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<h1>PostgreSQL driver in GRASS</h1>

The driver name is 'pg'.

<h2>Creating a PostgreSQL database</h2>

A new database is created with 'createdb', see the PostgreSQL manual
for details.

<h2>Connecting GRASS to PostgreSQL</h2>

<div class="code"><pre>
# example for connecting to a PostgreSQL server:
db.connect driver=pg database="host=myserver.osgeo.org,dbname=mydb"
# password is asked interactively if not specified:
db.login user=myname [pass=secret]
db.connect -p
db.tables -p
</pre></div>


<h2>Supported SQL commands</h2>

All SQL commands supported by PostgreSQL.

It's not possible to use C-like escapes (with backslash
like \n etc) within SQL syntax. 

<h2>Operators available in conditions</h2>

All SQL operators supported by PostgreSQL.


<h2>Adding an unique ID column</h2>

Import vector module require an unique ID column which can
be generated as follows in a PostgreSQL table:

<div class="code"><pre>
echo "
 ALTER TABLE mytable ADD ID integer;
 CREATE SEQUENCE mytable_seq;
 UPDATE mytabe SET ID = nextval('mytable_seq');
 DROP SEQUENCE mytable_seq;
" | db.execute
</pre></div>


<h2>Attribute Converters</h2>

CSV import into PostgreSQL:
<div class="code"><pre>
\h copy
COPY t1 FROM 'filename' USING DELIMITERS ',';
</pre></div>

<a href="http://www.klaban.torun.pl/prog/pg2xbase/">pg2xbase</a>: 
DBF to PostgreSQL converter.
<br>

<h2>Geometry import from PostgreSQL table</h2>

<em>v.in.db</em> creates a new vector (points) map from a database table
containing coordinates. See <a href="v.in.db.html">here</a> for examples.

<h2>PostGIS: PostgreSQL with vector geometry</h2>

<a href="http://postgis.refractions.net/">PostGIS</a>: 
adds geographic object support to PostgreSQL.

<h3>Example: Import from PostGIS</h3>

In an existing PostGIS database, create the following table:

<div class="code"><pre>
CREATE TABLE test
(
 id serial NOT NULL,
 mytime timestamp DEFAULT now(),
 text varchar,
 wkb_geometry geometry,
 CONSTRAINT test_pkey PRIMARY KEY (id)
) WITHOUT OIDS;

# insert value
INSERT INTO test (text, wkb_geometry)
 VALUES ('Name',geometryFromText('POLYGON((600000 200000,650000
 200000,650000 250000,600000 250000,600000 200000))',-1));

# register geometry column
select AddGeometryColumn ('postgis', 'test', 'geometry', -1, 'GEOMETRY', 2);
</pre></div>

GRASS can import this PostGIS polygon map as follows:

<div class="code"><pre>
v.in.ogr dsn="PG:host=localhost dbname=postgis user=neteler" layer=test \
         output=test type=boundary,centroid
v.db.select test
v.info -t test
</pre></div>


<h4>Geometry Converters</h4>
<ul>
<li><a href="http://postgis.refractions.net/download/">PostGIS with shp2pgsql</a>:<br>
 <tt>shp2pgsql -D lakespy2 lakespy2 test > lakespy2.sql</tt>
<br><br>
<li><a href="http://e00pg.sourceforge.net/">e00pg</a>: E00 to PostGIS filter,
see also <em><a href="v.in.e00.html">v.in.e00</a></em>.
<br><br>
<li>GDAL/OGR <a href="http://www.gdal.org/ogr/">ogrinfo and ogr2ogr</a>:
GIS vector format converter and library, e.g. ArcInfo or SHAPE to PostGIS.<br>
  <tt>ogr2ogr -f "PostgreSQL" shapefile ??</tt>
<br><br>
</ul>


<h2>SEE ALSO</h2>

<em>
<a href="db.connect.html">db.connect</a>,
<a href="db.execute.html">db.execute</a>,<br>
<a href="databaseintro.html">Database management in GRASS GIS</a>,<br>
<a href="database.html">Help pages for database modules</a>,<br>
<a href="sql.html">SQL support in GRASS GIS</a>
</em>
<br><br>
<em>
<a href="http://www.PostgreSQL.org">PostgreSQL web site</a>,<br>
<a href="http://www.pgadmin.org/">pgAdmin graphical user interface</a>
</em>
<p>
Book: <a href="http://www.postgresql.org/docs/books/awbook.html">PostgreSQL:
  Introduction and Concepts</a> by Bruce Momjian<br>
<em>
<a href="http://www.postgresql.org/docs/">PostgreSQL Documentation</a><br>
<a href="http://techdocs.postgresql.org/">PostgreSQL Technical Documentation</a><br>
<a href="http://www.gdal.org/ogr/drv_pg.html">GDAL/OGR PostgreSQL driver documentation</a><br>
<a href="http://mapserver.gis.umn.edu/cgi-bin/wiki.pl?MapServerWiki">MapServer Wiki</a>
</em>

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