MySQL - How to SUM times?

Question

I have a table that contains date-time values in this format:

START

1/13/2009 7:00:00AM

END

Answer 1

Check out the MySQL DateDiff Function

SELECT SUM(DATEDIFF(endtime, starttime)) 
FROM somerecordstable
WHERE starttime > '[some date]' AND endtime <= '[some date]'

You could also try:

SELECT SUM(TIMEDIFF(endtime, starttime)) 
FROM somerecordstable
WHERE starttime > '[some date]' AND endtime <= '[some date]'

I haven't tested the second one, but I know the first one should work.