Re: BOOLEAN RELATIONSHIPS: HARD QUESTION

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"Jacopo" <jacopols_at_libero.it> wrote in message news:mB%yc.55554$Wc.1725284_at_twister2.libero.it...
> I need to create a database for my company. We build machines and so we
have
> a part list of the components.
> I have created a model of the machine in which there is a list of
components
> to be filled in order to complete the design scheme.
> Every machine will be composed by:
> 1 mandatory element of type "A" among the entire list of A type items
> 1 mandatory element of type "B" among the entire list of B type items
> 4 mandatory element of type "C" among the entire list of C type items
> N optional element of type "D" among the entire list of D type items
>
> The problem is this. When you choose a specific element to fill the type
"A"
> box you can't then choose among all the items of list B to fill the type B
> box but among those B elements that matches the selected A items.
> As well the type C is influenced by the previous choices but in this case
> the list must be differently selected for any combination of the chosen A
> and B items.
> The optional elements on the other side can be present or not, according
to
> the selected A, B, C items or to a combination of them all.
>
> The problem is creating a solid model of relationships in order to let the
> user select among the only items that matches the previous ones.
> Definitely I don't want to create rules into the source code.
> The idea is giving them a mask in which, when they create a new item, they
> can link it with OR, AND, NOT, XOR, ecc. relationship.
> The problem for me is saving these rules. If just one "AND" relationship
> between two items was allowed a new table with matching couples would be
> enough, but in this case I should be able to implement a rule like:
>
> If you choose the item A38 in A AND B15 in B AND NOT C44 in C, then you
> can select the optional element among this list.
>
> Hard, hu?
> I guess the problem must have first of all an answer about database theory
> which I lack if not the basics. I would be grateful for any explanation or
> if you have white papers or you know any web page where this topic is
> treated please tell me. I would like to work with VB upon an ACCESS
> database.
> Thank you for the time spent in reading and answering to this message.
> Yours faithfully,
> Jacopo

Asking the right questions is half of the solution.

You may want to search for functional, multivalued and join dependencies. But I think you need to think more about the cause of dependencies between those components.

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