How can I avoid NULLs in my database, while also representing missing data?

Question

In SQL and Relational Theory (C.J. Date, 2009) chapter 4 advocates avoiding duplicate rows, and also to avoid NULL attributes in the data we store. While I have

Answer 1

nulls are a consequence of theory meeting reality and having to be adjusted to be usable. In my opinion attempting to avoid all null values will ultimately lead to uglier and less maintainable code than just using null where appropriate.