On Wed, Jul 06, 2005 at 04:25:05PM -0700, Tim Cook wrote: > On Wed, 2005-06-15 at 17:41 +0200, Karsten Hilbert wrote: > > > > > 3) do you allow any nulls in your database? > > > > Yes, hopefully only where appropriate. Please do point out any > > > > flaws you find. > > > There are no appropriate places for NULLS in a "relational" data > > model. > > Not in a "pure" relational model, true. I do think great care > > needs to be taken when using NULLs. All in all it's a > > religious issue. > > No. It is not a religious issue at all. It is a logical issue that > relates to the SQL deficiency. For quick insight; review the fact that > the WHERE clause, by definition returns a True or a False. What happens > when a NULL is an attribute value as the subject of the WHERE? Tim,
I do not understand the issue all too well, apparently. Can you give a simple hands-on example in terms of real tables and real data that clearly shows were using NULLs falls down *logically* ? > Otherwise your relations aren't atomic and your application code must be > created to handle these exceptions. Why of course. No doubt about that. Karsten -- GPG key ID E4071346 @ wwwkeys.pgp.net E167 67FD A291 2BEA 73BD 4537 78B9 A9F9 E407 1346 _______________________________________________ Gnumed-devel mailing list [email protected] http://lists.gnu.org/mailman/listinfo/gnumed-devel
