How to share same connection with multiple instances of the object? - php

Question

I was advised to rewrite how I handle connection, as it is now, my class creates new connection on every instance of the object. How would I change it to share connection between multiple objects created with this class?
/**
* This is Users class, deals with finding, updating, creating user
*/
class Users
{
private $host = DB_HOST;
private $user = DB_USERNAME;
private $pass = DB_PASSWORD;
private $dbname = DB_NAME;
private $conn;
private $stmt;
public $error;
function __construct()
{
$dsn = 'mysql:host='.$this->host.';dbname='.$this->dbname.';charset=utf8';
$options = array(
PDO::ATTR_EMULATE_PREPARES => false,
PDO::ATTR_PERSISTENT => true,
PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION
);
try {
$this->conn = new PDO($dsn,$this->user,$this->pass,$options);
} catch (PDOException $e) {
$this->error = $e->getMessage();
}
}
private function mysql_execute_query($sql,$params)
{
$this->stmt = $this->conn->prepare($sql);
$this->stmt->execute($params);
return $this->stmt;
}
public function find_user_by_provider_uid($provider,$provider_uid)
{
$sql = 'SELECT * FROM users WHERE provider = :provider AND provider_uid = :provider_uid LIMIT 1';
$params = array(
':provider' => $provider,
':provider_uid' => $provider_uid
);
$result = $this->mysql_execute_query($sql,$params);
return $result->fetch(PDO::FETCH_ASSOC);
}
}

Answer 1

If you really need that, define your property as static:
private static $conn;
Of course, make sure that accessing to that will be done right (i.e. not via $this, but via self (or class name) since it will be no longer belong to instance)
That, however, isn't a good practice: if you want manage connections - manage how many times you'll instantiate your class.