(){
        return mysql_set_charset($this->charset);
    }
    function query($sql){
        return mysql_query($sql);
    }
    function format($result){
        $a=1;
        $array = array();
        while ($categories = mysql_fetch_array($result)) {
            $array[] = $categories;
        }
        foreach($array as $key =>$value){
            echo "<b>№" . $a++ .
                "<b> Имя </b>: " . $value['firstName'] ."<br>" .
                "<b> <em> Текст: </em></b>" . $value['message'] . "<hr>";
        }
    }
    function sql(){
        $this->connect();
        $this->select_db();
        $this->charset();
    }
}
$db = new Db();
$db->format($db->query("SELECT * FROM guest_book"));