如何在PHP中的链接中“添加”两个GET

Question

There are two menus and both were made in order to filter the main content of my website. The Menu one will filter the category and the Menu two will filter the brand.

When clicking in a menu 01 option, it will output: mywebsite.com/?cat=accessories

When clicking in a menu 02 option, it will output: mywebsite.com/?brand=medicate

My main question is how can I get both together when one of them is already set, something like: mywebsite.com/?category=accessories&brand=medicate

Here is my basic code:

<h1>Menu One</h1>
<ul>
  <li><a href="?category=accessories">Option 01</a></li>
  <li><a href="?category=bolts">Option 01</a></li>
  <li><a href="?category=tools">Option 01</a></li>
</ul>

<h1>Menu Two</h1>
<ul>
  <li><a href="&brand=medicate">Brand 01</a></li>
  <li><a href="&brand=diasyst">Brand 02</a></li>
  <li><a href="&brand=clement">Brand 03</a></li>
</ul>

Answer 1

When you're displaying the menus, if one of the other filters is already set, you can add that to the URL in the other menu.

$cat = isset($_GET['category']) ? '&category=' . $_GET['category'] : '';
$brand = isset($_GET['brand']) ? '&brand=' . $_GET['brand'] : '';
?>

<h1>Menu One</h1>
<ul>
  <li><a href="?category=accessories<?php echo $brand ?>">Option 01</a></li>
  <li><a href="?category=bolts<?php echo $brand ?>">Option 01</a></li>
  <li><a href="?category=tools<?php echo $brand ?>">Option 01</a></li>
</ul>

<h1>Menu Two</h1>
<ul>
  <li><a href="?brand=medicate<?php echo $cat ?>">Brand 01</a></li>
  <li><a href="?brand=diasyst<?php echo $cat ?>">Brand 02</a></li>
  <li><a href="?brand=clement<?php echo $cat ?>">Brand 03</a></li>
</ul>