260 lines
8.7 KiB
HTML
260 lines
8.7 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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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<title>Generating Query Results : CodeIgniter User Guide</title>
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<style type='text/css' media='all'>@import url('../userguide.css');</style>
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<link rel='stylesheet' type='text/css' media='all' href='../userguide.css' />
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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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</head>
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<body>
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<!-- START NAVIGATION -->
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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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</table>
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<tr>
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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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Query Results
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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>Generating Query Results</h1>
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<p>There are several ways to generate query results:</p>
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<h2>result()</h2>
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<p>This function returns the query result as an array of <strong>objects</strong>, or <strong>an empty array</strong> on failure.
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Typically you'll use this in a foreach loop, like this:</p>
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<code>
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$query = $this->db->query("YOUR QUERY");<br />
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<br />
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foreach ($query->result() as $row)<br />
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{<br />
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echo $row->title;<br />
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echo $row->name;<br />
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echo $row->body;<br />
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}</code>
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<p>The above <dfn>function</dfn> is an alias of <dfn>result_object()</dfn>.</p>
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<p>If you run queries that might <strong>not</strong> produce a result, you are encouraged to test the result first:</p>
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<code>
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$query = $this->db->query("YOUR QUERY");<br />
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<br />
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if ($query->num_rows() > 0)<br />
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{<br />
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foreach ($query->result() as $row)<br />
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{<br />
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echo $row->title;<br />
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echo $row->name;<br />
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echo $row->body;<br />
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}<br />
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}
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</code>
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<p>You can also pass a string to result() which represents a class to instantiate for each result object (note: this class must be loaded)</p>
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<code>
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$query = $this->db->query("SELECT * FROM users;");<br />
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<br />
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foreach ($query->result('User') as $row)<br />
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{<br />
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echo $row->name; // call attributes<br />
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echo $row->reverse_name(); // or methods defined on the 'User' class<br />
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}
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</code>
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<h2>result_array()</h2>
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<p>This function returns the query result as a pure array, or an empty array when no result is produced. Typically you'll use this in a foreach loop, like this:</p>
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<code>
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$query = $this->db->query("YOUR QUERY");<br />
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<br />
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foreach ($query->result_array() as $row)<br />
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{<br />
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echo $row['title'];<br />
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echo $row['name'];<br />
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echo $row['body'];<br />
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}</code>
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<h2>row()</h2>
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<p>This function returns a single result row. If your query has more than one row, it returns only the first row.
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The result is returned as an <strong>object</strong>. Here's a usage example:</p>
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<code>
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$query = $this->db->query("YOUR QUERY");<br />
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<br />
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if ($query->num_rows() > 0)<br />
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{<br />
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$row = $query->row();
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<br /><br />
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echo $row->title;<br />
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echo $row->name;<br />
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echo $row->body;<br />
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}
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</code>
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<p>If you want a specific row returned you can submit the row number as a digit in the first parameter:</p>
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<code>$row = $query->row(<dfn>5</dfn>);</code>
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<p>You can also add a second String parameter, which is the name of a class to instantiate the row with:</p>
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<code>
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$query = $this->db->query("SELECT * FROM users LIMIT 1;");<br />
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<br />
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$query->row(0, 'User')<br />
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echo $row->name; // call attributes<br />
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echo $row->reverse_name(); // or methods defined on the 'User' class<br />
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</code>
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<h2>row_array()</h2>
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<p>Identical to the above <var>row()</var> function, except it returns an array. Example:</p>
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<code>
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$query = $this->db->query("YOUR QUERY");<br />
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<br />
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if ($query->num_rows() > 0)<br />
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{<br />
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$row = $query->row_array();
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<br /><br />
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echo $row['title'];<br />
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echo $row['name'];<br />
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echo $row['body'];<br />
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}
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</code>
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<p>If you want a specific row returned you can submit the row number as a digit in the first parameter:</p>
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<code>$row = $query->row_array(<dfn>5</dfn>);</code>
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<p>In addition, you can walk forward/backwards/first/last through your results using these variations:</p>
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<p>
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<strong>$row = $query->first_row()</strong><br />
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<strong>$row = $query->last_row()</strong><br />
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<strong>$row = $query->next_row()</strong><br />
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<strong>$row = $query->previous_row()</strong>
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</p>
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<p>By default they return an object unless you put the word "array" in the parameter:</p>
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<p>
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<strong>$row = $query->first_row('array')</strong><br />
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<strong>$row = $query->last_row('array')</strong><br />
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<strong>$row = $query->next_row('array')</strong><br />
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<strong>$row = $query->previous_row('array')</strong>
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</p>
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<h1>Result Helper Functions</h1>
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<h2>$query->num_rows()</h2>
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<p>The number of rows returned by the query. Note: In this example, <dfn>$query</dfn> is the variable that the query result object is assigned to:</p>
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<code>$query = $this->db->query('SELECT * FROM my_table');<br /><br />
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echo $query->num_rows();
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</code>
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<h2>$query->num_fields()</h2>
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<p>The number of FIELDS (columns) returned by the query. Make sure to call the function using your query result object:</p>
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<code>$query = $this->db->query('SELECT * FROM my_table');<br /><br />
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echo $query->num_fields();
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</code>
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<h2>$query->free_result()</h2>
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<p>It frees the memory associated with the result and deletes the result resource ID. Normally PHP frees its memory automatically at the end of script
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execution. However, if you are running a lot of queries in a particular script you might want to free the result after each query result has been
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generated in order to cut down on memory consumptions. Example:
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</p>
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<code>$query = $this->db->query('SELECT title FROM my_table');<br /><br />
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foreach ($query->result() as $row)<br />
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{<br />
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echo $row->title;<br />
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}<br />
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$query->free_result(); // The $query result object will no longer be available<br />
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<br />
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$query2 = $this->db->query('SELECT name FROM some_table');<br /><br />
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$row = $query2->row();<br />
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echo $row->name;<br />
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$query2->free_result(); // The $query2 result object will no longer be available
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</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="queries.html">Queries</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="helpers.html">Query Helper Functions</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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