You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
200 lines
7.7 KiB
200 lines
7.7 KiB
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> |
|
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> |
|
<head> |
|
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> |
|
<title>Transactions : CodeIgniter User Guide</title> |
|
|
|
<style type='text/css' media='all'>@import url('../userguide.css');</style> |
|
<link rel='stylesheet' type='text/css' media='all' href='../userguide.css' /> |
|
|
|
<script type="text/javascript" src="../nav/nav.js"></script> |
|
<script type="text/javascript" src="../nav/prototype.lite.js"></script> |
|
<script type="text/javascript" src="../nav/moo.fx.js"></script> |
|
<script type="text/javascript" src="../nav/user_guide_menu.js"></script> |
|
|
|
<meta http-equiv='expires' content='-1' /> |
|
<meta http-equiv= 'pragma' content='no-cache' /> |
|
<meta name='robots' content='all' /> |
|
<meta name='author' content='ExpressionEngine Dev Team' /> |
|
<meta name='description' content='CodeIgniter User Guide' /> |
|
|
|
</head> |
|
<body> |
|
|
|
<!-- START NAVIGATION --> |
|
<div id="nav"><div id="nav_inner"><script type="text/javascript">create_menu('../');</script></div></div> |
|
<div id="nav2"><a name="top"></a><a href="javascript:void(0);" onclick="myHeight.toggle();"><img src="../images/nav_toggle_darker.jpg" width="154" height="43" border="0" title="Toggle Table of Contents" alt="Toggle Table of Contents" /></a></div> |
|
<div id="masthead"> |
|
<table cellpadding="0" cellspacing="0" border="0" style="width:100%"> |
|
<tr> |
|
<td><h1>CodeIgniter User Guide Version 2.1.3</h1></td> |
|
<td id="breadcrumb_right"><a href="../toc.html">Table of Contents Page</a></td> |
|
</tr> |
|
</table> |
|
</div> |
|
<!-- END NAVIGATION --> |
|
|
|
|
|
|
|
<!-- START BREADCRUMB --> |
|
<table cellpadding="0" cellspacing="0" border="0" style="width:100%"> |
|
<tr> |
|
<td id="breadcrumb"> |
|
<a href="http://codeigniter.com/">CodeIgniter Home</a> › |
|
<a href="../index.html">User Guide Home</a> › |
|
<a href="index.html">Database Library</a> › |
|
Transactions |
|
</td> |
|
<td id="searchbox"><form method="get" action="http://www.google.com/search"><input type="hidden" name="as_sitesearch" id="as_sitesearch" value="codeigniter.com/user_guide/" />Search User Guide <input type="text" class="input" style="width:200px;" name="q" id="q" size="31" maxlength="255" value="" /> <input type="submit" class="submit" name="sa" value="Go" /></form></td> |
|
</tr> |
|
</table> |
|
<!-- END BREADCRUMB --> |
|
|
|
|
|
<br clear="all" /> |
|
|
|
|
|
<!-- START CONTENT --> |
|
<div id="content"> |
|
|
|
|
|
<h1>Transactions</h1> |
|
|
|
<p>CodeIgniter's database abstraction allows you to use <dfn>transactions</dfn> with databases that support transaction-safe table types. In MySQL, you'll need |
|
to be running InnoDB or BDB table types rather than the more common MyISAM. Most other database platforms support transactions natively.</p> |
|
|
|
<p>If you are not familiar with |
|
transactions we recommend you find a good online resource to learn about them for your particular database. The information below assumes you |
|
have a basic understanding of transactions. |
|
</p> |
|
|
|
<h2>CodeIgniter's Approach to Transactions</h2> |
|
|
|
<p>CodeIgniter utilizes an approach to transactions that is very similar to the process used by the popular database class ADODB. We've chosen that approach |
|
because it greatly simplifies the process of running transactions. In most cases all that is required are two lines of code.</p> |
|
|
|
<p>Traditionally, transactions have required a fair amount of work to implement since they demand that you to keep track of your queries |
|
and determine whether to <dfn>commit</dfn> or <dfn>rollback</dfn> based on the success or failure of your queries. This is particularly cumbersome with |
|
nested queries. In contrast, |
|
we've implemented a smart transaction system that does all this for you automatically (you can also manage your transactions manually if you choose to, |
|
but there's really no benefit).</p> |
|
|
|
<h2>Running Transactions</h2> |
|
|
|
<p>To run your queries using transactions you will use the <dfn>$this->db->trans_start()</dfn> and <dfn>$this->db->trans_complete()</dfn> functions as follows:</p> |
|
|
|
<code> |
|
<kbd>$this->db->trans_start();</kbd><br /> |
|
$this->db->query('AN SQL QUERY...');<br /> |
|
$this->db->query('ANOTHER QUERY...');<br /> |
|
$this->db->query('AND YET ANOTHER QUERY...');<br /> |
|
<kbd>$this->db->trans_complete();</kbd> |
|
</code> |
|
|
|
<p>You can run as many queries as you want between the start/complete functions and they will all be committed or rolled back based on success or failure |
|
of any given query.</p> |
|
|
|
|
|
<h2>Strict Mode</h2> |
|
|
|
<p>By default CodeIgniter runs all transactions in <dfn>Strict Mode</dfn>. When strict mode is enabled, if you are running multiple groups of |
|
transactions, if one group fails all groups will be rolled back. If strict mode is disabled, each group is treated independently, meaning |
|
a failure of one group will not affect any others.</p> |
|
|
|
<p>Strict Mode can be disabled as follows:</p> |
|
|
|
<code>$this->db->trans_strict(FALSE);</code> |
|
|
|
|
|
<h2>Managing Errors</h2> |
|
|
|
<p>If you have error reporting enabled in your <dfn>config/database.php</dfn> file you'll see a standard error message if the commit was unsuccessful. If debugging is turned off, you can |
|
manage your own errors like this:</p> |
|
|
|
<code> |
|
$this->db->trans_start();<br /> |
|
$this->db->query('AN SQL QUERY...');<br /> |
|
$this->db->query('ANOTHER QUERY...');<br /> |
|
$this->db->trans_complete();<br /> |
|
<br /> |
|
if (<kbd>$this->db->trans_status()</kbd> === FALSE)<br /> |
|
{<br /> |
|
// generate an error... or use the log_message() function to log your error<br /> |
|
} |
|
</code> |
|
|
|
|
|
<h2>Enabling Transactions</h2> |
|
|
|
<p>Transactions are enabled automatically the moment you use <dfn>$this->db->trans_start()</dfn>. If you would like to disable transactions you |
|
can do so using <dfn>$this->db->trans_off()</dfn>:</p> |
|
|
|
<code> |
|
<kbd>$this->db->trans_off()</kbd><br /><br /> |
|
|
|
$this->db->trans_start();<br /> |
|
$this->db->query('AN SQL QUERY...');<br /> |
|
$this->db->trans_complete(); |
|
</code> |
|
|
|
<p class="important">When transactions are disabled, your queries will be auto-commited, just as they are when running queries without transactions.</p> |
|
|
|
|
|
<h2>Test Mode</h2> |
|
|
|
<p>You can optionally put the transaction system into "test mode", which will cause your queries to be rolled back -- even if the queries produce a valid result. |
|
To use test mode simply set the first parameter in the <dfn>$this->db->trans_start()</dfn> function to <samp>TRUE</samp>:</p> |
|
|
|
<code> |
|
$this->db->trans_start(<samp>TRUE</samp>); // Query will be rolled back<br /> |
|
$this->db->query('AN SQL QUERY...');<br /> |
|
$this->db->trans_complete(); |
|
</code> |
|
|
|
|
|
<h2>Running Transactions Manually</h2> |
|
|
|
<p>If you would like to run transactions manually you can do so as follows:</p> |
|
|
|
<code> |
|
$this->db->trans_begin();<br /><br /> |
|
|
|
$this->db->query('AN SQL QUERY...');<br /> |
|
$this->db->query('ANOTHER QUERY...');<br /> |
|
$this->db->query('AND YET ANOTHER QUERY...');<br /> |
|
|
|
<br /> |
|
|
|
if ($this->db->trans_status() === FALSE)<br /> |
|
{<br /> |
|
$this->db->trans_rollback();<br /> |
|
}<br /> |
|
else<br /> |
|
{<br /> |
|
$this->db->trans_commit();<br /> |
|
}<br /> |
|
</code> |
|
|
|
<p class="important"><strong>Note:</strong> Make sure to use <kbd>$this->db->trans_begin()</kbd> when running manual transactions, <strong>NOT</strong> |
|
<dfn>$this->db->trans_start()</dfn>.</p> |
|
|
|
|
|
|
|
|
|
</div> |
|
<!-- END CONTENT --> |
|
|
|
|
|
<div id="footer"> |
|
<p> |
|
Previous Topic: <a href="fields.html">Field MetaData</a> · |
|
<a href="#top">Top of Page</a> · |
|
<a href="../index.html">User Guide Home</a> · |
|
Next Topic: <a href="table_data.html">Table Metadata</a> |
|
</p> |
|
<p><a href="http://codeigniter.com">CodeIgniter</a> · Copyright © 2006 - 2012 · <a href="http://ellislab.com/">EllisLab, Inc.</a></p> |
|
</div> |
|
|
|
</body> |
|
</html> |