>>Can someone explain to me why Nulls should not be allowed in a database regardless of what type of field it is? TIA
>
>1. Politics
>2. Incorrect aggregate values
>3. More code required
>
>Now who can tell us when and why to use null values?

Also, if you want to show off your uber-normalized database to other developers, NULLS don't belong (anything that can be NULL belongs in a related table because it is not 100% dependant on the key).

>2. Incorrect aggregate values

This is a biggie IMO. I can count on one hand how many SQL shops I've worked with that had a written policy on ANSI null settings and code review that looked for lazy aggregate code.