Question

mySQL total user count

Grouping by month

I want to list the total count of registered users grouped by month

Well, the difficulty about this is that I don’t want the count per month,
but the the total count of users up to (and including) the month.

User table structure

+---------------+--------------+------+-------------------+----------------+
| Field         | Type         | Null | Default           | Extra          |
+---------------+--------------+------+-------------------+----------------+
| ID            | int(11)      | NO   | NULL              | auto_increment |
| email         | varchar(225) | NO   | NULL              |                |
................................-CUT-.......................................
| registered    | timestamp    | NO   | CURRENT_TIMESTAMP |                |
+---------------+--------------+------+-------------------+----------------+

Example data

1 example1@mail 2012-04-04 xx:xx:xx
2 example2@mail 2012-05-04 xx:xx:xx
3 example3@mail 2012-05-04 xx:xx:xx

Preferred output

+------+-------+-------+
| Year | Month | Count |
+------+-------+-------+
| 2012 | 01    | 0     |
| 2012 | 02    | 0     |
| 2012 | 03    | 0     |
| 2012 | 04    | 1     |
| 2012 | 05    | 3     |
+------+-------+-------+

The NULL results aren’t necessary.

How could I achieve that result in pure mySQL?

Answer 1

I have not tried this but something along these lines should work –

SELECT tots.*, @var := @var + tots.`count`
FROM (
    SELECT
        YEAR(registered) AS `year`,
        MONTH(registered) AS `month`,
        COUNT(*) AS `count`
    FROM user
    GROUP BY `year`, `month`
) AS tots, (SELECT @var := 0) AS inc