daftar tanggal mysql dengan hitungan bahkan jika tidak ada data pada tanggal tertentu

Dengan asumsi postid . Anda s bersebelahan di tabel Anda, maka kueri ini:

SELECT
  DATE_FORMAT(b.date, '%Y-%m-%d') date,
  COUNT(c.postid)
FROM
(
  SELECT
    (SELECT MAX(date) FROM ex) + INTERVAL 3 DAY - INTERVAL a.postid DAY AS date
  FROM
    ex a
) b
LEFT JOIN
  ex c ON c.date = b.date
GROUP BY
  b.date
ORDER BY
  b.date

menghasilkan:

date    COUNT(c.postid)
2012-01-01  2
2012-01-02  2
2012-01-03  0
2012-01-04  2
2012-01-05  1
2012-01-06  0
2012-01-07  0

Lihat http://sqlfiddle.com/#!2/2cf8d/2

Jika postid . Anda s tidak bersebelahan, maka Anda dapat menggunakan ids tabel id yang berdekatan:

SELECT
  DATE_FORMAT(b.date, '%Y-%m-%d') date,
  COUNT(c.postid)
FROM
(
  SELECT
    (SELECT MAX(date) FROM ex) + INTERVAL 3 DAY - INTERVAL a.id DAY AS date
  FROM
    ids a
) b
LEFT JOIN
  ex c ON c.date = b.date
GROUP BY
  b.date
ORDER BY
  b.date DESC
LIMIT 7

Lihat http://sqlfiddle.com/#!2/13035/1