SELECT t.id2,
       COUNT(IF(YEAR(t_sept.datetime) = YEAR(CURDATE()) AND
             MONTH(t_sept.datetime) =  9 , t_sept.datetime, NULL)) as september,

       COUNT(IF(YEAR(t_oct.datetime) = YEAR(CURDATE()) AND
             MONTH(t_oct.datetime) =  10 , t_oct.datetime, NULL))  as october
						 
FROM my_table t

  LEFT JOIN my_table t_sept on t.id=t_sept.id
  LEFT JOIN my_table t_oct on t.id=t_oct.id

group by t.id2

#
# Структура таблицы `my_table`
#

CREATE TABLE `my_table` (
  `id` int( 11 ) NOT NULL auto_increment,
  `id2` int( 11 ) NOT NULL default '0',
  `datetime` datetime NOT NULL default '0000-00-00 00:00:00',
  PRIMARY KEY  (`id`)
) TYPE=MyISAM AUTO_INCREMENT= 7  ;

#
# Дамп данных таблицы `my_table`
#

INSERT INTO `my_table` VALUES ( 1 ,  25 , '2003-09-18 23:00:28');
INSERT INTO `my_table` VALUES ( 2 ,  50 , '2003-09-18 23:08:59');
INSERT INTO `my_table` VALUES ( 3 ,  78 , '2003-09-18 23:10:05');
INSERT INTO `my_table` VALUES ( 4 ,  55 , '2003-09-18 23:24:42');
INSERT INTO `my_table` VALUES ( 5 ,  50 , '2003-09-18 13:08:59');
INSERT INTO `my_table` VALUES ( 6 ,  55 , '2003-10-19 10:00:00');
    

  
id2  september  october  
 25         1           0  
 50         2           0  
 55         1           1  
 78         1           0