Validate against "2nd" value in dropdown-list
I've got a room reservation form. The database table for the rooms also contains the max. number of seats for each room.
The customer can select the room and in another field enter the number of people taking part of the meeting .
Now I'd like to validate the entered value against the max. number of seats in the room database table.
I can't find a way to validate this. How can I solve this problem?
Thanks for any help.