How to prevent a php script form changing to another page - php

Question

I used a sample I found here with a HTML page calling a PHP script, both are listed below.
It all works well - BUT, I end up with the PHP scrip page and I want to avoid it - I want to stay on the HTML page and NOT move anywhere. I read in some places that I will need JS or AJAX but can't see any actual example.
I am working on my PC under Windows 7 with IIS version 7.5 installed, PHP 5.3.28.
and executing the HTML file inside c:\inetpub.wwwroot
HTML
<div id="contact">
<h2>Enter your First and Last Name</h2>
<form action="frm_script.php" method="post" target="_parent">
<p><strong>First Name:</strong><br /> <input type="text" name="firstName" /></p>
<p><strong>Last Name:</strong><br /> <input type="text" name="lastName"/></p>
<input type="submit" name="submit" value="Add Customer" />
</form>
</div>
PHP Script
<?php
if(isset($_POST['submit']))
{
//get the name and comment entered by user
$firstName = $_POST['firstName'];
$lastName = $_POST['lastName'];
//connect to the database
$dbc = mysqli_connect('localhost', 'root', 'root', 'mdpdata') or die('Error connecting to
MySQL server');
$check=mysqli_query($dbc,"select * from clients where firstname='$firstname' and
lastname='$lastname'");
$checkrows=mysqli_num_rows($check);
if($checkrows>0)
{
print "customer exists";
}
else
{
//insert results from the form input
$query = "INSERT INTO clients(firstName, lastName) VALUES('$firstName', '$lastName')";
$result = mysqli_query($dbc, $query) or die("Sorry, Duplicate Record.'$php_errormsg'");
mysqli_close($dbc);
}
print '<script type="text/javascript">';
print 'alert("The Customer is NOW registered")';
print '</script>';
};
?>

Answer 1

A html document containing a form with an action="" statement results to change to the assigned page. Like yours, to frm_script.php
If you don´t want this to occure, you need an AJAX-request, as you mentioned above, or you can add a
header(location: 'FPRM.HTML');
to the bottom of the php script. So after processing, which should be very fast, the original page is loaded again.
Or you don´t use two pages at all. Just put the html code from FPRM.HTML to the bottom, after the php code, so the page just will be reloaded once the form values are saved. In this case, call the concatenated document simply FPRM.php, and the form action must be set to action="FPRM.php" or is simply not needed, as the form without action statement loads the same page anyway.