数据库访问 - 面向php面向对象

I need a little help in accessing my connection object from another class. I've defined this class:

class CurrentEnvironment {

public static $connection = null;

static public function connect() {

    // we don't need to connect twice
    if (self::$connection ) {

        return self::$connection;
    }

    // data for making connection 
    $serverName = "(local)";
$connectionInfo = array( "Database"=>"E-TICKET");

    // try to connect                    
    self::$connection = sqlsrv_connect($serverName, $connectionInfo);
    if(!self::$connection ){

        return null;
    } else
    {

        return self::$connection;
    }


}

The problem is that every time I call the CurrentEnvironment::connect() a new connection is generated. But I think that I don't need to connect twice..

Is there a way I can use to connect once and get a reference to the connection object every time I need it?

PS: I'm new in PHP object oriented