On Wed, Jul 27, 2005 at 08:45:53AM -0400, Merlin Moncure wrote:
> > > again, in this case the color should be the id and using a surrogate
> key
> > > is poor design. If that's too much typing you have the option of a
> > > check constraint which is superior to enum in just about every way,
> > > particularly if encapsulated into a domain (although inferior to RI
> > > solution, IMO).
> >
> > Please go back through the original thread. The original comment was
> > regarding adding an enum type that actually made sense; ie: it stored
> an
> > int in the base table that referenced a parent table. The original
> > poster was arguing that enum didn't really buy anything over doing
> that
> > the manual method (create seperate table; fill that table with values;
> > create base table with RI, and finally, make sure that everything that
> > touches the base table can do mapping, or add a bunch of other stuff
> to
> > do the mapping automatically). My argument is that simply specifying
>
> You're right, I did jump on this (mostly off-topic) thread. Also, I was
> not aware that the enum did an id-id relationship internally.
> Regardless, on the surface enum is essentially a check constraint.
> Check constraints offer the same functionality and while marginally more
> verbose they are much more powerful and more standard to boot.
>
> Putting my advocacy hat on I'd rather highlight PostgreSQL's very well
> implemented constraint system. However, if enum was implemented as
> syntax sugar for a constraint in a similar way that serial is syntax
> sugar for the default value then I suppose it would not be a bad idea.
Keep in mind that my original point was to go after items that were the
biggest headache for migration from mysql to postgresql. Enum was just
an example I picked out of thin air.
--
Jim C. Nasby, Database Consultant decibel@decibel.org
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