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<title>FastDB::Delete - Delete selected data from FastDB database</title>
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<ul>
<li><a href="#name">NAME</a></li>
<li><a href="#synopsis">SYNOPSIS</a></li>
<li><a href="#example">EXAMPLE</a></li>
<li><a href="#description">DESCRIPTION</a></li>
<li><a href="#functions">Functions</a></li>
<li><a href="#notes">NOTES</a></li>
<li><a href="#install">INSTALL</a></li>
<li><a href="#authors">AUTHORS</a></li>
<li><a href="#copyright">COPYRIGHT</a></li>
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<p>
</p>
<h1><a name="name">NAME</a></h1>
<p>FastDB::Delete - Delete selected data from FastDB database</p>
<p>
</p>
<hr />
<h1><a name="synopsis">SYNOPSIS</a></h1>
<pre>
<span class="keyword">use</span> <span class="variable">FastDB::Delete</span><span class="operator">;</span>
</pre>
<pre>
<span class="keyword">my</span> <span class="variable">$obj</span> <span class="operator">=</span> <span class="variable">Delete</span><span class="operator">-></span><span class="variable">new</span><span class="operator">(</span>
<span class="string">'Schema file'</span> <span class="operator">=></span> <span class="variable">$SchemaFile</span><span class="operator">,</span>
<span class="string">'Allow deletion with no filters'</span> <span class="operator">=></span> <span class="variable">yes</span><span class="operator">|</span><span class="keyword">no</span> <span class="operator">,</span>
<span class="string">'Show activity at standard output'</span> <span class="operator">=></span> <span class="variable">yes</span><span class="operator">|</span><span class="keyword">no</span> <span class="operator">);</span>
</pre>
<pre>
<span class="variable">$obj</span><span class="operator">-></span><span class="variable">delete</span><span class="operator">(</span> <span class="string">col1</span> <span class="operator">=></span> <span class="string">'Perl code1'</span> <span class="operator">,</span> <span class="string">col2</span> <span class="operator">=></span> <span class="string">'Perl code2'</span><span class="operator">,</span> <span class="operator">...</span> <span class="operator">);</span>
</pre>
<p>
</p>
<hr />
<h1><a name="example">EXAMPLE</a></h1>
<pre>
<span class="keyword">my</span> <span class="variable">$obj</span> <span class="operator">=</span> <span class="variable">Delete</span><span class="operator">-></span><span class="variable">new</span><span class="operator">(</span>
<span class="string">'Schema file'</span> <span class="operator">=></span> <span class="string">'/work/FastDB test/db/Export cargo.schema'</span><span class="operator">,</span>
<span class="string">'Allow deletion with no filters'</span> <span class="operator">=></span> <span class="string">'No'</span><span class="operator">,</span>
<span class="string">'Show activity at standard output'</span> <span class="operator">=></span> <span class="string">'yes'</span> <span class="operator">);</span>
</pre>
<pre>
<span class="variable">$obj</span><span class="operator">-></span><span class="variable">delete</span><span class="operator">(</span>
<span class="string">'WEIGHT'</span> <span class="operator">=></span> <span class="string">'(DATA > 2000) and (DATA <= 100000) and ( DATA % 2 == 0)'</span> <span class="operator">,</span>
<span class="string">'EXTRA_YEAR'</span> <span class="operator">=></span> <span class="string">'DATA == 2011'</span> <span class="operator">);</span>
</pre>
<p>
</p>
<hr />
<h1><a name="description">DESCRIPTION</a></h1>
<p>Delete selected data from FastDB databases. You can select data for deletion
using Filters. Only rows that all their column Filters are true can be deleted.</p>
<p>You can have multiple Filters. Every Filter is assigned only to one column.
The Filter's order is not important. Every Filter is simple Perl code. The
last returned value of your code is examined if it is TRUE or FALSE.
The special string DATA is replaced with column values.</p>
<p>
</p>
<hr />
<h1><a name="functions">Functions</a></h1>
<dl>
<dt><strong><a name="new" class="item">my $obj = Delete->new( %hash );</a></strong></dt>
<dd>
<p>Creates a new FastDB::Delete object. %hash must have the keys</p>
<p><strong><em>Schema file</em></strong></p>
<p>This is where your schema File is. The schema file is a unique file
for every database, and it is created at first data load, inside data directory. Its name is "$DatabaseName.schema"</p>
<p><strong><em>Allow deletion with no filters</em></strong></p>
<p>Yes or No. If it is No, you are not allowed to delete data if you do not specify any Filters. If it yes and you
do not define any Filters, then all your database data will be deleted.</p>
<p><strong><em>Show activity at standard output</em></strong></p>
<p>Yes or No. If it is yes it displays at standard output short information of its activity.</p>
</dd>
<dt><strong><a name="delete" class="item">$load->delete( %Filters );</a></strong></dt>
<dd>
<p>delete deletes the data. Accepts a hash with columns as keys and generic Perl code as values.
Every filter evaluate only the data of its column. That means at Perl code you can not
write column names . The special string DATA is replaced with current column value.</p>
</dd>
</dl>
<p>
</p>
<hr />
<h1><a name="notes">NOTES</a></h1>
<p>This module is written with pure perl, so it can run on all operating systems. It is
designed to work as fast your disk and operating system is.</p>
<p>
</p>
<hr />
<h1><a name="install">INSTALL</a></h1>
<p>Because this module is implemented with pure Perl it is enough to copy FastDB directory somewhere at your @INC
or where your script is. For your convenient you can use the following commands to install/uninstall the module</p>
<pre>
Install: setup_module.pl -install --module=FastDB</pre>
<pre>
Uninstall: setup_module.pl -uninstall --module=FastDB</pre>
<p>
</p>
<hr />
<h1><a name="authors">AUTHORS</a></h1>
<p>Author:
<a href="mailto:gravitalsun@hotmail.com">gravitalsun@hotmail.com</a> (George Mpouras)</p>
<p>
</p>
<hr />
<h1><a name="copyright">COPYRIGHT</a></h1>
<p>Copyright (c) 2011, George Mpouras, <a href="mailto:gravitalsun@hotmail.com">gravitalsun@hotmail.com</a> All rights reserved.</p>
<p>This program is free software; you may redistribute it and/or
modify it under the same terms as Perl itself.</p>
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