On Dec 19, 2006, at 11:05 AM, Kirk Wythers wrote:
I am trying to use qgis to view a PostGIS database of climate data.
However, I'm getting an error upon trying to load my first postgis
layer. The layer shows up in the "Add PostGIS Table(s)" thingy. But
then halts with an error message about invalid layer. Any ideas?
The first thing that strikes me is you have two geometry columns. I'm
not sure if thats the problem or not. I haven't tested QGIS with a
PostGIS table containing 2 geometry columns.
The column "id" is a unique site id value that is shared in all
tables. I would like to start by viewing the site locations, but
then move on to displaying the climate data that is related to each
site location. Is this possible in qgis? If so, does it require a
view that contains both climate data and site geometry? Any advice
would be much appreciated.
Yes, you will need a view to do the relates.
Thanks.
The basic database looks like this:
met_data=# \d
List of relations
Schema | Name | Type | Owner
--------+------------------+-------+----------
public | climate | view | kwythers
public | geometry_columns | table | kwythers
public | radiationtype | table | kwythers
public | sites | table | kwythers
public | solar | table | kwythers
public | spatial_ref_sys | table | kwythers
public | weather | table | kwythers
(7 rows)
Where the table "weather" contains max and min temps, and
precipitation. The table solar contains solar radiation values. The
view "climate" combines weather and solar. And finally the table
"sites" holds the geometry information for each site location.
Below are the gory details of each table
met_data=# \d weather
Table "public.weather"
Column | Type | Modifiers
--------+----------+-----------
id | integer |
year | smallint |
month | smallint |
day | smallint |
doy | smallint |
date | date |
precip | real |
tmin | real |
tmax | real |
Foreign-key constraints:
"idfk" FOREIGN KEY (id) REFERENCES sites(id)
met_data=# \d solar
Table "public.solar"
Column | Type | Modifiers
--------+----------+-----------
id | integer |
year | smallint |
month | smallint |
day | smallint |
doy | smallint |
date | date |
rad | real |
Foreign-key constraints:
"idfk" FOREIGN KEY (id) REFERENCES sites(id)
met_data=# \d climate
View "public.climate"
Column | Type | Modifiers
--------+----------+-----------
id | integer |
year | smallint |
doy | smallint |
tmax | real |
tmin | real |
rad | real |
precip | real |
View definition:
SELECT weather.id, weather."year", weather.doy, weather.tmax,
weather.tmin, solar.rad, weather.precip
FROM weather, solar
WHERE weather.id = solar.id AND weather.date = solar.date;
met_data=# \d sites
Table "public.sites"
Column | Type | Modifiers
-----------------+-------------------+-----------
id | integer | not null
name | character varying |
longname | character varying |
state | character varying |
lat | double precision |
lon | double precision |
the_geom_lonlat | geometry |
the_geom_meters | geometry | not null
Indexes:
"sites_pkey" PRIMARY KEY, btree (id)
"sites_id_key" UNIQUE, btree (id)
"idx_sites_the_geom_lonlat" gist (the_geom_lonlat)
"idx_sites_the_geom_meters" gist (the_geom_meters) CLUSTER
Check constraints:
"enforce_dims_the_geom_meters" CHECK (ndims(the_geom_meters) = 2)
"enforce_dims_the_goem_lonlat" CHECK (ndims(the_geom_lonlat) = 2)
"enforce_geotype_the_geom_meters" CHECK (geometrytype
(the_geom_meters) = 'POINT'::text OR the_geom_meters IS NULL)
"enforce_geotype_the_goem_lonlat" CHECK (geometrytype
(the_geom_lonlat) = 'POINT'::text OR the_geom_lonlat IS NULL)
"enforce_srid_the_geom_meters" CHECK (srid(the_geom_meters) =
32661)
"enforce_srid_the_goem_lonlat" CHECK (srid(the_geom_lonlat) =
4269)
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