Stop multiple inserts on refresh

tbobker

After inserting my form into the database i want to stop it inserting it again if i refresh the page.

I cant seem to work it out

here is my code;

<?php

if(isset($_POST['submit'])) {


	$first = mysql_real_escape_string($_POST['fname']);
	$last = mysql_real_escape_string($_POST['lname']);
	$address = mysql_real_escape_string($_POST['address']);
	$email = mysql_real_escape_string($_POST['email']);
	$pcode = mysql_real_escape_string($_POST['pcode']);
	$country = mysql_real_escape_string($_POST['country']);
	$comment = mysql_real_escape_string($_POST['comment']);

	$conn = mysql_connect("localhost","user","pass");
	mysql_select_db("tbobker_hwpi",$conn);

	$today = date("j, n, Y"); 

	$sql = "insert into petition values ('','$today','$first','$last','$address','$email','$pcode','$country','$comment');";
	$result = mysql_query($sql,$conn);

	$sql2 = "select id from petition";
	$result2 = mysql_query($sql2,$conn);
	$num_rows = mysql_num_rows($result2);




	echo "<div height='300px'><h1>Thankyou for signing the petition</h1><br>".$first."&nbsp;".$last." you have made a positive step forward</div>";
	echo "<br><h2>You are person&nbsp;<span style='color: red'>".$num_rows."</span>";

}else { echo '




<html>

etully

On the PHP page where you build the form itself, pick a random 10 digit number. Embed that number in the form with a hidden tag. Then write the number to a database table called "permitted_codes".

On the next page, where you do your insert into the database, take the value and check to see if it exists in the "permitted_codes" table. If yes, then do your insert AND delete that code from the "permitted_codes" table. That way, if you refresh, the code will get posted to the PHP page again but the code won't exist in the "permitted_codes" table so the insert statement won't happen.