keep $_GET values except two specified - php

Question

I have a HTML form that i am using to search a database, the form method is GET:
<form method="get" action="">
Then my SQL Query selects from a database using the $_GET values
i run the SQL, then have this function - (http://pastebin.com/J3RL3MxC) - that i run underneath the query
So in total, it looks like:
$sql="SELECT * FROM customer ORDER BY company";
$i=0;
$array = ShowRecords($sql, "customer");
foreach($array["results"] as $ret) {
}
and i echo my results in the foreach loop
this is working fine, however when navigating through the pages that the function creates i loose the $_GET values so i also loose what i have searched for
how can i keep the $_GET values but keep in mind that the $_GET["pagenum"] needs to be removed/changed so the page will change
I have already added this code:
$query_string = '?';
foreach($_GET as $q => $k) {
if($q == 'id' or $q == 'pagenum') {
//
} else {
if($q != '') {
$query_string = '&'.$q.'='.$k;
}
}
}
at the top of my function to try to do what is needed ($_GET["id"] also needs to be removed) but its not keeping the values
What is the best way to keep all $_GET values except the specified ones?
P.S: I know i should be using PDO which i will be as soon as i have this issue sorted, i will then change my code to use PDO

Answer 1

Use http_build_query to build your query string instead of doing it manually:
http://php.net/manual/en/function.http-build-query.php
I would just store all of the request vars in an array and updated it as needed. When ready to output any links just use http_build_query to generate the query string
$request = $_GET;
unset($request['id']);
$request['pagenum'] = 2;
//etc
$query_string = '?' . http_build_query($request);

Answer 2

$id = isset($_GET["id"]) ? $_GET["id"] : NULL;
$pagenum = isset($_GET["pagenum"]) ? $_GET["pagenum"] : NULL;
if($id) {
}
if($pagenum) {
}