How to get variable from header in multi query? - php

Question

i already had forms where I got the variable from the header but the forms have always been pdo and always one single query. This form is connected via mysqli and I just can't figure out how to get a variable.
<?php
$mysqli = new mysqli("localhost:3307", "root", "root", "test");
if($mysqli->connect_errno)
die ("Connection failed".$mysqli->connect_error);
$query = "SELECT * FROM contacts WHERE id = ?;";
$query .= "SELECT * FROM companies WHERE id = ?;";
if($mysqli->multi_query($query)) {
do{
$result = $mysqli->store_result();
$finfo = $result->fetch_fields();
echo"<table border ='1'>";
echo "<tr>";
foreach($finfo as $f) {
echo "<th>".$f->name."</th>";
}
echo "<br>";
echo "<br>";
echo "</tr>";
while($row = $result->fetch_assoc()) {
echo "<tr>";
foreach($row as $v) {
echo "<td>".$v."</td>";
}
echo "</tr>";
}
} while ($mysqli->more_results() && $mysqli->next_result());
}
?>
So the column "id" in both tables is the PK/FK and I want to retrieve information where id = ?.
How do I get the ? variable from the header and pass it on?
I feel like in my past tries I got the variable successfully with this code
$id=isset($_GET['id']) ? $_GET['id'] : die('ERROR: Record ID not found.');
[...]
$statement = $mysqli->prepare($query);
$statement->bindParam(1, $id);
$statement->execute();
but didn't echo it correctly.
Thank you in advance!