Re: Can function results be used in WHERE?

On 7/10/06, Bryce Nesbitt <bryce1(at)obviously(dot)com> wrote:
>
> Aaron Bono wrote:
> >
> >
> > On 7/10/06, *Bryce Nesbitt* <bryce1(at)obviously(dot)com
> > <mailto:bryce1(at)obviously(dot)com>> wrote:
> >
> >
> > I think it is ugly also, but no other syntax seems to work:
> >
> > stage=# select
> > pod_code,lat,lon,calculate_distance(lat,lon,37.789629,-122.422082)
> as
> > dist from eg_pod where dist < 1 order by dist desc limit 10;
> > ERROR: column "dist" does not exist
> >
> >
> > SELECT
> > pod_code,
> > lat,
> > lon,
> > calculate_distance(lat,lon,37.789629,-122.422082) as dist
> > FROM eg_pod
> > WHERE calculate_distance(lat,lon, 37.789629,-122.422082) < 1
> > ORDER BY calculate_distance(lat,lon,37.789629,-122.422082) desc limit
> 10;
> Yep, that works. I guess with IMMUTABLE it's even effecient.
> But I have to pass 6 arguments, not 2. Is there a way to make it look
> cleaner?
> I had expected using the column label (e.g. "dist") to work with WHERE,
> just as it does with ORDER BY.

You can also try

SELECT
pod_code,
lat,
lon,
dist
FROM (
SELECT
pod_code,
lat,
lon,
calculate_distance(lat,lon,37.789629,-122.422082) as dist
FROM eg_pod
) eg_prod
WHERE dist < 1
ORDER BY dist desc limit 10;

If the 37.789629 and -122.422082 are static values you can create a view for
it. Otherwise you can create a function or stored procedure that takes 2
arguments and returns the results of the subquery.

Just some options. Not sure which you would prefer. I am sure there are
more ways to do it.

-Aaron Bono