PHP PDO Connection

I want create a connection class for database connection using PDO in PHP

开发者_运维百科here is my code :

<?php
class DatabaseConnection {

private $dbname     = "db_01";
private $host       = "localhost";
private $user       = "xxx";
private $password   = "xxxxxx";
private $port       = 5432;

private $DBH;

public function __construct() {
    try {
        $this->DBH  = new PDO("pgsql:host=$this->host;port=$this->port;dbname=$this->dbname;user=$this->user;password=$this->password");
    } catch(PDOException $e) {
        echo    $e->getMessage();  
    }

}
public function disconnect() {
    $this->DBH  = null; 
}
}
?>

For query in PDO i must use $DBH->query('SELECT * from user');

but how if i user my connection class in other class ?

example

<?php
include "DatabaseConnection.php";
class User {
    private $connection;

    public function getUser() {
        $this->connection = new DatabaseConnection();
        $STH = $this->connection->query('SELECT * from User');
    }
}
?>

But it's not work.

Any body can help me ? Thanks :)

UPDATE :

After follow Jonah suggest,

<?php

class DatabaseConnection extends PDO {

private $dbname     = "db_01";
private $host       = "localhost";
private $user       = "xxx";
private $password   = "xxxxxxxxx";
private $port       = 5432;

public function __construct() {
    try {
        parent::__construct("pgsql:host=$this->host;port=$this->port;dbname=$this->dbname;user=$this->user;password=$this->password");
    } catch(PDOException $e) {
        echo    $e->getMessage();  
    }

}
public function disconnect() {
    $this = null;   
}
}
?>

i got message "The connection was reset" in browser, whats wrong ?

That won't work. You either need to create a method that calls query in PDO:

class DatabaseConnection {
    // ...
    public function query($sql) {
        return $this->DBH->query($sql);
    }
    // ...
}

or extend PDO.

class DatabaseConnection extends PDO {
    // ...
}

Update: On the other hand, there is very little point in wrapping the PDO class at all. Why not just create a PDO object directly?

class User {
  private $connection;

  public function __construct ($connection) {
    $this->connection = $connection;
  }

  public function getUser() {
    $STH = $this->connection->query('SELECT * from User');
  }
}