Question

I am trying to allow users to sort mysql queries based on name, price, etc. This drop down gives them the power to do that, it changes the “ORDER BY” clause based on what the user chooses. It’s 3am here and I just can’t spot the mistake:

    <?php
        $sortBy = $_POST['sortBy'];
        if ($sortBy) {

            $priceLowToHigh = $_POST['price-low-to-high'];
            $priceHighToLow = $_POST['price-high-to-low'];
            $dateMostRecent = $_POST['date-most-recent'];
            $dateOldest = $_POST['date-oldest'];
            $alphabeticalOrder = $_POST['alphabetical-order'];

            if ($priceLowToHigh) {
                $sortOrder = "price ASC";
            } elseif ($priceHighToLow) {
                $sortOrder = "price DESC";
            } elseif ($dateMostRecent) {
                $sortOrder = "date DESC";
            } elseif ($dateOldest) {
                $sortOrder = "date ASC";
            } elseif ($alphabeticalOrder) {
                $sortOrder = "name ASC";
            }

        } else {
            $sortOrder = "date DESC";
        }
    ?>
    <form action="" method="post">
        <select name="sortBy" onchange="this.form.submit()">
            <option>Sort By</option>
            <option value="price-low-to-high">Price (low to high)</option>
            <option value="price-high-to-low">Price (high to low)</option>
            <option value="date-most-recent">Date (most recent)</option>
            <option value="date-oldest">Date (oldest)</option>
            <option value="alphabetical-order">Alphabetical Order</option>
        </select>
    </form>

later on the ORDER BY clause is used like this:

    $query = mysql_query("SELECT * FROM products WHERE category = $categoryId ORDER BY $sortOrder");

Answer 1

You’re handling your menu incorrectly. Your $sortBy variable will already be what the user selects, not separate $_POST fields.

This is what you should do instead –

<?php
    $sortBy = $_POST['sortBy'];
    if($sortBy == 'price-low-to-high') {
        $sortOrder = "price ASC";
    } else if($sortBy == 'price-high-to-low') {
        $sortOrder = "price DESC";
    } else if($sortBy == 'date-most-recent') {
        $sortOrder = "date DESC";
    } else if($sortBy == 'date-oldest') {
        $sortOrder = "date ASC";
    } else if($sortBy == 'alphabetical-order') {
        $sortOrder = "name ASC";
    } else {
        $sortOrder = "date DESC";
    }
?>