database updaten met gegevens array

<?php

class members {
   
    protected $member = array("id" => "", "username" => "", "email" => "");
    protected $mysqli;
   
    public function __set($key, $value){
        $sql="UPDATE members SET ".$key." = '".$this->mysqli->real_escape_string($value)."' WHERE id=".$this->member["id"];
        @$this->mysqli->query($sql) OR trigger_error($mysqli->error);
        $this->member[$key]=$value;
        return true;
       
    }
}

?>

<?php
 
class members {
 
    protected $member = array("id" => "", "username" => "", "email" => "");
    protected $mysqli;
 
    public function __set($key, $value){
        $sql="UPDATE members SET ".$key." = '".$this->mysqli->real_escape_string($value)."' WHERE id=".$this->member["id"];
        @$this->mysqli->query($sql) OR trigger_error($mysqli->error);
        $this->member[$key]=$value;
        return true;
 
    }
}
 
?>

<?php
$member->email="test@test.com";
?>

<?php
$member->email="test@test.com";
?>