Re: GROUPing problem

Hi all, I'm hoping someone can shed some light on something for me.
This will most likely be one of those newbie questions, but I'm having
a real hard time understanding this, and would appreciate some help.

I'm trying to build a query to return number of records per month. My
query looks like:

select date_part('month', signedup), count(*) from member group by
date_part;

...this works great, it returns:

date_part | count
-----------+-------
1 | 842
2 | 205
9 | 863
10 | 770
11 | 687
12 | 832

...however, the data is from september to february, so I'd like to
sort by year, to get the months in the proper order - so when I try:

date_part('month', signedup) as month, count(*) from member group by
date_part order by date_part('year', signedup) asc;

I get:

ERROR: Attribute member.signedup must be GROUPed or used in an
aggregate function

I don't understand why just adding the 'order by' makes
member.signedup suddenly need to be included in the group by section.
I want the same results, I just want them ordered differently. Plus,
if I do include member.signedup, it ruins my aggregation.

I'm using postgresql 7.2 on debian.

Any thoughts would be appreciated. Thanks!

/kurt