2010/8/4 Thom Brown <thom@linux.com>:
> On 4 August 2010 14:04, Robert Haas <robertmhaas@gmail.com> wrote:
>> On Wed, Aug 4, 2010 at 6:03 AM, Thom Brown <thom@linux.com> wrote:
>>> Actually, this rings a bell. =C2=A0I think this may have been raised
>>> before, something to do with the delimiter being accepted as one of
>>> the order by values. =C2=A0If this isn't really a bug, could someone
>>> mention it in the docs somewhere?
>>
>> Oh, yeah. =C2=A0I guess you need this:
>>
>> select thing, string_agg(stuff, ',' order by stuff) from agg_test
>> group by thing;
>>
>> Rather than this:
>>
>> select thing, string_agg(stuff order by stuff, ',') from agg_test
>> group by thing;
>>
>> It's all kinds of not obvious to me what the second one is supposed to
>> mean, but I remember this was discussed before. =C2=A0Perhaps we need a
>> <note> somewhere about multi-argument aggregates.
>>
>
> Yes, that works with the order clause. =C2=A0That's really weird! =C2=A0I=
t looks
> like part of the delimiter parameter, and that's undocumented, or at
> least impossible to gleen from the documentation.
>
> This should be clarified as it looks like having ORDER BY *or* a
> delimiter is supported, but not both. =C2=A0It's horribly unintuitive!
> This is one of the very few cases where MySQL's version actually makes
> more sense.
this goes from ANSI SQL standard :( - I agree, this isn't intuitive
and pg can do better diagnostic now. But it has a sense. ORDER BY
hasn't sense for one parameter - only for complete function, so is
wrong to write ORDER BY over a some interesting parameter
Regards
Pavel Stehule
>
> Thom
>
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