Re: return MAX and when it happened

From: Scara Maccai <m_lists(at)yahoo(dot)it>
To: Sam Mason <sam(at)samason(dot)me(dot)uk>
Cc: pgsql-general(at)postgresql(dot)org
Subject: Re: return MAX and when it happened
Date: 2008-11-19 16:10:08
Message-ID: 49243A60.3030408@yahoo.it
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Sam Mason wrote:
> Do you really want the SUM of num1 and num2, because that makes it more
> fiddly and would be where having MAX accept a record/tuple would be
> best. If you don't, maybe something like:
>
> SELECT DISTINCT ON (date_trunc('day', mydate))
> date_trunc('day', mydate), num, num1+num2
> FROM mytab
> ORDER BY date_trunc('day', mydate), num DESC;
>
Unfortunately, I need:

- the SUM of some values, grouped per day
- the MAX of some other value, grouped per day
- the timestamp where the MAX above happened (per day, of course)

The "num" columns are events, and sometimes I need to know not only the
amount of a certain event per day, but also WHEN the MAX of some event
happened...

I guess I have to use a Composite Type (something like "numeric,
timestamp") + user defined aggregate?

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