Select the most recent row from a log table using timestamp - mysql

Question

I have a table for logging a Facebook application user actions. I want to get the latest row that is not older then 9 minutes for a specific action ID. The table has a lot of columns of other statistical information, so I will show only 2 of the rows that represent the problem:
timestamp facebookID producerID eventID actionID numOfTickets
2012-05-28 13:16:38 100003286974944 9 1741 cpf 2
2012-05-28 13:16:13 100003286974944 9 1741 cpf 4
What I want to do is getting the latest row where actionID = 'cpf'.
What I've tried is:
SELECT CONCAT_WS(' ', y.firstName, y.lastName) as fullName, x.facebookID, x.numOfTickets, MAX(x.timestamp)
FROM E4S_ANALYTICS.e4s_analytic_data x INNER JOIN E4S_FB.e4s_user_details y ON x.facebookID = y.facebookID
WHERE (x.actionID = 'CPF' AND x.numOfTickets > 0 AND x.producerID = 9 AND TIMEDIFF(NOW() , x.timestamp) < '00:09:00'
AND x.facebookID IN (SELECT facebookID FROM E4S_FB.e4s_session_data WHERE
TIMEDIFF(NOW() , sessionStart) < '00:09:00' ))
The result of the query is:
facebookID numOfTickets MAX(x.timestamp)
100003286974944 4 2012-05-28 13:16:38
The timestamp returned is correct but the numOfTickets is 4 instead of 2.
For note, the inner query:
SELECT facebookID FROM E4S_FB.e4s_session_data
WHERE TIMEDIFF(NOW() , sessionStart) < '00:09:00' ))
Is used to see who is still logged in to the application.

Answer 1

SELECT CONCAT_WS(' ', y.firstName, y.lastName) AS fullName,
x.facebookID,
x.numOfTickets,
x.timestamp
FROM (
SELECT *
FROM E4S_ANALYTICS.e4s_analytic_data
WHERE actionID = 'cpf'
AND numOfTickets > 0
AND producerID = 9
AND TIMEDIFF(NOW() , timestamp) < '00:09:00'
AND (facebookID, timestamp) IN (
SELECT facebookID, MAX(timestamp)
FROM E4S_ANALYTICS.e4s_analytic_data
WHERE actionID = 'cpf'
AND numOfTickets > 0
AND producerID = 9
AND TIMEDIFF(NOW() , timestamp) < '00:09:00'
AND facebookID IN (
SELECT facebookID
FROM E4S_FB.e4s_session_data
WHERE TIMEDIFF(NOW() , sessionStart) < '00:09:00'
)
GROUP BY facebookID
)
) AS x
INNER JOIN E4S_FB.e4s_user_details AS y USING (facebookID)

Answer 2

you can use order by timestamp desc to order the column according to latest first and then select the first row.
or try using max.

Answer 3

Have you tried not using MAX()?
Assuming you've checked JOIN and SUBQUERY results.
SELECT CONCAT_WS(' ', y.firstName, y.lastName) as fullName, x.facebookID, x.numOfTickets, MAX(x.timestamp)
FROM E4S_ANALYTICS.e4s_analytic_data x
INNER JOIN E4S_FB.e4s_user_details y ON x.facebookID = y.facebookID
GROUP BY x.facebookID
WHERE (x.actionID = 'CPF' AND x.numOfTickets > 0 AND x.producerID = 9 AND TIMEDIFF(NOW() , x.timestamp) < '00:09:00'
AND x.facebookID IN
(SELECT facebookID FROM E4S_FB.e4s_session_data
WHERE TIMEDIFF(NOW() , sessionStart) < '00:09:00' ))
ORDER BY x.timestamp DESC;