Richard Broersma wrote:
> On Tue, Jun 16, 2009 at 2:40 PM, Rob Sargent<robjsargent@gmail.com> wrote:
>
>
>> Is there a city without a reference to region?
>>
>
> I don't know, but the OP wanted to know complaints by region.
>
>
I didn't try this, but with regionless cities, you may need a full join
if you want a complete accounting of all complaints, some being logged
to the null region.
>
>
>
>> And wouldn't you want to count(cm.id)?
>>
>
> Count(cm.id) and Count(*) produce the same result. But I like
> Count(*) more since it helps to correctly express the idea that we are
> counting rows per group and not cm.id(s) per group.
>
>
>
>
"Same result" is not true. I loaded tables.
Using count(*) you get count=1 for regions without complaints. Using
count(complaint.id) you get count = 0. (The deference amount to
counting the left hand side (region) vs the right hand side (complaint)
which I believe is what OP is after).
