Best way to keep form data from posting if duplicate field

Posted: Sun Oct 01, 2017 3:46 pm

I have a form from which the data is posted to a db table but it is allowing duplicate forms to be posted from the same user.

I have tried ON DUPLICATE KEY UPDATE forumname = VALUES(forumname)")

Code:

$result = $db->sql_query('INSERT INTO `members` VALUES '."(NULL, '$forumname', '$firstname', '$lastname', '$gamename', '$address', '$city', '$state', '$zipcode', '$country', '$phone', '$email', '$comments') ON DUPLICATE KEY UPDATE forumname = VALUES(forumname)");





    include_once 'header.php';


    OpenTable();


   


    if ($result) {


        header ("Location: /modules.php?name=Member_Info_Thanks");


    } else {


        echo '<div class="text-center">Failed!<br /><br />' , _GOBACK , '</div>' , PHP_EOL;


    }


    CloseTable();

it stops duplicate entries but ... I would very much like to know...

Site Admin Joined: Aug 22, 2007 Posts: 1772

I would start at first a check with SELECT on the same db-table to compare the required fields with the incoming input values. Don't forget to filter the incoming data to prevent SQL-injections! Maybe to check: $forumname, $firstname, $lastname and $gamename. And only if no entry is found in the db-table then I would start the INSERT. In this case you could delete completeley: ON DUPLICATE KEY UPDATE forumname = VALUES(forumname).

You could replace:

php Code:

header ("Location: /modules.php?name=Member_Info_Thanks");

with

php Code:

echo '<div class="text-center">Thank you!<br /><br />' , _GOBACK , '</div>' , PHP_EOL;