<?php

Class dbObj{
/* Database connection start */
var $dbhost = "localhost";
var $username = "root";
var $password = "1";
var $dbname = "1";
var $conn;
function getConnstring() {
$con = mysqli_connect($this->dbhost, $this->username, $this->password, $this->dbname) or die("Connection failed: " . mysqli_connect_error());

/* check connection */
if (mysqli_connect_errno()) {
printf("Connect failed: %sn", mysqli_connect_error());
exit();
} else {
$this->conn = $con;
}
return $this->conn;
}
}

<?php
//include connection file
include_once("/var/www/html/ecom1/ekart/connection.php");
include_once('/var/www/html/ecom1/ekart/fpdf/fpdf.php');

class PDF extends FPDF
{
// Page header
function Header()
{
    // Logo
    $this->Image('logo.png',10,-1,70);
    $this->SetFont('Arial','B',13);
    // Move to the right
    $this->Cell(80);
    // Title
    $this->Cell(80,10,'Employee List',1,0,'C');
    // Line break
    $this->Ln(20);
}

// Page footer
function Footer()
{
    // Position at 1.5 cm from bottom
    $this->SetY(-15);
    // Arial italic 8
    $this->SetFont('Arial','I',8);
    // Page number
    $this->Cell(0,10,'Page '.$this->PageNo().'/{nb}',0,0,'C');
}
}

$db = new dbObj();
$connString =  $db->getConnstring();
$display_heading = array('id'=>'ID', 'order_id'=> 'Name', 'payment_type'=> 'payment');

$result = mysqli_query($connString, "SELECT id, order_id, payment_type FROM orders") or die("database error:". mysqli_error($connString));
$header = mysqli_query($connString, "SHOW columns FROM orders");

$pdf = new PDF();
//header
$pdf->AddPage();
//foter page
$pdf->AliasNbPages();
$pdf->SetFont('Arial','B',12);
foreach($header as $heading) {
$pdf->Cell(40,12,$display_heading[$heading['Field']],1);
}
foreach($result as $row) {
$pdf->Ln();
foreach($row as $column)
$pdf->Cell(40,12,$column,1);
}
$pdf->Output();
?>