Question

I have this database table ‘market’

id       market_id       shows       clicks        event       data
 1          158          1000         300           on       2012-03-01
 2          158          1500         600           off      2012-03-14
 3          158          1500         600           on       2012-03-14
 4          158          2500         700           off      2012-03-20            

I want to select it and get array like this:

$array  = array (
            array('from 2012-03-01 to 2012-03-14' => array('shows' => 500, 'clicks' => 300)
            array('from 2012-03-14 to 2012-03-20' => array('shows' => 1000, 'clicks' => 100)  

How to do that? Have I do that in Mysql or have I do that in php?

edit:

‘shows’ in array calculates like that 1500 – 1000, 1500 is from table where ‘event’ is off and 1000 is from table where ‘event’ is on, click’s calculate same.

Answer 1

Caveat: I can’t really work out what your intention is and hence there may be much better solutions that this but…
Here’s a query that works on your sample data.

SELECT
    t2.data as from_date,
    t1.data as to_date,
    (t1.shows-t2.shows) as shows,
    (t1.clicks - t2.clicks) as clicks
FROM `market` t1
    inner join market t2 
        on (t1.market_id=t2.market_id and t1.event='off' and t2.event='on' and t1.data>t2.data)
    left join market t3 
        on (t1.data>t3.data and t3.event='on' and t3.data>t2.data)
WHERE t3.id is null

To explain a little bit: the query joins the table onto it self to find all pairs of rows where one represents an “off” event that is later than an “on” event. This picks up all pairs (even 2012-03-20 ‘off’ and 2012-03-01 ‘on’) so then we do a LEFT JOIN again to check there are no other ‘on’ events between the ‘on’ row and the ‘off’ row.

btw, I think there’s an error in your sample results. The values for “shows” in your second result should be 1000.