Re: GROUPING

On Sat, 13 Oct 2001, Timothy J Hitchens wrote:

> It's been a while since I used postgresql but today I have converted one
> of my web apps but with one small problem. I goto do a group as
> designed and executed in mysql and I get told that this and this must be
> part of the aggreate etc I am puzzled and wonder if someone could bring
> me up to stratch with grouping in postgresql this is my current sql:
>
> SELECT * FROM telemetry WHERE beat > 12 GROUP BY buid;
>
> Result:
>
> Attribute telemetry.rpvuid must be GROUPed or used in an aggregate
> function
>
>
> Oh then if I include rpvuid I get you must include this field and on it
> goes.
>
> Thanks...

Well, that query doesn't necessarily return consistant results.
Let's say you have a table
a | b
-----
1 | 1
1 | 2
2 | 3

What should select * from table group by a; give? There are two
values of b that could be chosen for that group.

I believe the appropriate part of the spec is
from query specification (7.9 of my draft)

7) If T is a grouped table, then each <column reference> in each
<value expression> that references a column of T shall refer-
ence a grouping column or be specified within a <set function
specification>....