= Help on Posgis =
 back to Recipes for EDA [wiki:"CookBook Eda"]

Postgis book http://www.postgis.fr/book/print/156#413413413

== I would like to create a postgis table from a postgres table with x y ==

The data are in ''' lambert II étendu '''

{{{
select * from bdmap.spatial_ref_sys where srtext like '%Lambert%' and srtext like '%II%' 
}}}
seems to be 27572
{{{
SELECT AddGeometryColumn('bdmap', 'station','the_geom', 27572,'POINT',2) 
}}}
from Laurent
{{{
UPDATE bdmap
   SET the_geom=PointFromText('POINT(' || st_abcisse || ' ' || st_ordonnee || ')',27572);
}}}

I've got a message from '''Qgis ''' saying that '' I'm not allowed to use a table without int4 primary key or OID ''
{{{
ALTER TABLE bdmap.station SET WITH OIDS;
}}}
Here we add a validity constraint
{{{
ALTER TABLE bdmap.station ADD CONSTRAINT geometry_valid_check CHECK (isvalid(the_geom)); 
}}}
To transform the coordinate towards the CCM
{{{ 
SELECT ST_Transform(the_geom,3035) FROM bdmap.station;
}}}
Building an index (very quick with this table)
{{{
CREATE INDEX indexStations ON bdmap.station
  USING GIST ( the_geom GIST_GEOMETRY_OPS ); 
}}}
http://www.postgis.fr/documentation/debian/postgis-1.1.2/html/ch02.html#id2499646
Usefull functions in postgis, they take as argument a geom
 * Area2d()
 * geometrytype()
 * Distance(A,B) 
 * WithIn(A,B) A inside B
 * Min()
 * Distance()