Class connect{
        public $host = "localhost";
        public $user = "root";
        public $password = "";

        public $db = "test2";
        public $charset = "utf8";

        public $pdo = "";

        public function __construct() {
            $dsn = "mysql:host=$this->host;dbname=$this->db;charset=$this->charset";
            $opt = array(
                PDO::ATTR_ERRMODE            => PDO::ERRMODE_EXCEPTION,
                PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC
            );
            $this->pdo = new PDO($dsn, $this->user, $this->password, $opt);
        }
    }


    Class db extends connect{

        public function add($data)
        {
            $fields = $this->set_fields($data);
            $sql = "INSERT INTO `{$this->name_table}` SET".$fields;
            $stmt = $this->pdo->prepare( $sql );
            return $stmt->execute($data);
        }

        public function update($data, $where = "")
        {
            $fields = $this->set_fields($data);
            $sql = "UPDATE `{$this->name_table}` SET ".$fields;
            if(!empty($where)){
                $sql.= " WHERE ".$where;
            }
            $stmt = $this->pdo->prepare( $sql );
            return $stmt->execute($data);


        }

        public function set_fields( $items ){
            $str = array();
            foreach ($items as $key=>$item){
                $str[] = "`".$key."`=:".$key;
            }
            return implode(',', $str );
        }

    }

    Class Users extends db{
        public $name_table = "users";


    }


    $save = array("name" => "Владимир");
    $users = new Users();
    $res = $users->update($save, 'id=2');
    var_dump($res);