Not able to parse data from HTML form to PDF using php and mysql

i m in a situation where i need to transfer a data when submitted on HTML form to update in MYSQL database and generate pdf for that data submitted. This must also contain the increment values like generating receipt number.

My pdf code is here scripted in php.

<?php

require('fpdf.php');

    class PDF extends FPDF
{
//Page header
function Header()
{

    //Move to the right
    $this->Cell(130);
    //Title
    include('connection.php');
    mysql_select_db("inventory") or die("Couldn't find db");
    $data = mysql_query("SELECT * FROM sold WHERE imei = '6135352313'");//This is where i need help how to get data from the HTML form after updating in MYSQL
    while ($result1 = mysql_fetch_assoc($data))
{

    $this->Cell(50,10,'CP '.$result1["receiptnumber"],1,1,'C'); //receipt number to be pulled from Auto_increment field in database
    }
    //Move to the right
    $this->Cell(130);
    //Date
    $this->Cell(50,10,date("l F dS Y "),1,0,'C');
    //Line break
    $this->Ln(20);
}

//Instanciation of inherited class
$pdf=new PDF();
$pdf->AliasNbPages();
$pdf->AddPage();
$pdf->SetFont('Arial','B',10);
    include('connection.php');
    mysql_select_db("inventory") or die("Couldn't find db");
    $data = mysql_query("SELECT * FROM sold WHERE imei = '6135352313'"); //This is where i need help how to get data from the HTML form after updating in MYSQL

    while ($result = mysql_fetch_assoc($data))
{

    //Move to the right
    $pdf->Cell(50,5,'Invoice To ',0,0,'R');
    $pdf->SetFont('Arial','B',15);
    $pdf->Cell(140,8,$result["firstname"]." ".$result["lastname"],1,1,'C');
    $pdf->SetFont('Arial','B',10);

    }
$pdf->Output();
?>

You can get data into your SQL query like so:

$imei = mysql_real_escape_string($_POST['imei']);
$data = mysql_query("SELECT * FROM sold WHERE imei = '$imei'");

Don't forget to escape string you get from a user with mysql_real_escape_string().
Also don't forget to surround the $var in your query with single quotes ' as shown. (this is vital to make your code safe)

If you use mysql_query in any other way you will be vulnerable to SQL-injection attacks.