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Posted by Jason Kester on 08/10/06 14:25
Assuming these are actually the same thing, and that you simply want to
track that some are Customer defined, and that you'll want to enforce
relationships to either system or customer records, here's what I'd do:
DropDownValues
---------------------------------------
DropDownValuesID int identity
Name
Value
DropDownValues_SystemDefined
---------------------------------------
DropDownValuesID int
DropDownValues_CustomerDefined
----------------------------------------
DropDownValuesID int
CustomerID
DropDownValues would serve as the base of your two classes, and would
be used to generate keys and hold common information. Your customer
data could extend that table, and the system ones would simply need a
placeholder record to identify themselves.
Of course, if you won't need to enforce relationships to System or
Customer records (for instance, another record that can only hook up to
a System value, but not a Customer one), then you could simply add a
nullable CustomerID to the DropDownValues table and be done with it.
Good luck!
Jason Kester
Expat Software Consulting Services
http://www.expatsoftware.com/
---
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Christian H wrote:
> Hello,
>
> We have a problem we're not quite how to solve best. We're working on a
> Web-application where some values that are used, are pre-defined (default
> values), and other values should be user-defined (users can add additional
> values)
> Currently, the 2 different things have been separated into 2 different
> tables. The problem we're having now, is when the values from the 2 tables,
> should be referenced in another table, i.e when the items are saved as a
> part of a form-submission. Should we use 2 different columns to represent
> the ID for the 2 different tables?
>
> Here is an exmple of that design:
>
> DropDownValues_SystemDefined
> ---------------------------------------
> ID
> Name
> Value
>
> DropDownValues_CustomerDefined
> ----------------------------------------
> ID
> CustomerID
> Name
> Value
>
> DropDownValues_SavedItems
> ----------------------------------
> ID
> DropDownID_System
> DropDownID_Customer
>
>
>
> The other solution , as far as we can see, is to put all values into 1
> table, and use CustomerID=-1 or null when the item is a System-defined
> value, and not a customer-defined value.
>
> DropDownValues_CustomerAndSystemDefined
> ----------------------------------------
> ID
> CustomerID
> Name
> Value
>
>
> Regards Christian H.
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