public static function findColumns (array $columns, int $limit=0, string $order="DESC")
	{
		$order 	   	= static::validateOrder($order);
        $dbObject  	= Database::getInstance();
		$columns 	= joinArray($dbObject->escapeValues($columns), ', ');
		return static::limitFindBySql("SELECT {$columns} FROM ".static::$tableName." ORDER BY id {$order}", $limit);
	}