Question

I want to get a statistic of how many users submitted content each month for the last 4 months. I was thinking of a MySQL UNION but don’t think that will work, cause it will probably show duplicate rows, cause AFAIK UNION only appends 2 query result sets.

My table structure is like this (a typically node table from Drupal — for Drupal gurus):

+-----------+------------------+------+-----+---------+----------------+
| Field     | Type             | Null | Key | Default | Extra          |
+-----------+------------------+------+-----+---------+----------------+
| nid       | int(10) unsigned | NO   | PRI | NULL    | auto_increment |
| vid       | int(10) unsigned | NO   | UNI | 0       |                |
| type      | varchar(32)      | NO   | MUL |         |                |
| language  | varchar(12)      | NO   |     |         |                |
| title     | varchar(255)     | NO   | MUL |         |                |
| uid       | int(11)          | NO   | MUL | 0       |                |
| status    | int(11)          | NO   | MUL | 1       |                |
| created   | int(11)          | NO   | MUL | 0       |                |
| changed   | int(11)          | NO   | MUL | 0       |                |
| comment   | int(11)          | NO   |     | 0       |                |
| promote   | int(11)          | NO   | MUL | 0       |                |
| sticky    | int(11)          | NO   |     | 0       |                |
| tnid      | int(10) unsigned | NO   | MUL | 0       |                |
| translate | int(11)          | NO   | MUL | 0       |                |
+-----------+------------------+------+-----+---------+----------------+

And the column which holds the time a node was submitted is created.

Answer 1

maybe something like that (doesn’t seem that elegant…)

select count(distinct(t1.uid)) from node t1
inner join node t2 on t2.uid = t1.uid and t2.created between date_add(now(), interval -2 month) and date_add(now(), interval -1 month)
inner join node t3 on t3.uid = t1.uid and t3.created between date_add(now(), interval -3 month) and date_add(now(), interval -2 month)
inner join node t4 on t4.uid = t1.uid and t4.created between date_add(now(), interval -4 month) and date_add(now(), interval -3 month)
where t1.created between date_add(now(), interval -1 month) and now()