Question

I have a mysql table with the following fields:

_id, userId, objectId, timeStamp

I want to calculate the total time an object was interacted with by all users.

I created the query that calculates the time difference between a row and its subsequent row but this doesn’t take into consideration the order of actions by a given user. That query looks like this:

SELECT A._id, A.USERID, A.objectid, A.timeStamp,
    SUBSTRING(A.timeStamp, 12, 2) as hourOfDay,
    TIME_TO_SEC(TIMEDIFF(B.timeStamp, A.timeStamp)) as diff 
FROM InteractionsTBL A 
INNER JOIN InteractionsTBL B ON B._id = (A._id + 1) and B.USERID = A.USERID 
where A.timeStamp > '2012-04-18 1:00:00'
and A.timeStamp < '2012-04-18 23:59:00' 
group by hourOfDay, A.objectid 
ORDER BY A._id ASC

How do I calculate the sum total of time interaction with an object by all users grouped by the hour of the day and the objectId?

Answer 1

I ended up writing a pearl script to go in and calculate this difference after the fact. I’m not sure if this is possible in real time with SQL.