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Home -> Community -> Usenet -> c.d.o.server -> Re: Looking for a way to implement SQL-92 Domain
On Tue, 25 Mar 2003, forbrich_at_telusplanet.net wrote:
> Galen Boyer wrote:
>
>> You can't guarantee that the lookup field entered is contained within >> the correct domain, just that it exists within the entire domain of >> lookups. The seperate lookup tables assure that you have the correct >> domain as well, not just _any_ lookup value. >>
Looking at the description, I'd have to agree. :-)
> You need to add a ref_type or domain_type column, never filled, with a
> default and possibly a check constraint, that drives to the correct
> domain.
Sounds like Nuno's solution.
> The foreign key goes against the twinned 'domain' and 'value' columns.
> Works because the twinned columns are the primary key.
So then you have two columns for each lookup in the child table? Ughhh... I have some tables with many many lookups. You just doubled the number of lookup columns in that table.
I'd rather proliferate specific lookups but refer to them with a particular id in the child table. Use a naming convention on the lookup tables to help everybody either get to the one they need or exclude them all from view.
-- Galen deForest Boyer Sweet dreams and flying machines in pieces on the ground.Received on Mon Mar 24 2003 - 21:54:09 CST