dynamic creating and mapping new field in doctrine/symfony/mysql - mysql

Question

Every quartal (each 3-month) i need into table "report" add new "column" - for example "Y2014Q1" where Y=year and Q=quartal (1,2,3,4). After creating I need to make mapping of this new column in to object.
Part of my code is:
namespace backend\backendBundle\Entity;
use Doctrine\ORM\Mapping as ORM;
/**
* FactSheetData
*
* #ORM\Table(name="report")
* #ORM\Entity
*/
class ReportData
{
/**
* #var integer
*
* #ORM\Column(name="id", type="integer")
* #ORM\Id
* #ORM\GeneratedValue(strategy="AUTO")
*/
private $id;
/**
* #var string
*
* #ORM\Column(name="Y2016Q3", type="string")
*/
private $Y2016Q3;
/**
* #param string $Y2016Q3
*/
public function setY2016Q3($Y2016Q3)
{
$this->Y2016Q3 = $Y2016Q3;
}
/**
* #return string
*/
public function getY2016Q4()
{
return $this->Y2016Q4;
}
....
I need to do something like this when new period comes:
class ReportData {
public function __construct() {
// if new perriod alter table
if (test_new_perriod) {
$new_period='Y2016Q4';
$sql="ALTER TABLE `report` ADD COLUMN `".$new_period."` VARCHAR(50) NULL DEFAULT NULL;";
$stmt = $this->getEntityManager()->getConnection()->prepare($sql);
$stmt->execute();
//and now - this is problem how to do - dynamic maping
/**
* #var string
*
* #ORM\Column(name="$new_period", type="string")
*/
private $new_period;
/**
* #param string $new_period
*/
public function set$new_period($new_period)
{
$this->$new_period =$new_period;
}
/**
* #return string
*/
public function get$new_period()
{
return $this->$new_period;
}
}
}
Hope I describe clear... Thanx for any advice.