How to echo a variable from a processing page? - php

Question

I have a separate file that generates a PDF, saves select information to a database, creates the PDF and then emails it to the user. What I am trying to do is echo the sql statement on the confirmation page.
request.php -> PDF-generation.php -> confirmation.php
The user never sees the PDF generation page.
Here is the function:
function LogToDatabase($holding_id, $to_email, $from_email, $subject, $message, $pdf) {
//Save record of PDF here
$db = new wpdb(DB_USER, DB_PASSWORD, 'webtransaction', DB_HOST);
$sql = "INSERT INTO 504_pdf_storage (`holding_id`, `to_email`, `from_email`, `subject`, `message`, `pdf`)
VALUES(" . $holding_id . "," . $to_email ."," . $from_email ."," . $subject ."," . $message ."," . $pdf . ");";
return $db->insert_id;
}
I want to echo the variable $sql from PDF-generation.php onto the confirmation.php but a simple "echo $sql;" gives an error saying "Undefined variable"
Please help and thanks!
EDIT: Here is the top of the confirmation page.
require_once('../../../../wp-load.php');
require_once('../includes/phpmailer/class.phpmailer.php');
require_once('../classes/504-send-request.php');
require_once ('../classes/pdf_generator.php');
$mh = new MobileHomeRequest();
$data = $mh->GetTempData($_POST['id']);
$holding_id = $data->SaveToDatabase();
$pdf = new PDFGen(null,$data);
echo $sql;
get_header();
if(!$pdf->RenderPDF()) { ?>
<script>
alert('Couldn\'t send your email because our servers seem to be really lame today.');
</script>
<?php } ?>

Answer 1

Save the value in a session variable, and then echo out the session variable on the confirmation page. You'll need session_start() at the top of each page.
function LogToDatabase($holding_id, $to_email, $from_email, $subject, $message, $pdf) {
//Save record of PDF here
$db = new wpdb(DB_USER, DB_PASSWORD, 'webtransaction', DB_HOST);
$sql = "INSERT INTO 504_pdf_storage (`holding_id`, `to_email`, `from_email`, `subject`, `message`, `pdf`)
VALUES(" . $holding_id . "," . $to_email ."," . $from_email ."," . $subject ."," . $message ."," . $pdf . ");";
//add this
$_SESSION['savedSQL'] = $sql;
return $db->insert_id;
}
Then on the confirmation page, it's a simple:
echo htmlentities($_SESSION['savedSQL'], ENT_QUOTES);
Side Note
As mentioned in the comments, a var_dump($sql) followed by exit() would be much better. Also note the htmlentities() to protect against XSS, since it is unknown where the variables in the query are coming from.