mysql - Function Dependancy PHP -

so in php im trying public variable in database class connects database when class created. -

<?php  class database {          public $_link;       public function __construct (){        $this->_link = new pdo("mysql:host=localhost; dbname=swinkidc_student", "swinkidc_student", "");     }   } 

and...

<?php  class user{      private $db;       public function __construct() {         $this->db = new database;     }      /**      * returns id of user.      * @param string $user      * @return mixed      */     public function getuserid($user){         $query =  $_link->prepare("select `user_id` `users` `username` = :user");         $query->bindparam(":user", $user);         $query->execute();                $result = $query->fetch(pdo::fetch_assoc);         return $result['user_id'];      }      /**      * checks if given user active.      * @param string $user      * @return bool returns true/false if user active.      */     public function isuseractive($user){      }  } 

if extened database in user can refer _link if make private , work, however, don't think should inherit getting that..

whenever try : fatal error: call member function prepare() on non-object in /home/swinkidc/public_html/studentreach/core/authentication/user.php on line 18

as said, if try inheritance way work, don't feel thats great way of doing this.

any suggestions please?

thanks!

link property of database , not property of user. therefore use:

$query =  $this->db->_link->...