158 lines
7.1 KiB
HTML
158 lines
7.1 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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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<title>Queries : 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='description' content='CodeIgniter User Guide' />
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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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<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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Queries
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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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<br clear="all" />
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<!-- START CONTENT -->
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<div id="content">
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<h1>Queries</h1>
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<h2>$this->db->query();</h2>
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<p>To submit a query, use the following function:</p>
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<code>$this->db->query('YOUR QUERY HERE');</code>
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<p>The <dfn>query()</dfn> function returns a database result <strong>object</strong> when "read" type queries are run,
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which you can use to <a href="results.html">show your results</a>. When "write" type queries are run it simply returns TRUE or FALSE
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depending on success or failure. When retrieving data you will typically assign the query to your own variable, like this:</p>
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<code><var>$query</var> = $this->db->query('YOUR QUERY HERE');</code>
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<h2>$this->db->simple_query();</h2>
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<p>This is a simplified version of the <dfn>$this->db->query()</dfn> function. It ONLY returns TRUE/FALSE on success or failure.
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It DOES NOT return a database result set, nor does it set the query timer, or compile bind data, or store your query for debugging.
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It simply lets you submit a query. Most users will rarely use this function.</p>
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<h1>Working with Database prefixes manually</h1>
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<p>If you have configured a database prefix and would like to prepend it to a table name for use in a native SQL query for example, then you can use the following:</p>
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<p><code>$this->db->dbprefix('tablename');<br />
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// outputs prefix_tablename</code></p>
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<p>If for any reason you would like to change the prefix programatically without needing to create a new connection, you can use this method:</p>
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<p><code>$this->db->set_dbprefix('newprefix');<br /><br />
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$this->db->dbprefix('tablename');<br />
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// outputs newprefix_tablename</code></p>
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<h1>Protecting identifiers</h1>
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<p>In many databases it is advisable to protect table and field names - for example with backticks in MySQL. <strong>Active Record queries are automatically protected</strong>, however if you need to manually protect an identifier you can use:</p>
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<p><code>$this->db->protect_identifiers('table_name');</code></p>
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<p>This function will also add a table prefix to your table, assuming you have a prefix specified in your database config file. To enable the prefixing set <kbd>TRUE</kbd> (boolen) via the second parameter:</p>
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<p><code>$this->db->protect_identifiers('table_name', <kbd>TRUE</kbd>);</code></p>
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<h1>Escaping Queries</h1>
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<p>It's a very good security practice to escape your data before submitting it into your database.
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CodeIgniter has three methods that help you do this:</p>
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<ol>
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<li><strong>$this->db->escape()</strong> This function determines the data type so that it
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can escape only string data. It also automatically adds single quotes around the data so you don't have to:
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<code>$sql = "INSERT INTO table (title) VALUES(".$this->db->escape($title).")";</code></li>
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<li><strong>$this->db->escape_str()</strong> This function escapes the data passed to it, regardless of type.
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Most of the time you'll use the above function rather than this one. Use the function like this:
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<code>$sql = "INSERT INTO table (title) VALUES('".$this->db->escape_str($title)."')";</code></li>
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<li><strong>$this->db->escape_like_str()</strong> This method should be used when strings are to be used in LIKE
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conditions so that LIKE wildcards ('%', '_') in the string are also properly escaped.
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<code>$search = '20% raise';<br />
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$sql = "SELECT id FROM table WHERE column LIKE '%".$this->db->escape_like_str($search)."%'";</code></li>
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</ol>
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<h1>Query Bindings</h1>
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<p>Bindings enable you to simplify your query syntax by letting the system put the queries together for you. Consider the following example:</p>
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<code>
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$sql = "SELECT * FROM some_table WHERE id = <var>?</var> AND status = <var>?</var> AND author = <var>?</var>";
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<br /><br />
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$this->db->query($sql, array(3, 'live', 'Rick'));
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</code>
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<p>The question marks in the query are automatically replaced with the values in the array in the second parameter of the query function.</p>
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<p class="important">The secondary benefit of using binds is that the values are automatically escaped, producing safer queries. You don't have to remember to manually escape data; the engine does it automatically for you.</p>
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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="connecting.html">Connecting to your Database</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="results.html">Query Results</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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