Options for eliminating NULLable columns from a DB model (in order to avoid SQL's three-valued logic)?

Question

Some while ago, I\'ve been reading through the book SQL and Relational Theory by C. J. Date. The author is well-known for criticising SQL\'s three-valued logic (3VL).

Answer 1

One alternative may be the entity-attribute-value model:

 entity  attribute    value
 1       name         Banana Man
 1       birthdate    1968-06-20

If the birthdate was unknown, you'd just omit its row.