sjsubscribe (1/20/2010)
Certainly the current practice is mixed at best or else no DBMS would allow null values as valid entries in a field. That's what the relational theory purists wants.
I can see no conflict between data normalization and accepting null values in non-key columns - as all rdbms out there allow and enforce.
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Pablo (Paul) Berzukov
Author of Understanding Database Administration available at Amazon and other bookstores.
Disclaimer: Advice is provided to the best of my knowledge but no implicit or explicit warranties are provided. Since the advisor explicitly encourages testing any and all suggestions on a test non-production environment advisor should not held liable or responsible for any actions taken based on the given advice.