How to make PHP makes this query - php

Question

As I am learning PHP, naturally, I decided to create a search feature on my webpage. However I wanted to make mine more unique, so rather than using just a simple html input field as the 'search' field, I created two html select tags which allow the user to select two options and search based upon that. I managed to get the php to generate the search query, however it wasn't the sql query I wanted. My php code managed to generate a query hat looked like this: .com/results.php?option1=london&option2=car whereas ideally I want it to generate something like this: .com/results.php?combinedoptions=london+car
I've researched thoroughly into this and I hate to ask, what may be, a very simple question on this site.
$input = $_GET['input'];
$topic = $_GET['topic'];
$location = $_GET['location'];
$combined = $input . $topic . '' . $location;
$terms = explode(" ", $combined);
$query = "SELECT * FROM search WHERE ";
foreach ($terms as $each){
$i++;
if ($i == 1)
$query .= "keywords LIKE '%$each%'";
else
$query .= "OR keywords LIKE '%$each%'";
}

Answer 1

You would just split the incoming string. Here's a piece of code:
<?php
$combinedoptions = 'london+car';
$array = explode("+", $combinedoptions);
if (sizeof($array) != 2) { /*problem here*/ echo 'bad parameters'; return; }
$option1 = $array[0];
$option2 = $array[1];
?>
Just using the explode() method. Compiled code.