Get Category ID in url

Question

I can not find nothing on internet about getting category id in url, so I post here.

I want an url like this : localhost/index.php&cat=1 , when I press submit button.

I use this code:

<form method="post" id="categories">
<select name="category">
<option value="">Select a category</option>
<?php
getCats();
?>
</select>
<button type="submit" form="categories" value="Submit">Submit</button>
</form>

and getcats:

function getCats(){
global $con;
$get_cats = "select * from category";
$run_cats = mysqli_query($con, $get_cats);
while ($row_cats=mysqli_fetch_array($run_cats)){
    $cat_id = $row_cats['cat_id'];
    $cat_name = $row_cats['name'];
echo "<li><button><a href='index.php?cat=$cat_id'>$cat_name</a></button></li>";
}
}

It's possible to use form action= in this case?

Answer 1

you most remind these two tip:

1) query string only on GET method are accessible.

2) query string starts whit ? and if parameters are more than one seperate with &

in your question you use this:

localhost/index.php&cat=1

but it must be:

localhost/index.php?cat=1&name=blah

if you use this tips now you can get data in your php code like this:

$cat = $_GET["cat"]; //will be '1'
$name = $_GET["name"]; // will be 'blah'