Validation database value with keyin value

Hello, i'm new to joomla and choronoforms, is there anyway that i can check the content of the form to the database first before submit it to the Database.
Eg: The form i have consists of Name, email,phone and booth number. I'm doing the form for the user to register a booth for a school event. So it will be first come first serve basis, i need to compare the user key in booth number to the database whether another user have registered or not. So is there anyway for me to do that ?
I attach a jpg file on how is my form look like.
My database name is jos_chronoforms_eca.

Anyone can help me ?

Thanks in advance,

Hi hhaneh,

I'd be inclined to do this 'properly' have a list of booth numbers (could be an array, or in the database) and in your form html check which ones are still free and only offer those for selection - you could use radio boxes or a 'select' dropdown.

This is actually simpler than having to check 'after' the selection.

Bob

you can also use the "server validation" feature to query your database and make the check in PHP upon submission, see the server validation part at the "validation" tab!

Regards
Max