Generate statistics in MySQL - mysql

Question

I have a table with posts and I want to generate a graph that shows how many posts were made the previous last 30 minutes, and the last 30 minutes before that etc. The posts are selected by their post_handler and post_status.
The table structure looks like this.
CREATE TABLE IF NOT EXISTS `posts` (
`post_title` varchar(255) NOT NULL,
`post_content` text NOT NULL,
`post_date_added` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
`post_handler` varchar(255) NOT NULL,
`post_status` tinyint(4) NOT NULL,
`id` int(11) NOT NULL AUTO_INCREMENT,
PRIMARY KEY (`id`),
KEY `post_status` (`post_status`),
KEY `post_status_2` (`post_status`,`id`),
KEY `post_handler` (`post_handler`),
KEY `post_date_added` (`post_date_added`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=2300131 ;
The results I'd like to receive, sorted after post_date_added.
period_start period_end posts
2011-12-06 19:23:44 2011-12-06 19:53:44 10
2011-12-06 19:53:44 2011-12-06 20:23:44 39
2011-12-06 20:23:44 2011-12-06 20:53:44 40
Right now I use solution where I have to run this query many times over, and then insert the data into another table from the PHP script.
SELECT COUNT(*) FROM posts WHERE post_handler = 'test' AND post_status = 1 AND post_date_added BETWEEN '2011-12-06 19:23:44' AND '2011-12-06 19:53:44'
Do you know any other solution? Is there any way to run a query that also inserts results into the database, all in one query?

Answer 1

Its fairly easy to group by distinctive time parameters, like hour, minute, day or whatever. If you want to group this by an hour, a possible query might look like this:
SELECT DATE_FORMAT(post_date_added,"%Y-%m-%d %H") AS "_Date",
COUNT(*)
FROM posts
WHERE post_handler = 'test'
AND post_status = 1
GROUP BY _Date;
(run this with a mysql query tool of your choice to see the output).
However, if you want to consider 30mins as the base of your group, the SQL part will get more tricky. For this special purpose, since you've only have to divide into two different subsets, maybe work with this approach:
SELECT DATE_FORMAT(post_date_added,"%Y-%m-%d %H") AS "_Date",
"00" AS "semihour",
COUNT(*)
FROM posts
WHERE post_handler = 'test'
AND DATE_FORMAT(post_date_added,"%i") < 30
AND post_status = 1
GROUP BY _Date
UNION
SELECT DATE_FORMAT(post_date_added,"%Y-%m-%d %H") AS "_Date",
"30" AS "semihour",
COUNT(*)
FROM posts
WHERE post_handler = 'test'
AND DATE_FORMAT(post_date_added,"%i") >= 30
AND post_status = 1
GROUP BY _Date;
Again, run this with a mysql query tool of your choice to see the output. You could add mathematical distinguishments there too working with CASE or IF and such, but personally I'd either group by hour or minute just to keep the SQL part way easier.
To directly add those numbers into your graph database, use this syntax:
INSERT INTO yourtable (yourfields)
SELECT ...
More details about this can be found here in the MySQL documentation.

Answer 2

In (very) brief: yes, you can insert the results of a query into another table. Take a look at INSERT ... SELECT here: http://dev.mysql.com/doc/refman/5.1/en/insert-select.html
Essentially, you'd just change what you have to something like
INSERT INTO post_statistics_table (period_start, period_end, posts)
SELECT ?, ?, COUNT(*) FROM posts
WHERE post_handler = 'test'
AND post_status = 1
AND post_date_added BETWEEN ? AND ?
and then fill in the four ?s with the same two DATETIMEs, repeated. ($from, $to, $from, $to)