I've got this query:
SELECT apple, banana, update_at FROM
(
SELECT DISTINCT ON (apple) *
FROM table
WHERE apple IN ('ad', 'sa')
ORDER BY apple, update_at DESC
) q
The purpose of this query is to get the rows that has apple "ad" or "sa", and return the most updated row (update_at (timestamp)). This query works.
My problem is that I want that instead of the update_at column, the query will show the difference between the timestamps (duration) of the query matched row and the row which preceded it.
Example:
apple---|banana---|update_at
============================
ad------|VAL------|2017-06-01 12:12:30
ad------|VAL------|2017-06-01 09:00:00
ad------|VAL------|2017-05-31 13:41:00
Result:
apple---|banana---|update_at
============================
ad------|VAL------|**03:12:30**
03:12:30 is the duration.
Hope that it clear enough.