So it's very dynamic here and I don't
know which would be the best approach
for storing every form field in
I apologise if I have misunderstood you here but I believe that you should design the database according to the data and not the form. It is difficult to comment without knowing the exact details of your situation so here is an example:
If you usually dump all the data from a form into a single table, but because sometimes this will involve submitting 5 values and other times this will involve submitting 10 and so you are unsure how many columns your table should have, then I think the problem is in the database design.
Work out what pieces of data are dependent on other pieces of data. For example, you mention checking "hotel" might open up more fields specific to that choice. Let's assume this involves things like "en-suite", "bed type" etc. Then you should have 3 tables, a registration table (assuming the user is using the form to buy these services), a hotel table and a registration_hotel table. The registration table will record a number of details specific to the registration only such as the customer's name and a unique id number. The hotel table will hold information specific to the hotel only, such as how many rooms have en-suite. The registration_hotel table will hold details specific to that registration at that hotel. You might want a column of type bool to record whether the user requested "en-suite".
When submitting the form, check which pieces the user entered with
if(isset($_POST['hotel']) && !empty($_POST['hotel'])). Then only send stuff to the registration_hotel table if that condition is true.
If this design results in making too many separate calls to the database, you might want to look into transactions which will help you to manage the speed and security of these calls.
If you can post in a specific example of something you don't know how to do, that would be useful.
You didn't specify how you can manage this dynamic form. Can you edit it's PHP/HTML source? One great thing would be if you can label your different variables like
If your submitted form is clear enough (i mean semantically correctly structured) you can store the whole submitted form serialized.
Note: this method only working when you don't need to search for specific items in your database.
Edit: maybe i'm misunderstood your problem.
You can create a
'metadata' table like this:
form_id | option_name | option_value
1 | hotel | true
1 | restaurant | false