I have following code

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<?php
include 'connect.php';
?>

<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>index</title>
</head>
<?php
function select_society()
{
if(isset($_POST['society']))
{
$society=$_POST['society'];
if($society=="select_society")
{

}
else
{
$sql=mysql_query("select society_code from society where society_name='$society'");
$result=mysql_fetch_array($sql);
$society_code=$result['society_code'];

echo "Selected society and its code are<br><Br>";
echo "society_code: ".$society_code."<br><br>";
echo "society_name: ".$society."<br><br>";
select_customer($society_code);
}
}
}

function select_customer($society_code)
{
$society_code2=$society_code;
$sql=mysql_query("select customer_id,customer_name from bill_cycle where society_code='$society_code2'");
$result=mysql_fetch_array($sql);
$customer_id=$result['customer_id'];
$customer_name=$result['customer_name'];

echo "The customer code is: '$customer_id' and customer name is: '$customer_name'<br><br>";

}

function select_next()
{
echo "here";
}

?>
<body>

<div id="wrapper">
<form name="index_form" method="post" action="index.php">
<div id="select_society">
<select name="society">
<option value="select_society">Select society</option>
<option value="shantinagar">Shantinagar</option>
<option value="Mahalakshminagar">Mahalakshminagar</option>
</select>
</div>
<div class="submit_button">
<input type="submit" name="submit" value="select society"/>
</div>

<?php
select_society();
?>

</form>
</div>
</body>
</html>
It gives me output as well

Selected society and its code are

society_code: s_11

society_name: shantinagar

The customer code is: '1' and customer name is: 'suyash'
Now my requirement is, I want to add a next button in this page, and when I click that button(or link), the next record from the database should be displayed on the same page.
I tried it by using next button and link but its not working. What are the options to do so?