ADDing and GROUPing times?

h4x0rmx

Simple question (I'd believe)
I have a bunch of data from some employees, I have the time the clock in and the time they clock out. I want to know how many hours each employee has worked over a period of time (i.e. a month).
I was trying to use some MySQL functions but I couldn't get them to work.
Here's an example of the data I have on the DB:


id	employee_id	myDate			time_in		time_out
24581	1111		7/20/2009 12:00:00 AM	13:55:00	19:55:00
24582	2222		7/25/2009 12:00:00 AM	3:58:00		6:35:00
24583	1111		7/21/2009 12:00:00 AM	14:05:00	19:59:00
24584	3333		7/24/2009 12:00:00 AM	8:00:00		13:25:00
24585	2222		7/30/2009 12:00:00 AM	14:01:00	16:55:00

where id and employee_id are INTs, date is a DATE, time_in and time_out are TIMEs

I was trying to SUM the TIMEDIFFs between time_in and time_out and then GROUP BY employee_id, but I couldn't get it to work
Any help would be appreciated.

Thanks in advance!

h4x0rmx

So this is what I have so far:

SELECT 
	employee_id,
	TIMEDIFF( TIMESTAMP(CONCAT('2009-01-01 ', time_out)), TIMESTAMP(CONCAT('2009-01-01 ', time_in)))
FROM 
	punches
WHERE
	date >= '2009-08-01'
GROUP BY
	employee_id

Of course this is not adding the hours, I have no idea of how to do it since ADDTIME() requires two parameters... but which ones?