Mysql untuk memilih catatan per bulan meskipun data tidak ada

Saya tidak akan berbicara banyak tentang efisiensi karena saya belum mengujinya dengan metode lain tetapi tanpa memiliki tabel temp, ini sepertinya cara yang adil.

   SELECT COUNT(u.userID) AS total, m.month
     FROM (
           SELECT 'Jan' AS MONTH
           UNION SELECT 'Feb' AS MONTH
           UNION SELECT 'Mar' AS MONTH
           UNION SELECT 'Apr' AS MONTH
           UNION SELECT 'May' AS MONTH
           UNION SELECT 'Jun' AS MONTH
           UNION SELECT 'Jul' AS MONTH
           UNION SELECT 'Aug' AS MONTH
           UNION SELECT 'Sep' AS MONTH
           UNION SELECT 'Oct' AS MONTH
           UNION SELECT 'Nov' AS MONTH
           UNION SELECT 'Dec' AS MONTH
          ) AS m
LEFT JOIN users u 
ON MONTH(STR_TO_DATE(CONCAT(m.month, ' 2013'),'%M %Y')) = MONTH(u.userRegistredDate)
   AND YEAR(u.userRegistredDate) = '2013'
GROUP BY m.month
ORDER BY 1+1;

Jika Anda membuat gabungan berdasarkan format tanggal, Anda bahkan dapat mengurangi pekerjaan dan memuat kueri.

   SELECT COUNT(u.userID) AS total, DATE_FORMAT(merge_date,'%b') AS month, YEAR(m.merge_date) AS year
     FROM (
           SELECT '2013-01-01' AS merge_date
           UNION SELECT '2013-02-01' AS merge_date
           UNION SELECT '2013-03-01' AS merge_date
           UNION SELECT '2013-04-01' AS merge_date
           UNION SELECT '2013-05-01' AS merge_date
           UNION SELECT '2013-06-01' AS merge_date
           UNION SELECT '2013-07-01' AS merge_date
           UNION SELECT '2013-08-01' AS merge_date
           UNION SELECT '2013-09-01' AS merge_date
           UNION SELECT '2013-10-01' AS merge_date
           UNION SELECT '2013-11-01' AS merge_date
           UNION SELECT '2013-12-01' AS merge_date
          ) AS m
LEFT JOIN users u 
       ON MONTH(m.merge_date) = MONTH(u.userRegistredDate)
          AND YEAR(m.merge_date) = YEAR(u.userRegistredDate)
GROUP BY m.merge_date
ORDER BY 1+1;

DEMO langsung dari kedua kueri.