Handling Three-Value Logic

I have just finished reading Applied Mathematics for Database Professionals By Lex de Haan and Toon Koppelaars. I was struck by the discussion about nulls in Appendix D, especially about the inconsistent handling of NULLs between constraints and predicates in SQL (see p.344)

SQL and Relational Theory: How to Write Accurate SQL Code

I have just finished reading SQL and Relational Theory: How to Write Accurate SQL Code by C.J.Date. Here are some of my thoughts on the book.