protected function describe()
	{
		if(is_null($this->_tableName) == false)
		{
			$this->_query = 'DESCRIBE '.$this->_tableName;
            if($this->_db->execute($this->_query) !== false)
			{
				$res = $this->_db->getAllRows();
                unset($this->_fields);
                unset($this->_primaryKey);
                $this->_fields = array();
                foreach($res as $r)
                {
                    $this->_fields[] = $r['Field'];
                    if($r['Key'] == 'PRI')
                    	$this->_primaryKey = $r['Field'];
                }
				return true;
			}
		}
		return false;
	}