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<title>DBD::File - Base class for writing DBI drivers</title>
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<h1><a>DBD::File - Base class for writing DBI drivers</a></h1>
<p><a name="__index__"></a></p>

<!-- INDEX BEGIN -->

<ul>

	<li><a href="#name">NAME</a></li>
	<li><a href="#synopsis">SYNOPSIS</a></li>
	<li><a href="#description">DESCRIPTION</a></li>
	<ul>

		<li><a href="#metadata">Metadata</a></li>
		<li><a href="#driver_private_methods">Driver private methods</a></li>
	</ul>

	<li><a href="#known_bugs">KNOWN BUGS</a></li>
	<li><a href="#author_and_copyright">AUTHOR AND COPYRIGHT</a></li>
	<li><a href="#see_also">SEE ALSO</a></li>
</ul>
<!-- INDEX END -->

<hr />
<p>
</p>
<h1><a name="name">NAME</a></h1>
<p>DBD::File - Base class for writing DBI drivers</p>
<p>
</p>
<hr />
<h1><a name="synopsis">SYNOPSIS</a></h1>
<pre>
 This module is a base class for writing other DBDs.
 It is not intended to function as a DBD itself.
 If you want to access flatfiles, use DBD::AnyData, or DBD::CSV,
 (both of which are subclasses of DBD::File).</pre>
<p>
</p>
<hr />
<h1><a name="description">DESCRIPTION</a></h1>
<p>The DBD::File module is not a true DBI driver, but an abstract
base class for deriving concrete DBI drivers from it. The implication is,
that these drivers work with plain files, for example CSV files or
INI files. The module is based on the SQL::Statement module, a simple
SQL engine.</p>
<p>See <a href="../../lib/DBI.html">the DBI manpage</a> for details on DBI, <a href="../../SQL/Statement.html">the SQL::Statement manpage</a> for details on
SQL::Statement and <a href="../../DBD/CSV.html">the DBD::CSV manpage</a> or <a href="../../DBD/IniFile.html">the DBD::IniFile manpage</a> for example
drivers.</p>
<p>
</p>
<h2><a name="metadata">Metadata</a></h2>
<p>The following attributes are handled by DBI itself and not by DBD::File,
thus they all work like expected:</p>
<pre>
    Active
    ActiveKids
    CachedKids
    CompatMode             (Not used)
    InactiveDestroy
    Kids
    PrintError
    RaiseError
    Warn                   (Not used)</pre>
<p>The following DBI attributes are handled by DBD::File:</p>
<dl>
<dt><strong><a name="item_autocommit">AutoCommit</a></strong>

<dd>
<p>Always on</p>
</dd>
</li>
<dt><strong><a name="item_chopblanks">ChopBlanks</a></strong>

<dd>
<p>Works</p>
</dd>
</li>
<dt><strong><a name="item_num_of_fields">NUM_OF_FIELDS</a></strong>

<dd>
<p>Valid after <code>$sth-</code>execute&gt;</p>
</dd>
</li>
<dt><strong><a name="item_num_of_params">NUM_OF_PARAMS</a></strong>

<dd>
<p>Valid after <code>$sth-</code>prepare&gt;</p>
</dd>
</li>
<dt><strong><a name="item_name">NAME</a></strong>

<dd>
<p>Valid after <code>$sth-</code>execute&gt;; undef for Non-Select statements.</p>
</dd>
</li>
<dt><strong><a name="item_nullable">NULLABLE</a></strong>

<dd>
<p>Not really working, always returns an array ref of one's, as DBD::CSV
doesn't verify input data. Valid after <code>$sth-</code>execute&gt;; undef for
Non-Select statements.</p>
</dd>
</li>
</dl>
<p>These attributes and methods are not supported:</p>
<pre>
    bind_param_inout
    CursorName
    LongReadLen
    LongTruncOk</pre>
<p>Additional to the DBI attributes, you can use the following dbh
attribute:</p>
<dl>
<dt><strong><a name="item_f_dir">f_dir</a></strong>

<dd>
<p>This attribute is used for setting the directory where CSV files are
opened. Usually you set it in the dbh, it defaults to the current
directory (&quot;.&quot;). However, it is overwritable in the statement handles.</p>
</dd>
</li>
</dl>
<p>
</p>
<h2><a name="driver_private_methods">Driver private methods</a></h2>
<dl>
<dt><strong><a name="item_data_sources">data_sources</a></strong>

<dd>
<p>The <a href="#item_data_sources"><code>data_sources</code></a> method returns a list of subdirectories of the current
directory in the form &quot;DBI:CSV:f_dir=$dirname&quot;.</p>
</dd>
<dd>
<p>If you want to read the subdirectories of another directory, use</p>
</dd>
<dd>
<pre>
    <span class="keyword">my</span><span class="operator">(</span><span class="variable">$drh</span><span class="operator">)</span> <span class="operator">=</span> <span class="variable">DBI</span><span class="operator">-&gt;</span><span class="variable">install_driver</span><span class="operator">(</span><span class="string">"CSV"</span><span class="operator">);</span>
    <span class="keyword">my</span><span class="operator">(</span><span class="variable">@list</span><span class="operator">)</span> <span class="operator">=</span> <span class="variable">$drh</span><span class="operator">-&gt;</span><span class="variable">data_sources</span><span class="operator">(</span><span class="string">'f_dir'</span> <span class="operator">=&gt;</span> <span class="string">'/usr/local/csv_data'</span> <span class="operator">);</span>
</pre>
</dd>
</li>
<dt><strong><a name="item_list_tables">list_tables</a></strong>

<dd>
<p>This method returns a list of file names inside $dbh-&gt;{'f_dir'}.
Example:</p>
</dd>
<dd>
<pre>
    <span class="keyword">my</span><span class="operator">(</span><span class="variable">$dbh</span><span class="operator">)</span> <span class="operator">=</span> <span class="variable">DBI</span><span class="operator">-&gt;</span><span class="keyword">connect</span><span class="operator">(</span><span class="string">"DBI:CSV:f_dir=/usr/local/csv_data"</span><span class="operator">);</span>
    <span class="keyword">my</span><span class="operator">(</span><span class="variable">@list</span><span class="operator">)</span> <span class="operator">=</span> <span class="variable">$dbh</span><span class="operator">-&gt;</span><span class="variable">func</span><span class="operator">(</span><span class="string">'list_tables'</span><span class="operator">);</span>
</pre>
</dd>
<dd>
<p>Note that the list includes all files contained in the directory, even
those that have non-valid table names, from the view of SQL.</p>
</dd>
</li>
</dl>
<p>
</p>
<hr />
<h1><a name="known_bugs">KNOWN BUGS</a></h1>
<ul>
<li>
<p>The module is using <a href="../../lib/Pod/perlfunc.html#item_flock"><code>flock()</code></a> internally. However, this function is not
available on all platforms. Using <a href="../../lib/Pod/perlfunc.html#item_flock"><code>flock()</code></a> is disabled on MacOS and
Windows 95: There's no locking at all (perhaps not so important on
MacOS and Windows 95, as there's a single user anyways).</p>
</li>
</ul>
<p>
</p>
<hr />
<h1><a name="author_and_copyright">AUTHOR AND COPYRIGHT</a></h1>
<p>This module is currently maintained by</p>
<p>Jeff Zucker &lt; jzucker @ cpan.org &gt;</p>
<p>The original author is Jochen Wiedmann.</p>
<p>Copyright (C) 2004 by Jeff Zucker
Copyright (C) 1998 by Jochen Wiedmann</p>
<p>All rights reserved.</p>
<p>You may freely distribute and/or modify this module under the terms of either the GNU General Public License (GPL) or the Artistic License, as specified in
the Perl README file.</p>
<p>
</p>
<hr />
<h1><a name="see_also">SEE ALSO</a></h1>
<p><a href="../../lib/DBI.html">the DBI manpage</a>, <a href="../../Text/CSV_XS.html">the Text::CSV_XS manpage</a>, <a href="../../SQL/Statement.html">the SQL::Statement manpage</a></p>

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