=?Utf-8?B?RGVubmlz?= wrote in
:

My background is with large commercial insurance companies. All
of the companies have had relational databases designed to the 3rd
normal form.

The determination of whether or not those tables were actually
normalized depends on the chosen definition of the entity being
modelled in the table. I would consder the 200-field table you
mention later to be unquestionably denormalized, even though I know
nothing at all about the content/function of those fields. That
sounds like a table that has a bunch of fields that are used only
for a single record type, so that an auto insurance policy has one
set of fields, but a renter's insurance policy has a different set
of fields. Any time you're using some fields for some records and
not for others, it's an indication to me that the entity has been
misdefined, and should probably be broken into at least two tables,
with a narrow header table and a long child table, where each row
stores what was formerly a field in the wide table.

All that said, my conclusion could be wrong for any particular
application. But "fields are expensive, rows are cheap" is a
generalized rule of thumb, not a hard-and-fast law of nature. It
allows for exceptions for certain purposes, but is a starting point
for evaluating a schema design.

--
David W. Fenton http://www.dfenton.com/
usenet at dfenton dot com http://www.dfenton.com/DFA/