.

If I were you I would start off writing use cases like:

customer -> (rent vehicle) << include >> (drop-off vehicle), (pick-up vehicle), (make reservation)

GNBranchStaff -> (make reservation)

GV Admin -> (manage stock) << include >> (manage stock at drop-off), (manage stock at pick-up), (manage vehicle type availability)

system -> (manage pool) << include >> (optimize availability)

GV Admin -> (manage car yard stock) << include >> (ship vehicle to branch)

and then write event flows, identify subsystems, identify components and finally identify DB tables.

Here is an example:
http://www.mycgiserver.com/~nsenthil...ndbdesign.html

Good luck,
Nalla

There is a Car Hire Data Model on my Database Answers which will give you a Kick-Start in the right direction :-
http://www.databaseanswers.com/data_...hire/index.htm

A free Access Database is available.

Barry Williams
Principal Consultant
Database Answers