I have a form where people can order tickets.
A maximum of 300 tickets can be sold.
When I open the form, I would like to have a check on the database where a certain field of all records is summarised.
If that value exceeds 300, I want the form to display an error message or something like that.
Can someone point me in the right direction?

Hello,

You can use the following article as a starting point:
www.rsjoomla.com/support/documentation/r...for-submissions.html

Thank you.
This problem is solved
I found te correct code in your help file

$max = 300;
// Get a database connection.
$db = JFactory::getDbo();
// Setup the query. Deze query sums het veld Aantal_kaarten van het huidige formulier
// $formId contains the ID of the current form.
$db->setQuery("SELECT SUM(`FieldValue`) FROM #__rsform_submission_values WHERE `FormId`='".(int) $formId."'"." AND `FieldName`='Aantal_kaarten'");
$inschrijvingen = $db->loadResult();
if ($inschrijvingen >= $max) {
$formLayout = 'Sorry, het maximum aantal inschrijvingen voor deze uitvoering is bereikt..';
}

After the sum reaches 300 the form gives the Sorry notification

Now I would like to get that value on the screen somewhere. But I have opened a separate topic for that.