Geografic-Information-System/scripts/v.db.droprow/v.db.droprow.html

<h2>DESCRIPTION</h2>

<em>v.db.droprow</em> removes vector object(s) (point, line, area, face etc.) 
from a vector map through attribute selection in the table connected
to the given vector map. It automatically checks the connection for the specified
layer.

<h2>NOTES</h2>

v.db.droprow is a front-end to <em>v.extract</em> (reverse selection)
to allow easier usage.

The existing database connection(s) can be verified with <em>v.db.connect</em>.

<h2>EXAMPLES</h2>

Dropping all vector points without elevation attribute (North Carolina data set):<br>
<div class="code"><pre>
g.region rast=elevation -p
v.random output=rand5k_elev n=5000 

v.db.addtable map=rand5k_elev column="elevation double precision"
v.what.rast vect=rand5k_elev rast=elevation column=elevation

# verify absence of some elevation attributes ("number of NULL attributes"):
v.univar rand5k_elev type=point column=elevation

# Remove all vector points lacking elevation attribute
v.db.droprow rand5k_elev output=rand5k_elev_filt where="elevation IS NULL"

# verify:
v.univar rand5k_elev_filt type=point column=elevation
</pre></div>

<h2>SEE ALSO</h2>

<em>
<a href="db.droptable.html">db.droptable</a>,
<a href="db.execute.html">db.execute</a>,
<a href="v.db.addcolumn.html">v.db.addcolumn</a>,
<a href="v.db.addtable.html">v.db.addtable</a>,
<a href="v.db.connect.html">v.db.connect</a>,
<a href="v.db.dropcolumn.html">v.db.dropcolumn</a>,
<a href="v.db.droptable.html">v.db.droptable</a>,
<a href="v.db.select.html">v.db.select</a>,
<a href="v.db.update.html">v.db.update</a>
</em>

<h2>AUTHOR</h2>

Markus Neteler

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