Geografic-Information-System/db/db.select/db.select.html

<h2>DESCRIPTION</h2>

<em>db.select</em> prints result of selection from database based on
SQL statement read from input file or from standard input to standard
output.

<h2>NOTE</h2>

If parameters for database connection are already set with
<em><a href="db.connect.html">db.connect</a></em>, they are taken as
default values and do not need to be specified each time. Output will
be displayed to standard output or can be directed to a file
(option <b>output</b>).

<h2>EXAMPLES</h2>

Basic usage:
<div class="code"><pre>
db.select sql="select * from roads"
</pre></div>
or
<div class="code"><pre>
echo "select * from roads" | db.select input=-
</pre></div>
or
<div class="code"><pre>
db.select input=file.sql
</pre></div>
or
<div class="code"><pre>
cat file.sql | db.select input=-
</pre></div>

<p>
Select all from table roads:
<div class="code"><pre>
db.select -c driver=odbc database=mydb table=roads \
          input=file.sql output=result.csv
</pre></div>

<p>
Select some string attribute, exclude others:
<div class="code"><pre>
db.select sql="SELECT * FROM archsites WHERE str1 &lt;&gt; 'No Name'"
</pre></div>

<p>
Select some string attribute with ZERO length:
<div class="code"><pre>
db.select sql="SELECT * FROM archsites WHERE str1 IS NULL"
</pre></div>

<p>
Select coordinates from PostGIS table:
<div class="code"><pre>
db.select sql="SELECT x(geo),y(geo) FROM localizzazione"
</pre></div>

<p>Execute multiple SQL statements:

<div class="code"><pre>
cat file.sql
SELECT * FROM busstopsall WHERE cat = 1
SELECT cat FROM busstopsall WHERE cat > 4 AND cat &lt; 8

db.select input=file.sql
</pre></div>

<p>

<em>Count number of cases falling into same position:</em><br>
When multiple observation have the spatial coordinates, they can still be counted
(if needed, coordinates can be uploaded to the attribute table by <em>v.to.db</em>:
<div class="code"><pre> 
db.select sql="SELECT long,lat,site_id,department,obs,COUNT(long) as count_cases \
               FROM diseases GROUP BY long,lat"
</pre></div>

<h2>SEE ALSO</h2>

<em>
  <a href="sql.html">GRASS SQL interface</a>
</em>

<p>
<em>
<a href="db.connect.html">db.connect</a>,
<a href="db.describe.html">db.describe</a>,
<a href="db.drivers.html">db.drivers</a>,
<a href="db.droptable.html">db.droptable</a>,
<a href="db.execute.html">db.execute</a>,
<a href="db.login.html">db.login</a>,
<a href="db.tables.html">db.tables</a>
</em>

<h2>AUTHOR</h2>

Original author unknown (probably CERL)<br>
Modifications by Radim Blazek, ITC-Irst, Trento, Italy<br>
Support for multiple statements by Martin Landa, Czech Technical University in Prague

<p>
<i>Last changed: $Date$</i>