Re: Database design question

. Every table should have a primary key. The Primary Key should be
an identity column, NOT business data

In regard to having a primary key, that comes right from Codd's 12 rules
for a RDBMS.

In regard to an identity column (the DBMS auto increments the value), that
may be fine for some tables, overkill for others. I definitely have a warm
spot in my heart for surrogate keys, which facilitate logical joins and
referential integrity; my preference is to generate them in database event
handlers (behind triggers) rather than in application code.

In regard to "NOT business data", what about code files (e.g. state codes)?

. Create business key as unique from business data, not Primary Key

Fine, if the primary key fails to meet all application requirements, which
is often the case.