Remove null variables from url - php

Question

I have this form, when I press the submit button i will get redirected to select.inc.php.
But sometimes I dont want to fill out every field of the form but all the "variables"(?) are still getting appended to the URL.
When I only enter an id and will press the button the url will look like this: localhost/inc/select.inc.php?id=1?username=?email=?password=?rank=.
What I want is this: localhost/inc/select.inc.php?id=1
<form action="inc/select.inc.php" method="GET">
<h1 id="h1-select">Select</h1>
<div class="row">
<input type="text" name="id" placeholder="Id">
</div>
<div class="row">
<input type="text" name="username" placeholder="Username">
</div>
<div class="row">
<input type="text" name="email" placeholder="E-Mail">
</div>
<div class="row">
<input type="password" name="password" placeholder="Password">
</div>
<div class="row">
<input type="text" name="rank" placeholder="Rank">
</div>
<div class="row">
<button type="submit" name="submit">Select</button>
</div>
</form>
I want this to show stuff from the MySQL database on a page like when I want to list all users with the rank "1".

Answer 1

If you want to remove all empty strings (you get them as empty strings, not null), you can run $_GET through array_filter():
$_GET = array_filter($_GET, function ($val) {
return $val !== '';
});
Now the $_GET-param will only contain non empty strings.
If you don't need to keep 0 either, you can just do:
$_GET = array_filter($_GET);
That removes any param where the value is falsy