PHP drop down box not showing selected value - php

Question

Hi I have a piece of php code which takes php variables from a database and then populates A drop down box. This works fine but once the page updates it doesn't display the selected value and instead just displays the original list again.
I have played around with some different ideas of using isset to displays the selected value, but then it just displays that value and nothing else.
I have attached the original code where it works but always only shows the original list of values from the database.
If any body could provide a solution or even a nudge in the right direction then it would be much appreciated.
Thanks
if (isset($select) && $select != "location") {
$select = $_POST['location'];
}
?>
<select name="location">
<?php
// Get records from database (table "name_list").
$list = mysql_query("select DISTINCT region_name from masterip_details WHERE country_code='GB' AND TRIM(IFNULL(region_name,'')) <> '' order by region_name asc");
// Show records by while loop.
while ($row_list = mysql_fetch_assoc($list)) {
$location = $_POST['location']; ?>
<option value="<?php echo $row_list['region_name']; ?>"
<?php if $row_list['region_name'] == $select) {
echo "selected";
} ?>><?php echo $row_list['region_name']; ?></option>
<?php } ?>

Answer 1

You are sure you send that form with a post request?
Your code is unreadable
Better do something like this:
<?php
//database request don't belong in the presentation layer
$list=mysql_query("select DISTINCT region_name from masterip_details WHERE country_code='GB' AND TRIM(IFNULL(region_name,'')) <> '' order by region_name asc");
$location = "";
$isSelect = "";
if(isset($_POST['location'])){
$location = $_POST['location'];
}
while($row_list=mysql_fetch_assoc($list)){
if($row_list['region_name'] == $location ){
$isSelect = "selected";
}
echo '<option value="'.$row_list['region_name'].'" '.$isSelect.' >'. $row_list['region_name'].'</option>';
}
?>

Answer 2

You are not checking the select value properly.
Change this:
if (isset($select) && $select != "location") {
$select = $_POST['location'];
}
TO
if (isset($_POST['location']) && $_POST['location'] != "location") {
$select = $_POST['location'];
}

Answer 3

While creating the <option> tag, you may use the following:
<?php if ($row_list['region_name'] == $select) { echo "selected='true'"; } ?>
You may also like to check if the condition $row_list['region_name'] == $select is returning true. You may try to echo their result separately as:
echo ($row_list['region_name'] == $select)
or something similar that would show if you get true or not.

Answer 4

The problem lies in the first line - actually the system will never execute 2nd line to assign $select because $select is never set:
if(isset($_POST['select']) && $select!="location") { $select=$_POST['location']; } ?>