[postgis-users] Finding a polygon containing a specified point

[krill]

Hi all,

I am attempting to import and use the Federal Electoral Districts, a
shapefile provided by Elections Canada (http://geobase.ca/geobase/en/
data/admin/index.html).  I converted and loaded the shapefile as
follows:

&dol; shp2pgsql -c -W ISO-8859-1 -s 4617 -DI FED_CA_1_0_0_ENG.shp
federal_ridings > federal_ridings_import.sql
&dol; psql -U username -d dbname -f federal_ridings_import.sql

The resulting structure of the table is:

  Column   |          Type          |
Modifiers
------------+------------------------
+---------------------------------------------------------------
 gid        | integer                | not null default
nextval('federal_ridings_gid_seq'::regclass)
 nid        | character varying(36)  |
 fednum     | integer                |
 enname     | character varying(100) |
 frname     | character varying(100) |
 provcode   | character varying(2)   |
 creadt     | character varying(8)   |
 revdt      | character varying(8)   |
 reporder   | character varying(8)   |
 decpopcnt  | integer                |
 quipopcnt  | integer                |
 enlegaldsc | character varying(200) |
 frlegaldsc | character varying(200) |
 shape_area | numeric                |
 shape_len  | numeric                |
 the_geom   | geometry               |
Indexes:
    "federal_ridings_pkey" PRIMARY KEY, btree (gid)
    "federal_ridings_the_geom_gist" gist (the_geom)
Check constraints:
    "enforce_dims_the_geom" CHECK (st_ndims(the_geom) = 2)
    "enforce_geotype_the_geom" CHECK (geometrytype(the_geom) =
'MULTIPOLYGON'::text OR the_geom IS NULL)
    "enforce_srid_the_geom" CHECK (st_srid(the_geom) = 4617)

The other table I'm using has some postal codes:

id |  city_name  | postal_code | city_type |  province_name   |
province_abbr | latitude  |  longitude
----+-------------+-------------+-----------+------------------
+---------------+-----------+-------------
  8 | Fredericton | E3A 1A4     | D         | New Brunswick    |
NB            | 45.977710 |  -66.678430
  9 | Montreal    | H1E 6M9     | D         | Quebec           |
QC            | 45.641710 |  -73.577240
 10 | Ottawa      | K1K 2K3     | D         | Ontario          |
ON            | 45.433880 |  -75.635240
 11 | Toronto     | M4M 1X2     | D         | Ontario          |
ON            | 43.665720 |  -79.346550
 12 | Vancouver   | V5N 1X1     | D         | British Columbia |
BC            | 49.262270 | -123.056050



I am trying to determine which electoral district a postal code is
in.  For this I used the following query:

  mydb=# select gid from federal_ridings fr where
ST_Contains(fr.the_geom, ST_GeomFromText('POINT(' || -123.056050 || '
' || 49.262270 || ')', 4617));

But the query returns no records.

I have confirmed that the lon/lat is converted to a spacial geometry
point:

  mydb=# select ST_GeomFromText('POINT(' || -123.056050 || ' ' ||
49.262270 || ')', 4617);
                    st_geomfromtext
  ----------------------------------------------------
   010100002009120000363CBD5296C35EC0685C381092A14840
  (1 row)


Do you see anything I am doing wrong?