Contactus table schema - php

Question

I have two HTML form in first form i am adding Id and product and second form is contact us form. I have created one table with column name is ID,Product,name,email,mobile.In first form i am adding id and product and rest of values are NULL,than form will redirect to contact us form there i am updating name,email,mobile..I am getting pop is updated successfully but when i checked in database there was no update....please help me
//insert code
<?php
try{
$product=$_POST['product'];
/*
$product2=$_POST['product2'];
$product3=$_POST['product3'];
*/
// form data
//database Connection details
$servername = "localhost";
$username = "root";
$password = "";
$database="store";
$error = "";
$conn=mysql_connect($servername, $username, $password) or die('Connection failed: ' . mysql_error());
#mysql_select_db($database, $conn) or die("Could not select your database".mysql_error());
$insertQuery = "Insert into contactus(Id,Product) values('null','$product')";
$result = mysql_query($insertQuery);
mysql_close($conn);
header('Location: /newstore/contact.html');
}
catch(Exception $e) {
echo ("<script>alert('Something went terribly wrong. Please try again later.');location.href = ''../index.html';</script>");
return false;
}
?>
//Update code
<?php
// Start the session
session_start();
?>
<?php
$_SESSION['user_name1']=$_POST['product'];
try{
// form data
$name=$_POST['name'];
$email=$_POST['email'];
$mobile=$_POST['mobile'];
$product=$_SESSION['user_name1'];
//database Connection details
$servername = "localhost";
$username = "root";
$password = "";
$database="store";
$error = "";
$conn=mysql_connect($servername, $username, $password) or die('Connection failed: ' . mysql_error());
#mysql_select_db($database, $conn) or die("Could not select your database".mysql_error());
;if ((strlen($name) < 3) or (strlen($email) < 3) or(strlen($mobile) < 3))
{
echo ("<script>alert('Something went wrong with your data inserted. Please fill the form again.');location.href = '../newstore/index.html';</script>");
}else
{
//$insertQuery = "Insert into contactus(Id,Name,Email,Mobile,Product) values('null','$name','$email','$mobile','$product')";
//$UpdateQuery = "update contactus set Name='$name',Email='$email',Mobile='$mobile' where Product='$product' ";
$UpdateQuery = "update contactus set Name='".$name."',Email='".$email."',Mobile='".$mobile."' where Product='$product' ";
$result = mysql_query($UpdateQuery);
if($result){
echo "<script>alert('Thank You. Your Data Received Succefully.');location.href = '../newstore/index.html';</script>";
}
else
{
echo "<script>alert('Something went wrong with your data inserted. Please fill the form again.');location.href = '../newstore/index.html';</script>";
}
}
mysql_close($conn);
}
catch(Exception $e) {
echo ("<script>alert('Something went terribly wrong. Please try again later.');location.href = ''../newstore/index.html';</script>");
return false;
}
?>