-- Database: `qw`

-- Table structure for table `log`

CREATE TABLE IF NOT EXISTS `log` (
  `month` date NOT NULL,
  `status` text NOT NULL
) ENGINE=MyISAM DEFAULT CHARSET=cp1251;

INSERT INTO `log` (`month`, `status`) VALUES
('2012-01-17', 'success'),
('2012-01-03', 'error'),
('2012-02-19', 'success'),
('2012-02-03', 'error'),
('2012-02-03', 'error'),
('2012-03-09', 'error'),
('2012-03-09', 'error'),
('2012-03-15', 'error'),
('2012-03-30', 'success'),
('2012-04-15', 'error'),
('2012-04-16', 'error'),
('2012-05-21', 'error'),
('2012-05-22', 'error'),
('2012-06-01', 'error'),
('2012-06-06', 'error');

 $rVisitsResult = mysql_query("SELECT GROUP_CONCAT(t.s) FROM (SELECT COUNT(*) s FROM `log` WHERE status='error' GROUP BY `month` ) t");
 $array = mysql_fetch_row($rVisitsResult); 
  $visites=( $array); 

 $array = mysql_fetch_row($rVisitsResult); 
   echo json_encode($array );  

 ["1,2,1,2,2,1,1,1"]

 ["1","2","4","2","2","2"]

01 месяц - 1 error
02 месяц - 2 error
03 месяц - 4 error
04 месяц - 2 error
05 месяц - 2 error
06 месяц - 2 error

 ["1","2","4","2","2","2"]

2012.01.03   -1 error
2012.02.03   -2 error
2012.03.09   -2 error
2012.03.15   -1 error
2012.04.15   -1 error
2012.04.16   -1 error
2012.05.21   -1 error
2012.05.22   -1 error
2012.06.01   -1 error
2012.06.06   -1 error

 ["1,2,1,2,2,1,1,1"] (Должен быть каждому значению отдельная кавычка: "1","2"...)

SELECT month, COUNT(*) s FROM `log` WHERE status='error' GROUP BY `month`

  $rgVisites = array();
  $rVisitsResult = mysql_query("SELECT COUNT(*) s FROM `log` WHERE status='error' GROUP BY `month`");
  while ($rgRow = mysql_fetch_assoc($rVisitsResult)) {
  $rgVisites[] = $rgRow['s'];
  echo json_encode($rgVisites );  

["1","2","2","1","1","1","1","1","1","1"]

$rVisitsResult = mysql_query("SELECT COUNT(*) s FROM `log` WHERE status='error' GROUP BY `month`");

GROUP BY MONTH(`month`)

SELECT GROUP_CONCAT(t.s) FROM
(SELECT 
COUNT(status) as s
FROM `log` 
WHERE status='error'
GROUP BY SUBSTR(month,6,2)
ORDER BY month) t