Php price asc function is not working - php

Question

I'm trying to do price ascending or descending filter in php, but it is not working. Could some one help to fix it? Thanks
<select name='sort'>
<option value='ASC'> Price Low to High </option>
<option value='DESC'> Price High to Low </option>
</select>
<?php
$query = 'SELECT prd_price FROM products ORDER BY '.$_REQUEST['sort'];
$run_query = mysqli_query($con,$query);
$row = mysqli_fetch_array($run_query);
?>

Answer 1

You can't do it like this. Cause your select is not processed.
When you read the php docs about $_REQUEST you see that it only processes the values of $_POST, $_GET and $_COOKIE.
If you would like to make this working, you could do something like this:
<form method="post">
<select name="sort">
<option value="asc">Price Low to High</option>
<option value="desc">Prive High to Low</option>
</select>
<input type="submit" value="Sort">
</form>
<?php
// check if the server recieved a post:
if ($_SERVER['REQUEST_METHOD'] == "POST") {
if (isset($_POST['sort'])) {
if ($_POST['sort'] == "asc") {
$query = "SELECT prd_price FROM products ORDER BY prd_price ASC";
} else {
$query = "SELECT prd_price FROM products ORDER BY prd_price DESC";
}
}
// execute query here.
}
?>
And try to avoid using $_REQUEST