public function using($column)
	{
		if ($this->active_join === null)
		{
			throw new \Peyote\Exception("You need to start a join before calling \Peyote\Join::using()");
		}

		list($table, $type) = $this->active_join;
		$this->active_join = null;
		$this->joins[] = array("USING", $table, $type, $column);
		return $this;
	}