Toggle mysql concat sql query

Question

I have a drop down menu on a form that lists GPs by their surname, surgery name and town:
$query_gp = "SELECT CONCAT(gp_surname, ' - ', gp_surgery, ', ', gp_town) as gplist, gp_id  FROM gp ORDER BY gplist";
$gp = mysql_query($query_gp, $mypms) or die(mysql_error());
$row_gp = mysql_fetch_assoc($gp);
$totalRows_gp = mysql_num_rows($gp);
and then the php to put on the page and update a foreign key in a separate table:
<select name="gplist" class="main_text_field" id="gplist"style="width:150px;">
<?php
     do { 
?>
<option value="<?php echo $row_gp['gp_id']?>"<?php if (!(strcmp($row_gp['gp_id'], $row_demographics['FK_gp_id']))) {echo "SELECTED";} ?>><?php echo $row_gp['gplist']?></option>
<?php
     } while ($row_gp = mysql_fetch_assoc($gp));
     $rows = mysql_num_rows($gp);#
     if($rows > 0) {
          mysql_data_seek($gp, 0);
          $row_gp = mysql_fetch_assoc($gp);
?>
            </select>
Using a pair of radio buttons, I want to toggle the list order so that it is displayed in town order, I haven't got the foggiest about where to start - help please :-(

Answer 1

I am assuming what Bregent and Nancy mean is to allocate a value to the radio buttons then send that value to the page to process in what order you want the list to appear, either ORDER by gplist or gp_town
<form action="xxxxxxxxxx.php" method="post">
<input type="radio" name="gp" value="gpName">List by GP Name<br>
<input type="radio" name="gp" value="gpTown">List by Town
<input type="submit" value="Submit">
</form>
You would then use some php to get the value of 'gp' - the 'name' given to the radio button group (as above). The value of the radio button is assigned to a variable called $action and then re-assigned with the database column name you want the list to be ORDERED by.
<?php
$action = $_POST['gp'];
if ($action == "gpName") {
$action = "gplist";
elseif ($action == "gpTown") {
$action = "gp_town";
?>
Enclose the database query in a php if/else statement. IF the variable $action 'isset' then the list will be ordered by whatever radio button value is selected otherwise it will just be ordered by gplist:
if(isset($action)) {
$query_gp = "SELECT CONCAT(gp_surname, ' - ', gp_surgery, ', ', gp_town) as gplist, gp_id  FROM gp ORDER BY '".$action."' ASC";
$gp = mysql_query($query_gp, $mypms) or die(mysql_error());
$row_gp = mysql_fetch_assoc($gp);
$totalRows_gp = mysql_num_rows($gp);
else {
$query_gp = "SELECT CONCAT(gp_surname, ' - ', gp_surgery, ', ', gp_town) as gplist, gp_id  FROM gp ORDER BY gplist";
$gp = mysql_query($query_gp, $mypms) or die(mysql_error());
$row_gp = mysql_fetch_assoc($gp);
$totalRows_gp = mysql_num_rows($gp);