Re: aggregate question

Dnia 2003-06-23 20:59, Użytkownik Ryan napisał:
> I know this one is simple enough.
>
> I have two tables: packages and package_log.

<cut>

> I must be a total space case today because I can't hammer out the sql to
> get a listing of all the packages with a count() of the package_log by
> package_id.
>
> Thanks,
> Ryan

select package_name,
count(*) as n_packages
from
packages
join package_log using (package_id);

This query is the simplest one, but doesn't display packages without any logs.
If you need this, try this one:
select p.package_name,
(select count(*) from package_log pl where pl.package_id=p.package_id)
as n_packages
from packages p;

And one more:
select package_name,
sum(case when package_log.package_id is not null then 1 else 0 end)
as n_packages
from
packages
left join package_log using (package_id);

Regards,
Tomasz Myrta