在PHP中扩展与不扩展一个类

我是新人下面是尝试与数据库进行交互的开始。如果语法不正确，请让我知道，它似乎在我的本地主机上工作。

我想我可以输入class Database extends Mysqli，对吗?这样就可以直接访问mysql的方法，而不是通过在类本身中创建的实例。那样会比我所做的更好吗?

class Database {
    #The variable that stores the database handle
    public $db;
    #The Database objects's datbase parameters
    public $host;
    public $user;
    public $password;
    public $database;
    #creates a Database object with the required databases details
    public function __construct($host, $user, $password, $database) {
        $this->host = $host;
        $this->user = $user;
        $this->password = $password;
        $this->database = $database;
    }
    #Stores the database handle as a var $db of the Database instance 
    public function connect() {
        if ($this->db = new Mysqli($this->host, $this->user, $this->password, $this->database)) {
            if ($this->db->connect_errno) {
                echo "No connection could be made <br/>";
            } else {
                echo "database succesfully connected <br/>";
            }
        }
    }
}