188 lines
7.6 KiB
HTML
188 lines
7.6 KiB
HTML
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<title>Connecting to your Database : CodeIgniter User Guide</title>
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<style type='text/css' media='all'>@import url('../userguide.css');</style>
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<meta name='author' content='ExpressionEngine Dev Team' />
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<meta name='description' content='CodeIgniter User Guide' />
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<div id="nav"><div id="nav_inner"><script type="text/javascript">create_menu('../');</script></div></div>
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<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>
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<table cellpadding="0" cellspacing="0" border="0" style="width:100%">
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<tr>
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<td><h1>CodeIgniter User Guide Version 2.1.4</h1></td>
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<td id="breadcrumb_right"><a href="../toc.html">Table of Contents Page</a></td>
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<tr>
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<td id="breadcrumb">
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<a href="http://codeigniter.com/">CodeIgniter Home</a> ›
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<a href="../index.html">User Guide Home</a> ›
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<a href="index.html">Database Library</a> ›
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Connecting
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</td>
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<td id="searchbox"><form method="get" action="http://www.google.com/search"><input type="hidden" name="as_sitesearch" id="as_sitesearch" value="ellislab.com/codeigniter/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>
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</tr>
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</table>
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<br clear="all" />
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<!-- START CONTENT -->
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<div id="content">
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<h1>Connecting to your Database</h1>
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<p>There are two ways to connect to a database:</p>
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<h2>Automatically Connecting</h2>
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<p>The "auto connect" feature will load and instantiate the database class with every page load.
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To enable "auto connecting", add the word <var>database</var> to the library array, as indicated in the following file:</p>
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<p><kbd>application/config/autoload.php</kbd></p>
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<h2>Manually Connecting</h2>
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<p>If only some of your pages require database connectivity you can manually connect to your database by adding this
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line of code in any function where it is needed, or in your class constructor to make the database
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available globally in that class.</p>
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<code>$this->load->database();</code>
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<p class="important">If the above function does <strong>not</strong> contain any information in the first parameter it will connect
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to the group specified in your database config file. For most people, this is the preferred method of use.</p>
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<h3>Available Parameters</h3>
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<ol>
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<li>The database connection values, passed either as an array or a DSN string.</li>
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<li>TRUE/FALSE (boolean). Whether to return the connection ID (see Connecting to Multiple Databases below).</li>
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<li>TRUE/FALSE (boolean). Whether to enable the Active Record class. Set to TRUE by default.</li>
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</ol>
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<h3>Manually Connecting to a Database</h3>
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<p>The first parameter of this function can <strong>optionally</strong> be used to specify a particular database group
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from your config file, or you can even submit connection values for a database that is not specified in your config file.
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Examples:</p>
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<p>To choose a specific group from your config file you can do this:</p>
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<code>$this->load->database('<samp>group_name</samp>');</code>
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<p>Where <samp>group_name</samp> is the name of the connection group from your config file.</p>
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<p>To connect manually to a desired database you can pass an array of values:</p>
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<code>$config['hostname'] = "localhost";<br />
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$config['username'] = "myusername";<br />
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$config['password'] = "mypassword";<br />
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$config['database'] = "mydatabase";<br />
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$config['dbdriver'] = "mysql";<br />
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$config['dbprefix'] = "";<br />
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$config['pconnect'] = FALSE;<br />
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$config['db_debug'] = TRUE;<br />
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$config['cache_on'] = FALSE;<br />
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$config['cachedir'] = "";<br />
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$config['char_set'] = "utf8";<br />
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$config['dbcollat'] = "utf8_general_ci";<br />
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<br />
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$this->load->database(<samp>$config</samp>);</code>
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<p>For information on each of these values please see the <a href="configuration.html">configuration page</a>.</p>
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<p>Or you can submit your database values as a Data Source Name. DSNs must have this prototype:</p>
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<code>$dsn = 'dbdriver://username:password@hostname/database';<br />
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<br />
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$this->load->database(<samp>$dsn</samp>);</code>
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<p>To override default config values when connecting with a DSN string, add the config variables as a query string.</p>
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<code>$dsn = 'dbdriver://username:password@hostname/database?char_set=utf8&dbcollat=utf8_general_ci&cache_on=true&cachedir=/path/to/cache';<br />
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<br />
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$this->load->database(<samp>$dsn</samp>);</code>
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<h2>Connecting to Multiple Databases</h2>
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<p>If you need to connect to more than one database simultaneously you can do so as follows:</p>
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<code>$DB1 = $this->load->database('group_one', TRUE);<br />
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$DB2 = $this->load->database('group_two', TRUE);
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</code>
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<p>Note: Change the words "group_one" and "group_two" to the specific group names you are connecting to (or
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you can pass the connection values as indicated above).</p>
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<p>By setting the second parameter to TRUE (boolean) the function will return the database object.</p>
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<div class="important">
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<p>When you connect this way, you will use your object name to issue commands rather than the syntax used throughout this guide. In other words, rather than issuing commands with:</p>
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<p>$this->db->query();<br />$this->db->result();<br /> etc...</p>
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<p>You will instead use:</p>
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<p>$DB1->query();<br />$DB1->result();<br /> etc...</p>
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</div>
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<h2>Reconnecting / Keeping the Connection Alive</h2>
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<p>If the database server's idle timeout is exceeded while you're doing some heavy PHP lifting (processing an image, for instance), you should consider pinging the server by using the <dfn>reconnect()</dfn> method before sending further queries, which can gracefully keep the connection alive or re-establish it.</p>
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<code>$this->db->reconnect();</code>
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<h2>Manually closing the Connection</h2>
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<p>While CodeIgniter intelligently takes care of closing your database connections, you can explicitly close the connection.</p>
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<code>$this->db->close();</code>
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</div>
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<!-- END CONTENT -->
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<div id="footer">
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<p>
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Previous Topic: <a href="configuration.html">Database Configuration</a>
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·
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<a href="#top">Top of Page</a> ·
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<a href="../index.html">User Guide Home</a> ·
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Next Topic: <a href="queries.html">Queries</a>
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</p>
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<p><a href="http://codeigniter.com">CodeIgniter</a> · Copyright © 2006 - 2012 · <a href="http://ellislab.com/">EllisLab, Inc.</a></p>
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</div>
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</body>
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</html>
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