Data Duplication in Database on page refresh

pixeljuggler

Hi I was wondering how do I stop the data from being re-entered into the database table when a page is refreshed. I have heard that page redirection is best though I can't seem to get that working. Here is my code:

<?php

// If magic quotes is tuned on then strip slashes
if (get_magic_quotes_gpc()) {
  foreach ($_POST as $key => $value) {
    $_POST[$key] = stripslashes($value);
  }
}

// Extract form submission
$name = (isset($_POST["name"]))?$_POST["name"]:"";
$email = (isset($_POST["email"]))?$_POST["email"]:"";
$submitAdd = (isset($_POST["submitAdd"]))?$_POST["submitAdd"]:"";

// Open connection to database
include("db_connect.php");

// Prepare data for database
  $db_name = addslashes($name);
  $db_email = addslashes($email);

// If form has been submitted, insert entry into database
if ($submitAdd) {
  $sql = "INSERT INTO list
    (name,email)
    VALUES ('$db_name', '$db_email')";
  $result = mysql_query($sql);
  if (!$result) {
    $message = "Failed to insert post. MySQL said " . mysql_error();
  } else {
    $message = "Success! $name, your details were added to our email list.";
  }
}
?>

<!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">
<head>

<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1" />
<title></title>
</head>

<body>

	<?php if (isset($message)) { echo "<p class='message'>$message</p>"; } ?>

	<form method="post" action="<?php echo $_SERVER["PHP_SELF"] ?>" onsubmit="return validate()">
		<label for="name" class="formHeading">Name: </label>
	<input type="text" name="name" size="40" />
		<label for="email" class="formHeading">Email: </label>
	<input type="text" name="email" size="40" />
	<input type="Submit" name="submitAdd" value="Get Updated!"/>
	</form>		
</div>

</div>


</body>
</html>

sneakyimp

You aren't trying to redirect in your code. If it was me, I would redirect immediately after the success or failure of my query.

  if (!$result) { 
    $message = "Failed to insert post. MySQL said " . mysql_error(); 
    header('location: failure.php?mesg=' . urlencode($message));
    exit();
  } else { 
    $message = "Success! $name, your details were added to our email list."; 
    header('location: success.php?mesg=' . urlencode($message));
    exit();
  }

You can also use a meta tag to redirect a page. That's what they do here at phpbuilders:

echo "<meta http-equiv=\"refresh\" content=\"2;url=http://mydomain.com/success.php\">";