For drop down. I want to apply validation for update drop down. Everything works fine. Updated value inserted in data base - codeigniter-3

Question

But when i select drop down value and any error related firstname etc. and on update button it remove selected value and show old value.
<td align=left>Select Month:<select name=month id="month">
<?php
$date = $row->birth;
$stamp = strtotime($date);
?>
<?php
echo '<option .date("m", $stamp). '.$selected.'>'.date("m", $stamp).'</option>';
?>
<option name=""></option>
<option value='01'>January</option>
<option value='02'>February</option>
<option value='03'>March</option>
<option value='12'>December</option>
</select>
<?php echo form_error('month','<div style="color:red">', '</div>'); ?>
<span class="error"></span>
</td>

Answer 1

You can use codeigniter's set_select function to keep the selection if form validation fails:
Select Month:<select name=month id="month">
<option name=""></option>
<option value='01' <?php echo set_select('month', '01'); ?>>January</option>
<option value='02' <?php echo set_select('month', '02'); ?>>February</option>
<option value='03' <?php echo set_select('month', '03'); ?>>March</option>
<option value='12' <?php echo set_select('month', '12'); ?>>December</option>
</select>
See also: https://www.codeigniter.com/userguide3/helpers/form_helper.html#set_select
If you have a value you'd like to set in the dropdown when the page first loads, you can use the third argument:
Select Month:<select name=month id="month">
<?php
$date = $row->birth;
$stamp = strtotime($date);
$month = date("m", $stamp);
?>
<option name=""></option>
<option value='01' <?php echo set_select('month', '01', $month == '01'); ?>>January</option>
<option value='02' <?php echo set_select('month', '02', $month == '02'); ?>>February</option>
<option value='03' <?php echo set_select('month', '03', $month == '03'); ?>>March</option>
<option value='12' <?php echo set_select('month', '12', $month == '12'); ?>>December</option>
</select>