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

Try looking into UNIX_TIMESTAMP and SEC_TO_TIME.

You would sum up the differences between the timestamps, then use that value (would be in milliseconds) to get the time:

SELECT SEC_TO_TIME(time_milis / 1000)
FROM (
   SELECT SUM(UNIX_TIMESTAMP(date1) - UNIX_TIMESTAMP(date2)) as time_milis
   FROM table
)