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

SELECT some_grouping_column, SUM(TIMEDIFF(datecol1,datecol2)) as tot_time
FROM my_table
GROUP BY some_grouping_column;

Answer 2

I think you have to use this code... it works :)

SELECT  
  SEC_TO_TIME( SUM( TIME_TO_SEC( `time` ) ) ) AS total_time  
FROM time_table;

Answer 3

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.

Answer 4

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
)

Answer 5

Use TIMEDIFF().

SUM(TIMEDIFF(end, start))