Question

I have a datetime query that works qreat:

$q="SELECT COUNT(blocked) AS sum_blocked, DATE(created) AS date_label ".
   "FROM sms_subscribers WHERE blocked=0 GROUP BY DATE(created)";

The only problem is I can not figure out how / if I can fill dates with zero results with zero or null.

ie; if there are 5 records for 2011-08-25 and 7 records for 2011-08-27, I would like the result to return 5, 0, 7 or 5, null, 7

Any help would be greatly appreciated!

Answer 1

You could create an additional table with number of days and join two tables. Here it is an example, it works for specified month –

CREATE TABLE days (
  number INT(11) NOT NULL
);

CREATE TABLE sms_subscribers (
  id INT(11) NOT NULL AUTO_INCREMENT,
  created DATETIME DEFAULT NULL,
  PRIMARY KEY (id)
);

INSERT INTO days VALUES 
  (1), (2), (3), (4), (5), (6), (7), (8), (9), (10),
  (11), (12), (13), (14), (15), (16), (17), (18), (19), (20),
  (21), (22), (23), (24), (25), (26), (27), (28), (29), (30), (31);

INSERT INTO sms_subscribers VALUES 
  (1, '2011-08-25 08:35:27'),
  (2, '2011-08-11 08:35:30'),
  (3, '2011-08-06 08:35:35'),
  (4, '2011-06-06 08:35:40'),
  (5, '2011-06-19 08:35:47'),
  (6, '2011-06-01 08:35:53'),
  (7, '2011-08-28 08:36:02'),
  (8, '2011-08-25 08:57:58');


SELECT d.number, COUNT(t.created) FROM days d
  LEFT JOIN (SELECT * FROM sms_subscribers
              WHERE YEAR(created) = 2011 AND MONTH(created) = 8) t -- Specify year and monts here
    ON DAYOFMONTH(t.created) = d.number
WHERE
  d.number <= DAYOFMONTH(LAST_DAY('2011-08-01')) -- Specify any day in the specified month, it will help to found out max number of days in the month
GROUP BY d.number;

+--------+------------------+
| number | COUNT(t.created) |
+--------+------------------+
|      1 |                0 |
|      2 |                0 |
|      3 |                0 |
|      4 |                0 |
|      5 |                0 |
|      6 |                1 |
|      7 |                0 |
|      8 |                0 |
|      9 |                0 |
|     10 |                0 |
|     11 |                1 |
|     12 |                0 |
|     13 |                0 |
|     14 |                0 |
|     15 |                0 |
|     16 |                0 |
|     17 |                0 |
|     18 |                0 |
|     19 |                0 |
|     20 |                0 |
|     21 |                0 |
|     22 |                0 |
|     23 |                0 |
|     24 |                0 |
|     25 |                2 |
|     26 |                0 |
|     27 |                0 |
|     28 |                1 |
|     29 |                0 |
|     30 |                0 |
|     31 |                0 |
+--------+------------------+