Reason for undefined index in php

require('WriteHTML.php'); $pdf=new PDF_HTML(); $pdf->AliasNbPages(); $pdf->SetAutoPageBreak(true, 15); $pdf->AddPage(); //$pdf->Image('logo.png',18,13,33); $pdf->SetFont('Arial','B',14); $pdf->WriteHTML('ASSIGNMENT DETAILS

DEPARTMENT OF COMPUTER APPLICATIONS

'); $pdf->SetFont('Arial','B',7); */ session_start(); echo $_SESSION['subject']; $subject= $_SESSION['subject']; //'".$_SESSION['subject']."' //$_SESSION['subj_code']; if(isset($_POST['assign'])) $assign=$_POST['assign']; if(isset($_POST['tit'])) $title=$_POST['tit']; if(isset($_POST['sub_date'])) $sub_date=$_POST['sub_date'];

$con=mysql_connect("localhost","root",""); mysql_select_db("course",$con); $sql="INSERT INTO assign_detail(subj_code,assign_no,title,sub_date)VALUES('".$_SESSION['subject']."','".$_POST['assign']."','".$_POST['tit']."','".$_POST['sub_date']."')"; if(!mysql_query($sql,$con)) { die('Error:'.mysql_error()); } else echo "added"; //$res="SELECT subj_code,assign_no,title,sub_date FROM assign_detail"; /*$no = mysql_num_rows($res); if(!$no)echo 'No Data Found'; else { while($row=mysql_fetch_array($res)) { echo $row['assign_no']. " - ". $row['title']."-".$row['sub_date']."

"; }

//}*/
/*$query = "SELECT * FROM assign_detail"; 

$result = mysql_query($query) or die(mysql_error());

$row = mysql_fetch_array($result) or die(mysql_error()); //echo $row['assign_no']. " - ". $row['title']."-".$row['sub_date']."

";

$pdf->SetFont('Arial','B',10); $htmlTable=' Subj_code:'.$_POST['subject'].'

assign no:'.$_POST['assign'].' title:'.$_POST['tit'].' Submission date'.$_POST['sub_date'].' '; $pdf->WriteHTML2("





$htmlTable"); $pdf->SetFont('Arial','B',6); $pdf->Output(); */

mysql_close($con); ?>