T-SQL calculating average time

Question

I have a problem with calculating average time. This is the case: i have multiple rows, in each row there is data in time format so I need to calculate an average time of al

Answer 1

You can do this by doing a bunch of date arithmetic:

DECLARE @t TABLE(x TIME);

INSERT @t VALUES('00:01:30'),('00:02:25'),('00:03:25');

SELECT CONVERT(TIME, DATEADD(SECOND, AVG(DATEDIFF(SECOND, 0, x)), 0)) FROM @t;

However, what you should be doing is not using TIME to store an interval/duration. TIME is meant to store a point in time (and breaks down if you need to store more than 24 hours, for example). Instead you should store that start and end times for an event. You can always calculation the duration (and the average duration) if you have the two end points.