Question

I am trying to set up a filter system for a small shop I am developing. Basically, I am working the results off a list of variables. the page, products.php if there is no querystring will show all products. However, if there is a variable present I want it to alter the select statement where necessary.

however, I am having problems filtering. If i use the AND statement for all variables it does not filter appropriately neither does the OR. So if i wanted black size 5 shoes it would show all size fives regardless of color.

Is there a better approach to take with this as is becoming a fair old head scratcher!

if ($queryString == NULL){
    $query = "SELECT * FROM store_products 
JOIN store_cat on store_products.cat=store_cat.cat_id 
JOIN prod_sizes on store_products.prod_id=prod_sizes.product_id
JOIN prod_color on store_products.prod_id=prod_color.product_id 
GROUP BY store_products.prod_id";   
}else{
        $query = "SELECT * FROM store_products 
JOIN store_cat on store_products.cat=store_cat.cat_id 
JOIN prod_sizes on store_products.prod_id=prod_sizes.product_id
JOIN prod_color on store_products.prod_id=prod_color.product_id 
where store_products.sale='$sale' OR prod_color.color='$color' OR prod_sizes.size='$size' OR store_products.cat='$cat' GROUP BY store_products.prod_id";
}

example variable string

products.php?sale=&cat_id=1&size=&color=Yellow

Answer 1

Try building your WHERE criteria before running the query.

String:
products.php?sale=&cat_id=1&size=&color=Yellow

myfile.php

$criteria = "WHERE 1 ";

if (isset($_GET['sale']) {
    $criteria .= "AND tore_products.sale=$_GET['sale'] ";
}
if (isset($_GET['cat_id']) {
    $criteria .= "AND store_products.cat=$_GET['cat_id'] ";
}
if (isset($_GET['color']) {
    $criteria .= "AND tore_products.color=$_GET['color'] ";
}

And so on then run your query:

$query = "SELECT * FROM store_products 
JOIN store_cat on store_products.cat=store_cat.cat_id 
JOIN prod_sizes on store_products.prod_id=prod_sizes.product_id
JOIN prod_color on store_products.prod_id=prod_color.product_id
$criteria
GROUP BY store_products.prod_id";

And please remember to clean your $_GET variables prior to querying with them using mysql_real_escape_string, mysqli or PDO!