Why does "group by" need to match select fields? - Mailing list pgsql-general

From Omar Eljumaily
Subject Why does "group by" need to match select fields?
Date
Msg-id 45E61BF6.5090102@omnicode.com
Whole thread Raw
Responses Re: Why does "group by" need to match select fields?  (Bill Moran <wmoran@collaborativefusion.com>)
Re: Why does "group by" need to match select fields?  (Bruno Wolff III <bruno@wolff.to>)
List pgsql-general
Sorry if this isn't exactly postgresql specific.  I periodically run
into this problem, and I'm running into it now.  I'm wondering if
there's something about "group by" that I don't understand.  As an
example what I'd want to do is return the "id" value for the check to
each payee that has the highest amount.  It seems like there's no
problem with ambiguity in logic, but postgresql + other sql servers balk
at it.  The group by fields need to explicitly match the select fields
with the exception of the aggregate function(s?).

create table checks
{
    id serial,
    payee text,
    amount double
};

select max(amount), payee, id from checks group by payee;

Why won't the above work?  Is there another way to get the id for the
record with the highest amount for each payee?

Thanks.


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