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<title>Field Data : CodeIgniter User Guide</title>
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<td><h1>CodeIgniter User Guide Version 2.2.0</h1></td>
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<a href="http://codeigniter.com/">CodeIgniter Home</a> ›
<a href="../index.html">User Guide Home</a> ›
<a href="index.html">Database Library</a> ›
Field Names
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<h1>Field Data</h1>
<h2>$this->db->list_fields()</h2>
<p>Returns an array containing the field names. This query can be called two ways:</p>
<p>1. You can supply the table name and call it from the <dfn>$this->db-></dfn> object:</p>
<code>
$fields = $this->db->list_fields('table_name');<br /><br />
foreach ($fields as $field)<br />
{<br />
echo $field;<br />
}
</code>
<p>2. You can gather the field names associated with any query you run by calling the function
from your query result object:</p>
<code>
$query = $this->db->query('SELECT * FROM some_table');
<br /><br />
foreach ($query->list_fields() as $field)<br />
{<br />
echo $field;<br />
}
</code>
<h2>$this->db->field_exists()</h2>
<p>Sometimes it's helpful to know whether a particular field exists before performing an action.
Returns a boolean TRUE/FALSE. Usage example:</p>
<code>
if ($this->db->field_exists('field_name', 'table_name'))<br />
{<br />
// some code...<br />
}
</code>
<p>Note: Replace <em>field_name</em> with the name of the column you are looking for, and replace
<em>table_name</em> with the name of the table you are looking for.</p>
<h2>$this->db->field_data()</h2>
<p>Returns an array of objects containing field information.</p>
<p>Sometimes it's helpful to gather the field names or other metadata, like the column type, max length, etc.</p>
<p class="important">Note: Not all databases provide meta-data.</p>
<p>Usage example:</p>
<code>
$fields = $this->db->field_data('table_name');<br /><br />
foreach ($fields as $field)<br />
{<br />
echo $field->name;<br />
echo $field->type;<br />
echo $field->max_length;<br />
echo $field->primary_key;<br />
}
</code>
<p>If you have run a query already you can use the result object instead of supplying the table name:</p>
<code>
$query = $this->db->query("YOUR QUERY");<br />
$fields = $query->field_data();
</code>
<p>The following data is available from this function if supported by your database:</p>
<ul>
<li>name - column name</li>
<li>max_length - maximum length of the column</li>
<li>primary_key - 1 if the column is a primary key</li>
<li>type - the type of the column</li>
</ul>
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