php - How to use PDO prepare more than oncee in a class -

class dbconnection {      function connect(){         try{             $this->db_conn = new pdo("mysql:host=$this->db_host;dbname=$this->db_name", $this->db_user, $this->db_pass);             return $this->db_conn;         } catch(pdoexception $e) {             return $e->getmessage();         }     } }  class student{     public $link;      public function __construct(){         $db_connection = new dbconnection();         $this->link = $db_connection->connect();         return $this->link;     }      public function checklogin($username,$password){         $query = $this->link->prepare("select * studentprofiles username = :uname , logpassword = (select md5(:upassword));");         $query->execute(array(':uname' => $username, ':upassword' => $password));         $count = $query->rowcount();         if($count === 1){             $this->setsession($username);         }         return $count;         $query = null;     }      public static function display(){         $query = $this->link->prepare("select forename, surname studentprofiles username = :uname;"); //getting error here: fatal error: using $this when not in object context         $query->execute(array(':uname' => self::getsession()));         while($row = $query->fetch(pdo::fetch_assoc)) {             printf (" <span id='welcomename'> welcome: %s %s\n </span>",$row[0],$row[1]);         }         $query = null;     } } 

error using $this again prepare select statement, how use again function in same class? thank you

appreciate help, stuck on problem

hi can check code , prefer asign in value conection example

 $conn = new pdo('mysql:host=localhost;dbname=mydatabase', $username, $password);  $conn->setattribute(pdo::attr_errmode, pdo::errmode_exception);   

and in function make 1 how this

function connect(){         try{             $conn = new pdo('mysql:host=localhost;dbname=mydatabase', $username, $password);             $conn->setattribute(pdo::attr_errmode, pdo::errmode_exception);               return $conn;         } catch(pdoexception $e) {             return $e->getmessage();         }     } 

in complete example this:

$id = 5; try {     $conn = new pdo('mysql:host=localhost;dbname=mydatabase', $username, $password);     $conn->setattribute(pdo::attr_errmode, pdo::errmode_exception);          $stmt = $conn->prepare('select * mytable id = :id');     $stmt->execute(array('id' => $id));      while($row = $stmt->fetch()) {         print_r($row);     } } catch(pdoexception $e) {     echo 'error: ' . $e->getmessage(); } 

please try , luck