Oh, I do care about these columns.
But by using an group by on the key columns, I cannot select the columns as they are. Otherwise you get an error message.
So I have to use an aggregate functionlike min().
Best...
Uwe
On 19 April 2011 10:24, Robert Klemme <shortcutter@xxxxxxxxxxxxxx> wrote:
On Mon, Apr 18, 2011 at 7:13 PM, Uwe Bartels <uwe.bartels@xxxxxxxxx> wrote:If you do not care about the output of the non key columns, why do you
> the aggregate function I was talking about is the function I need to use for
> the non-group by columns like min() in my example.
> There are of course several function to choose from, and I wanted to know
> which causes as less as possible resources.
include them in the query at all? That would certainly be the
cheapest option.
If you need _any_ column value you can use a constant.
rklemme=> select * from t1;
k | v
---+---
0 | 0
0 | 1
1 | 2
1 | 3
2 | 4
2 | 5
3 | 6
3 | 7
4 | 8
4 | 9
(10 rows)
rklemme=> select k, 99 as v from t1 group by k order by k;
k | v
---+----
0 | 99
1 | 99
2 | 99
3 | 99
4 | 99
(5 rows)
rklemme=>
Greetings from Paderborn
robert
--
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/
