how do I create the MySQL code for this example?

eventstart = 2004-01-10 08:15:00 (these time values will be pulled from a record
eventend = 2004-01-12 15:25:00

eventduration = eventend - eventstart

Thanks;

select datediff(eventstart,eventend) as eventduration from ...

works in 4.1.1 and up

How about the ability to calculate the event duration from each record in a table and add it up for a totalduration? Would this be accurate, and how would I go about doing something like this?
Where can I find some good sites or references for queries, I got myself into this and I'm in need of good reference materials.
Thanks;

calculating a sum of durations is problematic

one good strategy is to convert each duration to seconds, sum up the seconds, and convert back to a duration (difficult)

best resource for mysql queries is this one