Re: normalisation

On Sat, 27 Apr 2002 13:06:47 GMT, "Chris" <c_at_coelle.net> wrote:

>Hi,
>
>I've got the following relation
>
>rental_booking (rental_booking_id, client_id, reg_number, car_type,
> rent_date, due_date, return_date,
>deliever_km,
> returned_km, rental_rate,
>drivers_license,
> amount_due)
>
>Coul someone please tell me what the repeating group is?
>

Not sure about "repeating groups", but it looks like there are some redundancies:

(1) Can't you calculate amount_due from the other data given?

(2) Assuming "drivers_license" is unique to the client, you should have either client_id or drivers_license (but not both) in this table.

(3) Is reg_number unique to each car? Then you shouldn't have "car_type" in the table either, but look it up in the table of cars.

(4) Presumably rental_rate is an attribute of the type of car; there might also be discounts depending on holidays, clients, days rented, etc. Presumably this could also be looked up and shouldn't be in the table.

Bob Hairgrove
rhairgroveNoSpam_at_Pleasebigfoot.com Received on Sat Apr 27 2002 - 15:51:17 CEST