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<h1 class="refname">PDO::sqliteCreateFunction</h1>
<p class="verinfo">(PHP 5 >= 5.1.0, PECL pdo_sqlite >= 1.0.0)</p><p class="refpurpose"><span class="refname">PDO::sqliteCreateFunction</span> — <span class="dc-title">
Registers a User Defined Function for use in SQL statements
</span></p>
</div>
<div class="refsect1 description" id="refsect1-pdo.sqlitecreatefunction-description">
<h3 class="title">Description</h3>
<div class="methodsynopsis dc-description">
<span class="modifier">public</span> <span class="type">bool</span> <span class="methodname"><strong>PDO::sqliteCreateFunction</strong></span>
( <span class="methodparam"><span class="type">string</span> <code class="parameter">$function_name</code></span>
, <span class="methodparam"><span class="type"><a href="language.types.callable.html" class="type callable">callable</a></span> <code class="parameter">$callback</code></span>
[, <span class="methodparam"><span class="type">int</span> <code class="parameter">$num_args</code></span>
] )</div>
<div class="warning"><strong class="warning">Warning</strong><p class="simpara">This function is
<em class="emphasis">EXPERIMENTAL</em>. The behaviour of this function, its name, and
surrounding documentation may change without notice in a future release of PHP.
This function should be used at your own risk.
</p></div>
<p class="para">
This method allows you to register a PHP function with SQLite as an
<acronym title="User Defined Functions">UDF</acronym> (User Defined Function), so that it can be called
from within your SQL statements.
</p>
<p class="para">
The UDF can be used in any SQL statement that can call functions, such as
SELECT and UPDATE statements and also in triggers.
</p>
</div>
<div class="refsect1 parameters" id="refsect1-pdo.sqlitecreatefunction-parameters">
<h3 class="title">Parameters</h3>
<p class="para">
<dl>
<dt>
<span class="term"><em><code class="parameter">function_name</code></em></span>
<dd>
<p class="para">
The name of the function used in SQL statements.
</p>
</dd>
</dt>
<dt>
<span class="term"><em><code class="parameter">callback</code></em></span>
<dd>
<p class="para">
Callback function to handle the defined SQL function.
</p>
<blockquote class="note"><p><strong class="note">Note</strong>:
<span class="simpara">
Callback functions should return a type understood by SQLite (i.e.
<a href="language.types.intro.html" class="link">scalar type</a>).
</span>
</p></blockquote>
</dd>
</dt>
<dt>
<span class="term"><em><code class="parameter">num_args</code></em></span>
<dd>
<p class="para">
Hint to the SQLite parser if the callback function accepts a
predetermined number of arguments.
</p>
</dd>
</dt>
</dl>
</p>
</div>
<div class="refsect1 returnvalues" id="refsect1-pdo.sqlitecreatefunction-returnvalues">
<h3 class="title">Return Values</h3>
<p class="para">
Returns <strong><code>TRUE</code></strong> on success or <strong><code>FALSE</code></strong> on failure.
</p>
</div>
<div class="refsect1 examples" id="refsect1-pdo.sqlitecreatefunction-examples">
<h3 class="title">Examples</h3>
<p class="para">
<div class="example" id="example-991">
<p><strong>Example #1 <span class="function"><strong>PDO::sqliteCreateFunction()</strong></span> example</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #007700">function </span><span style="color: #0000BB">md5_and_reverse</span><span style="color: #007700">(</span><span style="color: #0000BB">$string</span><span style="color: #007700">) <br />{<br /> return </span><span style="color: #0000BB">strrev</span><span style="color: #007700">(</span><span style="color: #0000BB">md5</span><span style="color: #007700">(</span><span style="color: #0000BB">$string</span><span style="color: #007700">));<br />}<br /><br /></span><span style="color: #0000BB">$db </span><span style="color: #007700">= new </span><span style="color: #0000BB">PDO</span><span style="color: #007700">(</span><span style="color: #DD0000">'sqlite:sqlitedb'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$db</span><span style="color: #007700">-></span><span style="color: #0000BB">sqliteCreateFunction</span><span style="color: #007700">(</span><span style="color: #DD0000">'md5rev'</span><span style="color: #007700">, </span><span style="color: #DD0000">'md5_and_reverse'</span><span style="color: #007700">, </span><span style="color: #0000BB">1</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$rows </span><span style="color: #007700">= </span><span style="color: #0000BB">$db</span><span style="color: #007700">-></span><span style="color: #0000BB">query</span><span style="color: #007700">(</span><span style="color: #DD0000">'SELECT md5rev(filename) FROM files'</span><span style="color: #007700">)-></span><span style="color: #0000BB">fetchAll</span><span style="color: #007700">();<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
</p>
<p class="para">
In this example, we have a function that calculates the md5 sum of a
string, and then reverses it. When the SQL statement executes, it
returns the value of the filename transformed by our function. The data
returned in <em><code class="parameter">$rows</code></em> contains the processed result.
</p>
<p class="para">
The beauty of this technique is that you do not need to process the
result using a <a href="control-structures.foreach.html" class="link">foreach</a> loop after you have queried for the data.
</p>
<div class="tip"><strong class="tip">Tip</strong>
<p class="para">
You can use <a href="pdo.sqlitecreatefunction.html" class="xref">PDO::sqliteCreateFunction</a> and
<a href="pdo.sqlitecreateaggregate.html" class="xref">PDO::sqliteCreateAggregate</a> to override SQLite
native SQL functions.
</p>
</div>
<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">
This method is not available with the SQLite2 driver.
Use the old style sqlite API for that instead.
</p>
</p></blockquote>
</div>
<div class="refsect1 seealso" id="refsect1-pdo.sqlitecreatefunction-seealso">
<h3 class="title">See Also</h3>
<p class="para">
<ul class="simplelist">
<li class="member"><a href="pdo.sqlitecreateaggregate.html" class="xref">PDO::sqliteCreateAggregate</a></li>
<li class="member"> <span class="function"><a href="function.sqlite-create-function.html" class="function" rel="rdfs-seeAlso">sqlite_create_function()</a> - Registers a "regular" User Defined Function for use in SQL statements</span></li>
<li class="member"> <span class="function"><a href="function.sqlite-create-aggregate.html" class="function" rel="rdfs-seeAlso">sqlite_create_aggregate()</a> - Register an aggregating UDF for use in SQL statements</span></li>
</ul>
</p>
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