sum of time?

[<jabbott]

I have a table doing time tracking.  I don't use timestamps, I use datetime fields to
record punch in times and punch out times.  I have this query that computes the amount of
time between a punch in and punch out:

select SEC_to_time(unix_timestamp(TTendTime) - unix_timestamp(TTstartTime))
as endtime
FROM TimeTracking
WHERE TTperson = 1
    and date(TTstartTime) = '2005-10-19'

And this works great except for when people punch in and out several times in one day.  Is
there any way I can total a number of records into one total time?  In this example case,
I am TTperson #1 and I punched in and out five times this day.

I know I can do it in the code, but if I can do it in sql, life would be better for me.

--ja

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