If you want to keep it all in one database it might be the easiest to just setup a category field where they would select which type of vehicle (?) they are adding to the db.
Then on your add form you could put all the same type fields such as price (that would relate to all records) in a main portion of the form. And then label different areas of the form for the specific vehicle type. Does that make sense.
For example:
Choose which category you are adding this to:
auto, truck, bicycle, etc.
Complete the following section for all categories:
year, make, model, price, etc.
Then create sections for each type of vehicle and add the fields specific for that vehicle.
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You could create different add_form but it would be much more involved and you would still need to add all the fields from the .cfg file in each form as either visible or hidden fields. Check out this thread reference:
Thread: http://gossamer-threads.com/p/100986
Subject: Multiple Forms
Elle - 17-Aug-00
Hope this provides some ideas, perhaps someone else will come along and provide more ideas.
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