<?php
    class ConnectionMySQL{
          private $server;
          private $user;
          private $pass;
          private $database;

     public function __construct($server, $user, $pass, $database){
            $this->server = $server;
            $this->user  = $user;
            $this->pass = $pass;
            $this->database = $database;
    }

      public function connect(){
         if(!mysql_connect($this->server, $this->user, $this->pass)){
            exit('Erro na Conexão : '.mysql_error());
         }
      }
      public function selectDb(){
        if(!mysql_select_db($this->database)){
        exit('Erro a Selecionar banco de Dados: '.mysql_error());
          }
     }

     public function start(){
        $this->connect();
        $this->selectDb();
     }

    }

    //Instancia a classe
    $conn = new ConnectionMySQL('localhost', 'root', '', 'banco_de_dados');
    //Inicia a conexão
    $conn->start();
?>