PHP Populate Dropdown From Database and then Update on Button Click - php

Question

I'm having trouble populating a dropdown list from a database and then updating the selected item on a button click. What I'm trying to have is that when you pick Option B in the dropdown, it'll update that option on the click of a submit button.
I can get the dropdown box to populate fine, but when clicking the button it won't update correctly. I'm learning as I go, any pointers would be appreciated.
<form id='filter' name='filter' method='post' action=''>
<?php
$getIssuedVouchers2 = "SELECT * FROM vouchercodes WHERE status = 'Active'";
$issuedVouchersResult2 = mysql_query($getIssuedVouchers);
?>
<select>
<?php
while ($ivSelectRow = mysql_fetch_array($issuedVouchersResult2)) {
echo "<option name='updatestatus'>" . $ivSelectRow['vouchId'] . "</option>";
}
?>
</select>
<INPUT TYPE="Submit" VALUE="Update the Record" NAME="Submit" />
<?php
if(isset($_POST['Submit'])) { //if the submit button is clicked
$updatingQuery = "UPDATE vouchercodes SET status='Expired' WHERE vouchId = '".$ivSelectRow['vouchId']."' ";
mysql_query($updatingQuery) or die("Cannot update");//update or error
}
?>
</form>

Answer 1

PHP is a server side language. It runs once when you request the page, and after it is done it serves the page to you. It does not run until you do another page request, which PHP can't do because that's a client side action.
What you are looking for is Javascript and Ajax. They are client side languages. I'd recommend using Jquery for this, it's pretty easy to use once you get the hang of it. It makes it a lot less awful than standard javascript.
If you aren't wanting to avoid a page reload (submit -> handler -> page reload), I can cook up an answer for you for that. Maybe.
Update from your comment:
You want to set the "selected" attribute, which makes that option selected on page load, correct? e.g. pick the second item in the dropdown instead of the first.
You need to use the selected attribute on your option tag. That makes it selected.
Here's an example I use on one of my sites.
<select data-wavenum='<?=$i;?>' id="enemy<?=$i;?>" name="enemy<?=$i;?>" class="enemylist">
<option value="assaulttrooper" <?=($enemy == 'assaulttrooper') ? "selected" : ""?>>Assault Trooper</option>
This prints out something like:
<option value="assaulttrooper" selected>Assault Trooper</option>
In this case, $enemy is my item that makes me print selected out which makes that option be selected.
In your case, this is what it would be. It's kind of ugly. I think I fixed some of your code, but without the DB backend I can't test.
while ($ivSelectRow = mysql_fetch_array($issuedVouchersResult2)) {
$selected = false;
if (isset($_POST['Submit'])) {
$selected = ($_POST['vouchId'] == $ivSelectRow['vouchId']);
}
echo "<option name=".$ivSelectRow['vouchId']." ".($selected) ? "selected" : "".">" . $ivSelectRow['vouchId'] . "</option>";
}
Please be aware that I could change the option name or send a POST that would cause you to expire a value, or delete your entire table as your data is not sanitized.