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</div><hr /><div id="pdo.error-handling" class="chapter">
<h1>Errors and error handling</h1>
<p class="para">
PDO offers you a choice of 3 different error handling strategies, to fit
your style of application development.
</p>
<ul class="itemizedlist">
<li class="listitem">
<p class="para">
<strong><code>PDO::ERRMODE_SILENT</code></strong>
</p>
<p class="para">
This is the default mode. PDO will simply set the error code for you
to inspect using the <span class="function"><a href="pdo.errorcode.html" class="function">PDO::errorCode()</a></span> and
<span class="function"><a href="pdo.errorinfo.html" class="function">PDO::errorInfo()</a></span> methods on both the
statement and database objects; if the error resulted from a call on a
statement object, you would invoke the
<span class="function"><a href="pdostatement.errorcode.html" class="function">PDOStatement::errorCode()</a></span> or
<span class="function"><a href="pdostatement.errorinfo.html" class="function">PDOStatement::errorInfo()</a></span>
method on that object. If the error resulted from a call on the
database object, you would invoke those methods on the database object
instead.
</p>
</li>
<li class="listitem">
<p class="para">
<strong><code>PDO::ERRMODE_WARNING</code></strong>
</p>
<p class="para">
In addition to setting the error code, PDO will emit a traditional
E_WARNING message. This setting is useful during debugging/testing, if
you just want to see what problems occurred without interrupting the
flow of the application.
</p>
</li>
<li class="listitem">
<p class="para">
<strong><code>PDO::ERRMODE_EXCEPTION</code></strong>
</p>
<p class="para">
In addition to setting the error code, PDO will throw a
<a href="class.pdoexception.html" class="classname">PDOException</a>
and set its properties to reflect the error code and error
information. This setting is also useful during debugging, as it will
effectively "blow up" the script at the point of the error, very
quickly pointing a finger at potential problem areas in your code
(remember: transactions are automatically rolled back if the exception
causes the script to terminate).
</p>
<p class="para">
Exception mode is also useful because you can structure your error
handling more clearly than with traditional PHP-style warnings, and
with less code/nesting than by running in silent mode and explicitly
checking the return value of each database call.
</p>
<p class="para">
See <a href="language.exceptions.html" class="link">Exceptions</a> for more
information about Exceptions in PHP.
</p>
</li>
</ul>
<p class="para">
PDO standardizes on using SQL-92 SQLSTATE error code strings; individual
PDO drivers are responsible for mapping their native codes to the
appropriate SQLSTATE codes. The <span class="function"><a href="pdo.errorcode.html" class="function">PDO::errorCode()</a></span>
method returns a single SQLSTATE code. If you need more specific
information about an error, PDO also offers an
<span class="function"><a href="pdo.errorinfo.html" class="function">PDO::errorInfo()</a></span> method which returns an array
containing the SQLSTATE code, the driver specific error code and driver
specific error string.
</p>
<p class="para">
<div class="example" id="example-910">
<p><strong>Example #1 Create a PDO instance and set the error mode</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />$dsn </span><span style="color: #007700">= </span><span style="color: #DD0000">'mysql:dbname=testdb;host=127.0.0.1'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$user </span><span style="color: #007700">= </span><span style="color: #DD0000">'dbuser'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$password </span><span style="color: #007700">= </span><span style="color: #DD0000">'dbpass'</span><span style="color: #007700">;<br /><br />try {<br /> </span><span style="color: #0000BB">$dbh </span><span style="color: #007700">= new </span><span style="color: #0000BB">PDO</span><span style="color: #007700">(</span><span style="color: #0000BB">$dsn</span><span style="color: #007700">, </span><span style="color: #0000BB">$user</span><span style="color: #007700">, </span><span style="color: #0000BB">$password</span><span style="color: #007700">);<br /> </span><span style="color: #0000BB">$dbh</span><span style="color: #007700">-></span><span style="color: #0000BB">setAttribute</span><span style="color: #007700">(</span><span style="color: #0000BB">PDO</span><span style="color: #007700">::</span><span style="color: #0000BB">ATTR_ERRMODE</span><span style="color: #007700">, </span><span style="color: #0000BB">PDO</span><span style="color: #007700">::</span><span style="color: #0000BB">ERRMODE_EXCEPTION</span><span style="color: #007700">);<br />} catch (</span><span style="color: #0000BB">PDOException $e</span><span style="color: #007700">) {<br /> echo </span><span style="color: #DD0000">'Connection failed: ' </span><span style="color: #007700">. </span><span style="color: #0000BB">$e</span><span style="color: #007700">-></span><span style="color: #0000BB">getMessage</span><span style="color: #007700">();<br />}<br /><br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
</div>
</p>
<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">
<span class="function"><a href="pdo.construct.html" class="function">PDO::__construct()</a></span> will always throw a <a href="class.pdoexception.html" class="classname">PDOException</a> if the connection fails
regardless of which <strong><code>PDO::ATTR_ERRMODE</code></strong> is currently set. Uncaught Exceptions are fatal.
</p>
</p></blockquote>
<p class="para">
<div class="example" id="example-911">
<p><strong>Example #2 Create a PDO instance and set the error mode from the constructor</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />$dsn </span><span style="color: #007700">= </span><span style="color: #DD0000">'mysql:dbname=test;host=127.0.0.1'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$user </span><span style="color: #007700">= </span><span style="color: #DD0000">'googleguy'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$password </span><span style="color: #007700">= </span><span style="color: #DD0000">'googleguy'</span><span style="color: #007700">;<br /><br /></span><span style="color: #FF8000">/*<br /> Using try/catch around the constructor is still valid even though we set the ERRMODE to WARNING since<br /> PDO::__construct will always throw a PDOException if the connection fails.<br />*/<br /></span><span style="color: #007700">try {<br /> </span><span style="color: #0000BB">$dbh </span><span style="color: #007700">= new </span><span style="color: #0000BB">PDO</span><span style="color: #007700">(</span><span style="color: #0000BB">$dsn</span><span style="color: #007700">, </span><span style="color: #0000BB">$user</span><span style="color: #007700">, </span><span style="color: #0000BB">$password</span><span style="color: #007700">, array(</span><span style="color: #0000BB">PDO</span><span style="color: #007700">::</span><span style="color: #0000BB">ATTR_ERRMODE </span><span style="color: #007700">=> </span><span style="color: #0000BB">PDO</span><span style="color: #007700">::</span><span style="color: #0000BB">ERRMODE_WARNING</span><span style="color: #007700">));<br />} catch (</span><span style="color: #0000BB">PDOException $e</span><span style="color: #007700">) {<br /> echo </span><span style="color: #DD0000">'Connection failed: ' </span><span style="color: #007700">. </span><span style="color: #0000BB">$e</span><span style="color: #007700">-></span><span style="color: #0000BB">getMessage</span><span style="color: #007700">();<br /> exit;<br />}<br /><br /></span><span style="color: #FF8000">// This will cause PDO to throw an error of level E_WARNING instead of an exception (when the table doesn't exist)<br /></span><span style="color: #0000BB">$dbh</span><span style="color: #007700">-></span><span style="color: #0000BB">query</span><span style="color: #007700">(</span><span style="color: #DD0000">"SELECT wrongcolumn FROM wrongtable"</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
<div class="example-contents"><p>The above example will output:</p></div>
<div class="example-contents screen">
<div class="cdata"><pre>
Warning: PDO::query(): SQLSTATE[42S02]: Base table or view not found: 1146 Table 'test.wrongtable' doesn't exist in
/tmp/pdo_test.php on line 18
</pre></div>
</div>
</div>
</p>
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