Question

what i basically want to do is: compute the difference of to attributes and then get the row with the biggest difference.

So, here is what i tried:

SELECT caller_aor, (end_time - start_time) as duration
    FROM cdrs
    GROUP BY caller_aor
    HAVING duration = (SELECT MAX(end_time - start_time) FROM cdrs);

duration in the HAVING clause gives an error but i cant figure out what i have to do there.

Help is appreciated.

Answer 1

You don’t want GROUP BY and HAVING (they are only used when aggregating columns).

You want a simple WHERE:

SELECT caller_aor, (end_time - start_time) as duration
FROM cdrs
WHERE (end_time - start_time) = (SELECT MAX(end_time - start_time) FROM cdrs);